M Etienne

Deloule Dr

M Jannick

M Yigang Xu

Mme Qin Wang

Liping Mme

Qin

Shaochen Liu

Prof Etienne Deloule

Prof Xia Qunke

implications for enrichment in the mantle source of intra-plate basalts

Keywords: water content, continental basalts, recycled oceanic crust, recycled oceanic sediments, Southeast China

The origin and genesis of intra-plate basalts, especially continental basalts, have been studied extensively but still are debated hotly during past several decades. The enriched geochemical characteristics of intra-plate basalts are usually suggested to be closely associated with the recycled crustal materials. The eastern China is an ideal area to decipher the effect and contributions of different recycled components in basalt source, where the Cenozoic basalts are widespread distributed. However, existing evidence for the Cenozoic basalts in eastern China failed to figure out clearly the source of the enriched components and their genesis. Previous studies have proposed several candidates inducing enrichment in the mantle source of eastern China basalts: a) the recycled subducted oceanic crusts and sediments, originated from ancient subduction events (e.g., Paleo-Tethyan, Paleo-Asian or Izanagi plate subductions) and present subduction event (i.e., Pacific subduction); b) the delaminated thicken lower continental crust and lithospheric mantle in Mesozoic; and c) the re-enriched continental lithosphere. The eastern China has undergone multiple subduction of oceanic plates since Mesozoic. In addition, geophysical studies have discovered plume structures in the mantle beneath the Changbaishan volcanic area in northeast China and the Hainan volcanic area in the most southern part of eastern China, respectively. Therefore, the complex geological history of eastern China offers an opportunity to conduct comparative studies on basalts from distinct geological backgrounds. In SE China, a stagnant Pacific slab exists in the mantle transition zone (MTZ) beneath the northern part (e.g, Zhejiang and Jiangxi provinces), a plume structure was found in the lower mantle beneath the southern part (e.g., South Guangdong and Hainan provinces), and neither stagnant slab nor plume has been discovered in the middle part (e.g., Fujian province). Therefore, the Cenozoic intra-plate basalts in SE China have three kinds of geological backgrounds.

H2O and Ce have similar partition coefficients between mantle minerals and melt.

Because their ratios remain unchanged through partial melting and crystal fractionation, the H2O/Ce ratios of melts contain information regarding the mantle source. Recycled components have H2O/Ce ratios that are distinguishable from mantle components.

Therefore, in combination with other trace elements ratios (e.g., Ba/Th, Nb/La, Ce/Pb), Abstract IV H2O/Ce ratios in basalts may serve as an index for identifying various components within mantle source. In addition, due to distinct oxygen isotope compositions between normal mantle and recycled crustal materials that acquired abnormal oxygen isotopic ratios by interacting with surface water, δ 18 O values can be used to recognize recycled materials. Several studies have reported H2O content and δ 18 O values in the Cenozoic basalts from NCC and successfully traced recycled oceanic materials in the mantle source combining with other elemental and isotopic compositions, however, such systematic investigations on the SE China basalts are lacking.

To decipher the relationship between the possible recycled components and the geochemical heterogeneities of the SE China basalts that formed on distinct geological backgrounds, the major and trace element contents and Sr-Nd-Pb isotopic compositions of the Cenozoic basalts from Zhejiang, Fujian and Hainan provinces have been measured. In particular, we recovered the H2O contents of the "initial" magmas based on the H2O contents of the clinopyroxene (cpx) phenocrysts and the partition coefficients of H2O between cpx and basaltic melts. Moreover, the oxygen isotope compositions of the cpx phenocrysts have been determined. The results of the Cenozoic basalts from three regions in SE China have given the new insight of the enrichment composition and the genesis of Cenozoic basalts in SE China: 1) Zhejiang Cenozoic basalts erupted in two stages, 20-27Ma and after 11Ma, respectively, with distinct geochemical features. The H2O contents of the Zhejiang basalts range from 1.3 to 2.6 (wt. %), falling within the range of the H2O contents of back-arc basin (BABs) or island arc basalts (IABs). The older basalts have more alkaline, lower Si and Al contents, higher trace element concentrations, La/Yb, Ce/Pb and Nb/La ratios, lower H2O/Ce and Ba/Th ratios, and stronger negative K, Pb, Zr, Hf and Ti anomalies than the younger ones. The younger basalts are less alkaline and have higher Si and Al contents; lower trace element concentrations; lower La/Yb, Ce/Pb and Nb/La ratios; higher H2O/Ce and Ba/Th ratios. The co-relationships between Ba/La, H2O/Ce, Nb/La, Ce/Pb and Ba/Th ratios in two groups of Zhejiang Cenozoic basalts indicate that a component of recycled dehydrated oceanic basalt is needed in the source of the older rocks, along with the depleted mantle component. Meanwhile, additional recycled dehydrated sediments together with recycled dehydrated oceanic basalts are required to serve as the enrichment components in the source of the younger rocks. The change of the recycled oceanic materials over time in the mantle source of Zhejiang Cenozoic basalts require a continuous supply of the recycled materials, demonstrating Abstract V the recycled oceanic components originated from the Pacific slab, which is the only subducted plate since 100 Ma in the Zhejiang region. Therefore, the recycled oceanic materials are likely to be provided by the stagnant Pacific slab, which has been revealed in the Zhejiang region by the geophysical evidence of the seismic image in the MTZ. 2) Fujian Cenozoic basaltic rocks erupted after 10Ma and have similar trace element patterns to Zhejiang Cenozoic basalts. All the Fujian samples have strong negative Th, U, and Pb anomalies in the extended trace element pattern. Unlike the basalts, the diabases have very weak or no negative K, Zr, Hf, and Ti anomalies in the extended trace element pattern. Fujian Cenozoic basalts have more radiogenic Sr, Nd, and Pb isotopic data than Zhejiang Cenozoic basalts. Unsimilar to Zhejiang, Fujian samples from three areas have heterogeneous H2O contents. The estimated H2O contents of initial basaltic melts for the Shiheng (SH) basalts range from 1.3 to 2.4

(wt. %) that is within the H2O contents range of BABBs and IABs; the Bailin (BL) diabases have "fake" basaltic melt water contents from 1.9 to 2.1 (wt. %), due to the later H re-equilibrium of the cpx phenocrysts; and the Mingxi (MX) basalts have lower initial H2O contents (0.3-0.5 wt. %), when the H-loss are excluded. The higher δ 18 O values of the cpx phenocryst from Fujian Cenozoic basalts than the normal mantle are observed, suggesting the recycled materials from the surface of earth in their mantle source. The highest δ 18 O values are found in the cpx phenocrysts with the intermediate ratios of Si/Al and Ca/Al and the relationship between Mg# and δ 18 O, suggesting a mixture of two kinds of magma. Fujian Cenozoic basalts display similar relationships between the ratios of Ba/La, Nb/La, Ce/Pb, and Ba/Th to Zhejiang Cenozoic basalts, indicating that the components of recycled dehydrated oceanic crusts and sediments are also needed in their mantle source along with the depleted mantle component. The heterogeneity of H2O contents in Fujian Cenozoic basalts may be the result of different degree of recycled materials dehydration or the heterogeneity of the mantle. Because of the fuzzy existence of the subducted slab beneath the Fujian region in the seismic image, the pronounced recycled oceanic materials are likely distributed in the upper mantle, most likely the residue of the previous subducted slab sunk to the lower mantle. 3) Relative to Fujian and Zhejiang Cenozoic basalts, Hainan Cenozoic basalts have complex trace element patterns, including HIMUs-like and EM-like characters. These differences indicate Hainan Cenozoic basalts have more heterogeneous mantle source than Zhejiang and Fujian Cenozoic basalts. Considering the more enriched Sr, Nd, and Pb isotopic ratios, and higher δ 18 O values of the cpx phenocrysts in Hainan Cenozoic Abstract VI basalts than those of the normal mantle, the recycled materials are also required in the mantle source. The Li isotopic data of the some basalts suggests the cpx phenocryst have undergone Li diffusion after crystallization. Some of Hainan Cenozoic basalts are almost dry, due to intense H-loss. H2O content the basalts from Leihuling (LH), Dayang (DY) and Fujitian (FJT) areas are 2.7 wt. %, 1.3 wt. %, and 2.6 wt. %, respectively. The coexistence of high and low δ 18 O cpx phenocrysts observed in the LH basalts, combined with their trace element composition, the recycled upper oceanic crust components are dominantly required in the LH basalts, while limited recycled lower oceanic gabbro components were also involved. The mixture of DMM, recycled oceanic sediments, and crusts most likely resulted in the DY and FJT basalts. These recycled materials should not be very old and are most likely caught by upwelling plume from the deep mantle. Overall, the SE China Cenozoic basalts with different geological backgrounds have involved the recycled oceanic materials in their mantle source. The H2O contents of the Cenozoic basalts in SE China are generally as enriched as in BABBs and IABs, although the basalts have various range of Sr-Nd-Pb radiogenic ratios, and discrepant trace element characteristics, implying various proportions of different compositions and the mantle heterogeneity. The recycled oceanic materials have different existential state and locations, when the geological history of SE China are considered. The subducted Pacific slab most likely effect the composition of mantle in SE China.

Acknowledgements:

The first and greatest gratitude should go to my thesis supervisors, Prof. Qunke Xia and Prof. Etienne Deloule. During past years, Prof. Xia and Prof. Etienne Deloule gave me so many concerns and guide not only on my research but also on my life.

It is so lucky for me to work together with intelligent and enthusiastic supervisors, Prof. Xia and Prof. Deloule. Prof. Xia`s famous and humorous pet phrase "from data to model" has always reminded the most basic method and attitude to do natural science and encouraged me to follow the most serious principle every day since we met nine years ago. I also appreciate the profound knowledge and kindness of Prof. Deloule, who help me so much when I studied in CRPG, France.

Those professors and experts have instructed me large numbers of geological knowledge and skills when I studied in USTC: Yongfei Zheng, Jiangfeng Chen, Zhi Xie, Fukun Chen, Xiaoyong Yang, Yilin Xiao, Fang Huang and so on. I appreciate their solid professional knowledge and kindly help for me.

I give my sincerely gratitude to Prof. Qicheng Fan providing the samples from Hainan to complete my study and research. My communication with Dr. Huaiyu He, Dr. Xinmin Zhou, Dr. Andrey A. Gurenko, Dr. Franz Weis, and Dr Jannick Ingrin are productive and impressive me so much. Their constructive suggestions gave me so much inspiration to finish this work.

I would like to thank Jiangling Xu and Mrs. Min Feng for their help in EPMA analysis; Miss Xiao and Mr. Jianfeng He for their help in TIMS analysis; Prof. Honglin Yuan and Assistant Prof. Hong Zhang in Northwest University for their help in ICP-MS analysis. Laurie Reisberg, Christiane Parmentier, Nordine Bouden, Johan Villeneuve, Aimeryc Schumacher and Catherine Zimmermann should also be thanked for their generous help and patient teaching on measurements by ion microprobe and TIMS/MC-ICP-MS in CRPG-CNRS. In addition, Xiaoyan Gu were my first teacher for FTIR analysis. I also appreciate Pei Li, Yantao Hao, and Jia Liu, for the discussion of scientific issues with them always inspired me.

The editorial work by Pei Li, Jia Liu, Suofei Dong, Hongluo Zhang and Mr. Markhand are much helpful to complete this thesis. I also enjoy the work and life together with other members in our group, Bo Zhao, Peipei Zhang, Guicai Yang, Yaping Zhang, Ling Liu, Jia Liu, Huan Chen, Zubing Jia, Zhenzhen Tian, Zizhen Wang, Haoran MORBs and IABs erupt in the inner regions of the continental or oceanic plates. The intra-plate basalts consist of "continental intra-plate basalts", "continental rift basalts" (CRBs), "continental flood basalts" (CFBs) and "oceanic island basalts" (OIBs). The CFBs and OIBs are often associated with mantle plumes (such as Siberian, Yellow Stone, Tarim, and Hawaii), whereas, the CRBs are located above the lithospheric deep rifts (such as East African rift). Meanwhile, the continental intra-plate basalts usually occur at broader active continental regions (such as East Asia). Due to fast ascent, the continental intra-plate basalts, particularly xenolith-bearing alkali basalts, avoid significant crustal contaminations. Therefore, the compositions of these basalts are considered to be able to represent the mantle source, making them one of the most important windows to observe the deep earth. However, despite intensive studies of several decades, the origin of the enriched components in the mantle source and the genesis of intra-plate basalts remain poorly constrained.

The source of intra-plate basalts

Because basalts are produced directly by partial melting of the mantle rocks, they can be used to deduce the composition information of the mantle source where from they are inherited. High-pressure experiments and observation of natural samples are the most important and effective methods to determine the relationship between the compositions of basalts and their source. After numerous researches, the divergences of the source properties for intra-plate basalts are mainly on the lithologies, geochemical characteristics, and the enrichment origin of the mantle source rocks, as well as, how these geochemical characteristics are produced. A number of high-pressure melting experiments on peridotites and other rocks have been conducted during last 30 1 Chapter 1 years to study the geochemical lithologies and compositions of the mantle source for various basalts [START_REF] Baker | Determining the composition of high-pressure mantle melts using diamond aggregates[END_REF][START_REF] Falloon | Melting of refractory mantle at 1[END_REF][START_REF] Hirose | Partial melting of dry peridotites at high pressures: determination of compositions of melts segregated from peridotite using aggregates of diamond[END_REF][START_REF] Laporte | A new experimental technique for extracting liquids from peridotite at very low degrees of melting: application to partial melting of depleted peridotite[END_REF][START_REF] Schwab | Melting systematics of modally variable, compositionally intermediate peridotites and the effects of mineral fertility[END_REF][START_REF] Walter | Melting of garnet peridotite and the origin of komatiite and depleted lithosphere[END_REF][START_REF] Wasylenki | Near-solidus melting of the shallow upper mantle: Partial melting experiments on depleted peridotite[END_REF]. Following the result of these melting experiments, the source lithologies of the intra-plate basalts may involve pyroxenites, eclogites (along with carbonated eclogites), as well as hornblendites, beside these the peridotites are also conventionally considered (Petermann and Hirschmann, 2003;[START_REF] Sobolev | An olivine-free mantle source of Hawaiian shield basalts[END_REF][START_REF] Sobolev | The amount of recycled crust in sources of mantle-derived melts[END_REF]; [START_REF] Dasgupta | Major element chemistry of ocean island basalts-conditions of mantle melting and heterogeneity of mantle source[END_REF][START_REF] Niu | The origin of intra-plate ocean island basalts (OIB): the lid effect and its geodynamic implications[END_REF][START_REF] Putirka | Mineralogy and composition of the oceanic mantle[END_REF]. Meanwhile, the existence of non-peridotite components is recognized by some natural samples from Hawaii OIBs [START_REF] Sobolev | The amount of recycled crust in sources of mantle-derived melts[END_REF][START_REF] Sobolev | An olivine-free mantle source of Hawaiian shield basalts[END_REF]. The geochemical compositions, heterogeneity, and the origin of enrichment the in the mantle source of the intra-plate basalts has remained the subject of interest for geoscientists in the past decades. The studies of trace elements and Sr-Nd-Pb about MORBs and OIBs revealed the primary understanding of the geochemical compositions and heterogeneity for the mantle (Hofmann and White, 1982;[START_REF] Zindler | Chemical geodynamics[END_REF][START_REF] Sun | Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes[END_REF]. The chemical composition of MORBs are relatively homogeneous. Comparing to MORBs, the intra-plate basalts, especially OIBs, display various geochemical characteristics [START_REF] Workman | Recycled metasomatized lithosphere as the origin of the enriched mantle II (EM2) end-member: Evidence from the Samoan volcanic chain[END_REF][START_REF] Zindler | Isotope and trace element geochemistry of young Pacific seamounts: implications for the scale of upper mantle heterogeneity[END_REF]. [START_REF] Zindler | Chemical geodynamics[END_REF] defined the four end mantle members on the basis of the Sr-Nd-Pb composition of OIBs to explain the composition variation of the mantle: (a) depleted MORBs mantle (DMM) has the most depleted 87 Most oceanic basalts lie within the tetrahedron delineated by the four mantle endmembers [START_REF] Hart | Mantle plumes and entrainment-isotopic evidence[END_REF]. The clarification on the origin of enrichments in the mantle always is the important research topic for geochemists. One widely accepted opinion involves recycled oceanic materials, to explain the genesis of the enriched composition in the mantle source of OIBs and some continental intra-plate basalts. Growing numbers of experimental and natural observations in the past decades have demonstrated that the Chapter 1 recycled materials can provide the enriched mantle components for intra-plate basalt genesis (Hofmann and White, 1982;Hirschmann and Stopler, 1996;[START_REF] Stracke | FOZO, HIMU, and the rest of the mantle zoo[END_REF][START_REF] Willbold | Trace element composition of mantle end-members: Implications for recycling of oceanic and upper and lower continental crust[END_REF]Jackson et al., 2007;[START_REF] Dasgupta | Major element chemistry of ocean island basalts-conditions of mantle melting and heterogeneity of mantle source[END_REF]. Nevertheless, these recycled materials have various lithologies and complicated petrogenesis. The recycled oceanic materials are subsumed at subduction zones, where the oceanic lithosphere consisting of pelagic sediments, altered oceanic crust and oceanic lithospheric mantle sink back into the convecting mantle and enter into the mantle source at different oceanic structures (Hofmann and White, 1982;Hirschmann and Stopler, 1996;[START_REF] Stracke | FOZO, HIMU, and the rest of the mantle zoo[END_REF][START_REF] Willbold | Trace element composition of mantle end-members: Implications for recycling of oceanic and upper and lower continental crust[END_REF]Jackson et al., 2007;[START_REF] Dasgupta | Major element chemistry of ocean island basalts-conditions of mantle melting and heterogeneity of mantle source[END_REF]. These subducted oceanic materials can be recycled to the shallow upper mantle again from the mantle transition zone (MTZ) or even the coremantle boundary (Hofmann and White, 1982;Hirschmann and Stopler, 1996;[START_REF] Herzberg | Identification of source lithology in the Hawaiian and Canary islands: implications for origins[END_REF]. However, some researchers believe that the enriched geochemical compositions of the OIBs originate from the mineral veins (like amphiboles) metasomatized by the infiltration of mantle melts derived by small degree of partial melting in the lithospheric mantle [START_REF] Halliday | Trace-element fractionation in plumes and the origin of HIMU mantle beneath the[END_REF][START_REF] Niu | Origin of ocean island basalts: A new perspective from petrology, geochemistry, and mineral physics considerations[END_REF][START_REF] Pilet | Metasomatized Lithosphere and the Origin of Alkaline Lavas[END_REF]. The origin of the enriched composition in the mantle source of the continental intra-plate basalts is more complex than that of the OIBs, due to existence of old and thickened continental lithospheric mantle [START_REF] Depaolo | Neodymium isotopes in basalts of the southwest basin and range and lithospheric thinning during continental extension[END_REF]. On one hand, Wang et al. (2008) and [START_REF] Liu | Recycled crust controls contrasting source compositions of Mesozoic and Cenozoic basalts in the North China Craton[END_REF] suggested that the continent lithospheric mantle could serve as the mantle source of the intra-plate basalts as in some Mesozoic basalts in eastern China.

The thick continental lithospheric mantle can be re-enriched and metasomatized by mantle derived fluids or melts [START_REF] Depaolo | Neodymium isotopes in basalts of the southwest basin and range and lithospheric thinning during continental extension[END_REF]. On the other hand, the thickened lower continental crust and lithospheric mantle enter into convective mantle by lithospheric delamination as observed from some Cenozoic intra-plate basalts in the North China Craton (Xu et al., 2004;[START_REF] Zeng | Crust recycling in the sources of two parallel volcanic chains in Shandong, North China[END_REF]. Therefore, identifying the contribution of each individual recycled material enriched in the mantle sources of intra-plate basalts is a grand challenge, which could offer a new insight and constraint to understand the origin of the enrichments in the mantle sources of the intra-plate basalts [START_REF] Castillo | The recycling of marine carbonates and sources of HIMU and FOZO ocean island basalts[END_REF][START_REF] Dixon | Recycled dehydrated lithosphere observed in plume-influenced mid-ocean-ridge basalt[END_REF][START_REF] Hofmann | Chemical differentiation of the Earth: the relationship between mantle, continental crust, and oceanic crust[END_REF]Jackson et al., 2007;[START_REF] Kuritani | Intensive hydration of the mantle transition zone beneath China caused by ancient slab stagnation[END_REF][START_REF] Sakuyama | Melting of dehydrated oceanic crust from the stagnant slab and of the hydrated mantle transition zone: Constraints from Cenozoic alkaline basalts in eastern China[END_REF][START_REF] Sobolev | The amount of recycled crust in sources of mantle-derived melts[END_REF][START_REF] Sobolev | An olivine-free mantle source of Hawaiian shield basalts[END_REF][START_REF] Workman | Recycled metasomatized lithosphere as the origin of the enriched mantle II (EM2) end-member: Evidence from the Samoan volcanic chain[END_REF]Xu et al., 2012a;[START_REF] Zindler | Isotope and trace element geochemistry of young Pacific seamounts: implications for the scale of upper mantle heterogeneity[END_REF].

Cenozoic alkali basalt in SE China

North China Crato~ Chapter 1

Image slice of P wave velocity perturbations in East China at MTZ depth (in percent from the average velocity) from [START_REF] Huang | High-resolution mantle tomography of China and surrounding regions[END_REF]. Red and blue colors denote low and high velocities, respectively.

Chapter 1

H2O in nominally anhydrous minerals and basaltic magma

Hydrogen is a chemically active element in nature. It usually loses an electron and exists as proton with positive charge (H + ), such as H2O, -OH. When hydrogen is under reduced conditions, it usually exists as CH4 or H2. Hydrogen can also be present in hydrated fluids or hydrous melts in the crevices of minerals, when water contents exceed the storage capacity of host minerals. Hydrogen can be bound with oxygen and be stored in hydrous minerals, such as phlogopite and hornblende, which have hydrogen in its chemical formula. Meanwhile, hydrogen can also enter into the defects of crystalline lattices of nominally anhydrous minerals (NAMs) as impurities, such as olivine (ol) and pyroxene. The NAMs can store up to thousands of ppm of H2O, as the form of -OH. Different forms of "water" can be transformed from one to another between fluid/melts, hydrous minerals, and the NAMs depending on the chemical and physical conditions around.

The physical and chemical properties of minerals and rocks in the mantle are remarkably effected when even limited amount of water exists, such as electrical conductivity (e.g., [START_REF] Karato | The role of hydrogen in the electrical conductivity of the upper mantle[END_REF][START_REF] Huang | Water content in the transition zone from electrical conductivity of wadsleyite and ringwoodite[END_REF]Wang et al., 2006;[START_REF] Yoshino | Hydrous olivine unable to account for conductivity anomaly at the top of the asthenosphere[END_REF][START_REF] Yoshino | Electrical conductivity of mantle minerals: role of water in conductivity anomalies[END_REF], ionic diffusivities (e.g., [START_REF] Wang | Effect of H + on Fe-Mg inter-diffusion in olivine, (Fe, Mg)2SiO4[END_REF]Hier-Majumder et al., 2005a and b;[START_REF] Demouchy | Influence of hydrogen on Fe-Mg interdiffusion in (Mg, Fe)O and implications for Earth's lower mantle[END_REF][START_REF] Costa | The effect of water on Si and O diffusion rates in olivine and implications for transport properties and processes in the upper mantle[END_REF][START_REF] Otsuka | The influence of ferric iron and hydrogen on Fe-Mg inter diffusion in ferropericlase ((Mg, Fe)O) in the lower mantle[END_REF], rheology (e.g., [START_REF] Mackwell | The role of water in the deformation of olivine single crystals[END_REF][START_REF] Karato | Rheology of synthetic olivine aggregates: influence of grain size and water[END_REF][START_REF] Otsuka | The influence of ferric iron and hydrogen on Fe-Mg inter diffusion in ferropericlase ((Mg, Fe)O) in the lower mantle[END_REF][START_REF] Karato | Rheology of the upper mantle-A synthesis[END_REF][START_REF] Chen | Strength and water weakening of mantle minerals, olivine, wadsleyite and ringwoodite[END_REF]Mei andKohlstedt, 2000a, 2000b;Dixon et al., 2004;Hier-Majumder et al., 2005a;Karato, 2010aKarato, , 2010b;;[START_REF] Manthilake | The effect of aluminum and water on the development of deformation fabrics of orthopyroxene[END_REF], seismic velocity (e.g., [START_REF] Karato | Water, partial melting and the origin of the seismic low velocity and high attenuation zone in the upper mantle[END_REF][START_REF] Jung | Water-induced fabric transitions in olivine[END_REF][START_REF] Falus | Deformation and seismic anisotropy of the lithospheric mantle in the southeastern Carpathians inferred from the study of mantle xenoliths[END_REF][START_REF] Karato | Geodynamic significance of seismic anisotropy of the upper mantle: new insights from laboratory studies[END_REF], and the temperature and pressure of partial melting (e.g., [START_REF] Hirth | Water in the oceanic upper mantle: implications for rheology, melt extraction and the evolution of the lithosphere[END_REF][START_REF] Gaetani | The influence of water on melting of mantle peridotite[END_REF][START_REF] Asimow | The importance of water to oceanic mantle melting regimes[END_REF][START_REF] Hirschmann | Dehydration melting of nominally anhydrous mantle: The primacy of partitioning[END_REF][START_REF] Green | Water and its influence on the lithosphere-asthenosphere boundary[END_REF][START_REF] Green | Experimental study of the influence of water on melting and phase assemblages in the upper mantle[END_REF][START_REF] Kelley | Mantle melting as a function of water content beneath the Mariana Arc[END_REF]Tenner et al., 2012a). Water is also a fundamental factor in the evolution process of Earth, e.g. the stability of the craton, the generation of magma, the enrichment and migration of elements, and the movement of plates. Therefore, the research of the existence form and content of water in deep mantle, is one of the most important point to answer the question of petrology, geochemistry, geophysics, and geodynamics of the Earth evolution.

Water is an important influence factor for the generation and evolution of basaltic magma, because water can decrease the melting temperature and pressure, increase the Chapter 1 depth of starting melting, decrease the viscosity of magma and increase the ascending velocity of basaltic melting. The water content of basaltic magma have the potential to distinguish different geological structures, where the basalts are produced from. The basaltic magma produced from different geological structures have different water contents: (i) MORBs, about 0.1 to 0.3 wt. % [START_REF] Asimow | A hydrous melting and fractionation model for mid-ocean ridge basalts: application to the Mid-Atlantic Ridge near the Azores[END_REF]Danyushevsky et al., 2000;[START_REF] Dixon | Infrared spectroscopic measurements of CO2 and H2O in Juan de Fuca Ridge basaltic glasses[END_REF][START_REF] Michael | The concentration, behavior and storage of H2O in the suboceanic upper mantle: implications for mantle metasomatism[END_REF]Michael, , 1995;;[START_REF] Sobolev | H2O concentrations in primary melts from suprasubduction zones and mid-ocean ridges: implications for H2O storage and recycling in the mantle[END_REF][START_REF] Saal | Vapor undersaturation in primitive mid-ocean-ridge basalt and the volatile content of Earth's upper mantle[END_REF][START_REF] Simons | Volatiles in basaltic glasses from the Easter-Salas y Gomez Seamount Chain and Easter Microplate: implications for geochemical cycling of volatile elements[END_REF]; (ii) OIBs, about 0.3 to 1.0 wt.% [START_REF] Dixon | Volatiles in alkalic basalts from the North Arch Volcanic Field, Hawaii: extensive degassing of deep submarine-erupted alkalic series lavas[END_REF][START_REF] Dixon | Volatiles in basaltic glasses from Loihi Seamount, Hawaii: evidence for a relatively dry plume component[END_REF][START_REF] Nichols | Is the Iceland hot spot also wet? Evidence from the water contents of undegassed submarine and subglacial pillow basalts[END_REF][START_REF] Simons | Volatiles in basaltic glasses from the Easter-Salas y Gomez Seamount Chain and Easter Microplate: implications for geochemical cycling of volatile elements[END_REF][START_REF] Wallace | Water and partial melting in mantle plumes: inferences from the dissolved H2O concentrations of Hawaiian basaltic magmas[END_REF]; (iii) the back-arc basin basalts (BABBs), about 0.2 to 2.0 wt.% [START_REF] Danyushevsky | The H2O content of basalt glasses from southwest Pacific backarc basins[END_REF][START_REF] Hochstaedter | Volcanism in the Sumisu rift: I. Major element, volatile, and stable isotope geochemistry, the Mariana Trough[END_REF][START_REF] Stolper | The role of water in the petrogenesis of Mariana trough magmas[END_REF]; (iv) island arc magmas (IABs), about 2.0 to 8.0 wt.% [START_REF] Dobson | Water in boninite glass and coexisting orthopyroxene: concentration and partitioning[END_REF][START_REF] Sisson | H2O in basalt and basaltic andesite glass inclusions from four subduction-related volcanoes[END_REF][START_REF] Wallace | Volatiles in subduction zone magmas: concentrations and fluxes based on melt inclusion and volcanic gas data[END_REF]as shown in Fig. 123). The subducted oceanic slabs are believed to be able to carry large amount of water into deep mantle [START_REF] Niu | Generation and Evolution of Basaltic Magmas: Some Basic Concepts and a New View on the Origin of Mesozoic-Cenozoic Basaltic Volcanism in Eastern China[END_REF][START_REF] Garth | Order of magnitude increase in subducted H2O due to hydrated normal faults within the Wadati-Benioff zone[END_REF][START_REF] Shaw | Long-term preservation of slab signatures in the mantle inferred from hydrogen isotopes[END_REF]. Because H2O and Ce usually have similar behaviors during the magma process of partially melting and fractional crystallization, and the H2O/Ce ratios of basalts can remain its primitive values in mantle source [START_REF] Dixon | Volatiles in basaltic glasses from Loihi Seamount, Hawaii: evidence for a relatively dry plume component[END_REF]2004). The H2O/Ce ratios of basalts have the potential to represent the H2O/Ce ratios of the mantle sources for basalts and to identify the contribution of each different recycled material to the enriched components in the mantle source for basalts [START_REF] Dixon | Recycled dehydrated lithosphere observed in plume-influenced mid-ocean-ridge basalt[END_REF]Michael, 1995;[START_REF] Shaw | Long-term preservation of slab signatures in the mantle inferred from hydrogen isotopes[END_REF]. Different recycled components have distinct H2O/Ce ratios and are distinguishable from mantle components: (i) The H2O/Ce ratios of GLOSS can be up to 1200 [START_REF] Plank | The chemical composition of subducting sediment and its consequences for the crust and mantle[END_REF], while the H2O/Ce of sub-marine basaltic glasses in the Minus basin is up to 903, with δD values down to -126 and 3 He/ 4 He ratios up to 15 R/RA [START_REF] Shaw | Long-term preservation of slab signatures in the mantle inferred from hydrogen isotopes[END_REF]. This recycled signature of subducted hydrous oceanic sediments can be preserved in the mantle longer than 1Gyr [START_REF] Shaw | Long-term preservation of slab signatures in the mantle inferred from hydrogen isotopes[END_REF]; (ii) the H2O/Ce ratios of dehydrated recycled oceanic crust (ROC) are approximately 100; (iii) the H2O/Ce ratios of DMM are about 200; and (iv) the H2O/Ce ratios of EM are closed to 100 [START_REF] Dixon | Recycled dehydrated lithosphere observed in plume-influenced mid-ocean-ridge basalt[END_REF].

Chapter 1

The ranges of H2O content for OIBs, MORBs, BABBs and IABs (Dixon et al. (2004) and the references therein).

Lithium and Oxygen isotopes

Lithium isotopes

The Lithium (Li) isotope could play an efficient role in distinguishing the contributions of different recycled materials to the enriched components in the mantle source of basalts and to trace hydrogen re-equilibrium of cpx phenocrysts after crystallization, due to the similar diffusion rate, respectively. Lithium belongs to the alkali metal group and has 2 isotopes: 6 Li and 7 Li. Both of them are stable isotopes with natural isotopic abundances of 7.52% and 92.48% in nature, respectively. Lithium is easy to lose an electron to form a monovalent cation, like other alkali metals. Therefore, Li is very active, and has no pure metal substance in nature. All the Li combines with other anions as crystals (such as triphane), or enters into the crystalline lattices defects as impurities (such as olivine), or is dissolved in solution (such as sea water). The mass Chapter 1 difference between 6 Li and 7 Li relative to the mass of the element is about 16%.

Therefore, the mass fractionation of the Lithium isotope is easy to be observed in nature.

A change of 25% of 6 Li/ 7 Li ratio were observed after the Li-solutions percolate through a zeolite column [START_REF] Taylor | Fractionation of the lithium and potassium isotopes by chemical exchange with zeolites[END_REF]. Thus, considerable fractionation of 6 Li and 7 Li can be expected in geochemical processes, such as rock weathering and mantle metasomatism. Meanwhile, different reservoirs in the nature have large Li isotopic variation (Fig. 1-4, Tomascak, 2004), which can be used to distinguish the origin of the enrichment in mantle source. The Li isotopic composition is usually expressed as:

δ 7 Li = [( 7 Li/ 6 Li)sample/( 7 Li/ 6 Li)L-SVEC-1]×1000, where L-SVEC is the Li2CO3 international standard with the 7 Li/ 6 Li ratio of 12.0192 [START_REF] Flesch | A secondary isotopic standard for 6Li/7Li determinations[END_REF].

The residence time of Li, as a conservative element, is about one million year in the ocean [START_REF] Misra | Lithium isotope history of Cenozoic seawater: changes in silicate weathering and reverse weathering[END_REF]. The Li in the ocean is consumed by (a) low temperature removal of Li into oceanic basalts; (b) deposited Li in the marine sediments, which return into deep earth at subduction zones as subducted oceanic sediments and crusts. The Li in the ocean is supplied by inputs of (a) dissolved Li from rivers (average δ 7 Li +23‰, Huh et al. 1998); (b) high-temperature hydrothermal fluids around ocean ridges; (c) re-dissolved Li from oceanic basalts and marine sediments. The oceanic Li can be considered as dynamic equilibrium. Mantle-derived basalts have a relatively uniform composition with δ 7 Li values of +4 ± 2‰ [START_REF] Tomaszak | Lithium isotopes in earth and planetary sciences[END_REF]). However, the continental crust generally has a lighter Li isotope composition than the upper mantle from which it was derived [START_REF] Teng | Lithium isotope composition and concentration of the upper continental crust[END_REF]). Therefore, Li isotope is considered to be used as a tracer to identify the existence of recycled material in the mantle (e.g. [START_REF] Moriguti | Across-arc variation of Li-isotopes in lavas and implications for crust /mantle recycling at subduction zones[END_REF][START_REF] Leeman | Boron and lithium isotopic variations in a hot subduction zone -the southern Washington Cascades[END_REF]). Unfortunately, some arc lavas display normal δ 7 Li values, being indistinguishable from MORBs, because Li is decoupled from other fluid mobile elements and is partitioned into Mg-silicates (pyroxene, olivine) in the mantle [START_REF] Tomascak | The control of lithium budgets in island arcs[END_REF].

Lithium diffuses rapidly in silicate minerals with D=1.0×10 -15 to 5×10 -10 at 1100 ℃ [START_REF] Vlastelic | Survival of lithium isotopic heterogeneities in the mantle supported by HIMU-lavas from Rurutu island[END_REF][START_REF] Parkinson | High-temperature lithium isotope fractionation: insights from lithium isotope diffusion in magmatic systems[END_REF]). In addition, the diffusivity of 6 Li is faster than 7 Li in both melts and minerals [START_REF] Richter | Isotope fractionation by chemical diffusion between molten basalt and rhyolite[END_REF][START_REF] Richter | Lithium isotope fractionation by diffusion in minerals. Part 1: Pyroxenes[END_REF]. Theoretical calculation shows that the Li content and Li isotope will change in a few days by Li diffusion under ~1100 ℃ and the change will exist for several years (Fig. 1-5, Li et al., 2012;[START_REF] Jeffcoate | Li isotope fractionation in peridotites and mafic melts[END_REF][START_REF] Parkinson | High-temperature lithium isotope fractionation: insights from lithium isotope diffusion in magmatic systems[END_REF]. The abundance of peridotite xenoliths entrained in most of the small isolated alkali basalts in eastern China required rapid magma ascent Chapter 1

and cooling (O'Reilly and [START_REF] O'reilly | Rates of magma ascent: constraints from mantlederived xenoliths[END_REF]. This suggests that the Li isotopic profiles of cpx phenocrysts in such basalts can preserve the information of Li diffusion of cpx phenocryst during the magma ascent and cooling after eruption, which can be used to deduce the magma evolution. Detailed Li diffusive profiles in mineral grains are also considered as a candidate for high-resolution geo-speedometer for timescales as short as a few to hundreds of days [START_REF] Jeffcoate | Li isotope fractionation in peridotites and mafic melts[END_REF][START_REF] Parkinson | High-temperature lithium isotope fractionation: insights from lithium isotope diffusion in magmatic systems[END_REF]. Meanwhile, because the Li and H diffuse very fast in minerals, at given high diffusion rate of H in cpx at 900℃, (D=10 -10 ~10 -10.5 m 2 /s, [START_REF] Hercule | Hydrogen in diopside: Diffusion, kinetics of extractionincorporation, and solubility[END_REF][START_REF] Ingrin | Diffusion of Hydrogen in Minerals[END_REF][START_REF] Ingrin | Hydrogen in nominally anhydrous upper-mantle minerals: concentration levels and implications[END_REF][START_REF] Woods | Hydrogen in diopside: Diffusion profiles[END_REF], detailed Li diffusive profiles of cpx phenocrysts measured by SIMS combined with the profiles of -OH measured by FTIR can be used to identify whether H diffusion took place or not, during the subsequent ascent of the basaltic melts.

Li isotopic compositions of Earth reservoirs, modified from Tang et al. (2010) expressed in Chapter 1

The Li content and Li isotope change with time by diffusion [START_REF] Pei | Anomalous Lithium Isotopic Compositions of the Cenozoic Lithospheric Mantle Beneath Penglai, Shandong Province: The ion Probe Analyses of Peridotite Xenoliths[END_REF].

Oxygen isotopes

Oxygen (O) is the most abundant element on Earth. It can be present as molecules in the air and as a compounds with other elements. The metal oxides usually have wide thermal stability over large range of temperature. Oxygen has three stable isotopes, i.e.

Chapter 1 16 O, 17 O and 18 O, these isotopes are some of the most important isotopes known to be used to trace the circulation of materials between the deep mantle and the shallow layers of Earth. The oxygen isotopes traditionally are displayed in two different δ-scales: δ 18 O (VSMOW) and δ 18 O (VPDB). The δ-scales of δ 18 O (VSMOW) are used in this thesis. The mantle rocks (if are represented by MORBs) have narrow but homogeneous oxygen isotope (δ 18 O ~5.7±0.2 ‰) (Fig. 1-6a, Eiler et al., 2001). The continental crust and oceanic materials generally have a wider range of oxygen isotope than that of the upper mantle.

The isotope fractionation of oxygen is controlled by the strength of chemical bonds and the equilibrium temperature of exchanging. Large fractionation of oxygen isotopes occur at low temperature and between two phases with distinct chemical compositions, such as water-rock exchange reaction. It is known that oxygen isotopes have small fractionation during igneous differentiation processes at high temperature. The pristine continental and fresh MORBs should not have large O isotope fractionation compared to the mantle source. Therefore, the various oxygen isotope of continental crust and oceanic crust materials must have been modified by secondary processes, such as low temperature water-rock reaction. The recycled materials often undergo low-temperature processes, and they usually have non-mantle-like δ 18 O values, such as the lower continental crust, oceanic sediments and altered oceanic crust. The recycled pelagic sediments and delaminated lower continental crust have high δ 18 O. The shallow oceanic basalts have higher δ 18 O values than the normal mantle because of low temperature water-rock reaction with sea water. Nevertheless, the lower gabbros have slight lower δ 18 O than normal mantle values due to high-temperature hydrothermal reaction (Fig. 1-6c). The contributions of subducted pelagic sediments and related fluids to subductionrelated lavas can also be constrained by the variations of oxygen isotope [START_REF] Eiler | Oxygen isotope geochemistry of oceanic arc lavas[END_REF][START_REF] Dorendorf | Hydrated sub-arc mantle: a source for the Kluchevskoy volcano, Kamchatka, Russia[END_REF], Zheng et al., 2012). The non-mantle-like δ 18 O values in basalts can be used to indicate the existence and origin of these recycled materials, if combined with other geochemical data. The variation of δ 18 O is larger than 5‰ among more than 2000 fresh basalts and glasses in the Neogene volcanic rocks all over the world, suggesting significant oxygen isotope heterogeneities in the mantle sources of the basalts [START_REF] Harmon | Oxygen isotope heterogeneity of the mantle deduced from global 18 O systematics of basalts from different geotectonic settings[END_REF].

Chapter 1

Oxygen isotope compositions of MORBs glasses and whole-rocks. [START_REF] Eiler | Oxygen Isotope Variations of Basaltic Lavas and Upper Mantle Rocks[END_REF] Oxygen in different geological units in Earth (Eiler, 2001. Fig. 7 in its book. Data sources are listed in the original text.); c. The idealized δ 18 O of altered, sediment-covered oceanic crust (Eiler, 2001. Fig. 7 in its book, based on [START_REF] Gregory | An oxygen isotope profile in a section of Cretaceous oceanic crust, Samail ophiolite, Oman: evidence for δ 18 O buffering of the oceans by deep (>5 km) seawater-hydrothermal circulation at mid-ocean ridges[END_REF] study of the Ibra section of the Oman ophiolite and marine sediments data sources are listed in the original text).

Chapter 1

Objectives of this work

The objectives of the present study are to decipher the origin of enriched compositions in the mantle sources of Cenozoic basalts in SE China through:

( (2) The characteristics of trace element ratios combined with O isotope in the mantle source of Cenozoic basalts in SE China. These distinctively useful index have been identified to trace the source process, because the unique geochemical characteristics in each enriched composition are believed not to be fractionated during mantle partial melting and crystallization during magma evolution, representing the mantle source. These characteristics can be used to determine the contributions of each kinds of recycled materials to enriched mantle source in Cenozoic basalts in, SE China.

(

Geological background and Samples

The eastern part of China continent has mainly three tectonic units of Cenozoic basalts: NE China block, the NCC, and SE China. The NE China consists of a group of blocks, mainly including, Erguna, Xingkai, Songnen, Jiamusi, Longgang, Khanka, and so on. These small blocks have their individual geological histories, and are assemble in early Mesozoic. The NCC is one of the oldest cratons in the world, containing the crust as old as 3.8Ga [START_REF] Liu | Remnants of 3800 Ma crust in the Chinese part of the Sino-Korean craton[END_REF]. The lithosphere under eastern part of China is one of the best example to study the lithosphere thinning in the world [START_REF] Windley | Delamination/thinning of subcontinental lithospheric mantle under Eastern China: the role of water and multiple subduction[END_REF]. Based on a series of studies on peridotite xenoliths, xenocrysts and mineral inclusions in diamonds from mid-Ordovician kimberlites, a typical cratonic lithospheric mantle with high thickness of 200km and low surface geothermal current value of 40 mW/m 2 until mid-Ordovician in the NCC is revealed. Recent geophysical seismic wave map discovered the root of old, cold and thickened lithosphere replaced by a hot (60-80 mW/m 2 ) and thin (80-60 km) lithospheric mantle during the late Mesozoic [START_REF] Griffin | Phanerozoic evolution of the lithosphere beneath the Sino-Korean Craton[END_REF][START_REF] Huang | High-resolution mantle tomography of China and surrounding regions[END_REF][START_REF] Menzies | Integration of geology, geophysics and geochemistry: A key to understanding the North China Craton[END_REF][START_REF] Menzies | Paleozoic and Cenozoic lithoprobes and the loss of >120 km of Archean lithosphere, Sino-Korean craton[END_REF]. The South China consists of the Yangtze Craton and SE China block (or the Southeast China fold belt, i.e., the Cathaysia block or the Cathaysia fold belt) and has been focus of many recent studies in relation to global tectonics, especially the Rodinia supercontinent history (e.g. Li et al., 2009;Li et al., 2010;[START_REF] Yao | Detrital zircon U-Pb geochronology, Hf-References isotopes and geochemistry-New clues for the Precambrian crustal evolution of Cathaysia block[END_REF]Wang et al., 2013). The SE China lies on the southeastern continental margin of Asian plate, separated from the Yangtze Craton by the Jiangshan-Shaoxing fault zones. The oldest age recorded in SE China crust is 3.76 Ga from zircons in the Mesozoic granites of the central SE China block [START_REF] Yu | Finding of ancient materials in Cathaysia and implication for the formation of Precambrian crust[END_REF]. In general, the most of ancient metamorphic basement of SE China is a series of complexes in the southwestern and northern

Zhejiang region with the age of 1.8-2.0 Ga [START_REF] Xiang | U-Pb zircon geochronology and Hf isotope study of metamorphosed basic-ultrabasic rocks from metamorphic basement in southwestern Zhejiang: The response of the Cathaysia Block to Indosinian orogenic event[END_REF][START_REF] Yu | A Paleoproterozoic orogeny recorded in a long-lived cratonic remnant (Wuyishan terrane), eastern Cathaysia Block, China[END_REF]. Towards the northeast fold belt resulted from an early Paleozoic orogeny, occupying almost whole SE China block more than 300,000 km 2 [START_REF] Faure | Intracontinental subduction: a possible mechanism for the Early Palaeozoic Orogen of SE China[END_REF]. During Neoproterozoic, the continental crust in SE China had experienced a sequence of continental reworking and growth events (Li et al., 2003a;Li et al., 2003b;Wang et al., 2006;[START_REF] Wu | Reworking of juvenile crust: Element and isotope evidence from Neoproterozoic granodiorite in South China[END_REF]Zhou et al., 2002a;[START_REF] Zhou | The Yanbian terrane (Southern Sichuan Province, SW China): A neoproterozoic are assemblage References in the western margin of the Yangtze block[END_REF]Zhou et al., 2002b). The basement of SE China has reworked in the early Paleozoic, on a large scale of anatexis and emplacement in Silurian [START_REF] Faure | Intracontinental subduction: a possible mechanism for the Early Palaeozoic Orogen of SE China[END_REF][START_REF] Charvet | Structural development of the Lower Paleozoic belt of South China: Genesis of an intra-continental orogen[END_REF]. Recent tectonic studies on SE China Fold Belt regard it as an intra-continental orogeny (Faure et al., Chapter 2 2009;Li et al., 2010;[START_REF] Charvet | Structural development of the Lower Paleozoic belt of South China: Genesis of an intra-continental orogen[END_REF]. Although the South China is not the typical thinning region like the NCC, during Mesozoic in traditional opinion, Li et al. (2009) show the evidence of coeval lithospheric extension and thinning in Yangtze craton. The deep Tan-Lu fault may trigger over-thickened lithosphere delamination and Archean lithospheric mantle replacement [START_REF] Huang | High-Mg adakitic rocks in the Dabie orogen, central China: implications for foundering mechanism of lower continental crust[END_REF][START_REF] Zheng | Nature and evolution of Cenozoic lithospheric mantle beneath Shandong peninsula[END_REF]. Its lithospheric mantle may have experienced a thinning process during Mesozoic, as recorded by the NCC [START_REF] Ho | 40 Ar/ 39 Ar dating and geochemical characteristics of late Cenozoic basaltic rocks from the Zhejiang-Fujian region, SE China: eruption ages, magma evolution and petrogenesis[END_REF][START_REF] Wu | Osmium isotopic constraints on the age of lithospheric mantle beneath northeastern China[END_REF][START_REF] Xu | Genesis of young lithospheric mantle in southeastern China: an LAM-ICPMS trace element study[END_REF][START_REF] Xu | Xenolith evidence for polybaric melting and stratification of the upper mantle beneath South China[END_REF]. Meanwhile, previous studies have suggested that SE China block has undergone several subduction events of the Izanagi plate, the Paleo-Tethyan plate, and the present Pacific plate [START_REF] Müller | Long-Term Sea-Level Fluctuations Driven by Ocean Basin Dynamics[END_REF][START_REF] Windley | Delamination/thinning of subcontinental lithospheric mantle under Eastern China: the role of water and multiple subduction[END_REF]. Meanwhile, the geophysical data has displayed the presence of a stagnant subducted Pacific slab in MTZ, beneath the northeastern part of China as shown in Fig. 2-1, [START_REF] Huang | High-resolution mantle tomography of China and surrounding regions[END_REF][START_REF] Li | Structure of the upper mantle and transition zone beneath Southeast Asia from traveltime tomography[END_REF][START_REF] Wei | East Asia mantle tomography: New insight into plate subduction and intraplate volcanism[END_REF][START_REF] Zhao | Deep slab subduction and dehydration and their geodynamic consequences: Evidence from seismology and mineral physics[END_REF]. Mesozoic basalts is SE China have both IABs-like and OIBs-like trace element patterns [START_REF] Chen | Was there Jurassic paleo-Pacific subduction in South China?: Constraints from 40 Ar/ 39 Ar dating, element and Sr-Nd-Pb isotopic geochemistry of the Mesozoic basalts[END_REF]Wang et al., 2008;[START_REF] Xie | Trace element and Nd-Sr-Pb isotope studies of Mesozoic and Cenozoic basalts in coastal area of SE China[END_REF], but dominant Cenozoic basalts have OIBs-like trace element patterns.

Chapter 2

Vertical cross section of P wave velocity perturbations along latitude N 30°, N 29°, N 27°, N 25° and at Hainan island (modified from [START_REF] Huang | High-resolution mantle tomography of China and surrounding regions[END_REF] and [START_REF] Wei | East Asia mantle tomography: New insight into plate subduction and intraplate volcanism[END_REF]). Red Chapter 2

Basalt locations and Samples

The SE China was in an extensional tectonic setting since Cenozoic [START_REF] Ma | Cenozoic extensional tectonics in China[END_REF]. Cenozoic basaltic volcanism in SE China occurred dispersive at small-scale and mainly controlled by a series of northeast-southwest trending fault systems (). The earliest basaltic volcanos in Early Tertiary (38-64 Ma) had only been restricted in the central and western Guangdong province [START_REF] Zhu | Geochronological and geochemical constraint of the Cenozoic extension of Cathaysian lithosphere and tectonic evolution of the border sea basins in East Asia[END_REF]. Only a few basaltic pipes have been found in the eastern Guangdong province, the Zhejiang Inner volcanic belt, the coast of Fujian, and the northern part of Hainan Island, during 34.3-16.3 Ma [START_REF] Ho | 40 Ar/ 39 Ar dating and geochemical characteristics of late Cenozoic basaltic rocks from the Zhejiang-Fujian region, SE China: eruption ages, magma evolution and petrogenesis[END_REF]. Miocene to Pliocene (after 17 Ma, dominantly younger than 6 Ma) basalts are widespread in SE China [START_REF] Zhu | Geochronological and geochemical constraint of the Cenozoic extension of Cathaysian lithosphere and tectonic evolution of the border sea basins in East Asia[END_REF][START_REF] Ho | 40 Ar/ 39 Ar dating and geochemical characteristics of late Cenozoic basaltic rocks from the Zhejiang-Fujian region, SE China: eruption ages, magma evolution and petrogenesis[END_REF]. The detailed information of locations of Cenozoic basalts in SE China is listed in Table 2-1.

Simplified tectonic units and distribution of the Cenozoic basalts in eastern China and the location of the basalt samples in Southeast China.

Cenozoic alkali basalts in the Zhejiang region

The age of Cenozoic basaltic volcanism of the Zhejiang region in the northeastern part of the Southeast China block can be divided into two stages [START_REF] Ho | 40 Ar/ 39 Ar dating and geochemical characteristics of late Cenozoic basaltic rocks from the Zhejiang-Fujian region, SE China: eruption ages, magma evolution and petrogenesis[END_REF]: (1) stage 1: ca. 26-17 Ma, composed primarily of basanites; and (2) stage 2: after 11 Ma, composed mainly of alkali olivine basalts, olivine tholeiites, quartz tholeiites and a small amount of basanites. Our samples were collected from Xilong (XL) and Xinchang The detailed locations of the basalt samples in the Zhejiang region.

Chapter 2

The google earth imagery showing the sample locations of the basalt samples in the Fujian region.

Cenozoic basalts in the Hainan Island

Hainan Island lies in the southern-most part of China continent, located at the northern edge of the South China Sea Basin. The mantle "plume" structure in upper mantle are revealed on the seismic wave map beneath Hainan region in Fig. 2-1e and f.

Cenozoic volcano in Hainan Island started to erupt since 28.4 Ma at the peak time of about Pleistocene (1.8-0.012 Ma) which gradually died down in the Holocene [START_REF] Ho | Geochronology and geochemistry of late Cenozoic basalts from the Leiqiong area, southern China[END_REF][START_REF] Fan | Periods of volcanic activity and magma evolution of Holocene in North Hainan Island[END_REF]. The Hainan basalts have OIBs-like incompatible element distributions, Dupal-like Pb isotopic signatures and depleted Sr-Nd isotopic compositions. Some early studies suggested that the Hainan basalts were mostly produced in the posterior stage of South China Sea Basin extension, whose intense time of eruption activity is the Pleistocene and Holocene [START_REF] Flower | Magmatism in the south China basin: 2. Post-spreading Quaternary basalts from Hainan Island, south China[END_REF][START_REF] Ho | Geochronology and geochemistry of late Cenozoic basalts from the Leiqiong area, southern China[END_REF][START_REF] Ho | 40 Ar/ 39 Ar dating and geochemical characteristics of late Cenozoic basaltic rocks from the Zhejiang-Fujian region, SE China: eruption ages, magma evolution and petrogenesis[END_REF]. Seven basalts samples are from the studies of [START_REF] Zou | U-Th isotopes in Hainan basalts: Implications for subasthenospheric origin of EM2 mantle endmember and the dynamics of melting beneath Hainan Island[END_REF], located in the northern part of the Hainan Island; including two Holocene samples from Maanling (ML), four Holocene samples from Leihuling (LH), and one Pleistocene sample from Sanjiaoyuan (SJY) as shown in Fig. 2-5. The ML samples are olivine tholeiites, the LH samples are mostly alkali olivine basalts (AOBs), and the SJY sample is olivine tholeiite.

The ML, LH and SJY cpx phenocrysts are all euhedral or subhedral crystal aggregation.

The SJY sample is relatively more compacted than other samples, and has about 5 vol. % Chapter 2 ol phenocrysts ranging from 0.5 to 1mm in size and 2 vol. % cpx phenocrysts about 0.5mm in size. The LH and ML samples have vesicular texture with enriched bubble and have a little ol and cpx phenocrysts.

There are 9 and 10 samples were collected from two locations of the Dayang (DY)

and Fujitian (FJT), respectively, lying in the east part of the Hainan Island around Penglai city. They erupted in Holocene [START_REF] Wang | Temperature, Pressure, and Composition of the Mantle Source Region of Late Cenozoic Basalts in Hainan Island, SE Asia: a Consequence of a Young Thermal References Mantle Plume close to Subduction Zones[END_REF], like ML and LH. All the DY and FJT samples are AOBs and carry large number of mantle peridotite xenoliths.

The FJT samples also entrained some cpx megacrysts. A little cpx megacrysts and peridotite xenoliths is relative wet analyzed by [START_REF] Zhang | Structural OH and Hydrogen and Oxygen Isotope of Pyroxenes from Upper Mantle in Fujitian, Hainan, China[END_REF]. Typical columnar joint structure are found in the DY basalts. The DY samples have less than 3 vol. % ol phenocrysts ranging from 0.5 to 2 mm in size and less than 1 vol. % cpx phenocrysts mostly smaller than 0.3 mm in size. Meanwhile, a few ol and cpx xenocrysts, even tiny xenoliths separated from broken peridotite xenocrysts were caught in the matrix, with reacting rim. The FJT samples have not only mantle peridotite xenoliths/xenocryst but also have very a few xenocrysts with low Mg# and TiO2, suggesting their origin may be the shallow layers of the earth (crust). The FJT basalts have very a little ol and cpx phenocrysts. The slight secondary alteration along the cracks of rocks are observed in some FJT samples. The FJT samples have less than 3 vol. % ol phenocrysts smaller than 1.5 mm in size and less than 1 vol. % cpx phenocrysts mostly smaller than 0.5 mm in size.

The google earth imagery showing the sample locations of the basalt samples in the Hainan Island.

Chapter 2

Analytical protocols 3.1 Sample preparations

The fresh samples were chosen for geochemical analysis. Some parts of basalt samples were sawed into slabs. The chips of 1-2 cm in size were prepared from the central parts of the basalt samples. The chips were cleaned using distilled water, dried at 110°C for 6 hours, and then crushed into powder of ~200mesh size in an agate mortar for bulk rock analysis. Meanwhile, the doubly polished thin sections were prepared, for the in situ analyses of the phenocrysts, by Fourier transform infrared spectroscopy (FTIR), electron microprobe (EMP), and secondary ion mass spectrometry (SIMS)

investigation. The doubly polished thin sections are controlled in thicknesses between 0.05 and 0.12 mm depending on the diameter of the cpx phenocrysts. For each unknown basalt sample, several cpx phenocryst grains were chosen for isotopic SIMS analysis after FTIR and EMP analysis, which show no-OH IR bands of hydrous minerals. The selected cpx grains are poked down from the doubly polished thin sections for SIMS, after the analyses of FTIR and EMP. Two cpx megacryst fragments are chosen as the standard materials to monitor the instrument drift of SIMS during analysis. Then these cpx grains were mounted in epoxy resin and polished to expose their interior, with standard procedures abrasive paper, in order from 9μ to 0.1μ. Then, the slices were washed by ethanol in ultrasonic cleaners and were coated with gold for analysis.

Analytical protocols

Realizing the aim of this thesis, much concern was paid to the technological approach in measuring the water contents of magma and the geochemical composition of the basalts. In this thesis; the water contents, chemical compositions, and Li as well as O isotope of cpx phenocrysts from the 9 Cenozoic alkali basalts in SE China were measured by FTIR and EPMA. The XRF (X-ray Fluorescence), ICP-MS (Inductively Coupled Plasma Mass Spectrometry), and TIMS (Thermal Ionization Mass Spectrometry) are used to analyze the bulk rock powders to get the composition of major elements, trace elements, and Sr-Nd and Pb isotope of Cenozoic basalts from 10 locations in SE China. For the precise and accurate analysis of Lithium and Oxygen isotope, the in-situ SIMS and appropriated standards are applied for cpx phenocrysts.

Chapter 3 standard were 0.511870 ± 0.000016 (2σ). An NBS981 standard solution was repeatedly measured to correct the mass fractionation of the Pb isotope. Further details of the analytical techniques used for the Sr and Nd isotopes are given in [START_REF] Chen | Nd-Sr-Pb isotopes of Tengchong Cenozoic volcanic rocks from western Yunnan, China: evidence for an enriched-mantle source[END_REF].

The reported Sr and Nd isotopic ratios were normalized to 86 Sr/ 88 Sr = 0.1194 and 146

Nd/ 144 Nd = 0.7219 [START_REF] Thirlwall | Long-term reproducibility of multicollector Sr and Nd isotope ratio analysis[END_REF], respectively.

Sr and Nd isotopic compositions of all the XL samples, SC-1, BL-6, BL -7, BL-9, BL-11 and MX-11 were measured on a Thermo TRITON Plus TIMS and on a Neptune plus, MC-ICP-MS NEPTUNE Plus with an Aridus II Desolvating Nebulizer System to enhance the sensitivity, respectively, at CRPG (Centre de Recherches Petrographiques et Geochimiques) in Nancy, France. Approximately 100 mg of sample powder was digested with a mixture of HF-HNO3-HClO4 (a few drops) in a screw-top Teflon beaker for 3 days at 130°C and then evaporated to dryness. The residues were re-dissolved with HCl (6 N) at 110°C for 2 days and were evaporated again and then re-dissolved in HCl (2.5 N) before an approximately 10% solution was loaded on Sr. Spec cationexchange resin to separate Sr. Sr was then eluted from the resin and purified twice. The TRU. Spec resins were used to separate LREEs from the rest of the solution, and Nd was then eluted using LN. Spec resins. The measured 87 Sr/ 86 Sr ratios were corrected for mass fractionation by normalization to a 86 Sr/ 88 Sr ratio of 0.1194. The average value of the 87 Sr/ 86 Sr ratios in the NBS 987 standard analysis during the last 3 years was 0.710255 ± 0.000032 (2, n = 111) in CRPG. 143 Nd/ 144 Nd ratios were normalized to a 146 Nd/ 144 Nd ratio of 0.7219 to correct for mass fractionation. Both the JNdi-1 and La Jolla standards were used to control the reproducibility and accuracy of the measurements during each session. Average values of 143 Nd/ 144 Nd of the JNdi-1 and La Jolla standards during the last 3 years were 0.512082 ± 0.000027 and 0.511831 ± 0.000028 (2), respectively. The 143 Nd/ 144 Nd ratios were corrected relative to 0.511852, which is the accepted value of the La Jolla standard.

Approaches to measure the water content of basalts

For the first two aims of this thesis, precise and accurate measurements of the water content of magma are critical. The H2O contents of the "initial" basaltic magmas can be approached by the direct measurement of melt inclusions captured by phenocrysts of basalts and of the quenched un-degassed glass for some kinds of basalts, or the indirect way recovered from the H2O content of phenocrysts and the partition coefficients of H2O between phenocrysts and basaltic melts. The most conventional Chapter 3 method to measure the water contents of magma are quenched un-degassed glass, special for some deep sea basalts, such as MORBs (Michael, 1995;[START_REF] Dixon | Volatiles in alkalic basalts from the North Arch Volcanic Field, Hawaii: extensive degassing of deep submarine-erupted alkalic series lavas[END_REF], as well as the melt inclusions captured by early crystallized phenocrysts [START_REF] Dixon | Volatiles in basaltic glasses from Loihi Seamount, Hawaii: evidence for a relatively dry plume component[END_REF]Sobolev and Shimizu, 2000). However, due to the restriction of the eruption and the preservation condition for the natural samples, the proper objects are rather limited. Quenched un-degassed glass is more suitable for the deep sea basalts, such as MORBs, seamount basalts which erupt under deep sea, fast cold down under high pressure. Nevertheless, the continental basalts do not only lack the glass, but also generally have undergone serious degassing and water loss, because of low erupting pressure. The water contents measured from inclusions are challenged by the measurement of apparatus and the preservation of water in early phenocrysts. SIMS and FTIR are the most common instruments used to analyze the water content of inclusions. The analysis of FTIR requires large enough size for inclusion bigger than 100µm atleast, if the thickness of double-polished section is considered. The careful blank control, instrumental corrections, proper standards and difficult sample preparation for the analysis of melt inclusion are the nightmare for most laboratories.

The most important is that the diffusion of water is too fast between the melt inclusions and the host minerals. It is too hard to preserve its initial water information for the melt inclusions, unless the melt inclusions are big enough and the cooling of the lava is fast enough [START_REF] Chen | The rate of water loss from olivinehosted melt inclusions[END_REF][START_REF] Gaetani | Rapid reequilibration of H2O and oxygen fugacity in olivine-hosted melt inclusions[END_REF], specially for Cenozoic basalts in SE China. Therefore, the direct measurement for quenched un-degassed glass and captured melt inclusion is an impractical analysis plan for our study areas and objects. [START_REF] Wade | Prediction of magmatic water contents via measurement of H2O in clinopyroxene phenocrysts[END_REF] used an Al-IV-dependent partitioning relationship to predict the magmatic water content from direct measurements of H2O content in clinopyroxene phenocrysts (Fig. 3-1). All the phenocrysts in basalts are NAMs such as cpx, ol, and pl.

O' Leary et al. (2010) measured and pooled the D cpx/melt for H2O values together (Aubaud et al., 2004(Aubaud et al., , 2008;;Hauri et al., 2006;[START_REF] Hirschmann | Dehydration melting of nominally anhydrous mantle: The primacy of partitioning[END_REF], then offered an equation of D cpx/melt based on the chemical compositions of the cpx phenocrysts, which are suitable for the wide range of the composition of the basaltic melts. The equation provided by [START_REF] O'leary | The effect of tetrahedral Al 3+ on the partitioning of water between clinopyroxene and silicate melt[END_REF] based on the chemical compositions of the cpx phenocrysts can be applied on the melts of various Al2O3 contents (from 0.2 % to 19 %, i.e. including

Al-free to high-Al basaltic melt) at 1.5 GPa pressure and 1275°C temperature, whose error is believed less than 15% (equation 10 in their paper). However, the widely suitable equation of D pl/melt H2O is still not available. Meanwhile, the water in ol grains Chapter 3 is hard to be preserved, due to the very fast H loss caused by decompression, during the magma ascent [START_REF] Li | Water contents in mantle xenoliths from the Colorado Plateau and vicinity: Implications for the mantle rheology and hydration-induced thinning of continental lithosphere[END_REF]Peslier et al., 2015). On the other hand, the uncertainty of applying the integral specific absorption coefficient for cpx (7.09 ppm-1 cm-2, [START_REF] Bell | Quantitative analysis of trace OH in garnet and pyroxenes[END_REF]) was expected to be <10%, with higher accuracy than that of pl.

Due to the relatively high accurate and available D cpx/melt , the cpx is one of the best approach to reversely calculate the magmatic water content from the H2O contents of phenocrysts and the partition coefficients of H2O between phenocrysts and basaltic melts. [START_REF] Wade | Prediction of magmatic water contents via measurement of H2O in clinopyroxene phenocrysts[END_REF] have tested their approach to calculate magmatic water content by the water content in phenocrysts from four arc volcanoes (Galunggung, Irazu, Arenal, and Augustine), compared with the results measured in olivine-hosted melt inclusions (Fig. 3-1). Both of the average and maximum magmatic H2O contents calculated by the cpx phenocrysts have the error less than 15% of the H2O contents measured from the melt inclusion for most of the samples.

Comparison of cpx and olivine-hosted melt inclusions H2O and Mg#. Figure 4 of [START_REF] Wade | Prediction of magmatic water contents via measurement of H2O in clinopyroxene phenocrysts[END_REF]. The error bar is 17%.

Chapter 3

H2O contents in cpx phenocrysts measured by FTIR

The H2O contents (by weight) of cpx phenocrysts were measured on a Nicolet 5700 FTIR spectrometer coupled with a Continuμm microscope at CMME-CAS, at USTC (Fig. 3-2). The shift of the integral areas over absorption bands during analysis monitored by augite megacrysts standard T3 from Cenozoic basaltic volcano, in Jiangsu

China is less than 4% (Fig. 3-3). Additional details of the analytical techniques are described in Xia et al. (2013) and Liu et al. (2015). A modified Beer-Lambert law (cH2O=A/(I×t)) was used to calculate the H2O content of cpx phenocrysts, where cH2O is the content of water (H2O ppm wt.), A is the total integral absorption of -OH bands (cm - Chapter 3

The instrument shift during analysis monitored by augitic megacryst standard T3 from Cenozoic basaltic volcano, in Jiangsu China. The shift of the integral areas over absorption bands of T3 is less than 4%.

Chemical compositions of cpx phenocrysts by EPMA

The major element contents of the cpx phenocrysts were analyzed using a Shimadzu Electron Probe Micro analyzer (EPMA 1600) at CMME-CAS, in USTC, under the following operating conditions: 15 kV accelerating voltage, 20 nA beam current and 1 µm beam diameter. Natural minerals and synthetic oxides were used as standards, and a program based on the ZAF procedure was used for data correction.

Analyzed points of the cpx phenocrysts were set within the corresponding FTIR analyzed region. Reproducibility is <1% for elements with concentrations >5% and <3%

for elements with concentrations >1%.

The profiles of major element contents of cpx phenocrysts measured after SIMS analysis for Lithium were analyzed using a Cameca SX100 electron microprobe at the Service Commun de Microscopies Electroniques et de Microanalyses X (SCMEM), University of Lorraine (France). The operating conditions were set at an accelerating voltage of 20 kV and a beam current of 20 nA. Alkaline elements were analyzed first to minimize errors due to element migration with counting times of 10 s on peak and 5 s for backgrounds. For other elements, counting times were 20 s on peak and 10 s for backgrounds. Analyzed points of the cpx phenocrysts were set close to the corresponding SIMS analyzed points. Reproducibility is <1% for elements with concentrations >5% and <3% for elements with concentrations >1%. The mean of their data source. (Su et al,20 15) b This total ion content are obtained by SAR..\If Ûl CRPG. Mg# are re-calculated by the reference materials, wlùch may not as same as the c values Ûl their source.

In-situ Li and O isotopic analysis of cpx phenocrysts

Secondary ion mass spectrometry

The SIMS consists of a primary ion source, a mass spectrometer and a secondary ion detection system (Fig. 3-4), which can quantitatively detect in situ all the elements (especially for light elements, e.g., H, Li, Be, B) reaching detection limits of part per million. The primary ions generally are O -or Cs + ions for geological materials. The O - source is usually used to generate the positive ions such as Lithium, whereas the Cs + source is used to generate the negative ions, such as Oxygen. Primary ions bombard the sample surface with high energy (4 to 20 keV) after focused by a series of electrostatic lenses at proper intensity and beam spot size. The energy of primary ions are transferred to samples. Some atoms obtained energy will break away from sample surface, as secondary ions (Fig. 345) and are accelerated by an electric field (Fig. 34). The secondary ions are commonly complex, due to uncertainty of the breaking of sample matrix. Then the secondary ions are transferred to mass spectrometry and go through the entrance slit. The SIMS has high resolution mass spectrometer to distinguish different ions and capture out interesting information. The collectors of SIMS usually are Faraday cups and single-ion detectors (electron multiplier), which are used to collect ions with intensities higher and lower than 10 6 cps, respectively. Here a noun of 'dead time' is introduced to describe the resetting ability of ion counting systems. The dead time refers to the time after each event during which the system cannot record another event, in the detection systems (SIMS) used to record discrete events, such as electron multiplier. The ion counting systems will lose the counts of secondary ions if two pulses of secondary ions arrive at the detector almost simultaneously before the detector are reset [START_REF] Deloule | Hydrogen isotope heterogeneities in the mantle from ion probe analysis of amphiboles from ultramafic rocks[END_REF]. Each element and isotope in different analytical session have its own dead times [START_REF] Zinner | Characterization of electron multipliers by charge distributions[END_REF], therefore, "dead time" will be measured at the beginning of every analytical session. The in situ ion microprobe analyses have been performed on Cameca IMS-1270 and IMS-1280 at CRPG-CNRS in Nancy, France (Fig. 3456). Chapter 3

In-situ δ 18 O analysis

The traditional analytical protocols of Oxygen are usually constrained on the analysis level of bulk rock powder or single mineral grain. The meaning of whole rock δ 18 O data has ambiguities. The whole rock δ 18 O-values have been documented more subtle and resolvable for differences among different types of basaltic lavas and minerals, by later laser-based extraction analysis methods based on small amounts of separated mineral phases (e.g. [START_REF] Eiler | Oxygen isotope constraints on the sources of Hawaiian volcanism[END_REF][START_REF] Eiler | Oxygen isotope geochemistry of oceanic arc lavas[END_REF][START_REF] Dorendorf | Hydrated sub-arc mantle: a source for the Kluchevskoy volcano, Kamchatka, Russia[END_REF][START_REF] Cooper | Oxygen isotope evidence for the originof enriched mantle beneath the mid-Atlantic ridge[END_REF][START_REF] Bindeman | Volcanic arc of Kamchatka: a province with high-δ 18 O magma sources and large scale 18 O/ 16 O depletion of the upper crust[END_REF][START_REF] Bindeman | Oxygen isotope evidence for slab melting in modern and ancient subduction zones[END_REF]. The limited spatial resolution of Oxygen traditional analytical protocols constrain the measurement of basalt phenocrysts in situ to study the evolution process of magma in different stages. SIMS analysis show unique superiority of spatial resolution for analysis of isotope and spatial resolution in microscale mineral grain samples. To sputter the secondary negative ions ( 16 O -and 18 O -), a primary beam of Cs + was used at intensities ranging from 8 to 15nA, with a diameter of about 20 μm. An electron flood gun incidence was used to compensate sample charging. The negative secondary ions of 18 O -and 16 O -counting rates range from 1.2×10 9 to 2×10 9 cps and 4×10 6 to 5×10 6 cps, mostly depending on the intensity of the primary beam. The oxygen secondary ions were accelerated through 10 kV and counted by two off-axis Faraday cups, L02 for 16 O - and H1 for 18 O -in multi-collection mode. The mass resolution was set at 3000 (M/ΔM) to separate isobaric 17 OH -or H2 16 O -from 18 O -and an energy slit were opened at 45 eV without energy offset. To elevate reproducibility, before each analysis of cpx grain, the primary beam and electron beam were tuned carefully, and then the secondary beam were automatically centered again by SIMS, before each measurement. Each analysis session contained a pre-sputtering of 60 s, automated centering and 40 cycles with the counting times of 4.96 s for 16 O -and 18 O -. The internal precision for one spot analysis was usually better than 0.1‰ (2r). Oxygen isotopic composition is expressed as δ 18 O, relative to Vienna Standard Mean Ocean Water (VSMOW, [START_REF] Gonfiantini | Standards for stable isotope measurements in natural compounds[END_REF]), i.e. To calibrate the offset between the true values and the measured values, caused by instrumental mass fractionation (IMF), defined as ∆IO (=δ 18 OSIMS-δ 18 Oreference). ∆IO consists of matrix effect and the drift of instrument. In chemical analysis, matrix refers to the components of a sample other than the analyte of interest (IUPAC, 1997), which can considerably effect on the conducted analysis and the obtained result quality. Such effects are called matrix effects. The effect which is usually considered correlation to the compositions of cpx, suggested by [START_REF] Gurenko | Magma ascent and contamination beneath one intraplate volcano: evidence from S and O isotopes in glass inclusions and their host clinopyroxenes from Miocene basaltic hyaloclastites southwest of Gran Canaria (Canary Islands)[END_REF]. A series of cpx megacrysts hosted by basanites in Nushan, Eastern China are used, including NSH2, NSH5, NSH8 and NSH14, whose oxygen isotopic ratios were obtained by the laser fluorination method, reported by Xia et al. (2004), listed in Table 3-3, and whose chemical composition is very close to those of the cpx phenocrysts analyzed in this study. The IMF correction of samples analysis is made up by two parts: 1) the matrix effect calculated by the Mg# of unknown sample and the matrix effect line built by cpx standards; 2) the drift of instrument, which is calibrated by the δ 18 O difference between cpx standards on the sample holder and the same one on the holder of standards. The δ 18 O IMF of the Nushan standards decreases with the Mg# decreasing, and the R 2 usually are better than 0.9 (Fig. 34567). Meanwhile, to trace a possible instrumental drift during analysis, a reference standard cpx NSH9 or NSH5 was fixed on every section Chapter 3 and was measured repeatedly per 2-4 cpx grain analyses (i.e. 5-15 analyses of points).

The raw analytical results of the standard (NSH9 or NSH5) and the Fujian cpx phenocrysts are listed in Table 3-4. The δ 18 O IMF of replicate analyses of Nushan standard on several sections are presented in Fig. 3-8, indicating the SIMS drift is limited during every analysis session. The general combined internal precision and external accuracy is better than 0.5‰ (2SD) for each cpx grain.

The relation between IMF and the Mg# of cpx standards for Oxygen

Chapter 3

The duplicate analysis of the cpx standards for Oxygen isotope

In-situ Li isotope composition

An O -primary beam was accelerated at 13 kV, with an intensity ranging from 8 to 15 nA, to sputter the secondary positive ions of 7 Li + and 6 Li + . The elliptical spot area diameter was approximately 20-30 μm. The secondary ions of Li were accelerated through 10 kV and were counted using an electron multiplier in mono counting mode.

The counting rates of 7 Li + and 6 Li + depended on the Li contents of samples and the intensity of the primary beam. The mass resolution was set at 1100 (M/ΔM) to separate the isobaric inference of 6 LiH + on 7 Li + . After a pre-sputtering of 120 s, 30 cycles were accumulated with the counting times of 16 s for 6 Li + , 4 s for 7 Li + and 4 s for background at the 5.8 relative atomic mass. Li isotopic composition is expressed as δ 7 Li, relative to the National Institute of Standards L-SVEC ( 7 Li/ 6 Li=12.0192, [START_REF] Flesch | A secondary isotopic standard for 6Li/7Li determinations[END_REF]), i.e.

δ 7 Li = [( 7 Li/ 6 Li)sample/( 7 Li/ 6 Li)L-SVEC -1]×1000 (‰).

The 7 Li/ 6 Li variations of magmatic phenocrysts are noticed to deduce the cooling history in their parent magmas, and to infer the mantle source processes and the feature of mantle reservoirs. The high spatial resolution of SIMS allows to measure intragranular profiles of Li concentration and isotope to infer diffusion-process and the variations of surroundings. The SIMS results of unknown samples calibrated by known standards are different from their true values, when the compositions of unknown samples are not close to used standards [START_REF] Bell | Lithium isotope analysis of olivine by SIMS: Calibration of a matrix effect and application to magmatic phenocrysts[END_REF][START_REF] Gurenko | Magma ascent and contamination beneath one intraplate volcano: evidence from S and O isotopes in glass inclusions and their host clinopyroxenes from Miocene basaltic hyaloclastites southwest of Gran Canaria (Canary Islands)[END_REF]. The matrix effects are defined as ∆ILi =δ 7 LiSIMS-δ 7 Lireference [START_REF] Decitre | Behavior of Li and its isotopes during serpentinization of oceanic peridotites[END_REF]. In general, Chapter 3 ∆ILi varies due to change of the instrumental settings or aging of electron multiplier ages between different analytical sessions [START_REF] Deloule | Isotope fractionation, energy distribution and H + emission processes from hydroxylated minerals[END_REF]. [START_REF] Decitre | Behavior of Li and its isotopes during serpentinization of oceanic peridotites[END_REF] and some other studies considered the matrix effect of Li in SIMS is negligible [START_REF] Barrat | Lithium behavior during cooling of a dry basalt: An ion-microprobe study of the lunar meteorite Northwest Africa 479 (NWA 479)[END_REF][START_REF] Beck | Li isotopic variations in single pyroxenes from the Northwest Africa 480 shergottite (NWA 480): a record of degassing of Martian magmas?[END_REF][START_REF] Beck | Diffusion induced Li isotopic fractionation during the cooling of magmatic rocks: The case of pyroxene phenocrysts from nakhlite meteorites[END_REF], and the IMF of Li in cpx can use the calibration from any kind of reference standard, such as glass. Later studies suggested possible matrix effect in the analysis of Li isotope by SIMS [START_REF] Kasemann | Lithium isotope composition of basalt glass reference material[END_REF]Herig et al., 2004;[START_REF] Jeffcoate | Li isotope fractionation in peridotites and mafic melts[END_REF]. However, the correlation between the composition of cpx and the matrix effect for analysis by SIMS remain mystery [START_REF] Decitre | Behavior of Li and its isotopes during serpentinization of oceanic peridotites[END_REF][START_REF] Su | Potential Orthopyroxene, Clinopyroxene and Olivine Reference Materials for In Situ Lithium Isotope Determination[END_REF]. The various matrix effect usually are considered to link to the compositions of samples for Li isotopic system, like that for ol. [START_REF] Bell | Lithium isotope analysis of olivine by SIMS: Calibration of a matrix effect and application to magmatic phenocrysts[END_REF] and [START_REF] Su | Potential Orthopyroxene, Clinopyroxene and Olivine Reference Materials for In Situ Lithium Isotope Determination[END_REF] studied the olivine and found that the matrix effect have a relationship to its composition, such as Mg# (Mg# = MolMg / (MolMg + MolFe)*100). A series of standard minerals from mantle xenoliths, described in detail by [START_REF] Su | Potential Orthopyroxene, Clinopyroxene and Olivine Reference Materials for In Situ Lithium Isotope Determination[END_REF] and [START_REF] Xiao | Large Lithium Isotopic Variations in Minerals from Peridotite Xenoliths from the Eastern North China Craton[END_REF], are used to calibrate the offset between the true values and the measured values. The Li concentrations are calculated by comparing the average rates of the 7 Li cps (counting per second) of standard, because the sputtered 7 Li of specimens can be regarded as being divided by an average ion yield of these standards. The estimated precision of such procedure should be better than 20%. The replicate analyses results for Lithium isotopic data of the standard cpx are listed in Table 3-2 and plotted in Fig. 3456789.

The duplicate analysis of the cpx standards for Lithium isotopic data

Chapter 3

The Li concentration and isotopic composition, and major compositions of 06JY06 cpx and 06JY29 cpx follow those in [START_REF] Su | Potential Orthopyroxene, Clinopyroxene and Olivine Reference Materials for In Situ Lithium Isotope Determination[END_REF], while the Li concentration and isotopic composition, major compositions of CLB-25 cpx and CLB-35 cpx were measured by MC-ICP-MS and SARM/EMP in CRPG, the reference values of standard in detail are presented in

NSH-cpx-b@ 1 6.5 0. 1 1.1 0.2 NSH-cpx-b@2 6.4 0.1 1.0 NSH-cpx-b@3 6.1 0.1 0.7 NSH-cpx-b@4 6.5 0. 1 1.2 NSH-cpx-b@ 5 6.8 0. 1 1.5 NSH-cpx-b@ 6 6.1 0. 1 0.7 NSH-cpx-b@ 7 6.6 0.1 1.3 NSH-cpx-b@8 6.7 0.1 1.4 NSH-cpx-b@ 9 6.5 0. 1 1.1 NSH-cpx-b@ 10 6.4 0. 1 1.0 NSH-cpx-b@ 11 6.5 0.1 1.2 4 NSH-cpx-f@ 1 6.2 0.1 0.4 0.2 NSH-cpx-f@ 2 6.1 0. 1 0.2 NSH-cpx-f@ 3 6.2 0. 1 0.3 NSH-cpx-f@4 5.8 0.1 -0.1 NSH-cpx-f@ 5 6.5 0.1 0.6 NSH-cpx-f@ 6 5.8 0. 1 0.0 NSH-cpx-f@ 7 6.4 0. 1 0.5 NSH-cpx-f@8 6.2 0.1 0.3 NSH-cpx-f@9 6.3 0.1 0.4 NSH-cpx-f@ 10 6.2 0.1 0.3 NSH-cpx-f@ 11 6.1 0. 1 0.2
Chapter 4 Following the results, the best index to calibrate matrix effect in cpx for Li isotope analysis by SIMS is Si or Mg#.

Calibration of matrix effect in

The correlation between the Si (afu) raw data vs. IMF for Lithium isotope in each session.

Chapter 4

The matrix effect for Li isotope analysis by SIMS for cpx increase up to 1.2‰ per Mg# increasing, or increase up to 5.7‰ per 0.1 afu of Si increasing. It demonstrates that before each analysis by SIMS for Li isotope of cpx unknown samples, the matrix effect relevance to the cpx composition should be evaluated. Despite, [START_REF] Bell | Lithium isotope analysis of olivine by SIMS: Calibration of a matrix effect and application to magmatic phenocrysts[END_REF] suggested a considerable matrix effect for the Li isotope analysis of olivine, the matrix effect for the Li isotope analysis of cpx have rarely been discussed. Mostly in previous studies [START_REF] Barrat | Lithium behavior during cooling of a dry basalt: An ion-microprobe study of the lunar meteorite Northwest Africa 479 (NWA 479)[END_REF][START_REF] Beck | Li isotopic variations in single pyroxenes from the Northwest Africa 480 shergottite (NWA 480): a record of degassing of Martian magmas?[END_REF][START_REF] Beck | Diffusion induced Li isotopic fractionation during the cooling of magmatic rocks: The case of pyroxene phenocrysts from nakhlite meteorites[END_REF][START_REF] Jeffcoate | Li isotope fractionation in peridotites and mafic melts[END_REF][START_REF] Xiao | Large Lithium Isotopic Variations in Minerals from Peridotite Xenoliths from the Eastern North China Craton[END_REF], even the unknown cpx samples have large chemical composition variation, only one or limited standards are determined to calibrate the matrix effect of analysis by SIMS. Meanwhile, the analysis result of the same cpx standard by SIMS display considerable difference in different sections (Fig. 3456789). In the studies of [START_REF] Bell | Lithium isotope analysis of olivine by SIMS: Calibration of a matrix effect and application to magmatic phenocrysts[END_REF] The correlation between mean Ca (afu) vs. IMF for Lithium isotope in each session.

Applications of Li calibration

Li content and isotope results of cpx grains

To Chapter 4

The 5-4-8 and 10-0-17 are entire cpx phenocrysts without xenocryst core, as type II cpx phenocryst. All the analysis points have almost same Mg# except the outermost rim of 10-0-17 , and limited variation of Li content respectively (Table 4-2, Fig. 4-10) within the range of error for SIMS analysis method (Chapter 3).

However, the δ 7 Li 10-0-17 are not totally homogeneous from core to rim. The 5-4-8

show almost same δ 7 Li either in the core or rim, as shown in Fig. 4-10 (7-10‰ in Mg# calibration), and share the similar Mg#, Si, and Li content (3-5ppm) from core to rim.

The 10-0-17 grain shows more complex δ 7 Li profile from core to rim than the 5-4-8 grain: the core of cpx phenocrysts have relative high Mg#, as well as the lower Mg# are observed in mantle and edge of cpx phenocryst grain (Table 4-

Difference between the calibration of Mg# and Si

The calibration of cpx phenocrysts from Si have relative lower δ 7 Li unknown, corrected than the calibration of cpx phenocrysts from Mg# (Table 4- 4-3). This suggests that the unknown samples have relatively lower Si or higher Al (IV) than the standards. It should be noted that the Si-Al and Mg-Fe is not the same replacing process in pyroxene.

and Mg 2+ =Fe 2+ (4-7)

Mg 2+ + Si 4+ =Al 3+ (VI) + Al 3+(IV) or Mg 2+ + Si 4+ =Fe 3+(VI) + Al 3+(IV) (4-8)

Unlike olivine, 4-7 is the unique replacement mechanism formula, 4-7 and 4-8

Chapter 4

formulas are the two most common replacement mechanism in clinopyroxeney and can take place in clinopyroxeney at the same time. Meanwhile the Fe 3+ also can enter into the octahedral voids (Morimote, 1988). The 4-7 and 4-8 do not always take place at the Chapter 4

The profile of Mg# Li content and Li isotope for type II clinopyroxeney phenocryst.

Discussion of the variation of Li content and Li isotope

The 6 Li diffuses faster than the 7 Li during diffusion, the difference of diffusion speed will result in the fraction of 6 Li and 7 Li. In essence, the physicochemical condition variation result in the fractionation of Li [START_REF] Richter | Lithium isotope fractionation by diffusion in minerals. Part 1: Pyroxenes[END_REF] and diopside at 2.0±0.2, independent of temperature. The pl/cpx DLi range from 0.08 to 0.6 when the temperature ranges from 950 to 1200 °C [START_REF] Coogan | Rates of hydrothermal cooling of new oceanic upper crust derived from lithium-geospeedometry[END_REF]. Therefore, the D Li ol/melt = 0.4, D Li cpx/melt =0.2, and D Li pl/melt =0.02 are assumed for crystallization calculation. Meanwhile, the crystallization ratios of ol, cpx and pl are assumed for 3:2:1 and 1:1:0 respectively. The Drock is 0.27 and 0.3 respectively. The calculation results are listed in Table 4-3 for F=0.01, 0.02, 0.05, 0.10, 0.15, 0.2 and 0.25, which is the degree of crystallization.

The content of Li and Mg# are calculated below:

Cl=C0/[D*F+(1-F)] (4-9) Cs= D*C0/[D*F+(1-F)] (4-10)
For "Equilibrium Crystallization" model.

Cl=Co*(1-F) D-1 (4-11) Cs= D*Co*(1-F) D-1 (4-12)
For "Fractional Crystallization" model.

The Li content of cpx phenocrysts will increase no more than 20% compared with the initial cpx phenocryst, when the degrees of crystallization of magma are below 0.2 (Table 4- more than 1‰ [START_REF] Tomascak | The absence of lithium isotope fractionation during basalt differentiation: new measurements by multicollector sector ICP-MS[END_REF]. Meanwhile, the fractionation of Li also appears in the mantle and core of the cpx phenocryst of 10-0-17, where there is no significant difference of Mg#, arguing against magma evolution, including fractional crystallization, magma mixture, and crust assimilation. The "W"-like δ 7 Li profile in the 10-0-17 cpx and the high Li content in its rim (Fig. 4-10) is similar to the Li diffusion pattern reported by [START_REF] Beck | Diffusion induced Li isotopic fractionation during the cooling of magmatic rocks: The case of pyroxene phenocrysts from nakhlite meteorites[END_REF] and the calculation in [START_REF] Richter | Lithium isotope fractionation by diffusion in minerals. Part 1: Pyroxenes[END_REF]. The δ 7 Li fractionation is so limited dissent with the result of fractional crystallization [START_REF] Beck | Li isotopic variations in single pyroxenes from the Northwest Africa 480 shergottite (NWA 480): a record of degassing of Martian magmas?[END_REF]. [START_REF] Richter | Lithium isotope fractionation by diffusion in minerals. Part 1: Pyroxenes[END_REF]

Conclusion

Chapter 4

(1) The composition related matrix effect for the analysis of Lithium isotope by SIMS are confirmed based on the analysis result of the known cpx standards.

(2) The Si and Mg# are the most suitable index to correct the IMF of Li isotope, other than Al, Ti, Ca, or Cr.

(3) The Si and Mg# calibration may result in systematic difference of the corrected Li isotope, due to the compositional difference between cpx standards and unknown samples. This two calibrations can get the same result and conclusion in single grain, but comparison with the corrected results by different calibrations among different grains cannot be used together simply.

(4) The change of Li content and Li isotopic data can be used to distinguish the difference between xenocrysts and phenocrysts, as well as the Li diffusion after cpx crystallization in basalts. 5-4-8b@ l 5-4-8b@2 5-4-8b@3 5-4-8b@4 5-4-8b@5 5-4-8b@6 5-4-8b@7 5-4-8b@8 5-3-10a@06 5-3-10a@l05 5-3-10a@04 5-3-10a@03 5-3-10a@02 5-3-!0a@l 5-3-10a@07 5-3-10a@08 5-3-10a@09 5-3-!0a@ IO 5-3-!0a@ l l 5-11-7a@l 5-11-7a@2 5-ll-7a@3 5-ll-7-2a@ l 5-11-7-23@2 5-11-7-23@3 5-11-7-23@4 5-11-7-23@5 10-0-17 -0@ 1 10-0-17 -0@02 10-0-17 -0@03 10-0-17 -0@04 10-0-17-0@05 10-0-17 -0@06 10-0-17-0@07 10-0-17 -0@08 10-0-17 -0@09 10-0-17-0@ 10 10-0-17-0@ 11 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.8

.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.
1.8 1.8 1.8 1.9 1.9 1.9 1.9 1.9

1.8 1.9 1.9 1.9 1.9 1.8 1.9 1.9 1.9 1.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9

-74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9

-74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9 -74.9

Bulk-rock major and trace elements

Twenty-three samples are plotted on a total alkali versus silica (TAS) diagram (Fig.

5-1)

. All the samples have low LOI (loss on ignition) < 2.3%, and most have LOI <1.5%.

The Zhejiang basalts can be subdivided into two groups with different ages, forming two distinct positive correlations. Group 1: the XL samples, consist of strongly alkaline rocks with older ages (26-24 Ma), have lower SiO2 (<43%) and higher total alkalis (Na2O+K2O, 5.0-7.5%), they lie in the field of basanite. Meanwhile, Group 2: the GP and SC samples are composed of weakly alkaline rocks with younger ages (10-5 Ma), have higher SiO2 and lower total alkalis and fall in the range from basanite to basalt.

Fig. 5-1 shows major oxide contents plotted against MgO as the differentiation index.

In the plots of SiO2, Al2O3 and MnO vs. MgO (Fig. 5-2 a-c), a coherent trend is observed from Group 1 through Group 2. In the plots of CaO, TiO2, Na2O, Fe2O3 T , and K2O vs.

MgO (Fig. 5-2 d-h), the Group 2 samples display continuous linear trends marking their cogenetic origin. Meanwhile, the Group 1 basanites do not show a coherent trend with the Group 2 samples, possibly implying a different source composition. In addition to lower SiO2 and higher total alkali content (Fig. 5-1), the Group 1 basalts have lower Al2O3 (<10%) and higher MgO (>12%) content than the Group 2 samples (Fig. 5-2a and 3c).

Chondrite-normalized rare earth element (REE) patterns in the Zhejiang basalts show similar characteristics, with light rare earth element (LREE) enrichment (Fig. 5-3). Group 1 samples have higher concentrations of REEs than Group 2 samples (Fig. 5-3). The (La/Yb)N ratios (where N represents chondrite-normalized, [START_REF] Sun | Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes[END_REF])) of the Group 1 samples (31-37) are higher than those of the Group 2 samples (10-16), as are (Sm/Yb)N and (La/Sm)N. In the Group 2 samples, we observe a slightly positive Eu anomaly (EuN/Eu*=1.04-1.19, Eu*=(Eu)N/((Sm)N*(Gd)N) 1/2 ).

The EuN/Eu* values of Group 1 samples range from 1.00 to 1.05 (Fig. 5-3).

TAS plots of the Zhejiang basalts. Classification of rock after Le [START_REF] Bas | A Chemical Classification of Volcanic Rocks Based on the Total Alkali-Silica Diagram[END_REF], and line separating the alkali basalts and tholeiites from [START_REF] Macdonald | Chemical Composition of Hawaiian Lavas1[END_REF].

In the primitive mantle-normalized extended trace element diagrams (Fig. 5-4), all of the samples show OIB-like patterns (i.e., enrichment of large ion lithophile elements and high field strength elements). The Group 1 samples show strongly positive anomalies in Nb and Ta, slightly positive anomalies in Sr and negative anomalies in U, K, Pb, Hf and Ti (Fig. 5-4). Most of the Group 1 samples are characterized by low Ba/Th (67-92) and Rb/Ba ((Rb/Ba)n<1, where n represents primitive mantle normalization [START_REF] Sun | Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes[END_REF])), high Ce/Pb (28-44) and high Nb/Ta (17.5-20.3) , as shown in Fig. 5-4. The Group 2 samples also exhibit positive anomalies in Nb and Ta and negative anomalies in U and Pb, but do not show pronounced anomalies in K, Ti and Hf. The Group 2 samples show stronger positive Sr and negative U anomalies than the Group 1 samples. The Group 2 samples are also characterized by higher (Rb/Ba)n (1.13-1.69) ratios and lower Ce/Pb (17-28) ratios than the Group 1 samples (Fig. 5-4). The Nb/Ta (18.3-20.0) ratios of the Group 2 samples share the same range as those of the Group 1 samples. The abundances of incompatible elements are higher in general in the Group 1 samples than those in the Group 2 samples.

Major element oxides vs. MgO in the Zhejiang basalts.

75

55 50 A A~ -45 ~ 0 i o"' 40 ~ <tl •:i • • •• ... êi)

35

• XL (Group 1) () GP (Group 2) A SC (Group 2)

30 15 12 ~ 1ft -~ 9 0 ! on 6 N ,.. ••• ~ < 3 0 3.2 ~ 0 2.8 ~ N / • 1 • • • 0 • i= 2.4 • 1 • 2.0 16 15 -~ 0 ! 14 on N Q) u..
;!!. 4 ! 0 i2 0 3 ~ 2 i 0 -L1 0 0 b .. , 4 ~, , A ~ d •/ '! ! "•• A A / • 1 f ~- ~~() ~ ~ a " h • • • • 1 ~A ...

Sr-Nd-Pb isotopic compositions

The bulk rock Sr-Nd-Pb isotopic data for the Zhejiang basalts are listed in Table 5-1 and plotted in Fig. 5-5. The Sr-Nd isotopic compositions are determined for both groups of samples and the Pb isotopic compositions only for the Group 2 samples. The Group 1 basanites show a limited range of 87 Sr/ 86 Sr (0.70366 to 0.70373) and 143 Nd/ 144 Nd (0.51289 to 0.51290; εNd(t) value approximately +5.0) ratios. [START_REF] Zou | Major, trace element, and Nd, Sr and Pb isotope studies of Cenozoic basalts in SE China: mantle sources, regional variations, and tectonic significance[END_REF] and [START_REF] Ho | 40 Ar/ 39 Ar dating and geochemical characteristics of late Cenozoic basaltic rocks from the Zhejiang-Fujian region, SE China: eruption ages, magma evolution and petrogenesis[END_REF] previously reported Sr-Nd-Pb isotopic data for XL basanites (Group 1 samples in this study) that were collected at the same locations and have similar geochemical compositions as of our samples. Their 87 Sr/ 86 Sr (0.70360 to 0.70370) and 143 Nd/ 144 Nd (0.51286 to 0.51290) ratios are in the same range as in our samples. Their Pb isotopic compositions of 206 Pb/ 204 Pb (~18.6), 207 Pb/ 204 Pb (~15.5), and 208 Pb/ 204 Pb (~38.5) for the basalts are therefore used in this work (Fig. 5-5b). The GP basalts have limited but moderately depleted 87 Sr/ 86 Sr (0.70326 to 0.70334) and 143 Nd/ 144 Nd (0.512960 to 0.513048; εNd(t) values of +6.3 to +8.0) ratios compared to those of the XL basanites. The SC alkali olivine basalts have relatively radiogenic 87 Sr/ 86 Sr ratios (0.70349 to 0.70367) and nonradiogenic 143 Nd/ 144 Nd ratios (0.51293 to 0.51296 (εNd(t) = +5.7 to 6.3)) compared to those of the GP samples. The plots of 87 Sr/ 86 Sr vs. 143 Nd/ 144 Nd ratios show a negative trend from DMM towards the EM components (Fig. 5-5a). The Group 2 samples have 206 Pb/ 204 Pb ratios of 18.4-18.5, 207 Pb/ 204 Pb ratios of 15.5-15.6, and 208 Pb/ 204 Pb ratios of 38.4-38.7. The Sr-Nd-Pb isotopic compositions of the Zhejiang basalts in general are, within the range of previously reported data for Cenozoic basalts from eastern China and within the mixing field of DMM and EMI/II [START_REF] Chen | Sources of Anfengshan basalts: Subducted lower crust in the Sulu UHP belt, China[END_REF][START_REF] Choi | Sr, Nd, Pb and Hf isotopic compositions of late Cenozoic alkali basalts in South Korea: Evidence for mixing between the two dominant asthenospheric mantle domains beneath East Asia[END_REF][START_REF] Fan | Petrogenesis and evolution of Quaternary basaltic rocks from the Wulanhada area, North China[END_REF]Guo et al., 2014;[START_REF] Ho | 40 Ar/ 39 Ar dating and geochemical characteristics of late Cenozoic basaltic rocks from the Zhejiang-Fujian region, SE China: eruption ages, magma evolution and petrogenesis[END_REF][START_REF] Ho | Late Cenozoic magmatic transitions in the central Great Xing'an Range, Northeast China: Geochemical and isotopic constraints on petrogenesis[END_REF][START_REF] Huang | Geochronology and geochemistry of Cenozoic basalts from eastern Guangdong, SE China: constraints on the lithosphere evolution beneath the northern margin of the South China Sea[END_REF][START_REF] Kuang | Petrogenetic evaluation of the Laohutai basalts from North China Craton: Melting of a two-component source during lithospheric thinning in the late Cretaceous-early Cenozoic[END_REF][START_REF] Kuritani | Intensive hydration of the mantle transition zone beneath China caused by ancient slab stagnation[END_REF][START_REF] Li | Geochemistry of Cenozoic basalts from the Bohai Bay Basin: Implications for a heterogeneous mantle source and lithospheric evolution beneath the eastern North China Craton[END_REF][START_REF] Sakuyama | Melting of dehydrated oceanic crust from the stagnant slab and of the hydrated mantle transition zone: Constraints from Cenozoic alkaline basalts in eastern China[END_REF][START_REF] Tang | Asthenosphere-lithospheric mantle interaction in an extensional regime: Implication from the geochemistry of Cenozoic basalts from Taihang Mountains, North China Craton[END_REF][START_REF] Wang | Temperature, Pressure, and Composition of the Mantle Source Region of Late Cenozoic Basalts in Hainan Island, SE Asia: a Consequence of a Young Thermal References Mantle Plume close to Subduction Zones[END_REF]Wang et al., 2013;[START_REF] Wang | Geochemical constraints on the nature of mantle source for Cenozoic continental basalts in east-central China[END_REF][START_REF] Xu | Role of lithosphereasthenosphere interaction in the genesis of Quaternary alkali and tholeiitic basalts from Datong, western North China Craton[END_REF]Xu et al., 2012a;Xu et al., 2012b;[START_REF] Yan | Cenozoic alkali basalts from Jingpohu, NE China: The role of lithosphere-asthenosphere interaction[END_REF][START_REF] Zeng | Crust recycling in the sources of two parallel volcanic chains in Shandong, North China[END_REF]Zhang et al., 2002a;[START_REF] Zhang | Geochemical evidence for interaction between oceanic crust and lithospheric mantle in the origin of Cenozoic continental basalts in east-central China[END_REF][START_REF] Zhang | The genesis of Cenozoic basalts from the Jining area, northern China: Sr-Nd-Pb-Hf isotope evidence[END_REF]Zhang et al., 2002b;[START_REF] Zhao | Geochemistry of Quaternary basaltic lavas from the Nuomin volcanic field, Inner Mongolia: Implications for the origin of potassic volcanic rocks in Northeastern China[END_REF][START_REF] Zou | U-Th isotopes in Hainan basalts: Implications for subasthenospheric origin of EM2 mantle endmember and the dynamics of melting beneath Hainan Island[END_REF][START_REF] Zou | U-Th systematics of dispersed young volcanoes in NE China: Asthenosphere upwelling caused by piling up and upward thickening of stagnant Pacific slab[END_REF][START_REF] Zou | Constraints on the origin of historic potassic basalts from northeast China by U-Th disequilibrium data[END_REF][START_REF] Zou | Major, trace element, and Nd, Sr and Pb isotope studies of Cenozoic basalts in SE China: mantle sources, regional variations, and tectonic significance[END_REF] , as shown in Fig. 5-5b. et al. (2003) and [START_REF] Zou | Major, trace element, and Nd, Sr and Pb isotope studies of Cenozoic basalts in SE China: mantle sources, regional variations, and tectonic significance[END_REF]). Approximate compositions for isotopic mantle endmember components (named DMM, HIMU, EM I, and EM II) obtained from a previous study [START_REF] Workman | Major and trace element composition of the depleted MORB mantle (DMM)[END_REF][START_REF] Zindler | Chemical geodynamics[END_REF]) are also shown. Isotopic compositions of Mariana trench sediments [START_REF] Plank | The chemical composition of subducting sediment and its consequences for the crust and mantle[END_REF] and ancient Pacific sediments (1.5 Ga) are assumed to be similar to those of recent sediment components [START_REF] Rehkämper | Recycled ocean crust and sediment in Indian Ocean MORB[END_REF]. The isotopic compositions of the altered Pacific crust were determined by [START_REF] Hauff | Sr-Nd-Pb composition of Mesozoic Pacific oceanic crust (Site 1149 and 801, ODP Leg 185): Implications for alteration of ocean crust and the input into the Izu-Bonin-Mariana subduction system[END_REF]. The isotopic compositions of Cenozoic basalts in East Chapter 5

China (including Southeast China) were obtained from [START_REF] Zou | Major, trace element, and Nd, Sr and Pb isotope studies of Cenozoic basalts in SE China: mantle sources, regional variations, and tectonic significance[END_REF], Zhang et al. (2002a), Zhang et al. (2002b), [START_REF] Zou | Constraints on the origin of historic potassic basalts from northeast China by U-Th disequilibrium data[END_REF], [START_REF] Ho | 40 Ar/ 39 Ar dating and geochemical characteristics of late Cenozoic basaltic rocks from the Zhejiang-Fujian region, SE China: eruption ages, magma evolution and petrogenesis[END_REF], [START_REF] Xu | Role of lithosphereasthenosphere interaction in the genesis of Quaternary alkali and tholeiitic basalts from Datong, western North China Craton[END_REF], [START_REF] Choi | Sr, Nd, Pb and Hf isotopic compositions of late Cenozoic alkali basalts in South Korea: Evidence for mixing between the two dominant asthenospheric mantle domains beneath East Asia[END_REF], [START_REF] Tang | Asthenosphere-lithospheric mantle interaction in an extensional regime: Implication from the geochemistry of Cenozoic basalts from Taihang Mountains, North China Craton[END_REF], [START_REF] Zou | U-Th systematics of dispersed young volcanoes in NE China: Asthenosphere upwelling caused by piling up and upward thickening of stagnant Pacific slab[END_REF], [START_REF] Yan | Cenozoic alkali basalts from Jingpohu, NE China: The role of lithosphere-asthenosphere interaction[END_REF], [START_REF] Chen | Sources of Anfengshan basalts: Subducted lower crust in the Sulu UHP belt, China[END_REF], [START_REF] Kuritani | Intensive hydration of the mantle transition zone beneath China caused by ancient slab stagnation[END_REF]), Zhang et al. (2009), [START_REF] Zou | U-Th isotopes in Hainan basalts: Implications for subasthenospheric origin of EM2 mantle endmember and the dynamics of melting beneath Hainan Island[END_REF], [START_REF] Wang | Geochemical constraints on the nature of mantle source for Cenozoic continental basalts in east-central China[END_REF], [START_REF] Wang | Temperature, Pressure, and Composition of the Mantle Source Region of Late Cenozoic Basalts in Hainan Island, SE Asia: a Consequence of a Young Thermal References Mantle Plume close to Subduction Zones[END_REF][START_REF] Zeng | Crust recycling in the sources of two parallel volcanic chains in Shandong, North China[END_REF]), Xu et al. (2012a), Xu et al. (2012b), [START_REF] Kuang | Petrogenetic evaluation of the Laohutai basalts from North China Craton: Melting of a two-component source during lithospheric thinning in the late Cretaceous-early Cenozoic[END_REF], Wang et al. (2013), [START_REF] Zhang | The genesis of Cenozoic basalts from the Jining area, northern China: Sr-Nd-Pb-Hf isotope evidence[END_REF], [START_REF] Ho | Late Cenozoic magmatic transitions in the central Great Xing'an Range, Northeast China: Geochemical and isotopic constraints on petrogenesis[END_REF], [START_REF] Huang | Geochronology and geochemistry of Cenozoic basalts from eastern Guangdong, SE China: constraints on the lithosphere evolution beneath the northern margin of the South China Sea[END_REF], [START_REF] Sakuyama | Melting of dehydrated oceanic crust from the stagnant slab and of the hydrated mantle transition zone: Constraints from Cenozoic alkaline basalts in eastern China[END_REF], [START_REF] Fan | Petrogenesis and evolution of Quaternary basaltic rocks from the Wulanhada area, North China[END_REF], [START_REF] Guo | Lithosphere thinning beneath west North China Craton: Evidence from geochemical and Sr-Nd-Hf isotope compositions of Jining basalts[END_REF], [START_REF] Li | Geochemistry of Cenozoic basalts from the Bohai Bay Basin: Implications for a heterogeneous mantle source and lithospheric evolution beneath the eastern North China Craton[END_REF] and [START_REF] Zhao | Geochemistry of Quaternary basaltic lavas from the Nuomin volcanic field, Inner Mongolia: Implications for the origin of potassic volcanic rocks in Northeastern China[END_REF].

Water content of cpx phenocrysts and equilibrated melts

The cpx phenocrysts of the Zhejiang basalts are augitic to diopsidic, with Mg# varying from less than 70 to 84. All of the cpx phenocrysts in the Zhejiang basalts exhibit IR absorption spectra in the OH-typical stretching vibration region (3000-3800 cm -1 ), and the IR bands are centered at 3630 cm -1 and 3540 cm -1 (Fig. 5-6a), which is consistent with the positions of structural OH bands in cpx from previous studies [START_REF] Bell | Quantitative analysis of trace OH in garnet and pyroxenes[END_REF][START_REF] Denis | Evidence of dehydration in peridotites from Eifel Volcanic Field and estimates of the rate of magma ascent[END_REF][START_REF] Ingrin | Hydrogen in nominally anhydrous upper-mantle minerals: concentration levels and implications[END_REF][START_REF] Kovacs | An Experimental Study of Water in Nominally Anhydrous Minerals in the Upper Mantle near the Water-saturated Solidus[END_REF][START_REF] Li | Water contents in mantle xenoliths from the Colorado Plateau and vicinity: Implications for the mantle rheology and hydration-induced thinning of continental lithosphere[END_REF][START_REF] Peslier | Low water contents in pyroxenes from spinelperidotites of the oxidized, sub-arc mantle wedge[END_REF][START_REF] Skogby | Hydroxide in pyroxene: Variations in the natural-environment[END_REF][START_REF] Sundvall | Water in upper mantle pyroxene megacrysts and xenocrysts: A survey study[END_REF][START_REF] Xia | Low water content of the Cenozoic lithospheric mantle beneath the eastern part of the North China Craton[END_REF]Xia et al., 2013;[START_REF] Xia | Early Paleozoic crust-mantle interaction and lithosphere delamination in South China Block: Evidence from geochronology, References geochemistry, and Sr-Nd-Hf isotopes of granites[END_REF]. The calculated H2O contents of the cpx phenocrysts for the Group 1 samples range from 13 to 675 ppm, and those for the Group 2 samples range from 0 to 756 ppm (0-264 ppm for the SC samples and 94-756 ppm for the GP samples). The major element contents, absorbance of OH bands, thin section thicknesses, and the calculated H2O contents of the cpx phenocrysts are listed in the Table 5-3. The H2O contents of the equilibrated melts of the cpx phenocrysts can be deduced via the H2O content of cpx phenocrysts and the partition coefficient (D cpx-melt ) for H2O between cpx phenocrysts and basaltic melts. The latter can be calculated using an equation provided by [START_REF] O'leary | The effect of tetrahedral Al 3+ on the partitioning of water between clinopyroxene and silicate melt[END_REF] based on the chemical compositions of the cpx phenocrysts (equation 10 in their paper). The H2O content of the melts equilibrated with the Zhejiang cpx phenocrysts ranges from 0.2% to 5.5% for Group 1 samples and from 0% to 4.79% for Group 2 samples. The detailed data are listed in

Discussions Source or processes?

Prior to eruption, basaltic melts undergo a series of low-pressure magmatic processes, such as crustal contamination and fractional crystallization. These processes could potentially modify the composition of primary basaltic melt. Therefore, we first evaluate the effects of these processes.

Crustal contamination

First, the abundance of peridotite xenoliths entrained in most of the Zhejiang basalts required rapid ascent of magma, leaving little time for crustal contamination [START_REF] O'reilly | Rates of magma ascent: constraints from mantlederived xenoliths[END_REF]. Second, geochemical evidence for negligible crustal contamination in the Zhejiang basalts includes the following: (1) No positive correlation between 87 Sr/ 86 Sr ratios and 1/Sr concentration (Fig. 5-7a), which is not expected for prominent crustal contamination because the continental crust has a lower Sr concentration and much higher 87 Sr/ 86 Sr ratios than the Zhejiang basalts [START_REF] Jahn | Crust-mantle interaction induced by deep subduction of the continental crust: Geochemical and Sr-Nd isotopic evidence from post-collisional mafic-ultramafic intrusions of the northern Dabie complex, central China[END_REF][START_REF] Rudnick | Composition of the Continental Crust[END_REF]; (2) Strongly negative Pb anomalies observed in all of the Zhejiang basalts (Fig. 5-4), are opposite to the effects of crustal contamination because both the upper and lower crusts contain very high abundances of Pb [START_REF] Rudnick | Composition of the Continental Crust[END_REF]and (3) No positive correlation between La/Nb and Ba/Nb (Fig. 5-7b), which is contrary to effective crustal contamination because crustal materials are generally characterized by high Ba/Nb and La/Nb ratios [START_REF] Hofmann | Nb and Pb in oceanic basalts: new constraints on mantle evolution[END_REF][START_REF] Rudnick | Composition of the Continental Crust[END_REF][START_REF] Workman | Major and trace element composition of the depleted MORB mantle (DMM)[END_REF].

Fractional crystallization

The correlations between Ni and Cr vs. MgO for the XL and GP samples (Fig. 5 The high Mg# values of the XL (65-70) and GP (62-64) samples approaching those of primary magmas [START_REF] Frey | Integrated Models of Basalt Petrogenesis: A Study of Quartz Tholeiites to Olivine Melilitites from South Eastern Australia Utilizing Geochemical and Experimental Petrological Data[END_REF], suggest the fractional crystallization of olivine was not very significant, while the Mg# values of the SC samples are the relatively low (58-60). The fractional crystallization of cpx from alkali basaltic magma results in a positive correlation between CaO/Al2O3 and Mg# [START_REF] Spath | Plume-lithosphere interaction and the origin of continental rift-related alkaline volcanism -the Chyulu Hills Volcanic Province, southern Kenya[END_REF], which is not Chapter 5 observed in the Zhejiang basalts (Fig. 5-8d). Thus, the fractional crystallization of cpx was limited. Nevertheless, the ratios of incompatible trace elements and Sr-Nd-Pb isotope compositions are not sensitive to olivine fractionation and can thus retain their original features. In addition, positive Ba, Sr and Eu anomalies in all of the Zhejiang basalts (Fig. 5-3 and 5-4) exclude significant fractional crystallization of feldspar.

H2O content in the initial magmas

To deduce the H2O content of the "initial" basaltic melts and mantle sources, we need to clarify the following: (1) the evolution of H2O contents within the ascending magmas, and (2) the H diffusion within the cpx phenocrysts after they crystallized from the magma.

Average H2O content of the melt calculated from the H2O content in cpx phenocrysts with the highest Mg# (XL and SC>80, GP >77) vs. the average value of water content estimated from cpx phenocrysts with the lower Mg# (XL and SC<80, GP <77).

Degassing, the fractional crystallization, and assimilation of surrounding rock during magma ascent can change the H2O content of basaltic melts, which can be reflected in the different H2O contents of cpx. Fractional crystallization increases the H2O content of melts because the olivine, cpx, and feldspar are removed, as they have smaller H2O contents (<1000 ppm). Meanwhile, degassing can intensively reduce the Chapter 5 H2O content of melts. Because the lower continental crust is usually considered dry [START_REF] Xia | Water in the lower crustal granulite xenoliths from Nushan, eastern China[END_REF]Yang et al., 2008a), assimilation of a small amount of surrounding rock does not increase the H2O content of the melt, and may even reduce it. The H2O content of the Zhejiang basalts estimated from the cpx phenocrysts with high Mg# are mostly higher than the results estimated from those with lower Mg# (Fig. 56789) in the same sample. This suggests that the parent magma of the lower Mg# cpx had lower H2O contents than the parent magmas of the higher Mg# cpx for most samples. These observations indicate the following: a) fractional crystallization did not play an important role in the H2O content variation in different cpx grains, which is consistent with the small numbers of phenocrysts in the basalts studied; b) the melts underwent noticeable degassing during magma ascent, which is reflected in the lower H2O content of the cpx with lower Mg#; and c) if the melts ascended rapidly, the subsequent degassing had little or no effect on the H2O content of the early-formed cpx phenocrysts.

Because the H2O content of cpx with low Mg# does not represent the "initial" H2O content of basalts, we can therefore estimate the "initial" H2O content from the cpx grains with the highest Mg#. Variations in the resultant "initial" H2O content between different samples reflect different degrees of partial melting of the same source or heterogeneities in the source materials, rather than the effect of degassing.

Given high diffusion rate of H in cpx (D=10 -10 ~10 -10.5 m 2 /s at 900℃ [START_REF] Hercule | Hydrogen in diopside: Diffusion, kinetics of extractionincorporation, and solubility[END_REF][START_REF] Ingrin | Diffusion of Hydrogen in Minerals[END_REF][START_REF] Ingrin | Hydrogen in nominally anhydrous upper-mantle minerals: concentration levels and implications[END_REF][START_REF] Woods | Hydrogen in diopside: Diffusion profiles[END_REF]), cpx phenocrysts might suffer diffusive loss of H during the subsequent ascent of the melts. It was noted that some cpx grains from the SC samples (SC-1 to SC-4) are totally "dry", showing no OH-related IR band at either the core or the rim (Fig. 5-6b).

In contrast, "dry" cpx phenocrysts are not observed in sample SC-5, which is similar to the GP basalts. Sample SC-5 has the highest inferred initial H2O content among the SC basalts. Therefore, we suggest the following: (1) some SC cpx phenocrysts might have suffered a loss of H2O during ascent; therefore the inferred H2O contents of the corresponding melts are underestimated, and the inferred H2O contents of these four samples (SC-1 to SC-4) do not represent the "initial" H2O content of the SC basalts; and (2) SC-5 may have retained the initial value of H2O, and its H2O content (1.3%), which is the best value we obtained to represent the "initial" SC basaltic melt. Thus, to calculate the "initial" H2O content of the Zhejiang basalts, following rules were adopted: (1) Select cpx grains with high Mg# (>80 for XL and SC, >77 for GP) in each sample, and calculate their D cpx-melt values of H2O. (2) Calculate the H2O content of melts equilibrated with the selected cpx grains and the average H2O contents for each sample. (3) Finally, omitted the samples whose cpx experienced obvious H diffusion.

Based on the above considerations, we suggest that the "initial" H2O content of the Zhejiang basalts ranged from 1.6 to 2.9 wt. % for the XL samples (Group 1), from 1.5 to 2.6 wt. % for the GP samples (Group 2) and was 1.3 wt. % for the SC samples (Group 2). These values fall within the range of H2O content expected for back-arc basin basalts (BABBs) and island arc basalts (IABs), as suggested by Dixon et al. (2004), displayed in Fig. 5-10. Note that these values are the minimum values for the H2O contents in the Zhejiang basalts.

Comparison of the calculated average H2O content of the Zhejiang "primary" basaltic melts and the ranges of H2O content for Northeast China, East North China, West North China, OIBs, MORBs, BABBs and IABs (data from [START_REF] Chen | Changing recycled oceanic components in the mantle source of the Shuangliao Cenozoic basalts, NE China: New constraints from water content[END_REF]; Dixon et al. (2004) and the references therein).

Source lithology

A number of high-pressure melting experiments on peridotites have been conducted during the last 30 years to decipher the genesis of intra-plate alkali basalts Chapter 5 of various compositions [START_REF] Baker | Determining the composition of high-pressure mantle melts using diamond aggregates[END_REF][START_REF] Falloon | Melting of refractory mantle at 1[END_REF][START_REF] Hirose | Partial melting of dry peridotites at high pressures: determination of compositions of melts segregated from peridotite using aggregates of diamond[END_REF][START_REF] Laporte | A new experimental technique for extracting liquids from peridotite at very low degrees of melting: application to partial melting of depleted peridotite[END_REF][START_REF] Schwab | Melting systematics of modally variable, compositionally intermediate peridotites and the effects of mineral fertility[END_REF][START_REF] Walter | Melting of garnet peridotite and the origin of komatiite and depleted lithosphere[END_REF][START_REF] Wasylenki | Near-solidus melting of the shallow upper mantle: Partial melting experiments on depleted peridotite[END_REF]. In the presence of CO2 and/or H2O, peridotite melts tend to have less Si and more Fe but are still too low in Ti compared with the Group 1 basalts (Fig. 5-11a-d). However, partial melts in high-pressure melting experiments without CO2 and/or H2O for non-peridotites ,such as eclogite, pyroxenite, and hornblendite are too low in alkali content to serve as a single source [START_REF] Dasgupta | Immiscible transition from carbonate-rich to silicate-rich melts in the 3 GPa melting interval of eclogite plus CO2 and genesis of silica-undersaturated ocean island lavas[END_REF][START_REF] Keshav | High-pressure melting experiments on garnet clinopyroxenite and the alkalic to tholefitic transition in ocean-island basalts[END_REF]Kogiso andHirschmann, 2001, 2006;[START_REF] Kogiso | High-pressure partial melting of mafic lithologies in the mantle[END_REF][START_REF] Pilet | Metasomatized Lithosphere and the Origin of Alkaline Lavas[END_REF] as shown in Fig. 5-12a. The SiO2, TiO2, FeO, and MgO abundances of melts produced from carbonated eclogites are consistent with the Zhejiang samples; however, they are too low in Na and K, and too high in Al (Fig. 11 and12a). The high alkali content is instead more consistent with a peridotite source (including CO2-bearing peridotite) (Fig.

5-12a

). Therefore, the Zhejiang basalts were likely produced by melting of a mixed source rather than by any single source lithology .

The presence of non-peridotite sources is also indicated by the Fe/Mn and Nb/Ta ratios. The distribution coefficients of DFe/DMn for cpx, opx, and garnet are less than 1, but they are greater than 1 for ol [START_REF] Le Roux | Mineralogical heterogeneities in the Earth's mantle: Constraints from Mn, Co, Ni and Zn partitioning during partial melting[END_REF]Pertermann and Hirschmann, 2003a;[START_REF] Walter | Melting of garnet peridotite and the origin of komatiite and depleted lithosphere[END_REF]. The averages are 1.35, 0.95, 0.65, and 0.69 for ol, opx, cpx, and garnet, respectively. Residual pyroxene in the mantle source thus leads to high Fe/Mn ratios in the basaltic melts. The Fe/Mn ratios are 58-67 (Mn 0.18-0.23%) for Group 1 samples and 67-78 (Mn 0.15-0.18%) for Group 2 samples and plot along the boundary of peridotite-and pyroxenite-derived melts (Fig. 5-11e). Meanwhile, the Nb/Ta ratios range up to 20.7 for Group 1 samples and from 18.2 to 20.0 for Group 2 samples, which are higher than the value of the Primitive Mantle (i.e., PM 17.4, after Sun (1989)). Tioxides, such as rutile or ilmenite, are common phases in eclogite or garnetclinopyroxenite and tend to have higher compatibility for Nb than for Ta [START_REF] Dasgupta | Deep global cycling of carbon constrained by the solidus of anhydrous, carbonated eclogite under upper mantle conditions[END_REF][START_REF] Kogiso | Trace element transport during dehydration processes in the subducted oceanic crust: 1. Experiments and implications for the origin of ocean island basalts[END_REF]Pertermann and Hirschmann, 2003a, b;[START_REF] Rapp | Reaction between slabderived melts and peridotite in the mantle wedge: experimental constraints at 3.8 GPa[END_REF][START_REF] Rapp | Dehydration melting of metabasalt at 8-32 kbar: References implications for continental growth and crust-mantle recycling[END_REF][START_REF] Xiong | Rutile stability and rutile/melt HFSE partitioning during partial melting of hydrous basalt: Implications for TTG genesis[END_REF]. The melting of such eclogite or garnetclinopyroxenite might thus produce the high Nb/Ta ratios observed in the Zhejiang basalts [START_REF] Klemme | Partitioning of trace elements between rutile and silicate melts: Implications for subduction zones[END_REF]. Recycled oceanic basalts transformed into garnet pyroxenites or eclogites are likely the non-peridotite sources of the Zhejiang basalts. In addition, trace elements indicate the presence of CO2 in the source. The Hfn/Hf* values are 0.5-0.7 for Group 1 samples and 0.7-0.9 for Group 2 samples, where Hfn/Hf* = Hfn/(Ndn/Smn) 1/2 and n represents normalization to the primitive mantle. The deficit of Chapter 5

Hf relative to Nd and Sm could be induced by carbonaceous compositions in the source [START_REF] Hoernle | Geochemistry of oceanic carbonatites compared with continental carbonatites: mantle recycling of oceanic crustal carbonate[END_REF]. The Tin/Ti* values are 0.5-0.7 for Group 1 samples and 0.9-1.0 for Group 2 samples, where Tin/Ti* = Tin/(Gdn/Eun) 1/2 . This deficit in Ti is also compatible with the ideas of [START_REF] Hoernle | Geochemistry of oceanic carbonatites compared with continental carbonatites: mantle recycling of oceanic crustal carbonate[END_REF]. Note that the high water content of the Zhejiang basalts indicates a hydrated mantle source. Chapter 5 vs. MgO for the Zhejiang basalt samples; (e) Fe/Mn vs. MnO. Data source: Hornblendite [START_REF] Pilet | Metasomatized Lithosphere and the Origin of Alkaline Lavas[END_REF]; Carbonated eclogite [START_REF] Dasgupta | Immiscible transition from carbonate-rich to silicate-rich melts in the 3 GPa melting interval of eclogite plus CO2 and genesis of silica-undersaturated ocean island lavas[END_REF]; dry eclogite [START_REF] Kogiso | Partial melting experiments of bimineralic eclogite and the role of recycled mafic oceanic crust in the genesis of ocean island basalts[END_REF]; Garnet-Pyroxenites [START_REF] Keshav | High-pressure melting experiments on garnet clinopyroxenite and the alkalic to tholefitic transition in ocean-island basalts[END_REF][START_REF] Kogiso | Experimental study of clinopyroxenite partial melting and the origin of ultra-calcic melt inclusions[END_REF][START_REF] Kogiso | High-pressure partial melting of mafic lithologies in the mantle[END_REF]; MORB-like Pyroxenites (Pertermann and Hirschmann, 2003b); Peridotite [START_REF] Baker | Determining the composition of high-pressure mantle melts using diamond aggregates[END_REF][START_REF] Falloon | Melting of refractory mantle at 1[END_REF][START_REF] Hirose | Partial melting of dry peridotites at high pressures: determination of compositions of melts segregated from peridotite using aggregates of diamond[END_REF][START_REF] Laporte | A new experimental technique for extracting liquids from peridotite at very low degrees of melting: application to partial melting of depleted peridotite[END_REF][START_REF] Schwab | Melting systematics of modally variable, compositionally intermediate peridotites and the effects of mineral fertility[END_REF][START_REF] Walter | Melting of garnet peridotite and the origin of komatiite and depleted lithosphere[END_REF][START_REF] Wasylenki | Near-solidus melting of the shallow upper mantle: Partial melting experiments on depleted peridotite[END_REF]; Hydrous peridotites [START_REF] Balta | Hydrous, Low-carbon Melting of Garnet Peridotite[END_REF][START_REF] Falloon | Melting of refractory mantle at 1[END_REF][START_REF] Gaetani | The influence of water on melting of mantle peridotite[END_REF][START_REF] Parman | Harzburgite melting with and without H2O: Experimental data and predictive modeling[END_REF]; Peridotite with CO2 [START_REF] Dasgupta | Partial melting experiments of peridotite+CO2 at 3 GPa and genesis of alkalic ocean island basalts[END_REF]; and Hydrous peridotites with CO2 [START_REF] Ghosh | Phase relations and melting of carbonated peridotite between 10 and 20 GPa: a proxy for alkali-and CO2-rich silicate melts in the deep mantle[END_REF].

Lithospheric or asthenospheric source?

It has been widely accepted that subducted oceanic material can return to the surface through mantle plumes from a thermal boundary layer or the deep mantle, but there is no evidence for a deep plume-like structure from the lower mantle in the study area in Fig. 2-3 b (Hang and Zhao, 2006;[START_REF] Li | Structure of the upper mantle and transition zone beneath Southeast Asia from traveltime tomography[END_REF][START_REF] Zhao | Deep slab subduction and dehydration and their geodynamic consequences: Evidence from seismology and mineral physics[END_REF][START_REF] Wei | East Asia mantle tomography: New insight into plate subduction and intraplate volcanism[END_REF]. Therefore, the mantle source of the Zhejiang basalts is either the subcontinental lithospheric mantle or the asthenosphere.

Although Cenozoic basalts from SE China display a DMM-EM II mixing trend in the Sr-Nd-Pb plots [START_REF] Choi | Sr, Nd, Pb and Hf isotopic compositions of late Cenozoic alkali basalts in South Korea: Evidence for mixing between the two dominant asthenospheric mantle domains beneath East Asia[END_REF][START_REF] Zou | Major, trace element, and Nd, Sr and Pb isotope studies of Cenozoic basalts in SE China: mantle sources, regional variations, and tectonic significance[END_REF], contemporaneous lithospheric peridotite xenoliths (including spinel and garnet peridotite) do not show EM II-like characteristics [START_REF] Fan | On and off the North China Craton: Where is the Archaean keel?[END_REF][START_REF] Tatsumoto | Sr, Nd, and Pb isotopes of ultramafic xenoliths in volcanic rocks of Eastern China: enriched components EMI and EMII in subcontinental lithosphere[END_REF][START_REF] Xu | Enrichment of upper mantle peridotite: petrological, trace element and isotopic evidence in xenoliths from SE China[END_REF]. The 87 Sr/ 86 Sr and 143 Nd/ 144 Nd ratios of the contemporaneous Zhejiang peridotite xenoliths range from 0.70278 to 0.70366 and from 0.51296 to 0.51326 [START_REF] Fan | On and off the North China Craton: Where is the Archaean keel?[END_REF], respectively. The Zhejiang peridotite xenoliths are more depleted than the Zhejiang Cenozoic basalts.

The spinel and garnet peridotites from other sites in SE China, such as Mingxi, are also more depleted than the Zhejiang basalts [START_REF] Tatsumoto | Sr, Nd, and Pb isotopes of ultramafic xenoliths in volcanic rocks of Eastern China: enriched components EMI and EMII in subcontinental lithosphere[END_REF][START_REF] Xu | Enrichment of upper mantle peridotite: petrological, trace element and isotopic evidence in xenoliths from SE China[END_REF].

Therefore, the radiogenic isotopic data represented by peridotite xenoliths do not support the direct generation of Cenozoic alkali basalts in SE China from the lithospheric mantle.

It can be checked whether the peridotite is "wet" enough to serve solely as the mantle source. To simplify the calculation, the "Continuous Fractional melting" model can be used. The H2O content of the mantle source for the Zhejiang basalts is calculated based on the initial H2O content of basaltic magma from cpx and the partition coefficients of H2O between peridotites and basaltic melts (0.005-0.013 [START_REF] Hirschmann | Dehydration melting of nominally anhydrous mantle: The primacy of partitioning[END_REF][START_REF] O'leary | The effect of tetrahedral Al 3+ on the partitioning of water between clinopyroxene and silicate melt[END_REF]). The results are listed in Table 5-2, with F=0.01, 0.02, 0.05, 0.10 and 0.15. When F=0.01 and D=0.005, the H2O content of the mantle source for Group 1 samples varies from 165 to 332 ppm, and that for Group 2 samples varies from 150 to 300 ppm (excluding dry samples SC-1 to SC-4). It is noteworthy that the H2O content of the mantle source increases with increasing F value or increasing partition coefficient (Table 5-2). Therefore, all of these results represent the lowest estimations of H2O content for the source, because we use the lowest partition coefficient. Both the Group 1 and 2 basalts entrained peridotite xenoliths (including spinel and garnet facies). The H2O contents of the peridotite xenoliths from Southeast China range between 40 and 95 ppm [START_REF] Yu | H2O contents and their modification in the Cenozoic subcontinental lithospheric mantle beneath the Cathaysia block, SE China[END_REF]. Clearly, the lowest estimations Chapter 5 of the H2O content for the mantle source of the Zhejiang basalts is higher than that of the lithospheric mantle, again contrary to the lithospheric mantle as a direct source for the Zhejiang basalts, if it is represented by peridotite xenoliths.

As noted above, in addition to peridotites, the source of basalts could also be eclogites, pyroxenites or hornblendites [START_REF] Dasgupta | Immiscible transition from carbonate-rich to silicate-rich melts in the 3 GPa melting interval of eclogite plus CO2 and genesis of silica-undersaturated ocean island lavas[END_REF][START_REF] Keshav | High-pressure melting experiments on garnet clinopyroxenite and the alkalic to tholefitic transition in ocean-island basalts[END_REF]Kogiso andHirschmann, 2001, 2006;[START_REF] Kogiso | High-pressure partial melting of mafic lithologies in the mantle[END_REF][START_REF] Pilet | Metasomatized Lithosphere and the Origin of Alkaline Lavas[END_REF]; regardless of which types of lithologies constitute the source, they should meet the unique trace element characteristics of the melt. Another possible alternative candidate is a lithospheric mantle metasomatized by the infiltration of small amounts of melts/fluids [START_REF] Pilet | Metasomatized Lithosphere and the Origin of Alkaline Lavas[END_REF]2011). The metasomatized lithospheric mantle could contain secondary hydrous minerals (e.g., amphibole or phlogopite) and has been suggested as an OIBs-like basaltic magma source [START_REF] Class | Plume-lithosphere interactions in the ocean basins: constraints from the source mineralogy[END_REF][START_REF] Pilet | Monte Carlo Simulations of Metasomatic Enrichment in the Lithosphere and Implications for the Source of Alkaline Basalts[END_REF][START_REF] Pilet | Metasomatized Lithosphere and the Origin of Alkaline Lavas[END_REF][START_REF] Pilet | The metasomatic alternative for ocean island basalt chemical heterogeneity[END_REF]. Involvement of hydrous minerals in the melting source usually results in the high concentration of incompatible elements (e.g., Rb and Ba), positive Nb (Ta), and possibly Ti anomalies and/or negative U, Th, K, and Pb anomalies in the magmas [START_REF] Pilet | Monte Carlo Simulations of Metasomatic Enrichment in the Lithosphere and Implications for the Source of Alkaline Basalts[END_REF][START_REF] Pilet | Metasomatized Lithosphere and the Origin of Alkaline Lavas[END_REF]. However, the geochemical characteristics of the Zhejiang basalts do not match such features and also differ from the experimental results of hornblendites [START_REF] Class | Plume-lithosphere interactions in the ocean basins: constraints from the source mineralogy[END_REF][START_REF] Pilet | Metasomatized Lithosphere and the Origin of Alkaline Lavas[END_REF][START_REF] Pilet | The metasomatic alternative for ocean island basalt chemical heterogeneity[END_REF]. The difference can be expressed as: (1) Residual K-bearing minerals result in negative K anomalies in basaltic melt as observed in Group 1 samples [START_REF] Class | Plume-lithosphere interactions in the ocean basins: constraints from the source mineralogy[END_REF], however, Group 2 samples show minor to no negative K anomalies (Fig. 5-4), reflecting a lack of residues of K-bearing minerals in the mantle source of Group 2 basalts; meanwhile, the strongly negative Ti anomalies for Group 1 basalts (Fig. 5-4) are also contrary to the results of the melting experiments of [START_REF] Pilet | Metasomatized Lithosphere and the Origin of Alkaline Lavas[END_REF]. (2) The total alkali (K2O+Na2O) contents of the Zhejiang basalts are highly variable within a narrow range of TiO2 content (Fig. 5-12a), which is different from the trend of the hornblendite melting experiments by [START_REF] Pilet | Metasomatized Lithosphere and the Origin of Alkaline Lavas[END_REF]; it is also notable that the TiO2 contents for the Zhejiang basalts are much lower than those of the hornblendite melts. The GP and XL samples contain garnet peridotite xenoliths (Liu et al., 2012;[START_REF] Zhang | Chemical and stable isotopic constraints on the nature and origin of volatiles in the sub-continental lithospheric mantle beneath eastern China[END_REF]. The work of [START_REF] Liu | The Xinchang peridotite xenoliths reveal mantle replacement and accretion in southeastern China[END_REF] indicates that the equilibrium temperature of the garnet peridotites in Southeast China is higher than 1200℃. Host basalts are produced at greater depths and have higher temperatures, which are too high for hornblendite to be stable. Additionally, phlogopite and amphibole maintain a relatively high compatibility of Sr relative to Ce. [START_REF] Yang | Constraints on the source components of lavas forming the Hawaiian North Arch and Honolulu volcanics[END_REF] Chapter 5

showed that residual phlogopite or amphibole results in melts that have a negative trend of Sr/Ce vs. Th, which is not the case in our samples (Fig. 5-12b). Instead, a positive trend of Sr/Ce vs. Th is identified in the Group 1 samples. D Sr/Ce for garnet/melt and clinopyroxene/melt are less than 1 [START_REF] Bennett | The effect of sodium and titanium on crystalmelt partitioning of trace elements[END_REF][START_REF] Gaetani | Mineral/melt partitioning of trace elements during hydrous peridotite partial melting[END_REF][START_REF] Hauri | Experimental and natural partitioning of Th, U, Pb and other trace elements between garnet, clinopyroxene and basaltic melts[END_REF]. Therefore, the positive correlation may be caused by residual garnet and/or clinopyroxene in the source. All of these observations indicate that the Zhejiang basalts are not likely to have been produced by residual hornblende and/or phlogopite in the lithospheric mantle. Therefore, the asthenosphere could be a prevalent source for the Zhejiang basalts.

Enriched components in mantle sources

The Zhejiang basalts are characterized by elevated concentrations of incompatible elements and enriched Sr-Nd-Pb isotopic compositions compared with those of MORBs (Figs. 5-4 and Fig. 5-5). These features demand enriched component(s) in the mantle source. Because of the unsuitability of the lithospheric mantle as a source, the enriched components must reside in the asthenosphere. Geophysical imaging has shown that beneath the Zhejiang area, there is seismic evidence for a continuous stagnant subducted slab in the MTZ extending to the Mariana trench [START_REF] Huang | High-resolution mantle tomography of China and surrounding regions[END_REF]; meanwhile, geochemical studies have suggested that SE China might have undergone lithospheric thinning similar to the NCC during the Mesozoic [START_REF] Ho | 40 Ar/ 39 Ar dating and geochemical characteristics of late Cenozoic basaltic rocks from the Zhejiang-Fujian region, SE China: eruption ages, magma evolution and petrogenesis[END_REF][START_REF] Ma | Cenozoic extensional tectonics in China[END_REF][START_REF] Wu | Osmium isotopic constraints on the age of lithospheric mantle beneath northeastern China[END_REF][START_REF] Xu | Genesis of young lithospheric mantle in southeastern China: an LAM-ICPMS trace element study[END_REF][START_REF] Xu | Xenolith evidence for polybaric melting and stratification of the upper mantle beneath South China[END_REF]. Therefore, the enriched components might be recycled oceanic crust, marine sediments, or oceanic lithospheric mantle [START_REF] Chen | Changing recycled oceanic components in the mantle source of the Shuangliao Cenozoic basalts, NE China: New constraints from water content[END_REF][START_REF] Kuritani | Intensive hydration of the mantle transition zone beneath China caused by ancient slab stagnation[END_REF]Liu et al., 2015b;[START_REF] Niu | Origin of ocean island basalts: A new perspective from petrology, geochemistry, and mineral physics considerations[END_REF][START_REF] Sakuyama | Melting of dehydrated oceanic crust from the stagnant slab and of the hydrated mantle transition zone: Constraints from Cenozoic alkaline basalts in eastern China[END_REF][START_REF] Wang | Geochemical constraints on the nature of mantle source for Cenozoic continental basalts in east-central China[END_REF]Xu et al., 2012a;Xu et al., 2012b;[START_REF] Zhang | Geochemical evidence for interaction between oceanic crust and lithospheric mantle in the origin of Cenozoic continental basalts in east-central China[END_REF], delaminated continental lithospheric mantle or lower continental crust associated with lithospheric thinning [START_REF] Chen | Sources of Anfengshan basalts: Subducted lower crust in the Sulu UHP belt, China[END_REF][START_REF] Gao | Recycling deep cratonic lithosphere and generation of intraplate magmatism in the North China Craton[END_REF][START_REF] Liu | Recycled crust controls contrasting source compositions of Mesozoic and Cenozoic basalts in the North China Craton[END_REF][START_REF] Zeng | Crust recycling in the sources of two parallel volcanic chains in Shandong, North China[END_REF]. Nevertheless, it should be noted that the Mariana trench lies distant from any major continent, and there is a back-arc basin between the continent and the trench. The Mariana trench is far from any river system, so its sediments show some distinctive geochemistry, such as relatively low radiogenic isotopic ratios, and it contain relatively small amounts of marine sediments (38-221m in thickness, [START_REF] Plank | The chemical composition of subducting sediment and its consequences for the crust and mantle[END_REF]).

Recycled/delaminated lithospheric mantle?

Chapter 5

Both subduction processes and lithospheric delamination can carry lithospheric mantle into the asthenosphere, forming distinct sources in the convecting mantle. [START_REF] Niu | Origin of ocean island basalts: A new perspective from petrology, geochemistry, and mineral physics considerations[END_REF] and [START_REF] Workman | Recycled metasomatized lithosphere as the origin of the enriched mantle II (EM2) end-member: Evidence from the Samoan volcanic chain[END_REF] proposed a model in which the recycled amphibole-bearing metasomatized oceanic lithospheric mantle could be a candidate for the source of OIBs. Amphibole is not stable above 3 GPa (~100 km depth) or 1200℃ [START_REF] Grove | The influence of H2O on mantle wedge melting[END_REF][START_REF] Niida | Stability and chemical composition of pargasitic amphibole in MORB pyrolite under upper mantle conditions[END_REF], and deep recycling (in the MTZ >450 km) of metasomatized lithospheric veins would cause amphibole breakdown and would not produce an EM-type trace element pattern. Therefore, recycled metasomatized oceanic lithospheric mantle is unlikely to be the source for the Zhejiang basalts.

Indeed, the studies [START_REF] Gao | Recycling deep cratonic lithosphere and generation of intraplate magmatism in the North China Craton[END_REF][START_REF] Xie | Trace element and Nd-Sr-Pb isotope studies of Mesozoic and Cenozoic basalts in coastal area of SE China[END_REF] have concluded that Mesozoic alkali basalts from both the NCC and SE China were derived from the lithospheric mantle. Their conclusions were mostly based on the significant negative Nb and Ta anomalies in the extended trace element patterns. Such negative Nb and Ta anomalies are frequently observed in the Mesozoic basalts and are considered as a key characteristic of the continental lithospheric mantle. The Zhejiang Cenozoic basalts, by contrast, do not share similar characteristics, exhibiting instead positive Nb and Ta anomalies (Fig. 5-4). Therefore, the delaminated continental lithospheric mantle is unlikely to be the source of the enriched components of the Zhejiang basalts.

Delaminated lower continental crust (LCC)

Delaminated LCC is also a candidate for the enriched source component of the Zhejiang basalts as observed in the Shandong Cenozoic basalts from the NCC [START_REF] Wang | Geochemical constraints on the nature of mantle source for Cenozoic continental basalts in east-central China[END_REF]). However, it is difficult to discriminate delaminated LCC from other enriched components, such as global subducting sediments (GLOSS, [START_REF] Plank | The chemical composition of subducting sediment and its consequences for the crust and mantle[END_REF]), based only on trace elements and Sr-Nd-Pb isotopes. These different source components (e.g., GLOSS, DMM, MORB, recycled oceanic crust (ROC), and LCC) tend to have distinct H2O/Ce ratios (Dixon et al., 2004;[START_REF] Dixon | Recycled dehydrated lithosphere observed in plume-influenced mid-ocean-ridge basalt[END_REF]Yang et al., 2008a), and the partition coefficients of H2O and Ce are similar when partial melting occurs in the mantle (Dixon et al., 2004;[START_REF] Dixon | Recycled dehydrated lithosphere observed in plume-influenced mid-ocean-ridge basalt[END_REF]. Therefore, the H2O/Ce ratio of basalts could represent that of their mantle source, if crustal assimilation and degassing during magma ascent are excluded. In the Section 5.2.2, we estimated the "initial" H2O content of the Zhejiang basalts. The H2O/Ce ratios range from 100 to 200 for the Group 1 samples, from 220 to 430 for the GP samples (Group 2), and the ratio for the SC-5 sample (Group 2) is 250. Previous works (Yang et al., Chapter 5 2008a) reported the H2O content of the LCC granulite xenoliths in Southeast China ranged from 200 to 375 ppm. The average Ce content of the LCC granulite from the same place is approximately 13 ppm [START_REF] Dai | Geochronology, geochemistry and Hf-Sr-Nd isotopic compositions of Huziyan mafic xenoliths, southern Hunan Province, South China: Petrogenesis and implications for lower crust evolution[END_REF][START_REF] Rudnick | Composition of the Continental Crust[END_REF]. H2O/Ce ratios of the LCC in Southeast China can thus be estimated at approximately 15 to 28, which is much lower than those of the Zhejiang basalts. Meanwhile, the H2O/Ce (67) of the residual Su-Lu eclogites estimated by Liu et al. (2015a) is also much lower than those of the Zhejiang basalts. In addition, the LCC has higher 87 Sr/ 86 Sr, 143 Nd/ 144 Nd, and U/Pb ratios and lower 206 Pb/ 204 Pb ratios (<18) [START_REF] Jahn | Crust-mantle interaction induced by deep subduction of the continental crust: Geochemical and Sr-Nd isotopic evidence from post-collisional mafic-ultramafic intrusions of the northern Dabie complex, central China[END_REF][START_REF] Rudnick | Composition of the Continental Crust[END_REF]. Unlike the basalts in NE China and the NCC, the Zhejiang basalts have relatively high 206 Pb/ 204 Pb (>18.4) ratios and EM II-like Sr-Nd-Pb isotopic ratios, ruling out the LCC as the source for the Zhejiang basalts.

Recycled oceanic materials?

As we have noted above, there is no seismic evidence for a mantle plume beneath SE China, and the basaltic source enrichment likely corresponds to recycled oceanic material in the asthenosphere rather than the lower mantle or subcontinental lithosphere.

One possible model is that this enrichment is long-lived and dispersed in the asthenosphere, involving an ancient recycled oceanic slab, delaminated continental lithospheric mantle/lower crust or other source, as in the plum-pudding model [START_REF] Chung | A new genetic model for the East Taiwan Ophiolite and its implications for Dupal domains in the Northern Hemisphere[END_REF], making it impossible to constrain the provenance of these sources. As recycled subducted lithospheric mantle, delaminated continental lithospheric mantle, and the LCC have been ruled out in the previous sections, recycled oceanic materials are the only candidates for the enriched source components of the Zhejiang basalts.

Recycled oceanic materials could be derived from ancient or relatively juvenile subduction processes, given the complex subduction history during the geological evolution of South China. However, the moderate depletion in the 87 Sr/ 86 Sr (low to 0.7032) and 143 Nd/ 144 Nd (high to 0.51305) ratios and nonradiogenic Pb isotope ( 206 Pb/ 204 Pb low to 18.4) ratios for the Zhejiang basalts argue against enrichment from an old source. Therefore, the recycled oceanic materials require a young origin, which implicates stagnant subducted Pacific oceanic material.

(a) Plots of Ba/Th vs. Ba/La for the Zhejiang basalts. The Ba/Th and Ba/La of DMM, recycled oceanic alkali basalts, and recycled sediments were obtained from [START_REF] Workman | Major and trace element composition of the depleted MORB mantle (DMM)[END_REF], [START_REF] Kelley | Composition of altered oceanic crust at ODP Sites 801 and 1149[END_REF], and [START_REF] Plank | The chemical composition of subducting sediment and its consequences for the crust and mantle[END_REF], respectively, and then calculated and modified by the fluid mobility in [START_REF] Kogiso | Trace element transport during dehydration processes in the subducted oceanic crust: 1. Experiments and implications for the origin of ocean island basalts[END_REF], [START_REF] Kessel | Trace element signature of subduction-zone fluids, melts and supercritical liquids at 120-180 km depth[END_REF], [START_REF] Aizawa | Element transport by dehydration of subducted sediments: Implication for arc and ocean island magmatism[END_REF] and [START_REF] Johnson | Dehydration and melting experiments constrain the fate of subducted sediments[END_REF]. (b) Ce/Pb vs. Ba/Th; (c) Nb/La vs. Ba/Th; and (d )H2O/Ce for the Zhejiang basalts. Gray squares show the possible end members of mantle sources. The ratios of H2O/Ce for GLOSS (~1280), DMM (~200), ROC (~100), LCC (<50) dehydrated sediments (several hundred) and recycled oceanic top alkali basalts (~100) are from [START_REF] Plank | The chemical composition of subducting sediment and its consequences for the crust and mantle[END_REF], [START_REF] Shaw | Long-term preservation of slab signatures in the mantle inferred from hydrogen isotopes[END_REF], [START_REF] Dixon | Recycled dehydrated lithosphere observed in plume-influenced mid-ocean-ridge basalt[END_REF] and references therein. The ratios of Ba/Th, Ba/La, Ce/Pb and Nb/La of DMM and GLOSS are from [START_REF] Workman | Major and trace element composition of the depleted MORB mantle (DMM)[END_REF] and [START_REF] Plank | The chemical composition of subducting sediment and its consequences for the crust and mantle[END_REF]. The ratios of Ba/Th, Nb/La and Ce/Pb of ROC and the recycled oceanic alkali basalts are calculated from the concentrations of average MORB and the data of ODPs 801 [START_REF] Gale | The mean composition of ocean ridge basalts[END_REF]Kelly et al., 2003) and the mobility [START_REF] Kogiso | Trace element transport during dehydration processes in the subducted oceanic crust: 1. Experiments and implications for the origin of ocean island basalts[END_REF][START_REF] Kessel | Trace element signature of subduction-zone fluids, melts and supercritical liquids at 120-180 km depth[END_REF]; the ratios of Ba/Th, Nb/La and Ce/Pb of recycled Mariana sediments and dehydrated GLOSS are calculated based on the data from [START_REF] Plank | The chemical composition of subducting sediment and its consequences for the crust and mantle[END_REF] and the mobility from [START_REF] Aizawa | Element transport by dehydration of subducted sediments: Implication for arc and ocean island magmatism[END_REF] and [START_REF] Johnson | Dehydration and melting experiments constrain the fate of subducted sediments[END_REF]. The error bar of H2O/Ce is 30%. Xu et al. (2012a) and [START_REF] Sakuyama | Melting of dehydrated oceanic crust from the stagnant slab and of the hydrated mantle transition zone: Constraints from Cenozoic alkaline basalts in eastern China[END_REF] recognized a recycled oceanic crustal signature in basalts from NE China and the NCC. The Group 1 basalts have high Nb/La (1.8-2.8), Ce/Pb (>30), and Fe2O3 T (>12.5%) and low Ba/Th (<90), which are similar to the key features of melts related to recycled oceanic crust [START_REF] Sakuyama | Melting of dehydrated oceanic crust from the stagnant slab and of the hydrated mantle transition zone: Constraints from Cenozoic alkaline basalts in eastern China[END_REF]Xu et al., 2012a). Recycled oceanic crust is composed of upper alkali basalts (sometimes known as seamounts), tholeiitic basalts (i.e. normal oceanic crust, MORBs), and lower gabbro cumulate. Recycled oceanic upper alkali basalts come from the tops of some anomalous oceanic crust segments [START_REF] Kelley | Composition of altered oceanic crust at ODP Sites 801 and 1149[END_REF], or from subducted oceanic islands or seamounts [START_REF] Straub | Temporal Evolution of the Mariana Arc: Mantle Wedge and Subducted Slab Controls Revealed with a Tephra Perspective[END_REF]. Meanwhile, recycled oceanic upper alkali basalts are also recognized as an important enrichment source for basalts related to subduction [START_REF] Staudigel | Seamounts in the Subduction Factory[END_REF][START_REF] Straub | Temporal Evolution of the Mariana Arc: Mantle Wedge and Subducted Slab Controls Revealed with a Tephra Perspective[END_REF]. These oceanic upper alkali basalts generally have distinctly different enriched isotope and trace element features compared with MORBs [START_REF] Straub | Temporal Evolution of the Mariana Arc: Mantle Wedge and Subducted Slab Controls Revealed with a Tephra Perspective[END_REF]. Therefore, in addition to normal MORBs, the top alkali basalts are also regarded as an important recycled component during plate subduction. Due to the marked mobility of trace elements, the dehydration process, occurring at depths where subduction begins, greatly changes the concentrations (and ratios) of trace elements in the oceanic crust and sediments [START_REF] Aizawa | Element transport by dehydration of subducted sediments: Implication for arc and ocean island magmatism[END_REF][START_REF] Johnson | Dehydration and melting experiments constrain the fate of subducted sediments[END_REF][START_REF] Kessel | Trace element signature of subduction-zone fluids, melts and supercritical liquids at 120-180 km depth[END_REF][START_REF] Kogiso | Trace element transport during dehydration processes in the subducted oceanic crust: 1. Experiments and implications for the origin of ocean island basalts[END_REF]. La, Ba and Pb are more mobile than Nb, Th and Ce; therefore, the ratios of Nb/La and Ce/Pb are much higher in dehydrated ROC than in fresh oceanic crust, and the Ba/Th ratio is reduced in both dehydrated ROC and sediments [START_REF] Aizawa | Element transport by dehydration of subducted sediments: Implication for arc and ocean island magmatism[END_REF][START_REF] Johnson | Dehydration and melting experiments constrain the fate of subducted sediments[END_REF][START_REF] Kessel | Trace element signature of subduction-zone fluids, melts and supercritical liquids at 120-180 km depth[END_REF][START_REF] Kogiso | Trace element transport during dehydration processes in the subducted oceanic crust: 1. Experiments and implications for the origin of ocean island basalts[END_REF]. On the basis of mobility (or partition coefficients) from [START_REF] Kogiso | Trace element transport during dehydration processes in the subducted oceanic crust: 1. Experiments and implications for the origin of ocean island basalts[END_REF] or [START_REF] Kessel | Trace element signature of subduction-zone fluids, melts and supercritical liquids at 120-180 km depth[END_REF] and data for the average MORBs [START_REF] Gale | The mean composition of ocean ridge basalts[END_REF], the Nb/La, Ce/Pb and Ba/Th ratios of the recycled dehydrated oceanic crust can be changed to 2.0, 74 and 56 from their original values of 0.9, 24 and 71, respectively. Those ratios of recycled common MORBs are still too low to be the precursor source for the XL basalts (Nb/La = 1.8 to 2.8 and Ba/Th = 68 to 90).

Recycled oceanic crust in the source of Group 1 basalts

The Nb/La and Ba/Th ratios of the XL basalts are also higher than those of DMM. The trace element concentrations are more elevated in the upper alkali basalts overlying the tholeiitic basalts in oceanic crust. The ratios of Nb/La, Ce/Pb, and Ba/Th in dehydrated top alkali basalts (TABs) can be changed to 4.0, 120, and 82, from their original values of 1.8, 31, and 156, respectively, if we use the available data for alkali basalts from the ODPs 801, in the Pacific plate (TABs in [START_REF] Kelley | Composition of altered oceanic crust at ODP Sites 801 and 1149[END_REF]). Meanwhile, the Ba/La Chapter 5 ratio of dehydrated TABs is approximately 26, which is higher than that of ROC and similar to that of the XL basalts (Fig. 5-13 a). All of the Group 1 basalts form an explicit mixing line between the recycled oceanic TABs and DMM in the plots of Ba/La, Ce/Pb, and Nb/La vs. Ba/Th (Fig. 5-13 a-c). Such a mixing line can also be found in the plot of H2O/Ce vs. Ba/Th (Fig. 5-13d). The dehydrated top oceanic alkali basalts are therefore proposed as the enriched component source in the 26-Myr-old Group 1 samples.

Recycled sediment signature in the source of Group 2 basalts

Compared with the Group 1 samples, the younger Group 2 basalts have higher SiO2, H2O/Ce and Ba/Th ratios and lower Ce/Pb and Nb/La ratios. These features cannot be the result of a simple mixture between the recycled oceanic crust and DMM but require another wetter and more enriched source (Fig. 5678910111213). Subducted sediments can carry more water into the mantle than subducted oceanic crust [START_REF] Dixon | Recycled dehydrated lithosphere observed in plume-influenced mid-ocean-ridge basalt[END_REF][START_REF] Windley | Delamination/thinning of subcontinental lithospheric mantle under Eastern China: the role of water and multiple subduction[END_REF]. The H2O/Ce ratios of oceanic sediments can reach up to 1200 (Dixon et al., 2002;[START_REF] Plank | The chemical composition of subducting sediment and its consequences for the crust and mantle[END_REF]. Depending on the degree of dehydration, the H2O/Ce ratios of dehydrated GLOSS are thus expected to range from approximately 100 to several hundred, given the ratios of 100 for the recycled crust and 150-200 for the DMM [START_REF] Dixon | Recycled dehydrated lithosphere observed in plume-influenced mid-ocean-ridge basalt[END_REF]Michael, 1995;[START_REF] Shaw | Long-term preservation of slab signatures in the mantle inferred from hydrogen isotopes[END_REF]. Other candidates for a wet source include hydrous metasomatic minerals, such as hornblende, within the lithosphere beneath the Zhejiang region or recycled oceanic lithosphere, which was discussed and excluded above. According to the plots of Ba/Th, Ce/Pb and H2O/Ce vs. Ba/La (Fig. 5-13 a, b and d), the higher Ba/Th and H2O/Ce and lower Ce/Pb ratios of Group 2 samples require a sediment-like component. Meanwhile, Group 2 also has relatively high Nb/La and high Nb/U; therefore, we suggest that, in addition to a sediment-like component, there should also be a recycled oceanic crust component in the source of Group 2 basalts.

Modeling source

Start materials and elementary mobility

To better understand the sources of the Group 1 and Group 2 basalts, we use these Chapter 5 starting materials to recover the process of dehydration of the recycled TABs and sediments. The Pacific and Philippine Sea plates are subducting beneath East Asia along the Mariana, Izu-Bonin, Japan, and Ryukyu trenches, but the subduction along the Ryukyu trench stops at approximately 300 km depth [START_REF] Fukao | Subducting slabs stagnant in the mantle transition zone[END_REF]. Therefore, the recycled subducted materials under SE China can be represented by ODP materials near the Mariana trench.

The trace elements and isotopic compositions of start materials for modeling are Marianas sediments (or global average sea sediments), Pacific Oceanic top alkaline basalts in ODPs 801, and deplete mantle, from [START_REF] Plank | The chemical composition of subducting sediment and its consequences for the crust and mantle[END_REF], [START_REF] Kelley | Composition of altered oceanic crust at ODP Sites 801 and 1149[END_REF] and [START_REF] Hauff | Sr-Nd-Pb composition of Mesozoic Pacific oceanic crust (Site 1149 and 801, ODP Leg 185): Implications for alteration of ocean crust and the input into the Izu-Bonin-Mariana subduction system[END_REF], and [START_REF] Workman | Major and trace element composition of the depleted MORB mantle (DMM)[END_REF], respectively, which are listed in Table 5-4. The element mobility of recycled crust is determined from [START_REF] Kogiso | Trace element transport during dehydration processes in the subducted oceanic crust: 1. Experiments and implications for the origin of ocean island basalts[END_REF], [START_REF] Kessel | Trace element signature of subduction-zone fluids, melts and supercritical liquids at 120-180 km depth[END_REF], [START_REF] Aizawa | Element transport by dehydration of subducted sediments: Implication for arc and ocean island magmatism[END_REF], and [START_REF] Johnson | Dehydration and melting experiments constrain the fate of subducted sediments[END_REF], and the dehydration mobility of trace elements in sediments during subduction are from [START_REF] Aizawa | Element transport by dehydration of subducted sediments: Implication for arc and ocean island magmatism[END_REF] and re-calculated by the data from [START_REF] Johnson | Dehydration and melting experiments constrain the fate of subducted sediments[END_REF], while Mobility=(C s -C r )/C r , (C s is the start concentration, C r is the residual concentration). Then, the Mobility values we use are chosen from the calculated results for oceanic materials dehydration. The partition coefficients and the reaction ratio of the modified source follow [START_REF] Salters | Composition of the depleted mantle[END_REF] or [START_REF] Pilet | Monte Carlo Simulations of Metasomatic Enrichment in the Lithosphere and Implications for the Source of Alkaline Basalts[END_REF], which are based on the experimental data of [START_REF] Salters | Trace element partitioning during the initial stages of melting beneath mid-ocean ridges[END_REF] and the compilation of [START_REF] Halliday | Incompatible trace elements in OIB and MORB and source enrichment in the sub-oceanic mantle[END_REF], as well as the GERM partition coefficient database. Then the batch partial melting modeling is used to calculate the trace element composition of melts. The isotopic ratios of recycled materials are different from those of modern oceanic basalts, such as the ODPs 801 we use, due to time-integrated radiogenic ingrowth. Before we calculate the proportion of subducted material, we must estimate the age of the stagnant slab beneath the Zhejiang region. The modern subduction rate at the Mariana trench is 45 mm/a, [START_REF] Plank | The chemical composition of subducting sediment and its consequences for the crust and mantle[END_REF] and the distance in the horizontal direction between the Zhejiang region and the Mariana trench (E117° to E142°) is at least 2400 km, plus the depth of the stagnant slab (approximately 440-660 km, here we use 500 km), which thus moved more than 2900 km (2400 km+500 km) over approximately 65 Myr. If we take the age of the Group 1 basalts (approximately 26 Ma, Ho et al. (2003)), we can assume that these oceanic basalts subducted and dehydrated at least 90 Ma. Considering that the age of the Pacific slab is 157 Ma [START_REF] Kelley | Composition of altered oceanic crust at ODP Sites 801 and 1149[END_REF], therefore, we used a slab age of approximately 247 Ma for our recycled oceanic crust component [START_REF] Kelley | Composition of altered oceanic crust at ODP Sites 801 and 1149[END_REF]. [START_REF] Müller | Long-Term Sea-Level Fluctuations Driven by Ocean Basin Dynamics[END_REF] suggested that the Pacific plate has been subducting since the Cretaceous, which is consistent with our assumption. The isotopic calculation is based on following assumptions: (1) the recycled TABs and sediments subducted from 90 Ma, and the ages of TABs and sediments were 247 Ma and 90 Ma,respectively; (2) the source of TABs is DMM, and the trace elements and isotopic compositions of DMM are from [START_REF] Workman | Major and trace element composition of the depleted MORB mantle (DMM)[END_REF]; (3) the trace elements of recycled TABs and sediments are the result in Table 5-4; and(4 [START_REF] Kelley | Composition of altered oceanic crust at ODP Sites 801 and 1149[END_REF] and [START_REF] Hauff | Sr-Nd-Pb composition of Mesozoic Pacific oceanic crust (Site 1149 and 801, ODP Leg 185): Implications for alteration of ocean crust and the input into the Izu-Bonin-Mariana subduction system[END_REF], the assumed isotopic data of the DMM source are from [START_REF] Workman | Major and trace element composition of the depleted MORB mantle (DMM)[END_REF]). To simplify the calculation, we assume that the sediments retained their modern values of trace element concentrations and underwent a dehydration process similar to recycled TABs (ODPs 801). Then, we estimate the 90 Ma-time integrated isotopic compositions of the subducted sediments. Their chemical and isotopic compositions are also listed in Table 5-4. Based on this result, the proportions of recycled TABs (801) are calculated using a mixing equation of the 87 Sr/ 86 Sr isotopic ratio between the plate and DMM. from [START_REF] Workman | Major and trace element composition of the depleted MORB mantle (DMM)[END_REF] and also listed in Table 5-5. The average 87 Sr/ 86 Sr ratios of all XL samples are used to calculate the ratios of each recycled material composition.

The isotopic compositions of GP-3 and SC-1 are used for GP and SC, respectively. The isotopic compositions of goal mixtures for SC* is 0.703664 for 87 Sr/ 86 Sr (SC-1), and 0.512959 for 143 Nd/ 144 Nd (SC-3). The calculated proportions of XL, GP, SC and SC* are listed in Table 5-5. The partition coefficients and the reaction ratios of the modified sources follow [START_REF] Salters | Composition of the depleted mantle[END_REF] or Pilet et al. (2011) (Table 5-5), which are estimated based on the experimental data of [START_REF] Salters | Trace element partitioning during the initial stages of melting beneath mid-ocean ridges[END_REF] and [START_REF] Salters | Trace element partitioning during the initial stages of melting beneath mid-ocean ridges[END_REF], and the compilation of [START_REF] Halliday | Incompatible trace elements in OIB and MORB and source enrichment in the sub-oceanic mantle[END_REF], as well as the GERM partition coefficient database. The "Batch" melting model are used to calculate the melting compositions. We show the result of melting for XL, when F= 0.1%, 0.5%, 1%, 1.5% and 10% for example, in Table 5-5.

To obtain the average 87 Sr/ 86 Sr isotopic ratio of the Group 1 basalts, 3.95% recycled TABs (801) and 96.05% DMM are required. We estimate the melt compositions for different degrees of partial melting (0.1-10%) of the mixed source, which are shown in (2.4-2.9 vs. the source of the Group 2 basalts. These calculated melts are produced by small degrees of partial melting, and this may explain why the sites and volumes of basalts in Southeast China are so limited.

Links between enriched components and Pacific subduction

The variation in the source of the Zhejiang basalts indicates that the recycled materials in their source changed between 11 and 17 Ma. One of the most plausible interpretations of the change in these two group of basalts is that several new recycled material components were injected into the source of the basalts. On the other hand, intra-plate volcanism in the Zhejiang area, which had started in the Oligocene, continued and became more expansive in the Pliocene [START_REF] Ho | 40 Ar/ 39 Ar dating and geochemical characteristics of late Cenozoic basaltic rocks from the Zhejiang-Fujian region, SE China: eruption ages, magma evolution and petrogenesis[END_REF], requiring a continuous material supply. Since 100 Ma, the only plate subducted underneath SE China has been the Pacific Oceanic plate [START_REF] Fukao | Subducting slabs stagnant in the mantle transition zone[END_REF][START_REF] Müller | Long-Term Sea-Level Fluctuations Driven by Ocean Basin Dynamics[END_REF]. The presence of a stagnant subducted Pacific slab in the mantle transition zone (MTZ, 440-660 km) beneath eastern China is indicated by seismic images [START_REF] Huang | High-resolution mantle tomography of China and surrounding regions[END_REF][START_REF] Li | Structure of the upper mantle and transition zone beneath Southeast Asia from traveltime tomography[END_REF][START_REF] Wei | East Asia mantle tomography: New insight into plate subduction and intraplate volcanism[END_REF][START_REF] Zhao | Deep slab subduction and dehydration and their geodynamic consequences: Evidence from seismology and mineral physics[END_REF]) (Fig. 2-3b).

Therefore, the subducted Pacific slab is the most likely candidate for the recycled materials. Two other clues also point to the recent stagnant subducted Pacific slab. (1) The moderately depleted to slightly enriched Sr-Nd-Pb isotopic compositions require a recent enriched source; the subducted Pacific plate (since 120 Ma, Müller et al. (2008))

is the only young enriched source in South China. Other subductions are older than 200

Ma [START_REF] Windley | Delamination/thinning of subcontinental lithospheric mantle under Eastern China: the role of water and multiple subduction[END_REF], including the Paleo-Asian subduction from before 234 Ma [START_REF] Chen | Sources of Anfengshan basalts: Subducted lower crust in the Sulu UHP belt, China[END_REF][START_REF] Xiao | Accretion leading to collision and the Permian Solonker suture, Inner Mongolia, China: Termination of the central Asian orogenic belt[END_REF][START_REF] Xiao | End-Permian to mid-Triassic termination of the accretionary processes of the southern Altaids: implications for the geodynamic evolution, Phanerozoic continental growth, and metallogeny of Central Asia[END_REF] and, the Paleo-Tethyan subduction between North and South China and between South China and Indochina, which occurred either in the Middle or Late Triassic (245 to 210 Ma) [START_REF] Hacker | Hightemperature geochronology constraints on the tectonic history and architecture of the ultrahigh-pressure Dabie-Sulu Orogen[END_REF][START_REF] Liu | Mesozoic sedimentary basin development and tectonic implication, northern Yangtze Block, eastern China: record of continentcontinent collision[END_REF], or in the Early Triassic (245 Ma) [START_REF] Lepvrier | The Early Triassic Indosinian orogeny in Vietnam (Truong Son Belt and Kontum Massif); implications for the geodynamic evolution of Indochina[END_REF]. ( 2)

Although the geochemistry of the basalts in East China shows some differences in detail, the rocks share similar trace element features, such as positive anomalies in Nb (Ta)

and Sr and negative anomalies in Pb, Ti, Zr, Hf, and Sr-Nd-Pb isotopic compositions [START_REF] Chen | Changing recycled oceanic components in the mantle source of the Shuangliao Cenozoic basalts, NE China: New constraints from water content[END_REF][START_REF] Kuritani | Intensive hydration of the mantle transition zone beneath China caused by ancient slab stagnation[END_REF][START_REF] Li | Recycling of oceanic crust from a stagnant slab in the mantle transition zone: Evidence from Cenozoic continental basalts in Zhejiang Province, SE China[END_REF]Liu et al., 2015b;[START_REF] Sakuyama | Melting of dehydrated oceanic crust from the stagnant slab and of the hydrated mantle transition zone: Constraints from Cenozoic alkaline basalts in eastern China[END_REF][START_REF] Wang | Geochemical constraints on the nature of mantle source for Cenozoic continental basalts in east-central China[END_REF]Xu et al., 2012a;Xu et al., 2012b;[START_REF] Zhang | The genesis of Cenozoic basalts from the Jining area, northern China: Sr-Nd-Pb-Hf isotope evidence[END_REF], implying that Southeast China basalts possibly share a common geodynamic factor with those of North and East China.

As we noted above (Section 5.3.4), the source materials of the Zhejiang basalts Chapter 5

show temporal variation and consist of fusible CO2-bearing pyroxenite/eclogite veins and wall rock peridotites. The Pacific plate has been subducting with abundant water and other volatiles, such as CO2 (Dixon et al., 2004;[START_REF] Dixon | Recycled dehydrated lithosphere observed in plume-influenced mid-ocean-ridge basalt[END_REF][START_REF] Plank | The chemical composition of subducting sediment and its consequences for the crust and mantle[END_REF][START_REF] Shaw | Long-term preservation of slab signatures in the mantle inferred from hydrogen isotopes[END_REF] since possibly the Mesozoic [START_REF] Müller | Long-Term Sea-Level Fluctuations Driven by Ocean Basin Dynamics[END_REF].

The presence of CO2 and H2O lowers the solidus temperature of peridotites and eclogites/pyroxenites [START_REF] Dasgupta | Partial melting experiments of peridotite+CO2 at 3 GPa and genesis of alkalic ocean island basalts[END_REF][START_REF] Hirose | Partial melt compositions of carbonated peridotite at 3 GPa and role of CO2 in alkali-basalt magma generation[END_REF][START_REF] Kovacs | An Experimental Study of Water in Nominally Anhydrous Minerals in the Upper Mantle near the Water-saturated Solidus[END_REF], which may have triggered the Cenozoic intraplate volcanism in East Asia. Upwelling of this type of mantle started in the Oligocene, which produced the Group 1 (XL) basalts (Fig.

5-15a

). With constant subduction of the Pacific plate, the recycled materials were continuously supplied by their source and participated in the melting processes (Fig. 5-15b). The upwelling of the recycled material may have moved eastward due to slab roll back and trench retreat (Fig. 5-15a and b) [START_REF] Niu | Subduction initiation, trench retreat and global tectonic consequences: The origin of backarc basins in the western Pacific and effect on eastern China geology since the Mesozoic[END_REF], resulting in a variation in the recycled materials. Most of the volatile components together with some incompatible elements might have been lost during dehydration of the slab approximately at 150 km depth, as shown in Fig. 5-15a [START_REF] Aizawa | Element transport by dehydration of subducted sediments: Implication for arc and ocean island magmatism[END_REF][START_REF] Johnson | Dehydration and melting experiments constrain the fate of subducted sediments[END_REF][START_REF] Kessel | Trace element signature of subduction-zone fluids, melts and supercritical liquids at 120-180 km depth[END_REF][START_REF] Kogiso | Trace element transport during dehydration processes in the subducted oceanic crust: 1. Experiments and implications for the origin of ocean island basalts[END_REF]. However, considering the scale of the subducted oceanic slab, some water and other volatiles were carried into the deep mantle (the MTZ) by transitioning to high-pressure hydrous phases, such as D and H [START_REF] Nishi | Deep water cycle: Mantle hydration[END_REF][START_REF] Nishi | Stability of hydrous silicate at high pressures and water transport to the deep lower mantle[END_REF]Ohtani, 2005a, b;[START_REF] Poli | Petrology of Subducted Slabs[END_REF]. When these hydrous phases were broken down, they released large amounts of H2O, which resulted in a reduction of the solidus in the surrounding and overlying mantle [START_REF] Niu | Generation and Evolution of Basaltic Magmas: Some Basic Concepts and a New View on the Origin of Mesozoic-Cenozoic Basaltic Volcanism in Eastern China[END_REF][START_REF] Windley | Delamination/thinning of subcontinental lithospheric mantle under Eastern China: the role of water and multiple subduction[END_REF] (Fig.

5-15c).

A cartoon to illustrate different subducted oceanic material components in two-stage

Conclusions

(1) Two groups of Zhejiang Cenozoic basalts are recognized by their obvious distinctions in major and trace element compositions; furthermore, both the groups erupted during different periods. The samples from Group 1 (older group)are characterized by relatively low Si, Al, and alkali contents, low Ba/Th ratios, and high Ce/Pb and Nb/La ratios. Meanwhile, they exhibit strongly negative K, Ti, Hf, and Pb anomalies in the extended trace element patterns. The Group 2 (younger group) samples have higher Si and Al and less alkali content than the Group 1 samples and exhibit highly positive Sr anomalies without obvious K and Ti anomalies. The two groups are not likely to be genetically linked.

(2) Most of the cpx phenocrysts in the Zhejiang basalts maintain their original H2O content inherited from the parent magma, despite some basalts possibly experiencing H2O loss during magma ascent. The "initial" H2O content of the melts, reversely calculated from the H2O content of the cpx phenocrysts and the corresponding partition coefficients of H2O between cpx and basaltic melts, is 1.4 to 2.2 wt. % for the Group 1 samples and 1.3 to 2.6 wt. % for the Group 2 samples. The "initial" H2O content of the Zhejiang basalts falls within the range of BABBs and IABs, indicating recycled oceanic materials in the mantle source.

(3) The Zhejiang basalts were produced by two components: depleted mantle and enriched recycled materials. The Group 1 samples exhibit higher Nb/La and Ce/Pb ratios than the Group 2 samples, plotting on the mixing curve between DMM and recycled dehydrated oceanic alkali basalts. The Group 2 samples show higher H2O/Ce and Ba/Th ratios than the Group 1 samples, reflecting enriched sources of recycled dehydrated oceanic sediments together with the oceanic crust. This evidence implies that the stagnant slab of the Pacific plate served as a continuous material source for the Cenozoic basalts in the Zhejiang area. Lu 0.12 0.12 0.12 0.12 0. 11 0.1 2 0.12 0.12 0. 12 0.11 0.13

Geochemical heterogeneity in the source of Cenozoic basaltic rocks in the Fujian region 6.1 Results

Bulk-rock major and trace elements

The Fujian samples are plotted within a total alkali versus silica (TAS) diagram

Sr-Nd-Pb isotopic compositions

Bulk rock Sr-Nd-Pb isotopic compositions of the Fujian samples are listed in The Sr-Nd isotopic ratio of the NTS samples are from 0.703999 to 0.704049 and from 0.512778 to 0.512840, respectively. The Fujian samples share almost similar radiogenic Sr-Nd isotopic composition, consistent with the previous studies [START_REF] Zou | Major, trace element, and Nd, Sr and Pb isotope studies of Cenozoic basalts in SE China: mantle sources, regional variations, and tectonic significance[END_REF]Ho Chapter 6 et al., 2003). The plots of 87 Sr/ 86 Sr vs. 143 Nd/ 144 Nd ratios of the Fujian samples display a mixing trend together from DMM with EM components (Fig. 6-4a and b) and within the range of previously reported data for the Cenozoic basalts from eastern China [START_REF] Chen | Sources of Anfengshan basalts: Subducted lower crust in the Sulu UHP belt, China[END_REF][START_REF] Choi | Sr, Nd, Pb and Hf isotopic compositions of late Cenozoic alkali basalts in South Korea: Evidence for mixing between the two dominant asthenospheric mantle domains beneath East Asia[END_REF][START_REF] Fan | Petrogenesis and evolution of Quaternary basaltic rocks from the Wulanhada area, North China[END_REF][START_REF] Guo | Lithosphere thinning beneath west North China Craton: Evidence from geochemical and Sr-Nd-Hf isotope compositions of Jining basalts[END_REF][START_REF] Ho | 40 Ar/ 39 Ar dating and geochemical characteristics of late Cenozoic basaltic rocks from the Zhejiang-Fujian region, SE China: eruption ages, magma evolution and petrogenesis[END_REF][START_REF] Ho | Late Cenozoic magmatic transitions in the central Great Xing'an Range, Northeast China: Geochemical and isotopic constraints on petrogenesis[END_REF][START_REF] Huang | Geochronology and geochemistry of Cenozoic basalts from eastern Guangdong, SE China: constraints on the lithosphere evolution beneath the northern margin of the South China Sea[END_REF][START_REF] Kuang | Petrogenetic evaluation of the Laohutai basalts from North China Craton: Melting of a two-component source during lithospheric thinning in the late Cretaceous-early Cenozoic[END_REF][START_REF] Kuritani | Intensive hydration of the mantle transition zone beneath China caused by ancient slab stagnation[END_REF][START_REF] Li | Geochemistry of Cenozoic basalts from the Bohai Bay Basin: Implications for a heterogeneous mantle source and lithospheric evolution beneath the eastern North China Craton[END_REF][START_REF] Sakuyama | Melting of dehydrated oceanic crust from the stagnant slab and of the hydrated mantle transition zone: Constraints from Cenozoic alkaline basalts in eastern China[END_REF][START_REF] Tang | Asthenosphere-lithospheric mantle interaction in an extensional regime: Implication from the geochemistry of Cenozoic basalts from Taihang Mountains, North China Craton[END_REF][START_REF] Wang | Temperature, Pressure, and Composition of the Mantle Source Region of Late Cenozoic Basalts in Hainan Island, SE Asia: a Consequence of a Young Thermal References Mantle Plume close to Subduction Zones[END_REF]Wang et al., 2013;[START_REF] Wang | Geochemical constraints on the nature of mantle source for Cenozoic continental basalts in east-central China[END_REF][START_REF] Xu | Role of lithosphereasthenosphere interaction in the genesis of Quaternary alkali and tholeiitic basalts from Datong, western North China Craton[END_REF]Xu et al., 2012a;Xu et al., 2012b;[START_REF] Yan | Cenozoic alkali basalts from Jingpohu, NE China: The role of lithosphere-asthenosphere interaction[END_REF][START_REF] Zeng | Crust recycling in the sources of two parallel volcanic chains in Shandong, North China[END_REF]Zhang et al., 2002a;[START_REF] Zhang | Geochemical evidence for interaction between oceanic crust and lithospheric mantle in the origin of Cenozoic continental basalts in east-central China[END_REF][START_REF] Zhang | The genesis of Cenozoic basalts from the Jining area, northern China: Sr-Nd-Pb-Hf isotope evidence[END_REF]Zhang et al., 2002b;[START_REF] Zhao | Geochemistry of Quaternary basaltic lavas from the Nuomin volcanic field, Inner Mongolia: Implications for the origin of potassic volcanic rocks in Northeastern China[END_REF][START_REF] Zou | U-Th isotopes in Hainan basalts: Implications for subasthenospheric origin of EM2 mantle endmember and the dynamics of melting beneath Hainan Island[END_REF][START_REF] Zou | U-Th systematics of dispersed young volcanoes in NE China: Asthenosphere upwelling caused by piling up and upward thickening of stagnant Pacific slab[END_REF][START_REF] Zou | Constraints on the origin of historic potassic basalts from northeast China by U-Th disequilibrium data[END_REF][START_REF] Zou | Major, trace element, and Nd, Sr and Pb isotope studies of Cenozoic basalts in SE China: mantle sources, regional variations, and tectonic significance[END_REF].

Li and O isotopic compositions of cpx phenocrysts

The Li and O isotope of cpx phenocrysts are analyzed for the MX, SH, and BL samples. All the analytical sessions of both Li and O isotope for the cpx standards display associated chemical composition matrix effect (Fig. 67).

(a) Plots of matrix effect vs. composition of standard for Lithium and (b) Plots of matrix effect vs. composition of standard for Lithium Oxygen. • • y = 0.96x -66.008, R 2 = 0.89 Mg# 80 82

• • • • • ••• • • • • 1 ... ~ . . ~ a 10~----------------------------~ 82

Li content and Li isotopic compositions

The matrix effect in the Li analysis through SMIS with various cpx element composition can be observed in our analysis (Fig. 67). The slopes of δ 7

O isotopic compositions

Beside very few parts, the chemical compositions of the Fujian cpx phenocrysts fall within the range of chemical composition of standards (Table 3-3

Discussions Crustal/peridotite assimilation and fractional crystallization

The assimilation of continental crusts or co-existing plutonic ultramafic • NTS

•• • • • • = (!;) 1.00 • •• • • O.HO e# •• Peridotite .~ contaminate • • BL 0.60
• d 50 •• • • • 40 • • Fraction al • .o: • ~zation • BL 30 • • • SH , • •

Variation of δ 7 Li and Li content

The entire δ 7 Li and Li content variation of the Fujian basalts have been described in section 6.1.3. The variation of δ 7 Li and Li content in cpx phenocryst are either the record of the magma evolution or the result of Li diffusion. Relative to the SH and BL cpx phenocrysts, the MX cpx phenocrysts that do not have xenocryst core have limited variation of δ 7 Li and Li content. The SH and BL cpx phenocryst have more complex δ 7 Li and Li content zonation. This zonation is an inherent feature of pristine phenocryst material and is not the result from an alteration effect from Li isotope fractionation during secondary alteration [START_REF] Pistiner | Lithium-isotope fractionation during continental weathering processes[END_REF]. The obvious complication to the zonation lies in the profiles observed in the cpx phenocrysts from the Fujian basalts (Fig. 678). The variability of Li isotope and Li content in the cpx phenocrysts must arise from changing physicochemical conditions during crystal growth or subsequent diffusion of Li in solid-state after magma eruption or invasion [START_REF] Rudnick | Lithium element and isotopic disequilibrium in minerals from peridotitic xenoliths from far-east Russia: product of recent meltfluid/rock reaction[END_REF]. The high diffusivity of Li ensure rapid isotopic equilibration at magmatic temperatures, equilibrium may be disturbed by continued diffusive movement of Li during cooling, at temperatures well below the point at which most cations are effectively immobile. The 6 Li diffuses faster than the 7 Li, the difference of diffusion speed will result in the fractionation of 6 Li and 7 Li. The variation of temperature (DLi cpx-melt ), fO2, the Li content, and δ 7 Li in melts can result in the fractionation of Li [START_REF] Richter | Lithium isotope fractionation by diffusion in minerals. Part 1: Pyroxenes[END_REF]. The Li diffuses fast in melts and minerals [START_REF] Richter | Isotope fractionation by chemical diffusion between molten basalt and rhyolite[END_REF], especially for cpx, with several orders of magnitude faster than other common metal cations in melts at magma temperature [START_REF] Coogan | Rates of hydrothermal cooling of new oceanic upper crust derived from lithium-geospeedometry[END_REF][START_REF] Van Orman | Rare earth element diffusion in diopside: influence of temperature, pressure, and ionic radius, and an elastic model for diffusion in silicates[END_REF][START_REF] Giletti | Alkali diffusion in plagioclase feldspar[END_REF]. The 1 mm wide zone of Li in cpx can disappear in thousands of years when temperature is 900 to 1000 ºC, corresponding to a Li diffusion coefficient from 10 -13 to 10 -12 m 2 s -1 [START_REF] Rudnick | Lithium element and isotopic disequilibrium in minerals from peridotitic xenoliths from far-east Russia: product of recent meltfluid/rock reaction[END_REF]. Any isotopic disequilibrium of Li can be generated in short before the magma cooling below Li isotope exchange closure temperature (700 ºC, [START_REF] Coogan | Rates of hydrothermal cooling of new oceanic upper crust derived from lithium-geospeedometry[END_REF].

All the xenocryst cores in the MX samples have relatively higher Li content than the cpx phenocrysts (Fig. 3 enough time after leaving from mantle source, then any Li isotopic heterogeneity in the mantle will be erased in a relatively short time [START_REF] Parkinson | High-temperature lithium isotope fractionation: insights from lithium isotope diffusion in magmatic systems[END_REF][START_REF] Halama | Tracking the lithium isotopic evolution of the mantle using carbonatites[END_REF][START_REF] Gallagher | Fractionation of lithium isotopes in magmatic systems as a natural consequence of cooling[END_REF]. The isochronous preserved information of δ 7 Li and

Li content for the xenocrysts also disagree with "totally rebalance" of cpx phenocrysts, but escaping co-existing xenocrysts.

The Li content of the MX bulk rock range from 7.7 to 11.0 ppm by ICP-MS, while the cpx phenocryst Li content mostly range from 2.0 to 7.0 ppm. The *DLi cpx-melt (about 0.5) calculated from the cpx phenocrysts and the melts is higher than the DLi cpx-melt (0.2) reported by [START_REF] Brenan | Behaviour of boron, beryllium, and lithium during melting and crystallization: constraints from mineral-melt partitioning experiments[END_REF]. When the Li content are compared among different samples, the larger range of the Li contents are observed in Fig. 6-8c (from 3 to 40ppm, mostly from 3 to 7 ppm), beyond the variation of Li equilibrium between the melts and cpx phenocrysts [START_REF] Beck | Li isotopic variations in single pyroxenes from the Northwest Africa 480 shergottite (NWA 480): a record of degassing of Martian magmas?[END_REF]2006;[START_REF] Jeffcoate | Li isotope fractionation in peridotites and mafic melts[END_REF][START_REF] Rudnick | Lithium element and isotopic disequilibrium in minerals from peridotitic xenoliths from far-east Russia: product of recent meltfluid/rock reaction[END_REF].

The cpx grain 5-3-9 has very high Li content (up to 30 ppm) but low Mg# (79). This grain cannot be crystallized from the MX magma directly, but may be the crystal from other magma or surrounding rocks. The Li content have limited intra-granular variation for most MX cpx phenocrysts, as shown in Fig. 6-8b. However, the wide range of δ 7 Li can be observed in Fig. 6-8c, although the Li content variation is limited, suggesting either the Li content or δ 7 Li is non-equilibrium. This non-equilibrium may be explained by ( 1

H2O content of initial magma

Water is one of the most important factors influencing the melting process in the mantle (Dixon et al., 2004;[START_REF] Hirth | Water in the oceanic upper mantle: implications for rheology, melt extraction and the evolution of the lithosphere[END_REF]Karato, 2010). The primary information of water in basalts are recovered based on the water content of cpx phenocryst and the corresponding partition coefficient of H2O between the cpx phenocryst and basaltic melts. Prior to declare the H2O content of the "initial" basaltic melts, it is important to understand: (1) the evolution history of magma H2O after they left melting source and during ascent to surface of earth, and ( 2) the H diffusion of cpx phenocrysts after they crystallized from magma, as suggested in Chapter 5. Meanwhile, the Li isotope are also used to trace the later diffusion of cpx phenocrysts.

Average H2O content of the melts calculated from cpx phenocrysts with Mg# higher than 80 vs. the average water contents estimated from cpx phenocrysts with Mg# higher than 75.

The evolution process of magma H2O and their geochemical composition in different stages can be recorded by cpx xenocrysts whose composition depend on their parent magma when they are crystallized. The H2O content of basaltic melts can be changed by degassing, fractional crystallization, and assimilation of surrounding rocks/xenoliths during magma ascent. Fractional crystallization usually increase the H2O content of melts, due to the low H2O (<<1000 ppm, 0.1%) in those removed crystals i.e., olivine and cpx, if the magma are not so "dry". On the other hand, low degree fractional crystallization will not change the H2O content of melts remarkably [START_REF] Chen | Changing recycled oceanic components in the mantle source of the Shuangliao Cenozoic basalts, NE China: New constraints from water content[END_REF]. The lower continental crust and peridotites are usually considered dry [START_REF] Hao | Partial melting control of water contents in the Cenozoic lithospheric mantle of the Cathaysia block of South China[END_REF][START_REF] Xia | Water in the lower crustal granulite xenoliths from Nushan, eastern China[END_REF]Yang et al., 2008b;[START_REF] Yu | H2O contents and their modification in the Cenozoic subcontinental lithospheric mantle beneath the Cathaysia block, SE China[END_REF], so the assimilation of a few surrounding rocks or peridotite xenoliths does not increase the H2O content of melts, or even reduce it.

(a)The plots of Mg# vs. the water content of corresponding melts for the MX basalts; (b)

The plots of Mg# vs. the water content of corresponding melts for the SH basalts; and (c)

The plots of Mg# vs. the water content of corresponding melts for the BL samples. Water content ofmelts

• 76 78 Mg# • 80 • 82 • • • • • • • MX • 84 SH • •• 4 • • • • • • li • •• • • , .. 2 0 72 5 4 3 • • • • •#f ...... • •• • .._ • . ••' ..... ... . ... • • • • •• • .. \ • • ••• • • . , ••••• • •• •• •• , .
• • • • • • • .
. .. ..,., .

2 j . •' . . .... ,. ~• •• • )re.:. .. • • • ~ .. , • •~• .. . . • • ~• .. ,. •f •• • • • •••••• • • • • • • ltn• ' • ' \ ~.Je• 1 0 72 77 • • • Mg# ••• •• •~ . 82 • • 1 • . 84 BL Chapter 6
Nevertheless, due to a rapid pressure decrease, the degassing process will intensively reduce the H2O content of the melts. The degassing usually takes place at the later stage of the magma eruption, which is corresponding to an evolved magma composition, i.e. low MgO of phenocryst. So, it can usually be observed that the parent melts corresponding to the cpx phenocrysts with low MgO or Mg# have lower water than those with higher MgO. This concludes that the parent melts of the cpx with higher MgO/Mg# are wetter than those with lower MgO/Mg#. So those cpx with lower MgO/Mg# cannot offer the "true" information of the "initial" melts. All trace elements and radiogenic isotopes are measured as bulk rock features. These features almost remain unchanged, if the erupted magma are considered as a nearly closed system in the Fujian region. So, when the H2O content of the magma are compared to other geochemical data, the "initial" H2O content are required. The "initial" H2O content of magma can only be estimated from those cpx with the highest Mg#/MgO. It is suggested to use those cpx phenocryst with Mg#>80 to stand the most early magma.

The water contents of the Fujian basalts estimated from the cpx phenocryst with Mg#>80 (if there are too rare cpx with Mg#>80, the cpx with Mg#>75 are used to satisfy statistical requirement) are 1.7-2.5%, 1.5-3.8%, 0.3-0.5%, for the BL, SH, and MX samples, respectively.

The second question is whether the cpx phenocryst can survive from later evolution and preserve its information of water. Due to a fast diffusion rate of H in cpx phenocryst measured by experiments (D=10 -10 ~10 -10.5 m 2 /s at 900℃, [START_REF] Hercule | Hydrogen in diopside: Diffusion, kinetics of extractionincorporation, and solubility[END_REF][START_REF] Ingrin | Diffusion of Hydrogen in Minerals[END_REF][START_REF] Ingrin | Hydrogen in nominally anhydrous upper-mantle minerals: concentration levels and implications[END_REF][START_REF] Woods | Hydrogen in diopside: Diffusion profiles[END_REF], the cpx phenocryst may suffer H-loss during magma ascent. The redox reaction:

OH -+ Fe 2+ ↔ O 2-+ Fe 3+ + 1/2 H2 (6-1)
is another possible ways for H loss [START_REF] Weis | Experimental hydration of natural volcanic clinopyroxene phenocrysts under hydrothermal pressures (0.5-3 kbar)[END_REF]. [START_REF] Weis | Magmatic water contents determined through clinopyroxene: Examples from the Western Canary Islands, Spain[END_REF] and [START_REF] Weis | Experimental hydration of natural volcanic clinopyroxene phenocrysts under hydrothermal pressures (0.5-3 kbar)[END_REF] have proved the cpx phenocrysts from Canary basalt have undergone significant H-loss, they suggest such H-loss mostly is related to an oxidation-driving and occurred during a long stage at shallow depth. Meanwhile, [START_REF] Weis | Experimental hydration of natural volcanic clinopyroxene phenocrysts under hydrothermal pressures (0.5-3 kbar)[END_REF] suggested the cpx crystals may undergo pressure-related and oxidation-related dehydration during the eruption as the SC basalts were observed in Chapter 5. Therefore, the water content of erupted clinopyroxene phenocrysts cannot be taken as the proxy to recover magmatic or mantle water contents directly, due to the fast dehydration, even the magma ascent rapid, only degas at minimal degree, and erupt subsequently more violently, that lead to quick quenching of the erupted crystals [START_REF] Weis | Experimental hydration of natural volcanic clinopyroxene phenocrysts under hydrothermal pressures (0.5-3 kbar)[END_REF]. The There are two clues to trace the H loss or diffusion. As well as, the Li also has a fast diffusion under 900 to 1000 ºC, corresponding to the Li diffusion coefficient from 10 -13 to 10 -12 m 2 /s [START_REF] Rudnick | Lithium element and isotopic disequilibrium in minerals from peridotitic xenoliths from far-east Russia: product of recent meltfluid/rock reaction[END_REF] to shallow process. However, although the BL diabases carried numbers of peridotite xenoliths, the Mg# of cpx phenocrysts related to corresponding melts water content is very weak (Fig. 6-14c). The -OH profile of BL-6-4 cpx grain also proves the large H variation (Fig. 6-6c), implying H re-equilibrium of the BL cpx phenocrysts. Therefore, the result of magma water content estimated from the cpx phenocrysts are suggested to stand for the "initial" system water content for the MX basalts, but not sure for the BL sample. The SH basalts may keep their original water content, at least the value of "initial" magma water is the low limit of the magma water. The true water content of the BL diabases may be concealed under the re-equilibrium of H2O if estimated from cpx phenocrysts.

The "initial" water contents of the SH and MX basalts are 1.5-3.8% and 0.3-0.5% respectively . The water content of the SH basalts fall within the range of BABBs and IABs, however, those of the MX basalts fall with the range of OIBs and MORBs (Dixon et al., 2004).

Origin of the oxygen isotopic anomaly

Origin of high δ 18 O value and its large variation

The fractionation of δ 18 O between cpx phenocrysts and basaltic melt is about -0.1 to -0.3 ‰, if are calculated from the difference between Δ 18 O cpx-ol of 0.4‰ and Δ 18 O melt-ol of 0.4 to 0.5‰ [START_REF] Eiler | Oxygen Isotope Variations of Basaltic Lavas and Upper Mantle Rocks[END_REF], or follow Δ cpx-melt= -0.3 [START_REF] Kyser | Oxygen isotope thermometry of basic lavas and mantle nodules[END_REF][START_REF] Harris | Oxygen and hydrogen isotope stratigraphy of the Rustenburg layered suite, Bushveld Complex: constraints on crustal contamination[END_REF], therefore, the measured δ 18 O of cpx phenocrysts can be looked approximately as those of corresponding basaltic magma. The cpx phenocrysts in the Fujian basaltic rocks have much higher and wider δ 18 O ranges (Fig. 6789) than those of typical MORBs (5.7±0.2‰, Mattey et al., 1994; Eiler et al., 1997, for δ 18 Ocpx range from +5.6±0.5‰, if Δ cpx-melt=-0.1) (Fig. 6-9), as well as higher than cpx δ 18 O from different kinds of OIBs lavas (+5.0 to 5.5%, +5.5 to 5.7% and +5.8 to +6.5%, for HIMU, EMII and EM II type OIBs, respectively [START_REF] Eiler | Oxygen isotope variations in ocean island basalt phenocrysts[END_REF]; [START_REF] Widom | Oxygen isotope signatures in olivines from Sao Miguel (Azores) basalts: implications for crustal and mantle processes[END_REF], for δ 18 Ocpx from +4.9 to 5.4%, +5.4 to 5.6% and +5.7 to +6.4%, respectively). [START_REF] Auer | The origin of hydrous, high-δ 18 O voluminous volcanism: diverse oxygen isotope values and high magmatic water contents within the volcanic record of Klyuchevskoy volcano, Kamchatka, Russia[END_REF] have reported Kamchatka cpx phenocrysts from Klyuchevskoy volcano displaying a similar δ 18 O range to our samples from +5.5 to +8.0‰, which are re-calculated by its ol phenocryst δ 18 O (+5.1 to +7.6%) and Δ 18 O cpx-ol (0.4%).

Magmatic processes, secondary alteration, crustal contamination, and so on will change the original Oxygen isotopic composition of magma. The variation of the δ 18 O of the magma caused by high temperature magma process should be less than the level of 0.1‰ (e.g. [START_REF] Eiler | Oxygen Isotope Variations of Basaltic Lavas and Upper Mantle Rocks[END_REF]Zhao and Zheng, 2003), by large numbers of natural observation and theoretical consideration. The effect at high temperature in closed system, such as partial melting, fractional crystallization, degassing excluding AFC processes, is not very large for Oxygen isotope [START_REF] Eiler | Oxygen Isotope Variations of Basaltic Lavas and Upper Mantle Rocks[END_REF]. The accuracy of SIMS analysis for Oxygen isotope is about 0.5‰, (Section 6. 1.3.3), covering the variation of the δ 18 O of the magma caused by high temperature magma process. Meanwhile, the Fujian samples have relative high bulk MgO contents except NTS, higher than 8 wt. %, [START_REF] Kuang | Petrogenetic evaluation of the Laohutai basalts from North China Craton: Melting of a two-component source during lithospheric thinning in the late Cretaceous-early Cenozoic[END_REF][START_REF] Yang | Geochronology and geochemistry of the Mesozoic volcanic rocks in Western Liaoning: implications for lithospheric thinning of the North China Craton[END_REF][START_REF] Fan | On and off the North China Craton: Where is the Archaean keel?[END_REF] arguing against δ 18 O effected by complex magmatic processes. However, the AFC processes and later waterrock will prominently alter the primary Oxygen isotopic composition. The crustal contamination or assimilation will not serve as a significant factor for the Fujian basalts

Chapter 6 as we mentioned in section 6.2.1, such as the bulk rock Ce/Pb and Nb/U ratios of most the Fujian basalts are higher than 28 except NTS and higher than 46, respectively.

Secondary alteration after eruption also does not seem a suitable explanation. Variable high δ 18 O values cannot be the result of altered hydrous minerals in cpx excluded by no hydrous mineral peak in the FTIR analysis and during the sample preparation.

Secondly, the oxygen diffusion rate in cpx at low temperature is too low, to result such significant δ 18 O increase for the young Fujian basalts (D0 is about 10 5 m 2 s -1 , 10 15 magnitude slower than those at 1000℃ [START_REF] Farver | Oxygen and strontium diffusion kinetics in apatite and potential applications to thermal history determinations[END_REF] Overall, the dominantly high δ 18 O values are considered as the original signature of the parent magmas, i.e. the characteristics of the mantle sources, especially for the cpx with higher Mg#. The heterogeneous δ 18 O of intra-granular and intergranular variations from single basalt sample can be up to 2‰, in the Taihang and Shandong Cenozoic basalts (Liu et al., 2015a and2015b), the Canary Island basalts [START_REF] Gurenko | Oxygen isotope heterogeneity of the mantle beneath the Canary Islands: insights from olivine phenocrysts[END_REF], the Borgarhraun basalt (Winpenny and Maclennan, 2014), and the Chifeng basalts (Wang et al., 2015). These heterogeneous δ 18 O are explained as complex magma system from heterogeneous mantle source region [START_REF] Gurenko | Oxygen isotope heterogeneity of the mantle beneath the Canary Islands: insights from olivine phenocrysts[END_REF]Winpenny and Maclennan, 2014).

Magma mixture

The caused by (2), it means the meteoric water probably penetrated into the lower continental crust, but it is too hard to penetrate for so large meteoric water. In addition, it is too difficult for the meteoric water to keep their low δ 18 O after penetration the thick crust without interaction with surrounding lower continental crusts, which have high δ 18 O. On the other hand the later water addition should also be recorded by the cpx, inconsistent of the lower water content in the cpx phenocrysts with low Mg#. The complex magma mixture and crystallization with variable δ 18 O values in plumbing system are considered to explain the various measured δ 18 O values, where distinct magma percolated along their separate channels [START_REF] Sobolev | Ultra-depleted primary melt included in an olivine from the Mid-Atlantic Ridge[END_REF][START_REF] Kelemen | A review of melt migration processes in the adiabatically upwelling mantle beneath oceanic spreading ridges[END_REF][START_REF] Spiegelman | Extreme chemical variability as a consequence of channelized melt transport[END_REF][START_REF] Gurenko | Oxygen isotope heterogeneity of the mantle beneath the Canary Islands: insights from olivine phenocrysts[END_REF][START_REF] Ruprecht | Feeding andesitic eruptions with a high-speed connection from the mantle[END_REF]. Then the cpx phenocrysts with heterogeneous δ 18 O were entrained by

Mantle heterogeneity and recycled component δ 18 O heterogeneity

The high δ 18 O anomalies of the cpx phenocrysts in all the Fujian basalts (Fig. 6789)

are inherited from their parental magmas and mantle sources, indicating recycled components in their source. The recycled oceanic/continental crust or crustal derived sediments usually have higher δ 18 O values than normal mantle. The high δ 18 O anomalies are considered by such recycled components involved in the mantle sources of the Fujian basalts [START_REF] Eiler | Oxygen isotope variations in ocean island basalt phenocrysts[END_REF][START_REF] Eiler | Oxygen Isotope Variations of Basaltic Lavas and Upper Mantle Rocks[END_REF]. The continental crust and sediments, subducted slab related fluids and melts, oceanic crust experienced water-rock interaction at low-T (<350°C), and marine sediments are expected to be the possible candidates being responsible for the high δ 18 O anomalies [START_REF] Eiler | Oxygen Isotope Variations of Basaltic Lavas and Upper Mantle Rocks[END_REF]Auer et al., 2008;[START_REF] Martin | The origin of high-Mg magmas in Mt Shasta and Medicine Lake volcanoes, Cascade Arc (California): higher and lower than mantle oxygen isotope signatures attributed to current and past subduction[END_REF][START_REF] Muehlenbachs | Alteration of the oceanic crust and the 18O history of seawater[END_REF][START_REF] Taylor | Igneous rocks; I, Processes of isotopic fractionation and isotope systematics[END_REF]. As discussed in Chapter 5, the high Nb/La, Nb/U and Ce/Pb ratios in the Fujian basalts (Fig. 6-16a) stifle possibility of the dominant proportion of continent-related components, including continental crust and sediments, as well as fluids from subducted slab, corresponding to high values of Pb and low values of Nb in continental crust [START_REF] Tatsumi | Chemical characteristics of fluid References phase released from a subducted lithosphere and origin of arc magmas: evidence from high-pressure experiments and natural rocks[END_REF][START_REF] Rudnick | Composition of the Continental Crust[END_REF][START_REF] Grove | The role of an H2Orich fluid component in the generation of primitive basaltic andesites and andesites from the Mt. Shasta region, N California[END_REF]. Therefore, the high δ 18 O values of cpx Chapter 6 phenocrysts indicate the involvement of recycled oceanic crust components exclusively in the mantle source of Fujian Cenozoic basalts. Although the low-temperature waterrock altered oceanic rocks were involved in the source of Fujian basalts, the higher Ba/Th and high Ba/U may also suggest another enrichment source. The enrichments are considered to involve dehydrated marine sediments, mantle source carbonate or recycled calc-silicate, appearing as relevant as limestone interaction and likely form a continuum in the subvolcanic environment (e.g., [START_REF] Gaeta | Carbonate assimilation in open magmatic systems: the role of melt-bearing skarns and cumulate forming processes[END_REF][START_REF] Deegan | Magma-carbonate interaction processes andassociated CO2 release at MerapiVolcano, Indonesia: insights from experimental petrology[END_REF].

The δ 18 O of carbonates usually are up to 30‰, clearly higher than that of the normal mantle.

Constraints for the enrichment origin

The the results of mixture between normal silicate magma with carbonated peridotite/pyroxenite or carbonatite [START_REF] Dasgupta | Partial melting experiments of peridotite+CO2 at 3 GPa and genesis of alkalic ocean island basalts[END_REF][START_REF] Bizimis | The brevity of carbonatite source in the mantle: evidence from Hf isotopes[END_REF], The H2O/Ce and water content are believed to be able to distinct the different origins of enrichment in the mantle source of basalts (Liu et al., 2015a and b;Xia et al., 2013).

2.2 ROC D 2 1 • • BL 1.8 ~ .. • • SH 1.6 1 ~ . • • ~-•- • MX --. .. 1.4 1 .. OMM • • NTS 1.2 D ~ • 1 10 20 30 40 50 Ce/Pb 1.4 • Eu/Eu* c 1.2 - , . -•-:t• ••E:J. • • BL • SH • MX
suggesting
However, despite the high Ba/Th in the MX samples, the MX basalts are almost dry relative to other intra-plate Cenozoic basalts in East China (Fig. 6-15a). The relative low water content are also observed in Shandong and SC (Liu et al., 2015 and Chapter 5), which has been proven to be the results of H loss in later magma process. When the H loss during later magma process are regarded as uselessness for the MX basalts, the low water contents are regarded as the natural feature of its source. The relative low Pb ratios, the most recent Pacific slab is the most-likely candidate. The involvement of oceanic crust components is also indirectly supported by the relationships among the basalts and the stagnant slab in close region, such as Zhejiang. Several studies have linked the stagnant slab from the Pacific plate from multiple independent lines of evidence (e.g. [START_REF] Sakuyama | Melting of dehydrated oceanic crust from the stagnant slab and of the hydrated mantle transition zone: Constraints from Cenozoic alkaline basalts in eastern China[END_REF]Xu et al., 2012a;Liu et al., 2015a and b;Liu et al., 2016). Despite the dubious existence of stagnant slab by many seismic topography studies, the similar geochemical and geological history imply a relevant geodynamics process. Because of the obscure existence of subducted slab, these recycled oceanic material component are most likely the residue of the previous subducted slab distributed in the upper mantle, after stagnant slab sunk to the lower mantle.

Conclusions

(1) The Li content and the Lithium isotopic results demonstrate all the cpx phenocrysts from the Fujian basaltic rocks have undergone varying degrees Li diffusion.

The Li diffusion in the MX basalts is limited, however, the SH basalts and the BL diabases have undergone relatively significant Li diffusion.

(2) The "initial" water contents of the MX and SH basalts are 0.3-0.5% and 1.5-3.8%, respectively. However, the BL diabases display re-equilibrated content of 2.1-2.5% for diabases. The diffusion of Li can help to identify whether the cpx phenocrysts preserve the information of Li from latter diffusion or not indirectly.

(3) The cpx phenocrysts in the Fujian basaltic rocks have higher δ 18 O values than o those of normal mantle cpx. These δ 18 O values are inherited from their source, implying recycled materials were involved in the mantle source of the Fujian basaltic rocks.

(4) The SH basalts and BL diabases involved both the upper and lower recycled oceanic crust components together with the recycled marine sediment components in their source, the MX basalts most likely involved the upper oceanic crust components together with the sediment components, at last, the NTS melts generation dominantly involved the re-melting of lower oceanic crust and recycled sediments residual components. The pronounced recycled oceanic materials are most likely the residue of the previous subducted slab distributed in the upper mantle. 6.2 6.2 6.5 6.2 6.6 6.8 6.3 6.5 Tb 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 12MX-A-1-3-S 5-4-8b@ l 5-4-Sb 02 5-4-b 03 5-4-Sb@04 5-4-Sb 05 5-4-Sb 06 5-4-8b@07 5-4-Sb 0 5-4-Sb 09 5-4-8b@ IO 12MX-A-1-3-ll 5-5-llb 1 5-5-llb@2 5-5-l lb 5-5-l lb 12MX-A-I-3 -1 0 5-3-1 Oa 6 5-3-IOa 05 5-3-10a@04 5-3-IOa 3 5-3-IOa 02 5-3-IOa@ l 5-3-IOa 07 5-3-IOa 08 5-3-10a@09 5-3-1 Oa 10 5-3-IOa Il 12MX-A-1-3-9 5-3-9a 1 5-3-9a@2 5-3-9a@3 5-3-9a 4

####### ####### ####### ####### ####### 0.
####### /t/1/J!/I!Ntl ####### ####### ####### 0.
12MX-A-1-3-6 5-2-6a@ l 5-2-6a 5-2-6a 5-2-6a@4 12MX-A-I-3-7 5-4-7b 1 5-4-7b@2 5-4-7b 3 5-4-7b 4 5-4-7b@5 5-4-7b 6 0.9 4.5 0.9 3.9 0.8 27.8 5.6 30.2 6.0 29.9 6.0 29.

6.0 32. 1 6.4 5.0 1.0 3.7 0.7 4.S 1.0 4.3 0.9 4.5 0.9 4.6 0.9 4.0 0.8 1 1 MX-B-1-4-24 5-13-24 1 5-13-24b@3 5-13-24 4 5-13-24 b@5 IIMX-B-2-4-19 6-7-19 6-7-19@2 6-7-19@3 6-7-1 9-2 1 6-7-1 9-2@2 6-7-19-2 6-7-1 9-2 IIMX-B-2-4-1 7 6-7-17 6-7-17@2 6-7-17@3 IIMX-B-2-4-18 6-7-18 6-7-18 6-7-18

IIMX-B-2-4-7 6-2-7 1 6-2-7@2 6-2-7 3 6-2-7 4 1 1 MX-B-2-4-3 6-3-3 1 6-3-3@2 6-3-3@3 6-3-3 4
Il MX-B-3-5-3 6--3@2 6-8-3 3 IIMX-B-3-5-5 6-11-5@ 6-11-5@2 6-1 1-5 6-11 -5@4 1 1 MX-B-3-5-1 6-9-1 1 6-9-1@2 6-9-1 6-9-1 4

IIMX-B-3-4-5 6-14-5@ 6-14-5 6-14-5@3 6-14-5@4 IIMX-B-3-4-6 6-14-6@ 6-14-6@2 6-14-6

IIMX-B-3-4-1 2 6-16-12 6-16-1 2 6-16-1 2@3 6-16-1 2 IIMX-B-3-5-7 6-12-7@ 6-12-7@2 6-12-7 . 1.18 0.5 78.9 1.18 0.4 78.9

1.18 0.4 7 .9

1.1 0.5 81.9 1.18 0.6 1.9 1.1 0.7 81.9

1.18 0.6 81.9

1.18 IIMX-B-4-5-5 6-1 7-5@1 6-1 7-5 6-1 7-5@3 6-1 7-5@4 Il MX-A-2-6-8 3-1 2-8@ 1 3-1 2-8@2 3-12-3 3-1 2-8 IIMX-A-2-6-7 3-12-7 1 3-1 2-7@2 3-1 2-7@3 3-12-7

IIMX-A-1 -6-19 3-9-19 1 3-9-1 9 2 3-9-1 9@3 3-9-19@4 IIMX-A-1-6-14 3-10-14-2 1 4.7 E+ l3 3-10-1 4-2@2 4.51E+ I3 3-10-14-2 3 4.46E+ 13 3-10-14-2@4 4

.13E+ I3 MX--2-1-16 1-3-16 1 1-3-16@2 1-3-1 6@3 1-3-16 4 MX-C-2-1-15 1-3-15 1 1-3-15 2 1-3-15@3 1-3-15@4 MX-C-2-1-36 1--36@ 1 1--36@2 1--36 3 1--36 4 MX--4-2-22 1-11-22 1 1-11 -22@2 1-11-22 1-11-22 4 MX-C-4-2-10 1-12-10 1 1-12-10 1-12-10@3 1-12-10 MX-C-2-1-12 1 2 1-5-12 3 1-5-1 2@4
MX--4-2-14 1-13-14 1-13-14@3 1-1 3- 12BL-3-3-I-18 10-0-1 8 1 1.46E+ 13 10-0-1 02 7.03E+ 12 10-0-1 8@03 6.84E+ 12 10-0-1 8@04 8.0 E+ 12 10-0-1 OS l.OIE+ I3 10-0-1 8@06 1.03E+ 13 10-0-1 8 7 8.18E+ I2 10-0-1 0 5.44 E+ 12 10-0-1 8@09 2.6 E+ l2 10-0-18 10 4.24E+ I2 10-0-18 Il 6.53E+ 12 10-0-1 8@ 12 8.19E+ I2

-5-3- MX-5-3- MX-5-3-7 MX-5-3-1 0 MX-1-6-12 MX-1-6-13 MX-1-6-14 MX-1-6-1 9 MX-1-6-22 MX-1-6-23 MX-1-6-24 MX-1-6-2 MX-1-6-29 MX-1-6-4 MX-1-6-6 MX-2-6-14 MX-2-6-4 MX-2-6-5 MX-2-6-7 MX-2-6- MX-2-7-2 MX-2-7-3
Table6-4 ample o.

5-4-03 5-4-8@04 5-4-5

5-4-5-3-10 3-8-12@ 3-8-13 3-1 0-14 3-10-14@4 3-1 0-1 6

3-5-22 3 3-7-23@ 3-6-24 3-4-2 3-1-29@ 3-1-29 3 3-1-29 3-1-29@6 3-2 1 3-3- 1 3-13-14@ 3-11 3-11-5 3-12-7@ 3-1 2- MX-2-7-4 3-1 6
MX-2-7-8 3-1 5-MX-2-7-.2 3-15-8-2@ 1 MX-4-3-4 5-9 MX-4-3-6 5-9-1 MX-4-3-7 5-11-7@ MX-4-4-13 5-1 4-13 4 MX-4-4-1 5-1 5-1 MX-4-4-18.2 5-15-18-2@ 1 MX-8-4-1 3 6-6-13 MX-8-4-16 6-7-18 MX-8-4-17 6-7-17@ MX-8-4-1 9 6-7-19 MX-9-5-1 6-9-1 1 MX-9-5-5 6-11-5@ MX-5-3-1 1 5-5-11 MX-5-4-14 3-1 9-14 MX-5-4-21 3-18-21 @ MX-7-2-4 14-3 MX-7-2-7 14-4-7 Mean Oxygcn isotope of cpx phcnocrysts in the Fujian basalts.

Mg# 0 .9 0 .9 0.9 O. 1.0 O.

1.0 1.0 0 .9 0 .9 0 .9 0 .9 0.9 1.0 0 .9 0 .9 0 .9 0.9 0 .9 0 .9 0.9 0 .9 0 .9 0 .9 0 .9 1.0 1.0 1.0 0 .9 0 .9 0.9 1.0 1.0 1.0 1.0 0.9 0 .9 0 .9 0 .9 0 .9 0 .9 0 .9 0 .9 0 .9 0 .9 0 .9 0 .9 1.0 0.9 0 .9 0 .9 a/Al 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0 .9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 12.970 0.9 -0. 1.8 1.9

1.9

1.8 1.9

1.9 1.8

1.8 1.8

1.8 1.9

1.9 1.9

1.8 1.9 1.8

1.8 1.9

1.9 1.9 1.7 1.9 1.7 1.9

1.9 1.9 1.8

1.9 1.8

1.9 1.9

1.8 1.9

1.9 1.8 1.9

1.9 1.9

1.8 1.8

1.9 1.9

1.8 1.8 1.9

1.9 1.9

1.9 1.9 Ca 0.8 0.9 0.9 0.9 0.9 0.9 0.8 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.8 0.8 0.9 0.8 0.9 0.9 0.8 0.9 0.9 0.9 0.9 0.8 0.9 0.9 0.9 0.8 0.9 0.7 0.9 0.9 0.9 0.8 0.9 0.9 0.8 0.8 0.9 0.9 0.9 0.8 0.9 0.9 0.7

Hainan basalts and the spatial chemical variation of Cenozoic basalts in East China

Results

Bulk-rock major and trace element compositions

The major element compositions of cpx phenocrysts for the Hainan basalts are listed in Table 7- (2010). The DY basalts have high Al2O3 (more than 13 wt. %), intermediate SiO2 (47.9 to 51 wt. %), TiO2 (2.2 to 2.5 wt. %), and Fe2O3 (about 12 wt. %), and variations in MgO (6.5 to 10.2 wt. %). Meanwhile, the FJT samples have similar MgO (7.8 to 10.1 wt. %) and Al2O3 (12.8 to 13.7 wt. %), higher Fe2O3 (>12 wt. %) and TiO2 (>2.7 wt. %), but lower SiO2 (46.3 to 47.2 wt. %).

In the primitive mantle-normalized extended trace element patterns (Fig. 7 Therefore, the totally "dry" cpx phenocryst are caused by the H-loss of cpx phenocrysts after the crystallization of cpx phenocryst. The LH basalts are suggested to be represented by HN9910 of 2.7% (Table 7-3). The measurable cpx phenocrysts are actually rare in most DY and FJT samples. Only five samples (2 from DY, and 3 from FJT samples) have the efficient results of the H2O content of a corresponding equilibrated melts deduced from its H2O content and its corresponding partition coefficient (D cpx-melt ). The preliminary results of the H2O content of corresponding equilibrated basaltic melts range from 0.7 to 1.3 wt. % for the FJT samples, and from 0.7 to 2.6 wt. % for the DY samples. The detailed calculated data of water content for cpx grains and corresponding equilibrated basaltic melts are presented in Therefore, beyond considerable upper recycled oceanic crust, a small quantity of gabbros from lower recycled oceanic crust are also involved for the young LH basalts, while the additional recycled oceanic sediments were involved in the relatively older

~•••~~------------------------------------------------~ --

The variation of geochemistry for Cenozoic basalts depended on latitude

Although, the Cenozoic basalts in the Southeast China almost display similar geochemical feature, the variation of geochemistry with latitude can be observed in Fig. 7-7. Trace element compositions also show systematic along-arc variations (Fig. 78and Fig. 789). As recognized in the isotopes, there is a significant change at the region of 24°N to 29°N, and some trace element ratios also change in this region. The Ba/Th, Zr/Hf, Nb/La, Nb/Zr, and Tin/Ti* have the highest values at about 29°N. The highest 143 Nd/ 144 Nd, and almost the lowest 87 Sr/ 86 Sr ratios are found at 29°N. However, the highest Pb radiogenic ratios are observed at 24°N. Meanwhile, the range and variation of trace element ratios from this section to the north or to the south are similar, such as Nb/Ta, Nb/La and Ba/Th. The systematics of isotope and trace element ratio variations with latitude appear to be coupled in this section. The latitude related systematics variation are also observed in the Izu-Bonin-Mariana (IBM) Trench system [START_REF] Ishizuka | Processes controlling along-arc isotopic variation of the southern Izu-Bonin arc[END_REF][START_REF] Staudigel | Seamounts in the Subduction Factory[END_REF]. The similar vibration are displayed in Fig. 7-8 and The variation of trace element ratios and isotopic composition with latitude in East China.

The data source of Cenozoic basalts are the same as in Fig. 5 ,1 .

r ..

~ 1• ' •• : •• : 1 . . .. •• 24 29 34 39 • 1 a \ 1 •• • • allle••l •• • ~ 1 . 24 29 34 39 . ' !' 1
.

1 1 JI • 1 f .1 1 1 -.: . • . . • J• !a . ' ~~• .
. . . .~fi' .

24 29

.

'

Il. JI l . . ' • • . . . . "i 24 29 • • . ,. • f •a 1 \:•1• f . . 24 29
• t. 1: .. . ' .

Latitude

Chapter 7

The systematic variations found in IBM Trench, are explained as the involvement of the HIMU-like contributions. The HIMU-like contribution are considered to inherit from the subducted Pacific slab, which enter into the IBM mantle wedge. The HIMUlike contributions should be a small scale of contribution, otherwise, it is hard to explain the lower Pb radiogenic isotopic ratios in Hainan Island. [START_REF] Ishizuka | Processes controlling along-arc isotopic variation of the southern Izu-Bonin arc[END_REF] and [START_REF] Staudigel | Seamounts in the Subduction Factory[END_REF] suggest the small scale HIMU-like contribution is the seamounts on the Pacific Plate east to the IBM Trench. These seamounts were emplaced on the ocean crust and remained on the seafloor between 100 and 120 Ma [START_REF] Koppers | Short-lived and discontinuous intraplate volcanism in the South Pacific: Hot spots or extensional volcanism?[END_REF]. This long-lived HIMU subduction related basalts suggest that the recycling of HIMU seamount is a significant contributor to mantle evolution. Chapter 7 in MTZ for a long time, reflected by EM I isotopic signature [START_REF] Kuritani | Intensive hydration of the mantle transition zone beneath China caused by ancient slab stagnation[END_REF][START_REF] Murphy | Lamproites from Gaussberg, Antarctica: Possible transition zone melts of Archaean subducted sediments[END_REF]. The older oceanic crust have relative high Pb radiogenic isotopic data, however, only the older recycled oceanic sediments or delamination of thickened lower continental crust could have served as source of the low Pb radiogenic isotope, like [START_REF] Kuritani | Intensive hydration of the mantle transition zone beneath China caused by ancient slab stagnation[END_REF] suggested for the Changbaishan basalts. Researchers have reported some evidences to demonstrate the occurrence of the recycled oceanic material in the MTZ beneath the NEC and NC (e.g. [START_REF] Kuritani | Intensive hydration of the mantle transition zone beneath China caused by ancient slab stagnation[END_REF][START_REF] Chen | Changing recycled oceanic components in the mantle source of the Shuangliao Cenozoic basalts, NE China: New constraints from water content[END_REF]Xu et al., 2012a). However, Southeast China lacks such subduction process or record like the Cenozoic basalts in the NCC and NE China, so SE China Cenozoic basalts show relatively clear geochemical mixture feature between recent recycled oceanic material and the depleted mantle source, which are the result from the subduction effect of the Pacific Oceanic Plate.

Conclusions

(1) The low water content in some Hainan basalts are the result of later H-loss.

The Hainan basalts have 2.7 wt. %, 1.3 wt. %, and 2.6 wt. % water content for the LH, DY, and FJT basalts, after the samples undergone H-loss are excluded.

( HN99-08-2 13-2-2@ 1 13-2-2 2 13-2-2@3 13-2-2@4 13-2-2 5 HN99-0 -1 13-2-1 @ 1 13-2-1 2 13-2-1 @3 13-2-1 @4 13-2-1 9

HN99-02-23 -02 13-11 -2 1 13-11-2 02 13-11 -2@03 13-11 -2@04 13-11-2 5 HN99-02-23-03 13-12-3@ 1 13-12-3 13-12-3@3 13-12-3 4 13-1 2-3 HN99-01-22-0 I 13-15-1 @ 1 HN99-0l -22-02 13-16-2@ 1 13-16-2@2 13-16-2 13-16-2@4 13-16-2@5 HN99-01-22-03 13-17-3@ 1 13-17-3@2 13-17-3 HN99-0I -22-06 13-19-6 1 13-19-6 13-19-6@3 13-19-6 4 13-19-6 HN99-0I-22-04 13-1 -4@ 1 13-1 -4 HN99-0I-22-05 13-20-5 1 13-20-5 13-20-5@3 13-20-5 Pl IMFST IMF Mean of ô o_ SD HN99-01 -22-01 13-1 5-1@ 1 82.5 HN99-01-22-02 13-16-2@ 1 81.8 HN99-01-22-03 13-17-3@ 1 78.1 HN99-01-22-03-r 13-17-3-a@ l 78. 1 IIN99-0 1-22-04 13-18-4@ 1 82.2 HN99-01-22-05 13-20-5@ 1 81.4

I-IN99-01-22-06 13-19-6@ 1 79.0 HN99-02-2J-OI 13-1 0-1@ 1 81.3 HN99•02-23-02 13-12-2@ 1 82.3 HN99-02-23-03 13-12-3@ 1 80.7 HN99-02-2J-03-r 13-12-3-a@ 1 80.7 HN99-10-21-12 13-5-12@ 1 75.7 HN99-10-21 -13 13-9-13@ 1 69.5 IIN99-10-21-2 13-8-2@ 1 77.9 IIN99-10-21-3 13-8-3@ 1 75.8 HN99-10-21-7 13-6-7@ 1 82.5 12-19-1 @ 1 81.5 13-28-1-2@ 1 75. 1 13-27-2@ 1 75.0 13-26-3@ 1 74.1 13-22-4@1 74.7

13-22-4-x@ 1 74.7 13-22-4@4 74.7

13-23-5@ 1 75.6

13-25-6@ 1 77.0 13-24-7@ 1 76.5 13-24-7@4 76.5

13-21-8@ 1 75.7

12-25-1@ 1 78.5

12-32-4@1 76.6

12-31-6@1 75.9

12-27-3@ 1 75.8

12-26-9@ 1 58.4

12-26-9-2@ 1 58.7

12-20-5@ 1 82.0 12-18-6@ 1 83.6 13-35-2@ 1 77.8 13-39-4@1 80.0 13-30-1@ 1 75.2 13-29-5@ 1 75.0 13-33-2@ 1 77.8

13-33-2-1 @ 1 75. 1 13-32-3@ 1 75. 1

13-32-3-1@ 1 75.1 13-32-3-1@.4 75. 1

13-31-4-1@ 1 71.9 and after 11Ma (Group 2), respectively, with distinct geochemical features. The "initial" H2O contents of the melts, reversely calculated from the H2O content of the cpx phenocrysts and the corresponding partition coefficients of H2O between cpx and basaltic melts, range from 1.4 to 2.2 wt. % for the Group 1 samples and from 1. shows that bedrock carbonate composition on the NE TP displays a much broader range of Sr/Ca and Mg/Ca ratios than restricted source carbonate endmembers reported upon in previous studies. This has clear implications for modem weathering studies in addition to paleo-reconstructions in this tectonically active and climatically variable area during the l.ate Cenozoic. Bedrock carbonate compositions are characterized by disseminated carbonates with higher Sr/Ca and Mg/Ca ratios, and sedimentary carbonates (mostly marine) with lower Sr/Ca, but variable Mg/Ca, ratios. The mostly authigenic carbonates fou nd in sediments show similar trends, with a gradient -0.97-1.00 in a plot of log (Sr/Ca) versus log (Mg/Ca), suggesting that 'calcite precipitation' processesi.e. the sources of the dissolved cations in the water -control the ir chemistry. Based on observations and modeling, we conclude that the mixing of authigenic and bedrock carbonate endmembers, plus the incongrue nt dissolution ofbedrock carbonates, accounts for the bulk carbonate composition of sediments (e.g.loess, sand and topsoil ).

A comparison of bedrock and sedimentary carbonate composition with reported fluvial water data in the NE TP suggests that weathering of carbonates in terrigenous sediments, rather than in bedrock, is mostly responsible for the changes in fluvial Sr, Mg and Ca compositions. Our study suggests that interactions between carbonates and water occur widely during the exposure, transport and deposition of sediments, significantly modifying regional carbonate compositions and fluvial geochemistry. © 2015 Elsevier B. V. Ali rights reserved.

Carbonates in bedrock and sediments can play a unique role both in the study of modern chemical processes and in paleo-reconstructions (e.g. Gaillardet et al., 1999;Dettman et al., 2003;Han and liu, 2004;Yokoo et al., 2004;Wu et al., 2005;[START_REF] Menzies | Integration of geology, geophysics and geochemistry: A key to understanding the North China Craton[END_REF]Jin et al., 2011: reconstructions are al ways hampered by the presence of detrital carbonates in sediments [START_REF] Menzies | Integration of geology, geophysics and geochemistry: A key to understanding the North China Craton[END_REF]li et al., 2013).lsolating the authigenic and detrital carbonates in sediments has therefore long been a challenge.

Mn/Ca ratios in bulk carbonate have been proposed as discriminatory indicators of detrital carbonate signatures in Chinese loess-paleosol sequences, where a binary mixing between secondary carbonate with low Mn/Ca and Mg/Ca ratios and detrital carbonate with high Mn/Ca and Mg/ca ratios is found ( Li et al., 2013). However , an abondance of Mn oxide coating du ring soi! development and possible Mn oxide dissolution by weak ace tic a cid (Chester and Hughes, 1967;Gourlan et al., 2010) complicates the valence and source of acid-exacted Mn. and thus limits the wider application of Mn/Ca ratios to carbonate analysis. Sr and Mg partition coefficients are < 1 in carbonates, and the co-variation ofboth elements (as opposed to Mn) is generally a more robust tool for describing the interactions between carbonates and water (e.g. Plummer and Mackenzie, 1974;Fairchild et al., 1994;Reeve and Perry, 1994;Galy et al., 1999;Tipper et al., 2008). Sinclair Zhang et al., 2013a;[START_REF] Li | Geochemistry of Cenozoic basalts from the Bohai Bay Basin: Implications for a heterogeneous mantle source and lithospheric evolution beneath the eastern North China Craton[END_REF]. Soi! carbonates, as typical products of the interactions between carb onates and water in eolian deposits or floodplain environments, provide a powerful tool fo r paleo-reconstructions (e.g. Cerling, 1984;Dettman et al., 2003). Proxies derived from soi! carbonates, e.g. 87 Srf6$r. ô 13 C. ô'SO. carbonate-clumped isotopes and trace elements, can be extensively used to explore paleoclimate, paleoenvironment and paleoelevation (e.g. Cerling et al., 1993;Rowley and Garzione, 2007;Quade et al., 1989Quade et al., , 1997Quade et al., , 2011Quade et al., , 2013;;[START_REF] Li | Geochemistry of Cenozoic basalts from the Bohai Bay Basin: Implications for a heterogeneous mantle source and lithospheric evolution beneath the eastern North China Craton[END_REF]. Unfortunately, such paleosol-based • Correspondîng author. E•mail address: yangyibo@itpeas.ac.cn (Y. Yang).

Introduction

ABSTRACT

Nominally anhydrous phases (clinopyroxene (cpx), orthopyroxene (opx ), and olivine ( ol)) of peridotite xenoliths hosted by the Cenozoic basalts from Beishan ( Hebei province), and Fansi (Shanxi province), Western part of the North China Craton (WNCC) have been investigated by Fourier transfonn infrared spectrometry (FTIR). The H2 0 contents ( wt.) of cpx, opx and ol are 30-255 ppm, 14-95 ppm and -0 pp m. respectively. Although potential H-loss during xenolith ascent cannat be excluded for olivine, pyroxenes (cpx and opx) largely preserve the H20 content oftheir mantle source inferred from (1) the homogenous H2 0 content within single pyroxene grains, and (2) equilibrium H2 0 partitioning between cpx and opx. Based on mineral modes and assuming a partition coefficient of 10 for H 2 0 between cp x and ol, the recalcula led whole-rock H20 contents range from 6 to 42 ppm. ln combination with previously reported data for other two localities (Hannuoba and. Yangyuan from Hebei province), the H 2 0 contents of cpx, opx and wh ole-rock of peridotite xenoliths (43 samples) hosted by the WNCC Cenozoic basalts range from 30 to 654 ppm, 14 to 225 ppm, and 6 to 262 ppm respectively. The H 2 0 contents of the Cenozoic lithospheric mantle represented by peridotite xenoliths fall in a similar range for bath WNCC and the eastern part of the NCC (Xia et al., 2010, j ournal of Geophysical Research). Clearly, the Cenozoic lithospheric mantle of the NCC is dominated by much lower watercontent compared to the MORB source (50-250 ppm). The low H2 0 content is not caused by oxidation of the mantle domain, and likely results from mantle reheating, possibly due to an upwelling asthenospheric flow du ring tht> la te Mesozoic-early Cenozoic lithospheric thinning of the NCC. If so, the pre sent NCC lithospheric mantle mostly represents relict ancient lithospheric mantle. Some newly accreted and cooled asthenospheric mantle may exist in localities close to deep fault.

© 2012 International Association for Gondwana Research. Published by Elsevier B.V. Ali rights reserved.

Cratons are old and stable parts of the continental lithosphere, usually occurring in the interiors of tectonic plates. Because of their refractory, low-density and anhydrous keels, cratons generally lack tectonic or volcanic activities and can survive for severa! billion years. The presence of structural! y bonded water in minerais which make up the lithospheric mantle of cratons can greatly <Jffect the physical ( rheology, electrical conductivity, seismi c velocity and attenuation) and chemical (elemental diffusion, partial mel ting) properties ofthese mantledomains (Hirth and Koh lstedt, 1996;[START_REF] Karato | Water, partial melting and the origin of the seismic low velocity and high attenuation zone in the upper mantle[END_REF][START_REF] Hirschmann | Dehydration melting of nominally anhydrous mantle: The primacy of partitioning[END_REF]Karato, 201 0). Therefore, water may weak the stability of the cratonic lithospheric mantle. of the lithospheric mantle. Therefore, the H20 contents of peridotite xenoliths may provide information about the d istribution of water in the lithospheric mantle. Although the mai n mine rais of peridotite xenoliths (olivine (ol), orthopyroxene (opx), clinopyroxene (cpx) and spinel (sp)/garnet) are nominally anhydrous, they still contain a significant amount of water as crystal defects (Bell a nd Rossman, 1992; lngrin and Skogby, 2000; Pesli er et al., 2010; Sundvall a nd Stalder, 2011 ).

The North China Craton ( NCC) is the Chine se partofthe Sino-Korean Craton. lt is one of the ancient cratons on the Earth, with th e oldest recorded crustal ages> 3.8 Ga (liu et al., 1992), and it is mainly composed of early Archean a nd Proterozoic m etamorphic rocks (Zhai a nd Santosh, 2011 ). The NCC can be divided into two topographically a nd tectonically different region s, the eastern part (ENCC) and the western part (WNCC), separated by the NS trending Daxing'anling-Taihangshan Gravity lineament (DTGL) (Fig. 1 ). The ENCC expe rienced widespread lithospheric thinning from a thick ( -200 km), cold ( -40 mW/ m 2 ) and highly refractory lithospheric mantle in the mid-Ordovician to a hot (60-80 mW/ m 2 ), thin (60-80 km) and fertile lithospheric mantle after the late Mesozoic (Menzies et a l., 2007, and references the rein). ln contrast, lithospheric removal was possibly relative limited in the Mantle-derived xenoliths are transported by alkali magmas to the Earth's surface during volcanic eruption in a very short time (few hours to days); they representthe "quenched" products oftheir manrie source and peridotite xenoliths are believed to be direct samples lt has been suggested that the longevity of cratons (i.e. ancient and stable cores of continents) is related in part to the low water content of their deep mantle roots; this gives them a higher viscosity than the underlying asthenosphere. Consequently, the removal of cratonic roots is expected to be closely connected to the hydration of the lithospheric mantle, but direct evidence for this speculation has been scarce. The eastern part of the North China (raton (NCC) is a clear example of a "'destroyed craton"'. ln this study the H2 0 content of clinopyroxene phenocrysts was measured in lithospheri.c mantle-derived high-magnesium basalts of the Feixian area, in the eastern part of the NCC. These lavas erupted in the earl y Cretaceous ( ~ 120 Ma), which was the peak ti me of the NCC destruction. Based on these data, it was estimated that the H20 content of the lithospheric mant le source of these basalts consists of more than 1000 ppm by weight. This water content is much higher than in the source of mid-ocean-ridge basalts (50-200 ppm by weight) and also higher than in the Kaapvaal cratonic ma ntle in South Africa ( ~ 120 ppm by weight); the latter is still stable after > 3 billion years. This study argues that a la rge a mount of water was indeed added to the NCC's lithospheric mantle, probably due to the mu! ti-stage subduction of oceanic plates since the earl y Paleozoic. This high water content significantly reduced the viscosity contras! between the lithospheric mantle and the underlying asthenosphere. and provided a prerequisite for the re moval of the cratonic root of the NCC by reducing its strength.

Introduction

( ratons are the ancient cores (Precambrian ) of continents. and their lithospheric mantle roots can extend down to more than 250 km and remain isolated from the convecting asthenosphere for more than 3 billion years (Boyd and Gurney, 1986;Boyd and Mertzman. 1987;Carlson et al., 2005 ;jordan. 1978 ;james et al., 2001 ;[START_REF] Le Roux | Mineralogical heterogeneities in the Earth's mantle: Constraints from Mn, Co, Ni and Zn partitioning during partial melting[END_REF]D'Reilly and Griffin, 201 0;Richardson et al., 2001 ;Walker et al., 1989). The cause for the longevity of the cratonic mantle is not full y understood, but it is genera lly thought to be related to its chemical buoyancy, low temperature and low water content (Carlson et al., 2005;[START_REF] Le Roux | Mineralogical heterogeneities in the Earth's mantle: Constraints from Mn, Co, Ni and Zn partitioning during partial melting[END_REF][START_REF] O'reilly | Rates of magma ascent: constraints from mantlederived xenoliths[END_REF]Peslier et al., 201 0;Sleep, 2003). ln sorne cases, cratonic roots can be removed and this process has been linked to lithospheric thinning a nd tectonic/magmatic activities (Carlson et al., 2005 ;[START_REF] Le Roux | Mineralogical heterogeneities in the Earth's mantle: Constraints from Mn, Co, Ni and Zn partitioning during partial melting[END_REF]O'Reilly et al., 2001 ). In add ition to che mi cal refertilization and temperature increase, wate r addition is a Iso e xpected to promote the removal of cratonic roots. Indeed, water ca n significantly reduce the viscosity of the lithospheric mantle, thus reducing the viscosity contrast between the lithosphe ric mantle and the asthenosphere [START_REF] Dixon | Lateral variation in upper mantle viscosity: role of water[END_REF][START_REF] Hirth | Water in the oceanic upper mantle: implications for rheology, melt extraction and the evolution of the lithosphere[END_REF]Hyndman et al., 2005;[START_REF] Li | Water contents in mantle xenoliths from the Colorado Plateau and vicinity: Implications for the mantle rheology and hydration-induced thinning of continental lithosphere[END_REF][START_REF] Mackwell | The role of water in the deformation of olivine single crystals[END_REF]Ka rato, 201 0). However, d irect evidence for this longstanding the01y has been scarce.

The eastern part of the North China Craton (NCC, Fig. 1 ) has very few relier Archean crus tai rocks a nd is a clear example of a 'destroyed craton• (i.e. a cra ton in which the lithospheric root has been removed; [START_REF] Griffin | Phanerozoic evolution of the lithosphere beneath the Sino-Korean Craton[END_REF]Menzies e t a l., 1993Menzies e t a l., , 2007;;W ind ley et al., 2010). The high-magnesium basalts of the Feixian area in the eastern part of the NCC erupted in the earl y Cretaceous ( -120 Ma), which was the peak ti me of the NCC destruction [START_REF] Gao | Recycling deep cratonic lithosphere and generation of intraplate magmatism in the North China Craton[END_REF]. In addition, detailed petrological and geochemical studies have demonstrated that these basalts wer e derived from the lithospheric mantle without significant crustal contamination [START_REF] Gao | Recycling deep cratonic lithosphere and generation of intraplate magmatism in the North China Craton[END_REF]. Therefore, t hese basalts can provide information on the lithospheric mantle of the NCC at th e peak time of its destruction. In this paper, the H 2 0 content of clinopyroxene phenocrysts (cpx) was measured in terms of OH defects. This was done using a Fourier transform infra red spectrometer (FTIR). Based on these data and the partition coefficie nt o f H 2 0 b etween 1. Introduction ABSTRACT Recognizing juvenile and relict lithospheric mantle is crucial in unraveling the mechanism of lithospheric thinning (delamination vs. thenmal/mechanic erosion). The H 2 0 contents and Sr-Nd isotopie compositions of juvenile lithospheric mantle are expected to be similar to the MORB source (asthenospheric mantle), whereas those of the relict lithospheric mantle should be of typical cratonic character. Con;equently, combined analysis of H,O contents and Sr-Nd isotope compositions could be an effective way to distinguish the juvenile and relict lithospheric mantle. Among the peridotite minerais, clinopyroxene is the major host for rare earth elements as weil as H,O contents, making it the most suitable target sample for such analyses. We collected fresh peridotite xenoliths hosted by Cenozoic basalts from Beiyan, Shandong province and Yangyuan, Hebei province to carry out combined analyses of major elements, trace elements, Sr-Nd isotopes and H,O contents for clinopyroxene. At bath Bei yan and Yangyuan, pyroxene from peri do tite xenoliths shows homogenous H 2 0 contents within individual grains, and equilibrium distribution of H 2 0 contents between clinopyroxene and orthopyroxene has been achieved. There is a positive correlation between H2 0 contents and Al contents in clinopyroxene and orthopyroxene, these features imply that the pyroxenes largely preserve the H2 0 contents oftheir mantle source. The variations ofH 20 contents in clinopyroxene are controlled by partial melting rather th an the later episode of mantle metasomatism, because there is a correlation between H,O contents of clinopyroxene and degree of partial melting index (Yb content of clinopyroxene and Mg# of olivine). Based on the correlation between H 2 0 contents and Sr isotope ratios of clinopyroxene, the estimated H 2 0 contents and 87 Sr/' 6 Sr ratios of mantle source of peridotites in Beiyan (450 to less than 600 ppm, and -0.7028 respecrively) are similar to the MORB source, thereby implying that the lithospheric mantle beneath Beiyan is juvenile. ln contrast, the variation of H2 0 contents and Sr-Nd isotope compositions of clinopyroxene from the Yangyuan peridotites is best explained as relict mantle (H20 contents less than 300 ppm and EMl -type Sr-Nd isotope ratios) coexisting with juvenile lithospheric mantle ( H 2 0 contents more than 600 ppm and 8 • 7 Sr/' 6 Sr about 0.7030). These conclusions are in agreement with previous studies which have demonstrated that the lithospheric mantle beneath Beiyan is made up of juvenile material accreted from the asthenosphere after the Norrh China Craton had undergone thinning.

© 2012 Elsevier B.V. Ali rights reserved.

The North China Craton (NCC) is one of the major cratons in eastern Eurasia w ith crustal remnants older than 3.8 Ga (liu et a l., 1992).

The eastem NCC experienced widespread lithospheric extension a nd dramatic changes of mantle characteristics. A thick (-200 km), cold ( -40 mW/ m 2 ) and highly refractory lithospheric mantle was in place until the mid-Ordovidan, but was replaced by a hot (60-80 mW/ m 2 ), thin (80-60 km) and fertile lithosph eric mantle during the late Mesozoic period (Menzies et al., 2007, and r eferences therein). The tim ing, spatial and temporal variation as weil as mechanism for lithospheric t hinning are hotly debated. Delineating the juvenile (e.g., newly accreted materials from upwelling asthenosphere after t he NCC thinning) versus re li ct lithospheric mantle is crucial to unravel the mechanism of lithospheric th inning (delamination vs. rhermal/mechanic erosion). The H 2 0 contents and Sr-Nd isotopie compositions of t he j uvenile lithospheric mantle a re expected to be sim ila r to Mid -Ocean Ridge Basait (MORB) source, whereas t he r elier lithospheric mantle should be more like rypical cratonic mantle. Therefore, combined analyses of H 2 0 con tents and Sr-Nd isotope compositions of mantle-derived xenolith s cou ld be an effective way to distinguish between the j uvenile an d r elier lithospheric mantle.

•

Introduction

Nu merous investigations have demonstrated that water can be stored in nominally anhydrous minerais (NAMs) as hydroge n structurally bound to specifie oxygen sites. NAMs cover a wide range of corn mon rock-forming minerais from the Earth' s crust (e.g., quartz and feldspars) and upper mantle (e.g., olivine, pyroxenes, and gamet) to the mantle transition zone (e.g., wadsleyite, ringwoodite, and majoritic gamet). H incorporation into NAMs has a significant influence on physical properties such as viscosity and electric conductivity as weil as on melting, mantle convection, and the stabilization of cratonic roots (e.g. [START_REF] Karato | The role of hydrogen in the electrical conductivity of the upper mantle[END_REF][START_REF] Chan | Lithium isotopic composition of submarine basalts: implications for the lithium cycle in the oceans[END_REF]Hirose and Kawamoto 1' 995 ;[START_REF] Hirth | Water in the oceanic upper mantle: implications for rheology, melt extraction and the evolution of the lithosphere[END_REF][START_REF] Asimow | The importance of water to oceanic mantle melting regimes[END_REF]Yang et al. 2008;Peslier et al. 2010;Green et al. 20 10 ).

Orthopyroxene is the second most abundant mineral in the upper mantle above the transition zone and may contain a trace water component in the form of O H defects (Bell and Rossman 1992). The water content in or thopyroxene is lower than in clinopyroxene, but far highe r tban in the coexisting olivine (Skogby 2006;[START_REF] Hirschmann | Dehydration melting of nominally anhydrous mantle: The primacy of partitioning[END_REF][START_REF] Green | Water and its influence on the lithosphere-asthenosphere boundary[END_REF][START_REF] Xia | Low water content of the Cenozoic lithospheric mantle beneath the eastern part of the North China Craton[END_REF]. So, based o n its great ah undance, orthopyroxene may be a major repository for water in the upper mantle. Fourier transform infrared (FTIR) spectroscopy is a widely used method for investigating H in NAM s. The hydrous components in minerais are mobile, so their speciation, physicochemical properties, and sites in the crystal structures may vary with temperature. However, the previous FTIR studies on OH in orthopyroxene were mainly undertaken at room temperature, providing a limited insight into the properties of minerais. Moreover, IR absorption coefficients of OH in sorne NAMs decrease with increasing temperature (Suzuki and Nakashi ma 1999; [START_REF] Zhang | Chemical and stable isotopic constraints on the nature and origin of volatiles in the sub-continental lithospheric mantle beneath eastern China[END_REF]Yang et al. 20 10). The aim of this study ~ Springer

Introduction 1 . 1

 11 Intra-plate basalts Mafic rocks usually develop in the most active or weakest regions on the earth, such as at active plate margins, hot spots, and deep faults. Mid Ocean Ridge Basalts (MORBs) and Island Arc Basalts (IABs) are the most important representatives of the basalts forming at the active plate margins. The intra-plate basalts being different from

  Sr/ 86 Sr and 143 Nd/ 144 Nd; (b) enriched mantle type I (EM I) has enriched 87 Sr/ 86 Sr and 143 Nd/ 144 Nd, but depleted Pb radiogenic isotope; (b) enriched mantle type II (EM II) also has enriched 87 Sr/ 86 Sr and 143 Nd/ 144 Nd, as well as Pb radiogenic isotope; and (d) high-μ (HIMU) has extremely enriched Pb radiogenic isotope, but moderately depleted to a little enriched 87 Sr/ 86 Sr and 143 Nd/ 144 Nd. Every mantle end-member also has unique trace element characteristics: (a) DMM is incompatible-element-depleted; (b) EM I and EM II have enriched incompatible elements; and (c) HIMU contains higher Nb and Ta than other incompatible elements.

Fig. 1

 1 Fig.1-1

  (a) The evolution of Li content with time; (b) the evolution of δ 7 Li with time. The numbers on the straight lines are durations in years.

  Fig. 9 in its book. Unfilled boxes are data collected using conventional (resistance heated) fluorination methods between 1966 and 1993; filled boxes are data collected only on glass using laserbased methods. Data sources are listed in the original text); b. The main composition of

1 )

 1 The water content distribution of the upper mantle in SE China during Cenozoic. Comparison of the water contents of Cenozoic basalts at different locations in SE China, as well as those of the peridotite xenoliths entrained by Cenozoic basalts do not only help us to understand the water content distribution of the upper mantle, including upper lithosphere and lower convective asthenosphere, but also provide a typical case to study the relationship between the water contents and the geochemical composition in the mantle source of Cenozoic basalts in SE China.

  ) The temporal and spatial variation of the enriched compositions in the mantle source of Cenozoic basalts in SE China. Comparison of the temporal and spatial variation of the enriched compositions in the mantle source with different geological backgrounds besides providing the new information and restriction to decipher the origin of these enrichment of Cenozoic basalts in SE China can also reveal the indispensable clues to determine the influence of important geological events and recover the geological history, if any.

  and blue colors denote low and high velocities, respectively. The latitude of Xilong and Xinchang (GP and SC) are in the range of N 29° to 29.5°. The latitude of Mingxi (MX and SH) and Bailing are close to N 26.4° and N 27.2°. The latitude of Niutoushan (NTS) are close to N 25°.

(

  including the Shuangcai (SC) and Gaoping (GP) volcanoes). The sample locations are shown in Fig. 2-2 and 2-3. The samples from XL are basanites, and those from SC are alkali olivine basalt. The GP samples are transitional rocks, from basanites to alkali olivine basalts. The XL and GP basalts have caught some mantle xenoliths, including spinel lherzolites, spinel harzburgites and garnet lherzolites. The XL basanites contain approximately 6 vol. % ol and <4 vol. % cpx phenocrysts. The GP basaltic rocks contain <3 vol. % ol, <2 vol. % cpx and <3 vol. % plagioclase (pl). The SC alkali olivine basalts contain 10-15 vol. % cpx and <2 vol. % ol and pl. The cpx phenocryst grains in the XL and GP basaltic rocks are normally <1 mm in size, but those in the SC samples are up to 3 mm. The Ar-Ar ages of the XL basanites range from 23 to 27 Ma associating them with stage 1 volcanism, and those of the GP and SC samples are from 5 to 10 Ma associating them with stage 2 volcanism (Ho et al., 2003). The stagnant subducted slabs of Pacific plate in the MTZ are revealed by geophysical evidence beneath Zhejiang region, as shown in Fig. 2-1a and b.

  (a) Pictures for the Cameca IMS 1270 and (b) Pictures for the Cameca 1280HR2, located at CRPG, Nancy Chapter 3

  δ 18 O = [( 18 O / 16 O)sample/( 18 O / 16 O)V-SMOW-1]×1000

1

 1 Calibration of IMF by the composition of cpxTo measure the Li isotopic composition of unknown cpx samples by SIMS, the accurate calibration based on a series of cpx standard with similar composition to the unknown samples of IMF are required. The composition of cpx standards from the peridotites (

  Fig.4-3). In the plots of Al and Ti vs. IMF in Fig.4-7 and 4-8, a relatively weaker linear relationship than those of Si and Mg# can be observed. The relevance of Al and Ti to IMF are not stable, with various R 2 in different analysis sessions. In Fig.4-5 and 4-6, IMF have no relationship with Cr and Ca. Therefore, Cr and Ca contents are not in obvious relevance to the matrix effect of Li isotope analysis by SIMS for cpx.

  opposite trends to the slop of IMF corrected line are displayed, suggesting that either existing slop or intercept is unsuitable to different sections or other kinds of minerals, like Bell et al. (2009) used the IMF corrected line from ol to calibrate the offset of cpx and opx unknown samples. Therefore, a series of cpx standards with known Li isotope and similar chemical composition to unknown cpx samples are needed to determine the Li isotope of unknown cpx with various chemical composition, such as phenocrysts in basaltic rocks or meteor.

  facilitate the discussion, the Li isotope result based on calibration of Mg# are mainly discussed in this section. The Li content and isotope of some cpx grains in basaltic rocks from the Fujian region are analyzed by SIMS to test the calibration of cpx, as example. Some cpx grains contain cpx xenocryst core inside the cpx phenocryst rim. The Mg# and Si for the cpx phenocrysts and xenocrysts range from 76 to 91 and from 1.76 to1.92 (afu) respectively. The known cpx standards have similar relevance between IMF and either Mg# or Si, however, the cpx standards have more similar range of Si to the unknown samples than that of Mg#. Therefore, more cpx phenocrysts fall within the range of Si from 1.78-1.97 (afu) of cpx standards, but not within the range of Mg# from 82.9 to 91.9. The IMF of δ 7 Li increase up to 1.2‰ per Mg# increase for known standards, and the 2SD of SIMS and EMP for Li isotope and major elements is about 2‰ and 1% respectively. Therefore, we suggest that the IMF correct line suitable range of Mg# are expanded to compare to that of Si. Four cpx grain profiles of major element compositions and Li isotope in basalts from the Fujian region are measured to discuss the calibration. The details of the profile are listed in Table4-2. The Li isotope profiles of cpx phenocryst samples were analyzed in the same sessions, according to the IMF line of 2015-Aug-1280 in Fig. 4-2 and 4-4 respectively. Two kinds of cpx grains are analyzed in this study for the Li isotopic calibration and the Li isotopic change during magma evolution: one kind cpx, type I, has xenocryst core and phenocryst rim. The xenocryst core has relatively high Cr and Mg#, which is the landmark of cpx xenocryst. Another kind of cpx phenocryst, type II, is total phenocryst without xenocryst. The 5-3-10 and 5-11-7 grains have clinopyroxeney xenocryst core and clinopyroxeney phenocryst rim, as type I cpx phenocrysts. The xenocryst core have Mg# higher than 88, as shown in Fig. 4-9. Based on both of the calibrations, the profiles of 5-3-10 and 5-11-7 show the large difference of Li content and Li isotope between the xenocryst core and the phenocryst rim, as shown in Fig. 4-9. The Li content and Li isotope profile of the grains of 5-3-10 are measured along with the line from one side rim to the core and to another side rim again. The cpx phenocryst rims at both sides have high δ 7 Li >10‰ in Mg# calibration and low Li content <8 ppm, but the cpx xenocryst core has low δ 7 Li <10‰ in Mg# calibration and high Li content >12ppm Chapter 4 except one point, if following the calibration of Mg#. The core of xenocryst have high Li content but low Li isotopic ratios, especially, in the grain of 5-11-7. The analysis of core xenocryst and rim phenocryst were replicated a few times in the grains 5-11-7, Fig. 4-9. The 5 replicate analyses of cpx xenocryst core and 3 replicate analyses of clinopyroxeney phenocryst rim display relative consistent values respectively. The profile of Mg#, Li content, Li isotope for type I clinopyroxeney phenocryst.

  2, Fig. 4-10b). The center part and the rim of 10-0-17 cpx grain displays high δ 7 Li values of 22 to 28 ‰ in Mg# calibration and high Li content of 3-4 ppm, while the mantle of cpx grain have lower δ 7 Li values from 13 to 19 ‰ in Mg# calibration, with lower Li content of about 2 ppm (Table 4-2, Fig. 4-10b).

  2 and Fig. 4-9 and 4-10) for the same grains. The absolute difference between the corrected results of Lithium isotopic data by two calibrations almost agree with those of each other among different analysis points for all the cpx phenocrysts. The difference between the corrected results of xenocryst is larger than those of the phenocryst (Fig. 4-9 and 4-10). The difference between the two kinds of calibrations is because of: 1) the error of the analysis results of major elements composition of cpx measure by EPM, however, unless the error is systematic one, it is hard to explain the different analysis points having such consistent difference of IMF for unknown samples; 2) the co-relationship of Si (afu) vs. Mg# for the composition are different between standards and unknown samples. Mg# about 90 for standards corresponds to 1.95 (afu) of Si, however, for unknown samples the analysis point of 90 Mg# have Si about 1.86 (afu) (Table

  same ratio during clinopyroxeney crystallization from magma. It is hard to point out which one among Mg, Fe, Si or other elements or ion results the matrix effect for clinopyroxeney, due to limited number as well as limited composition range of cpx standards. Fortunately, most of unknown clinopyroxeney have similar slop of Si vs.Mg# to that of standard, and the relative change of Li isotopic data between different parts of grains is the key point that we focused on and are interested in (Fig.4-11). So the calibration of Si and Mg# can calibrate similar Li content and Lithium isotopic information of cpx phenocrysts to recover the diffusion of Li during magma ascent and cooling, if they share similar slop of Si vs. Mg# to the standard, such as the four cpx phenocrysts from Fujian basalts. Although, the core of 5-3-10 and 5-11-7 do not show similar slop of Mg# vs Si to standard or on the same extending line of cpx phenocrysts as shown in Fig. 4-12, they have similar chemical compositions to the know cpx standards. The corrected results by the calibration of Si and Mg# of xenocryst core also have similar variation tendency that the high Li content and depleted δ 7 Li are observed from the core to rim of 5-3-10 and 5-11-7, as shown in Fig. 4-9. These corresponding changes of Li content and Lithium isotopic data trends suggest the calibration either of Si or Mg# can be used to distinguish the difference and variation of Li in cpx grains. The difference between the results corrected by the calibration of Si and Mg# may be caused by the difference of composition between standards used to build the correction line and unknown samples. However, the difference between corrected δ 7 Li by two kinds of calibrations in single grains are consistent. The consistency suggests the two calibrations can get the same result and conclusion in single grain, but the δ 7 Li results corrected by different calibrations among different grains or samples cannot be compared together simply. The calibration of Lithium for ol in Bell et al. (2009) and the calibration of Oxygen for cpx the calculation based on Mg# is used in this work. To simplify discussion, only the calibration of Mg# are used in later chapter.

  cpx-melt ), fO2, and the variation of ambient Li content and δ7 Li. The different variation of Li content and Li isotope in the cpx grains are considered because of: (1) the evolution of magma, such as ambient temperature decrease, fractional crystallization, and magma mixture; (2) the initial difference between xenocryst and phenocryst; and (3) the later Li diffusion after cpx crystallization from magma.The calculation of fractional crystallization infer that the Li content does not have large difference when the degrees of fractional crystallization of magma are below 20% (Fig.4-10), suggesting the high Li content and low δ7 Li inherited from their mantle source, but are not resulted by crystallization. To simplify the calculation, the "Equilibrium Crystallization" and "Fractional Crystallization" models are used for the crystallization of ol, cpx and pl. The calculation results are based on the partition coefficient D between mafic minerals and melts. The cpx/melt D Li=0.2 [START_REF] Brenan | Behaviour of boron, beryllium, and lithium during melting and crystallization: constraints from mineral-melt partitioning experiments[END_REF] are assumed during crystallization. The recent experiments conducted at 1.5 GPa and over a broad temperature range of 700 to 1100 °C by[START_REF] Yakob | Lithium partitioning between olivine and diopside at upper mantle conditions: An experimental study[END_REF], however, have confirmed a fixed equilibrium partition coefficient of Li between olivine

  [3][4][5][6][7][8][9][10][11][12]. The results suggest the difference of Li content in type I cpx was not caused by the crystallization. The Li would remove from the high content part to the low content part, when Li are re-equilibrated. The Li content in xenocryst core is Chapter 4 higher than that in phenocryst rim disagreeing with later diffusion of Li. Therefore, the large difference of Li content between phenocryst and xenocryst are initial characteristics. The 6 Li generally diffuses faster than the 7 Li, in melts and minerals (e.g.[START_REF] Richter | Lithium isotope fractionation by diffusion in minerals. Part 1: Pyroxenes[END_REF]. If the Li diffuse from the xenocryst core to the phenocryst rim, the6 Li will enter faster into the phenocryst than the7 Li, leaving elevated δ7 Li in the core. The discordant patterns of Li content in type I cpx grains argue against the later diffusion of Li in Fig. 4-10. The homogeneous low δ 7 Li in the xenocryst core in 5-11-17 with homogeneous Li content also dissent from the later diffusion of Li. Therefore, the lower δ 7 Li and high Li content in the core of type I cpx was not caused by Li diffusion, but the initial characteristic of xenocrysts. Relationship between Mg# and Si (afu) in clinopyroxeney for stand and unknown samples. The type II cpx phenocrysts are totally crystallized from the basaltic magma, the Li profiles in cpx phenocrysts are either the magma evolution records or the Li diffusion results. The Mg# zonation are only observed in the outermost in the 10-0-17 grains, as shown in Fig. 4-11. The high fractionation of δ 7 Li in the profile in 10-0-17 cpx cannot be the result of the fractional crystallization which is unable to fractionate Li isotopes Chapter 4

  have reported two Li content re-equilibrium experimental results: the sample of LiPx16 grain with 755 µm diameter within Li2SiO3 as Li diffusion source buffered by Ni-NiO, after 160h and LiPx8 grain with 550 µm diameter within the spodumene as Li diffusion source buffered by Ni-NiO. However, despite the consistency of Li content in the result of Richter et al. (2014), the reequilibrium require the valley-like. Evolution of Lithium content in melt during the crystallizations of different mineral assemblage. Therefore, the Li content and δ 7 Li profiles together with the major elements profiles of these cpx grains suggest: (1) the xenocryst core of 5-11-7 and 5-3-10 cpx grains have kept their origin features of Li contents and Li isotope, distinct from their phenocryst rims; (2) the Li profiles of the 10-0-17 cpx grains imply the later Li diffusion, rather than magma evolution record; (3) the Li profiles of the 5-4-8 may not be effected by the later Li diffusion.

  Fig.5-2

  Spider diagram of the Zhejiang basalt samples, normalized primitive mantle values are from Sun and McDonough, (1989). REE of the Zhejiang basalt samples normalized by chondrite values are Sun and McDonough, (1989), whereas Pm*= ((Sm)N *(Nd)N) 1/2 .

  Sr-Nd isotopic compositions for the Zhejiang basalts (XL* from Ho et al. (2003) and Zou et al. (2000)). and (b) Pb isotopic compositions for the Zhejiang basalts (XL* from Ho

  (a) Representative OH IR absorption spectrum of cpx phenocrysts. Dashed lines mark the positions of individual OH bands (normalized to a thickness of 1 cm). (b) The OH IR absorption profile of the "water-loss" phenocrysts of the cpx phenocrysts from SC.

  (a) 87 Sr/ 86 Sr ratios vs. 1/Sr (data for Xilong (XL*) from Ho et al. (2003) and Zou et al. (2000)); (b) La/Nb vs. Ba/Nb (the MORB range was obtained from Rapp et al. (2008)).

  -8a and 5-8b) suggest a chemical evolution of their primary magmas controlled by fractional crystallization of minerals, such as olivine and cpx. The SC samples show relatively low Ni (150-170 ppm), Mg# (58 to 60) and MgO content (7-8 wt. %), suggesting that some amount of olivine fractional crystallization might have occurred in this case. If a large amount of fractional crystallization of olivine occurs, the La concentration of the residual magma increases, while the La/Sm ratio remains relatively constant, as we observed in the SC samples. However, this prediction contrasts with the positive correlations between La/Sm and La (Fig. 5-8c) observed in the Group 1 and GP samples, which indicate a low to moderate degree of fractional crystallization of olivine. (a) Ni vs. MgO for the Zhejiang samples; (b) Cr vs. MgO for the Zhejiang samples; (c) La/Sm vs. La for the Zhejiang samples; and d) CaO/Al2O3 vs. Mg# for the Zhejiang samples.

  Comparison of Zhejiang basalt samples with high-pressure experimental melts of various starting materials. (a) SiO2 vs. MgO for the Zhejiang basalt samples; (b) TiO2 vs. MgO for the Zhejiang basalt samples; (c) Fe2O3 T vs. MgO for the Zhejiang basalt samples; (d) CaO

  Na2O+K2O vs. TiO2. Data sources are the same as in Fig. 5-11. (b) Sr/Ce vs. Th content, where Cpx indicates clinopyroxene and Grt indicates garnet.

  The modeling results of melt mixture sources for XL, GP, SC, and SC * . SC * is modeled by 143 Nd/ 144 Nd=0.512959 As mentioned above in the text, the proportions of recycled TABs and DMM in the Group 1 basalts and recycled TABs and sediments together with DMM in the Group 2 basalts are estimated based on their Sr-Nd isotopic compositions. The concentrations Chapter 5 and the Sr-Nd-Pb isotopic compositions of recycled TABs and sediments are the results from Table 5-4. The concentrations and Sr-Nd-Pb isotopic compositions of DMM are

Fig. 5 -

 5 Fig. 5-14a. The modeled melts show similar trace element patterns to the Group 1 basalts. They share most of the features of the trace elements (Fig. 5-14 a), including similar Ce/Pb (49-65 for calculated melts vs. 28-44 for the Group 1 basalts), Nb/La

Zhejiang

  Cenozoic basalts. (a) Subduction of the Pacific plate beneath Southeast China (Huang and Zhao, 2006) induced upper mantle convection and back-arc extension between 26-17 Ma; (b) Subduction of the Pacific plate beneath Southeast China (Huang and Zhao, 2006) induced upper mantle convection and back-arc extension after 11 Ma. Upwelling mantle flow rolled back and was focused along a fault, a lithospheric weak zone, which consisted of recycled TABs components between 26-17 Ma and contained both recycled TABs and sediment components after 11 Ma, probably derived from stagnant Pacific oceanic slabs in the MTZ. (c) Upwelling mantle flows with a temporal change of components in the source of basalts were caused by a continuous supply of recycled oceanic materials from stagnant Pacific oceanic slabs in the MTZ. Between 26 and 17 Ma, upwelling mantle flows only involved some recycled TABs. The very limited recycled TABs and the surrounding mantle could melt to generate highly alkaline basalts, on account of the relatively low water content in the recycled TABs. After approximately 11 Ma, due to the consumption of recycled TABs and the new supply from the subducted Pacific slab, upwelling mantle flows involved less recycled TABs and included some recycled wet sediments. Wet recycled sediments lowered the solidus of the surrounding mantle and generated both highly alkaline basalts and AOBs, due to the relatively high water content in the recycled sediments. Due to lower components of recycled TABs in their source, these rocks show higher Ba/Th and lower Ce/Pb, Nb/La.

(

  Fig.6-2

  However, weak positive trends for the MX samples and other samples together are observed in the plots of Fig. 6-4b respectively. All the plots of 207 Pb/ 204 Pb vs. 206 Pb/ 204 Pb in Fig. 6-4c fall within the data region of SE China (reference are as same as Fig. 6-4a), located the right part to the Meteorite isochron.

  (a) Sr-Nd isotopic compositions for the Fujian basalts; (b) Pb isotopic compositions for the Fujian basalts. The data source of Cenozoic basalts are the same as in Fig. 5-5.(a) Representative OH IR absorption spectrum of the MX cpx xenocrysts; (b) the profiles of OH IR absorption spectrum of the SH cpx phenocrysts; and (c) the profiles of OH IR absorption spectrum of the BL cpx phenocrysts.

  Fig.6-7

  ... ...... ...... ..... . ...... r• . . . . . . . ""Ji .........

  Fig. 6-8b. When the xenocrysts are excluded, the Mg# of cpx phenocrysts do not display linear relationship with corrected δ 7 Li values or Li content (Fig. 6-8c), both the lowest δ 7 Li and the highest δ 7 Li cpx phenocrysts are observed with Mg# around 80.The Li contents of cpx phenocrysts in SH range from 1.3 to 18.5 ppm and the δ 7 Li values range from -10 to +35‰ (Fig.6-8d). In the plots of δ 7 Li values vs. Li contents, most of the cpx phenocrysts fall below the line of y=-0.5x+20, suggesting the cpx phenocrysts with low Li contents usually have high δ7 Li while the cpx phenocryst with high Li content have low δ 7 L. The detailed intra-grain profiles of these cpx phenocrysts are more complex and can be divided into two kinds of profiles (Fig.6-8e): a) some cpx phenocrysts have high δ7 Li and high Li content in the core but lower δ7 Li and low Li content than those at the rim; b) some cpx phenocryst grains have the opposite of above trend. However, the homogeneous Li content and δ7 Li are rarely found in cpx

  ). The δ 18 O IMF of the Nushan standards decrease with the decreasing Mg# (Fig.6-7), and the R 2 usually are better than 0.9. The drift of SIMS are monitored by the standard grains fixed on the analysis sections. The raw analytical results of the standard (NSH9 or NSH5) and Fujian cpx phenocrysts are listed in Table6-4. The δ 18 O values with their Ca/Al, Si/ IV Al, and Mg# values are plotted in Fig 6-9 a, b, and c. The features observed in Fig 6-9a, b, and c are: (1) the δ 18 O values of the MX and BL cpx phenocrysts range from +4.3‰ to +8.2‰ and from +4.3‰ to +8.2‰, respectively, which straddle the typical normal mantle value of 5.7±0.2‰ (Eiler 2001; Mattey et al., 1994), and the SH cpx phenocrysts range from +5.4‰ to +8.2‰, most of the Fujian cpx phenocrysts have higher δ 18 O than the normal mantle value; (2) the highest δ 18 O values appear despite the Mg# of cpx phenocrysts in BL and SH basalts, but a weak positive relationship between the δ 18 O and the Mg# are observed in MX basalts, (3) the highest δ 18 O values appear in the cpx phenocryst with intermediate Ca/Al or Si/Al.(a) the plots of the δ 18 O values vs. Ca/Al (afu ratios) for the Fujian basalts samples; (b) the plots of the δ 18 O values vs. Si/ IV Al (afu ratios) for the Fujian basalts samples; and (c) the plots of the δ 18 O values vs. Mg# for the Fujian basalts samples.

  Fig. 6-11a. The influence of peridotite assimilation for these six MX samples are also suspected from the plots of major elements vs. MgO in Fig. 6-2c, f, and g. The assimilation of xenocrysts or mixture of xenocrysts into bulk rock powder should have limited influence on other MX samples. Although the major element compositions of these six MX samples are influenced by broken peridotite xenocrysts, the ratios of trace

  (a) Ce/Pb vs. Nb/U for the Fujian basalts samples (the MORB range was obtained from Rapp et al. (2008)); and (b) 87 Sr/ 86 Sr ratios vs. 1/Sr for the Fujian basalts samples. The BL and SH samples have almost same Ni concentration, suggest limited ol fractional crystallization or assimilation (Fig. 6-11a). Due to high contents of CaO in cpx, fractional crystallization of cpx from a basaltic magma results in decreasing (a) Ni vs. MgO for the Fujian basalts samples; (b) Cr vs.CaO for the Fujian basalts samples; (c) CaO/Al2O3 vs. Mg# for the Fujian basalts samples; and (d) La/Sm vs. La for the Fujian basalts samples

  Fig. 6-1 1

  -10 and Fig. 6-8c). The Li content is only about 8 ppm in the host magma of the 5-3-10 and 5-11-7 grains, disagreeing with the very high Li content signature in the xenocryst cores are caused by the later host magma Li entering. The heterogeneity of Li content suggests the information of Li contents in xenocrysts were preserved after entrained within the basalts magma and were not eliminated by later Li exchange. The cpx xenocryst cores also have lower δ 7 Li than coexisting cpx Chapter 6 phenocrysts (Fig. 3-10 and Fig 6-8c). If the xenocrysts and phenocrysts stay long

  ) the mixture of magma from different source; (2) the later diffusion of Li; (3) the record of magma evolution, such as fractional crystallization. As mentioned above, the fractionation of Li during fractional crystallization is less than 1‰, suggesting the expulsion of (3). The very limited various δ7 Li values observed in 5-4-8 grain (Fig.4-11a) together with its almost homogeneous Li content and Mg# suggest it have insignificant effect of Li diffusion. Although, some cpx grains have a little heavy δ 7 Li in the rims of phenocrysts, the cores of the cpx phenocrysts have almost homogeneous δ7 Li and Li content, suggesting only limited Li diffusion were occurred in the rim of cpx phenocryst, not effecting the phenocryst cores. Therefore, (1) the MX cpx phenocrysts have not undergone obvious Li diffusion after the crystallization, and (2) some cpx phenocrysts may not share the same source as other cpx phenocrysts.The cpx phenocryst in the SH basalts display a relatively large variation of Li content and δ 7 Li. The cores of phenocrysts usually have low Li content and heavy δ7 Li, but the rims of phenocrysts have high Li content and light δ 7 Li, suggesting faster diffusion of6 Li relative to7 Li into a crystal (Fig.6-8f). Only one grain have inconsistent Chapter 6 trend of Li content and δ 7. Meanwhile, the Li content is weak correlated with δ 7 Li (Fig.6-8e). The difference between SH and MX can be caused by three possibilities:(1) the SH basaltic magma is heterogeneous. The heterogeneity can be leaded by complex magma mixing from different sources before eruption. Then the heterogeneous Li information were preserved from the rebalance. The isochronous variation of Li content and δ7 Li record the variation of composition of magma; (2) the cpx phenocrysts have undergone several metasomatic events after crystallization like the lithospheric mantle peridotites[START_REF] Rudnick | Lithium element and isotopic disequilibrium in minerals from peridotitic xenoliths from far-east Russia: product of recent meltfluid/rock reaction[END_REF][START_REF] Xiao | Large Lithium Isotopic Variations in Minerals from Peridotite Xenoliths from the Eastern North China Craton[END_REF]; (3) the later diffusion of Li. The second situation is less impossible due to several different compositions of fluids or new melting are required to react with cpx phenocrysts in such a short time, before magma cooling. Therefore, the heterogeneity should be inherited from the magma or its source, or the result of Li diffusion. The isochronous Li content and δ 7 Li variation of cpx phenocrysts in SH basalts is the result of obvious Li diffusion. The cpx phenocryst with heavy δ 7 Li core also have higher Li content than other cpx phenocrysts, suggesting it was crystallized from different parent magma and magma mixture occurred.The BL basalts have homogeneous Li content but relatively heterogeneous δ 7 Li despite Mg# variation of cpx phenocrysts (Fig.6-8i). The largest δ 7 Li intra-granular variation (bigger than 80‰) are observed in the BL cpx phenocrysts. Such large intragranular variation of δ 7 Li is not caused by IMF correction or magma process, but can only be the results by either Li diffusion or magma mixing. Accordingly, the great heterogeneous δ 7 Li within grains and increased Li contents at the mineral rims, unambiguously point to a Li addition from later melts/fluids. The homogeneous Li contents but the large heterogeneous δ 7 Li within grains imply the Li diffusion process after re-equilibrium of Li. Otherwise, any later isotopic disequilibrium of δ 7 Li will be erased after re-equilibrium of Li content. The larger fraction of7 Li observed in the BL cpx phenocrysts require a distinct Li source from the BL samples[START_REF] Richter | Lithium isotope fractionation by diffusion in minerals. Part 1: Pyroxenes[END_REF], implying the high Li melts/fluids permeated with very short stay, if relative low Li content of bulk rocks are considered. Due to the long residence in deep crust the BL samples had enough time to experience such complex process. Therefore, (1) the cpx phenocrysts do not have large diffusion with the host magma after their formation in the MX samples; but (2) the SH samples may have undergone the Li diffusion; (3) the Li content and δ 7 Li of the BL cpx phenocrysts have undergone

  260

Fig

  Fig. 6-14

  phenocryst are rehydrated from 425 to 559 ppm by[START_REF] Weis | Experimental hydration of natural volcanic clinopyroxene phenocrysts under hydrothermal pressures (0.5-3 kbar)[END_REF] , as shown in Fig.6-12. Actually, the dehydration for most of the SC samples have been demonstrated in Chapter 5, and the result of their recovered water content is consistent with the estimated water content for the Group 2 basalts (in Chapter 5). On the other hand, the water content after annealing rehydration failed to distinguish the ability to store water and the real water contents, as usual debate for the water content of Ringwood in deep mantle. Meanwhile, the estimated water content result falls in the range of the lowest limit of the water content for the basaltic magma.Comparison of the calculated average H2O content of the Fujian "primary" basaltic melts and the ranges of H2O content for the Zhejiang "primary" basaltic melts, Northeast China, East North China, West North China, OIBs, MORBs, BABBs and IABs (data fromChen et al. (2015);Dixon et al. (2004) and the references therein).

  xenoliths and xenocrysts carried by the MX basalts, suggest a high eruption speed and leave short time to shallow process; (2) cpx xenocrysts show a relative high water content as similar as the peridotite xenoliths[START_REF] Yu | H2O contents and their modification in the Cenozoic subcontinental lithospheric mantle beneath the Cathaysia block, SE China[END_REF], if H-loss is the dominant cause for the low water content of cpx phenocrysts in the MX basalts, these concomitant cpx xenocrysts cannot survive from the same process; (3) the H-loss should be in disorder and unselective. However, a strong positive relationship between the water content of corresponding melts and cpx Mg# (Fig.6-13), as well as, the cpx phenocryst with high Mg# have the higher water content of corresponding melts (Fig.6-14a) excluding a later disorder diffusion of H. (4) The limited Li diffusion indirectly exclude a synchronous H diffusion; (5) the clear negative correlation of H2O/Ce with Ba/Th and Ce/Pb in Fig. 6-12. The cpx phenocrysts in SH and BL contain relatively high water content, implying their H-diffusion were insignificant or re-equilibrated. The SH basalts have the similar pattern of cpx phenocryst Mg# and the water content of corresponding melts (Fig. 6-14b) to MX disagreeing disorder H diffusion. Although the SH cpx phenocrysts also display Li diffusion, its -OH profile of SH-1-13 (Fig. 6-6b) cpx grain has limited variation arguing against the H re-equilibrium. Meanwhile, the SH basalts also contain some peridotite xenolith/xenocrysts, suggesting a rapid eruption and leaving short time

  positive correlation between δ 18 O and Mg# of the cpx phenocrysts in MX samples can be explained as five possibilities: (1) the systematic deviation caused by the correction of IMF; (2) meteoric water interaction with the magma at high temperature during crystallization of mafic minerals; (3) AFC process of the lower continental crust; (4) the composition or geochemical variation in the closed magma system; (5) magma mixing.From the above possibilities, the (3) and (4) can be excluded at earliest based on the discussion in section 6.2.5.1. The (1) is excluded because of following: All the Fujian samples δ 18 O are measured in disorder, and the MX samples were analyzed in different sessions. On the one hand, the IMF in different sessions is different, but the MX samples share the similar positive trend. On the other hand, the plots of the BL and SH samples do not display such a trend. If the δ 18 O decrease with Mg# decreasing were Chapter 6

  subsequent magmas and erupted on the surface of earth. The highest δ 18 O values are observed in the intermediate Ca/Al and Si/ IV Al ratios of the MX, BL, and SH cpx phenocrysts in Fig 6-9a and b, also suggesting that the mixture between complex magma occurred.

  high Nd and Ta content of the Fujian basalts require an asthenospheric mantle source, not the lithospheric mantle, as the Cenozoic basalts in Zhejiang and in the NCC (e.g.Liu et al., 2015a and b). The plots of 143 Nd/ 144 Nd vs. Ce/Pb (Fig.6-16a) form a positive trend suggesting a mixture depleted source end member with high Ce/Pb with enriched source end member with low Ce/Pb. The depleted but high Ce/Pb mantle source of Fujian Cenozoic basalts suggests the depleted mantle member pointing to young recycled oceanic crust(Xu et al., 2012) and the ambient mantle source for the Cenozoic basalts. On the one side, the La and Nb in peridotite and pyroxenite-melt systems display opposing partitioning behavior: the Nb and La share the really similar partition coefficient in the peridotite-melt system, however, the Nb have lower compatibility in the pyroxenite-melt systems. The Nb/La ratio is a potentially suitable tracer to distinct pyroxenite and peridotite source signature(Stracke and Bourdon, 2009). All the Fujian lavas have high Nb/La (Fig.6-16b), indicating melting of a pyroxenite source(Stracke and Bourdon 2009), pointing to the asthenosphere and the recycled oceanic crust. On the contrary, the Ce and Pb share the really similar partition coefficient in the pyroxenite system, however, the Pb have lower compatibility than Ce in the pyroxenite-melt systems. The Ce/Pb are considered to be the corresponding indexes as Nb/La(Stracke and Bourdon 2009). The negative of Nb/La vs. Ce/Pb together of the BL and SH samples are observed in Fig. 6-16b, whereas the MX samples show very weak correlation between Nb/La and Ce/Pb. The correlation between Nb/La vs. Ce/Pb can be caused by either different partial melting degree for source mantle rocks or the different proportion of pyroxenite in the mantle. The crucial factor to respond to the correlation between Nb/La vs. Ce/Pb of the BL and SH samples, should be the different proportion of pyroxenite in the mantle, which is illustrated by a rough positive correlation of Srn/Sr* vs. EuN/Eu* in Fig. 6-16c (Sr*=(Cen*Ndn) 1/2 , n means primitive-mantle normalized, meanwhile, Eu*=(SmN/NdN) 1/2 , N means chondrite normalized) in the SH basalts and the BL diabases. The Sr have different partitioning behavior with Sr* (DSr* = (DCe/DNd) 1/2 , Stracke and Bourdon 2009) in peridotite and pyroxenite-melt systems, the Srn/Sr* will increase when the proportion of pyroxenite increases in the melting source. The Eu does not have big fractionation than other REEs during the magma process in the mantle, without addition or loss of large numbers of fsp in system. Meanwhile, the variations of the partition coefficients between EuN and Eu* (DEu * = (DSm/DNd) 1/2 ) are also not sensitive to the change of the proportion of pyroxenite in the melting source (Stracke and Bourdon 2009). If the crucial factor to respond to the correlation between Nb/La vs. Ce/Pb is the result of partial melting, variation of Srn/Sr* should be observed with narrow range of EuN/Eu*. Therefore, the anomalies of Eu should be inherited from their source of basalts, when the fractionation or assimilation of fsp during magma ascent are excluded. The Srn/Sr* increase with increasing Al2O3 imply the assimilation of plagioclase for the gabbros of lower oceanic crust for the BL and SH samples (Fig. 6-16d). The BL and SH samples may share similar source in the mantle. Due to the re-equilibrated the water content of the BL sample are considered not to represent the origin information of the mantle source. The high H2O/Ce of the SH imply a wet mantle source (Fig. 6-17a and b), pointing to the recycled oceanic sediments. The common relative high Srn/Sr*, Eu/Eu*, 143 Nd/ 144 Nd and Pb radiogenic ratios for the BL and SH samples are considered as the result of the low-temperature water-rock altered oceanic upper crust and fsp-enriched lower crust together with the oceanic sediments.

( a )Fig

 a Fig. 6-16

  b

  display weak correlation in the plots of Nb/La vs. Ce/Pb and Srn/Sr* vs EuN/Eu* (Fig.6-16b and c). These trends declare against the simple increasing proportion of pyroxenite or different partial melting degree in the mantle source. The appearance of simultaneously depleted Sr isotopic ratios and lower Nb/La suggest the source for the MX samples are different than the SH and BL samples. It consists with the positive relationship between Zr/Hf vs 87 Sr/ 86 Sr (Fig.6-18). The partition coefficients of Zr and Hf are almost same in both peridotite and pyroxenitemelt systems(Stracke and Bourdon 2009), keeping its original ratio from mantle melting and magma evolution. The 87 Sr/ 86 Sr ratio also can stay from melting or magma process. The positive relationship of between Zr/Hf vs 87 Sr/ 86 Sr (Fig.6-18) are believed

  an enriched-carbon component in the mantle source. The MX basalts have almost uniform EuN/Eu*, with Srn/Sr* variation. The low Srn/Sr* <1 and very weak EuN/Eu* disagree with the dominant role of fsp component in its mantle source, against oceanic gabbro in the mantle source. The horizontal variation of Srn/Sr* and Al2O3 also reject the high proportion of gabbro component in the mantle source by Fig. 6-16d. The inconsistency in the MX basalts are also observed in the H2O/Ce and water content.

  water content is hard to answer whether the sediments exist or not. The low water content and high Ce/Pb, intermediate Ba/Th as well as high δ 18 O and 143 Nd/ 144 Nd all call up a recycled low temperature water-rock reaction altered oceanic crust in the mantle source of the Fujian basalts, without gabbro components from recycled low oceanic crust. The MX samples share more common characteristics with the XL basalt in Zhejiang. The lower water content in MX may suggest the deeper dehydration of enriched recycled oceanic crust component than the XL basalts. Chapter 6 (a) Plots of Ce/Pb vs. H2O/Ce for the Fujian basalts. (b) Plots of Ba/Th vs. H2O/Ce for the Zhejiang basalts. The error bar of H2O/Ce is 30%. The source data are the same as in Fig. 5-13. The NTS basalts show different evolution path which is the other than that of the Fujian basalts (Fig. 6-2). Despite its relative high SiO2 and low MgO, the NTS basalts also survived from the contamination of continent crust and secondary alteration. The NTS samples consist of tracybasalts and basaltic trachy-andesite in Fig. 6-1. The NTS samples have the HIMU-like pattern with high content of HFSEs, high Nb (Ta) and Zr (Hf). The NTS samples have the highest Pb radiogenic isotopic ratio in all the Cenozoic basalts in East China. Enriched Pb isotope signatures with time-integrated high Th/U and 235 U/Pb, in the mantle source, suggesting recycled oceanic crust components. The high HFSEs are caught by the Ti-enrich minerals, implying the involvement of the deep partial melting relicts of oceanic crust, i.e. eclogite. The eclogite contain large number of Ti-enrich minerals, such as rutile, consisting of the strong positive Ti anomaly (Fig. Chapter 6

1 .

 1 [START_REF] Zou | U-Th isotopes in Hainan basalts: Implications for subasthenospheric origin of EM2 mantle endmember and the dynamics of melting beneath Hainan Island[END_REF] have reported three very young basalts in the Hainan Islands (the ML with an age of less than 9 ka, LH with an age of less than 9 ka, and SJY with an age of less than 77ka). The Hainan samples are plotted within a total alkali versus silica (TAS) diagram (Fig.7-1), with less than 1.5 wt. % LOI (Table7-1).The Hainan samples show two continuous trends in TAS diagram (Fig.7-1): most samples from LH and all the DY and FJT samples are the alkaline rocks ranging from basalts through trachybasalts to basaltic trachyandesites, and the ML, SJY samples and one LH sample are sub-alkaline rocks ranging from basalts to basaltic andesite (Fig.7-1). The ML, LH, and SJY major and trace element compositions are fromZou et al.

Fig

  Fig. 7-3

  -... ----.;., ----.. oe ---,.;;, ---~• ~--1)_ ~• . . ~ .. l .-.--.-~ .. 1 !,..------isotope cpx phenocrysts are found in the Hainan basalts (Fig. 7-4c). Unlike the Hainan basalts, the high Oxygen isotope are observed in spite of Ca/Al ratios. The Oxygen isotope ratios of cpx phenocrysts of the Hainan basalts are listed in Table 7-4. The cpx phenocrysts δ 18 O values range from +4.5 to +8.3‰ (n=16), from which most fall within the range from +6.1 ‰ to +8.2‰ and only two are below +5.0‰, two are higher than +10.0‰ as shown in Fig. 7-4c. a) Cpx phenocryst intra-grain δ 7 Li and Li content profiles of the Hainan basalts; b) The plots of δ 7 Li and Li vs. Mg# of the Hainan basalts; (c) The plots of δ 18 O for the Hainan cpx phenocrysts. after H loss, disagreeing with the total dehydration. The totally "dry" water contents of cpx phenocrysts are very rare for all the basalts in East China. Three reasons are considered to lead towards the totally "dry" water contents of cpx phenocrysts: (a) the absence of water content in the source of the Hainan basalts; (b) the very intense dehydration before the crystallization of cpx phenocryst, during the Hainan basaltic magma upwelling; (c) the later H-loss after the crystallization of cpx phenocryst. The Li content and δ 7 Li profiles of Hainan Island basalts are almost like those of the cpx phenocrysts from BL diabases with regular variation with Li content and δ 7 Li from the core to rim (Fig. 7-4a), suggesting significant Li diffusion. If the BL samples are considered to have undergone later H re-equilibrium, these "dry" Hainan cpx phenocryst cannot survive from later H re-equilibrium. Although the samples of HN9907 in LH is really compacted, the samples of ML and some LH are actually enriched in volatiles because of vesicular texture with large number of holes after gaseous escape from magma, arguing against the intense dehydration before eruption.

  DY and FJT samples. Because the U-Th disequilibrium data and Nd isotopic compositions support for a model of deep melting in the MTZ or even in the lower mantle (plume melting) as suggested by[START_REF] Zou | U-Th isotopes in Hainan basalts: Implications for subasthenospheric origin of EM2 mantle endmember and the dynamics of melting beneath Hainan Island[END_REF], these recycled materials are more likely caught by the plume from deep mantle. Large number of recycled materials are required in the plume for the high δ 18 O values, but the varying radiogenic isotopic composition of Sr-Nd, and Pb, suggest the recycled oceanic materials are not too old, otherwise they should have much more radiogenic isotopic Sr-Nd-Pb composition. The ML and SYJ samples have less trace element concentrations (Fig.7-2), but similar trace element ratios as of the DY and FJT samples (Fig.7-5b), suggesting that they most likely share the similar genesis as of DY and FJT, but have larger degree of melting.

Fig. 7

 7 Fig.7-9, which are from the[START_REF] Ishizuka | Processes controlling along-arc isotopic variation of the southern Izu-Bonin arc[END_REF] and[START_REF] Staudigel | Seamounts in the Subduction Factory[END_REF], respectively. The section from 24°N to 29°N along East China coast can be found in the section from 23°N to 25°N in IBM Trench.

  The variation of trace element ratios and isotopic composition in IBM trench, from[START_REF] Ishizuka | Processes controlling along-arc isotopic variation of the southern Izu-Bonin arc[END_REF].The Cenozoic basalts show similar143 Nd/ 144 Nd and 87 Sr/ 86 Sr range in SE China, the NCC, and NE China (Fig. 7-10a). However, Cenozoic basalts in SE China and the NCC together with NE China are located at right and left side of DMM respectively, on Chapter 7 the plots of 206 Pb/ 204 Pb vs 87 Sr/ 86 Sr ratios (Fig. 7-10b). Relative to the NCC and NE China, Cenozoic basalts in SE China display clearer pattern of variation of geochemical feature with latitude than those of the NCC and NE China (Fig. 7-7). However, the generation of this difference between north and south are still unclear. Two possibilities are proposed to explain the difference between the Cenozoic basalts in the northern China and in southern China: 1) the indistinct geochemical feature is the result of complex geological history in Mesozoic including old subduction events and delamination of thickened lower continental crust and lithospheric mantle; 2) the lack of the HIMU-like contributions, just are similar to the northern part of the IBM trench system. The variation of trace element ratios and isotopic composition in IBM trench, from Staudigel et al. (2010). Cenozoic basalts in SE China fall in the right part of DMM in Fig. 7-10b, consistent of the recent subduction event Pacific slab subduction, with slight radiogenic isotopic enrichment. However, the NCC and NE China Cenozoic basalts have scarcely any enriched Pb isotopic data, despite is enriched Sr isotopic data and depleted Nd isotopic data, unless no recycled oceanic crust component in their source, if the older than 200Ma subducted oceanic crust components are considered (Chapter 5). If the low 206 Pb/ 204 Pb are considered as the results of the successor of the northern part of the Pacific slab, they should display more enriched Pb isotope (Fig. 7-10b) like SE China basalts.

  ) The Hainan basalts have higherδ 18 O than normal mantle values. The coexistence of high and low δ 18 O cpx phenocrysts observed in the LH basalts, combined with their trace element composition, the recycled upper oceanic crust components altered by low temperature hydrothermal reaction are dominantly required in the LH basalts, while limited recycled lower oceanic gabbro components altered by high temperature hydrothermal reaction were also involved. The DY and FJT basalts are suggested as the results of the mixture of DMM, recycled oceanic sediments and crusts. These recycled materials should not be very old and are most likely caught by upwelling plume from the deep mantle. (3) Cenozoic basalts in East China have systematic variation of geochemical composition with the latitude; their radiogenic isotopic and trace element ratios display opposite symmetrical variation from N 25-29º section to south Hainan Island and from N 25-29º section to NE China, respectively. The spatial chemical and isotopic variation are observed both along the coast in East China and IBM trench. The consistency imply the spatial chemical variation may be caused by either the systematic varying chemical and isotopic composition of upper mantle or the influence of upper mantle by the Pacific Plate subduction.

FIT

( 1 )

 1 Water content of basaltic magma is an efficient index to identify the origin of different recycled materials in the mantle source. Most of Cenozoic basalts in SE China have kept their original water contents except the SC, BL, LH, SJY, and ML basaltic rocks. These basalts have IABs or BABBs-like water content suggesting wet enriched melting source underneath SE China. The magma water contents for the Zhejiang basalts range from 1.3 to 2.9 wt. %, for the Fujian basalts range from 0.3 to 0.5 wt. % (for "dry" basalts) and from 1.5 to 3.8 wt. % ("wet" basalts), and from 1.3 to 2.6 wt. % for the Hainan basalts. The H loss and re-equilibrium are identified from unusual low water content, OH profiles and the Li content and δ 7 Li profiles of cpx grains, as well as the relationship between Mg# and the water content of corresponding magma. The BL cpx phenocrysts have re-equilibrated water content. Some cpx phenocrysts in such as SC basalts have experienced a loss of the origin water during the magma ascent or after eruption.(2) Cenozoic basalts in SE China almost had survived from the crust contamination, while a little fractional crystallization occurred. Their chemical compositions can be used to deduce the geochemical feature of their mantle source.Cenozoic basalts in SE China display the geochemical signature of different recycled oceanic material components: a. The Zhejiang case: Zhejiang Cenozoic basalts erupted in 20-27Ma (Group 1)

  3 to 2.6 wt. % for the Group 2 samples, falling within the water content range of BABBs and IABs, and indicating wet materials in the mantle source. More alkaline, lower Si and Al contents, higher trace element concentrations, La/Yb, Ce/Pb, and Nb/La ratios, lower H2O/Ce, Ba/La, and Ba/Th ratios, and stronger negative K, Pb, Zr, Hf and Ti anomalies are observed in the older Group 1 basalts than those in the younger Group 2 ones. The Group 1 samples are plotted on the mixing curve between DMM and recycled oceanic alkali basalt component. The Group 2 samples show higher H2O/Ce, Ba/La and Ba/Th ratios than the Group 1 samples, reflecting enriched sources involved recycled Chapter 8 normal mantle values. Combined with the more enriched Sr, Nd, and Pb isotopic ratios of Hainan Cenozoic basalts than those of the normal mantle, the recycled materials are also required in the mantle source. Most of the ML, LH, and SJY basalts have dry cpx phenocrysts, while one LH sample (HN9910) have kept its original water content of 2.7 w.t. %. The DY and FJT samples have the water content of 2.6 wt. % and 1.3 wt. %, respectively. The coexistence of high and low δ 18 O cpx phenocrysts observed in the LH basalts, combined with their trace element composition, the recycled upper oceanic crust components are dominantly required in the LH basalts, while limited volume of recycled lower oceanic crust gabbro component was also involved. The DY and FJT basalts are suggested as the results of the mixture of DMM, recycled oceanic sediment, and crust components. These recycled materials are most likely caught by upwelling plume from the deep mantle.(3) Cenozoic basalts, especially in SE China, have systematic variation of geochemical composition with the latitude. The radiogenic isotopic and trace element ratios display opposite symmetrical variation from N 25-29º section to south Hainan Island and from N 25-29º section to NE China, respectively. The spatial chemical and isotopic variation are observed both along the coast in East China and IBM trench. The consistency implies the spatial chemical variation may be caused by either the systematic varying chemical and isotopic composition of upper mantle or the influence of upper mantle by the Pacific subduction. The difference of radiogenic isotope between the northern part of eastern China and the southern part of eastern China may be caused by the difference of their enriched component in the mantle source; the mixture of young and old subducted crust and sediments as well as recycled continental crust might occur, due to the complex history in the northern part, however, the southern part only might involve young subducted materials in the mantle Introduction Intra-plate basait is one of the most important windows for observing the deep earth. However, the genesis of intraplate basalts and the constituents of their mantle sources remain poorly known. In past decades, growing numbers of experimental and natural observations have demonstrated IQ SpringerReducing the strength of the lithospheric mantle is necessary for the destruction of stable cratons, and hydration of the lithosphere mamie is one of the most effective causes of weakening of the lithospheric mantle[1][2][3][4]. The North China Craton (NCC) experienced strong destruction in the Mesozoic thal peaked in the early Cretaceous[5]. Studies of the water content of the earl y Cretaceous ( ~ 120 Ma) high-magnesium basalts that erupted at Feixian in the Shandong Province have confirmed thal the eastern part of the NCC lithospheric mantle was indeed strongly hydrated (>1,000 ppm HzO by weight)[ 1]. The NCC had undergone multistage subduction of oceanic plates since the early Paleozoic-the Paleo-Pacific plate from the eastside; the oceanic plates along the Solonker and Mongol-Okhotsk sutures from the north side; and the oceanic plates along the Dabie Shan and Song Ma sutures from the south side are ali subducting the NCC[6, 7], and ali of these subduction events could hydrate the lithospheric mantle of the NCC. If the north and south side subductions have dominant roles in the hydration of the NCC lithospheric mantle, then the early Cretaceous lithospheric mantle beneath the southern part of the Taihang Mountains should be rich in water as is the contemporary lithospheric mantle beneath the Feixian region ( ~ 1,000 ppm). However, if the west side subduction of the Paleo-Pacific plate is the main cause of the hydration [8], then the earl y Cretaceous lithosphere mantle beneath the southern part of the Taihang Mountains should not be as hydrated as thal of the Feixian region because the subducted Pacifie plate has extended as far as the Taihang Mountains. Based on the above considerations, we analyzed the water contents of six peridotite xenoliths that are hosted by the early Cretaceous high-magnesium diorites of Fushan of the south-central part of the Taihang Mountains with Fourier transform infrared (FTIR) spectroscopy to determine the mechanism responsible for the

•

  corresponding author. Tel.: + 86 551 3607008: fax: + 86 5513607656. E-mail address: qkxia@usrc.edu.cn ( Q.-K. Xia). 0012-821X/$ -see front matter e 2012 Elsevier B.V. Ali rights reserved. hrtp ://dx.doi.org/1 0.101 6/j.epsl.2012.11.024 © 2012 Elsevier B. V. Ail rights reserved.

Table 2 -

 2 1 The sample locations and numbers of Cenozoic basalts from the SE China

	Location	Samples No.	GPS	Rock type	Age	Xeno
	Zhejiang	Xilong	XL-1	N 29° 3'46.00"	Basanite	23.7-26.4Ma a	Yes
			XL-2	E 118°58'52.40" Basanite		Yes
			XL-3		Basanite		Yes
			XL-4		Basanite		Yes
			XL-5		Basanite		Yes
			XL-6		Basanite		Yes
			XL-7		Basanite		Yes
			XL-8		Basanite		Yes
			XL-9		Basanite		Yes
			XL-10		Basanite		Yes
			XL-11		Basanite		Yes
			XL-12		Basanite		Yes
			XL-13		Basanite		Yes
		Gaoping	GP-1	N 29° 3'46.00"	Basanite	4.7-5.3Ma a	Yes

Table 2

 2

			-1 continuted
		MX-12		Basanite		Yes
	Shenghe	SH-1	N 26°20'37"	AOB	2.95 Ma a	Yes
		SH-2	E 117°16'12.2"	AOB		Yes
		SH-3		AOB		Yes
		SH-4		Basanite		Yes
		SH-5		Basanite		Yes

Table 3 -

 3 1 The chemical and Lithium isotopie compositions of cpx standards used for SIMS

	Standard No. 06JY06CPX' 06JY29CPX' 06JY31 CP X'		CLB25CP X CLB35CPX
	Si0 2	52.36	53.58	53.62	Si02	52.55	48.09
	Ti0 2	0.59	0. 18	0.29	Ti0 1	0.45	1.70
	All0 3	0.77	1.18	4.38	Al20 3	6.66	8.88
	Cr 2 0 3	5.09	4.33	1.22	Cr 2 0 3	n.d.	n.d.
	FeO	3.04	2.44	2.83	F~03b	3.64	5.57
	:\linO	0.09	0.08	0.09	~!nO	0. 10	0.10
	~gO	15.31	15.48	16.20	MgO	15.30	13.67
	CaO	20.85	20.43	20.51	CaO	19.36	20.52
	Na 2 0	1.08	1.39	1.17	Nap	1.93	1.25
	K20	0.01	0.01	0.01	K 20	0.02	0.04
	NiO	0.04	0.05	0.05	NiO	n.d.	n.d.
	Total	99.23	99.15	100.37	Total	100.01	99.82
	Mg#'	90.0	91.9	91.1
					Mg#c	89.3	82.9
	Si	1.94	1.97	1.93		1.90	1.78
	Ti	0.02	0.00	0.01		0.01	0.05
	Al	0.03	0.05	0.19		0.28	0.39
	Cr	0.15	0.13	0.03		0.00	0.00
	Fe	0.09	0.08	0.09		0. 10	0.15
	:Mn	0.00	0.00	0.00		0.00	0.00
	:vfg	0.85	0.85	0.87		0.83	0.75
	Ca	0.83	0.81	0.79		0.75	0.81
	Na	0.08	0.10	0.08		0. 14	0.09
	K	0.00	0.00	0.00		0.00	0.00
	Ki	0.00	0.00	0.00		0.00	0.00
	Total	3.99	3.99	3.99		4.01	4.03
	Li (ppm)	1.10	0.80	1.00		2.55	3.44
	s•u (%.)	1.30	-2.60	-2.40		-1.02	-5.68
	2o	0.04	0.53	0.45
	a

Table 3 -

 3 3. The chemical composition and ô 1 :s0 of cpx standards used for SMS.Mg# are re-calculated by the reference material.s, which may not as same as the values in their source.

	Yf.ineral type :Vlegacryst :\11egacryst Megacryst :\11egacryst Megacryst	Peridotite Peridotite	Peridotite		Peridotite Peridotite
	Standard 1\o. 1\SH-2	KSH-5	NSH-8 1\SH-14 J-ÇSH-9	06JY06CPX 06JY29CPX 06JY31 CPX		CLB25CPX CLB35CPX
	Si02	48.84	50.69	49.42	49.04	50.22	52.36	53.58	53.62	Si02	52.55	48.09
	Ti02	1.52	0.82	1.04	1.47	0.89	0.59	0.18	0.29	Ti02	0.45	1.70
	A1 2 0 3	9.68	8.20	8.98	9.82	8.50	0.77	1.18	4.38
				1.81	2. 11	1.42	1.08	1.39	1.1 7	Ka10	1.93	1.25
	K20	0.0 1	1.56	0.02	0.01	n.d.	0.01	0.01	0.01	K20	0.02	0.04
	1\iO	0.00	0.01	0.00	0.00	0.00	0.04	0.05	0.05	1\iO	n.d.	n.d.
	Total	99.41	99.78	98.56	99.38	98.93	99.23	99.15	100.37	Total	100.01	99.82
	:\11g#*	72.85	80.34	77.77	71.61	80.04	89.98	91.86	91.07	:\llg#a	89.28	82.94
	ÔISO (%o)	5.46	5.88	5.99	5.07	5.33
	2a	0.07	0.02	0. 12	0. 15	0.21
	Li (ppm)						1.10	0.80	1.00		2.55	3.44
	ô-Li (%o)						1.30	-2.60	-2.40		-1.02	-5.68
	2a						0.04	0.53	0.45
	a

b

This total ion content are obtained by SAR...\11 in CRPG.

  Table 3-1.Based on the Li isotope analyses on this series mantle cpx standards, a strong relationship between the composition of cpx and the matrix effect are obtained comparing the results measured by MC-ICP-MS/LA-ICP-MS and SIMS. Our observation prompt that the recognition of the matrix effect of cpx in Li isotopic system in the analysis of SIMS can be calibrated by its composition.

		NSH5cpx-f@8 NSH5cpx-f@10 NSH2cpx	5. 8 6.4	o. 1 O. 1	80.3 80.3 72. 9	0.0 0.5 2.9	o.
	01/05/2016	NSH5cpx-f@11 NSH5cpx-f@12 NSH2cpx NSH5cpx-f@13 NSH5cpx NSH5cpx-f@14 NSH8cpx NSH14cpx	6.2 6. 3 6.2 6. 1	O. 1 o. 1 o. 1 o. 1	80.3 80.3 72.9 80.3 80. 3 80.3 77. 8 71. 6	0.3 1.1 0.4 0.6 0.3 0.6 0.2 1.4	O. 0.0 0.0 o.
	18/10/2015 NSH5cpx-g@1 NSH10cpx	5. 5	0.0	80.3 82. 3	-0.4 O. 5	O.
	01/06/2016	NSH5cpx-g@2 NSH5cpx-g@3 NSH2cpx NSH5cpx	5.9 5. 7	o. 1 o. 1	80.3 80.3 72. 9 80. 3	0.0 2. 1 -0.2 o. 7	o. o.
		NSH8cpx-g@1 NSH8cpx NSH8cpx-g@2 NSH14cpx NSH8cpx-g@3 NSH10cpx	5. 7 5.2 5. 2	O. 1 O. 1 o. 1	77.8 77.8 0.0 71. 6 0.0 82. 3	0.9 -0.3 2. 5 -0.8 -0.8 0.6	0.0 o. O.
	02/05/2016	NSH2cpx-g@1 NSH2cpx NSH2cpx-g@2 NSH5cpx NSH2cpx-g@3 NSH8cpx NSH14cpx	5.9 5. 7 5. 3	O. 1 O. 1 o. 1	72.9 72.9 72.9 80.3 72.9 77.8 71. 6	1.1 0.4 o. 3 0.2 O. 9 -0.1 1.6	o. o. 0.0 O.
		NSH14cpx-g@1 NSH10cpx	5. 7	o. 1	71.6 82. 3	0.6 0.2	o.
		NSH14cpx-g@2	5.6	0.0	71.6	0.5
		NSH14cpx-g@3	5. 3	O. 1	71.6	0.3
		NSH5cpx-g@4	5. 7	o. 1	80.3	-0.2
		NSH5cpx-g@5	5.6	o. 1	80.3	-0.2
		NSH5cpx-g@6	5.4	O. 1	80.3	-0.5
		NSH8cpx-g@4	6.0	o. 1	77.8	0.0
	NSH8cpx-g@5 77.8 12/ 10/2015 5. 9 o. 1 NSH2cpx 72.9	3. 1	0.1
		NSH5cpx			80.3	2. 1	0.2
		NSH8cpx			77.8	2.3	0.1
		NSH14cpx			71.6	3.8	0.1
	12/ 11/2015	NSH2cpx			72. 9	2. 3	O.
		NSH5cpx			80. 3	1.3	O.
		NSH8cpx			77.8	1.5	o.
	NSH14cpx NSH14cpx-c@2 NSH10cpx	6. 5	O. 1 o. 1	71.6 71. 6 71.6 82. 3	2. 5 2.1 1.4 1.2	O. O.
	NSH14cpx-c@3 12/12/2015 NSH5cpx	7. 1	o. 1	71.6 80. 3	2.0 2.6	o.
		NSH5cpx-c@1 NSH8cpx NSH5cpx-c@2 NSH14cpx NSH5cpx-c@3 NSH10cpx NSH10cpx NSH5cpx-c@4 NSH5cpx	6.0 5. 7 5. 6 5.4	o. 1 o. 1 O. 1 O. 1	80.3 77.8 80.3 71. 6 80.3 82. 3 82. 3 80.3 80. 3	2. 6 0.1 3. 8 -0.2 2. 3 -0.2 2. 6 -0.4 2. 7	o. o. O. O. o.
		NSH8cpx-c@1 NSH8cpx NSH14cpx	6. 2	o. 1	77.8 77.8 71. 6	3.0 0.2 3. 7	o. O.
		NSH8cpx-c@2	6. 2	O. 1	77.8	0.2

Table 3 - 5

 35

	Measure 8	18 0 Err or	IMF	SD
	1 NSH-cpx-12@ 1	5.0	0.1	-0.4	0.2
	NSH-cpx-12@2	4.4	0.1	-1.0
	NSH-cpx-12@ 3	4.6	0.0	-0.7
	NSH-cpx-12@4	4.8	0. 1	-0.6
	NSH-cpx-12@ 5	4.7	0.1	-0.6
	NSH-cpx-12@6	4.8	0.1	-0.5
	NSH-cpx-12@7	5.0	0.1	-0.4
	2 NSH-CPX@ 1	6.3	0.1	1.0	0.2
	NSH-CPX@ 2	6.6	0.1	1.3
	NSH-CPX@ 3	6.4	0.1	1.1
	NSH-CPX@4	6.1	0. 1	0.8
	NSH-CPX@ 5	6.8	0. 1	1.5
	NSH-CPX@ 6	6.7	0. 1	1.4
	NSH-CPX@ 7	6.6	0.1	1.3
	NSH-CPX@8	6.2	0.1	0.9
	3

ReElicate anal~ses results for 8 18 0 of the CEX standards.

Session No. Standard No.

  Table 3-1) are used to calibrate the potential matrix effect for the Li isotope analyzed through SIMS. The Li isotopic data results of the peridotite standards of every analysis point are listed in Table 4-1. The raw Li isotope data are represented as [cps ( 7 Li) /cps ( 6 Li)]SIMS. So the Li isotope ratios of [cps ( 7 Li)/cps ( 6 Li)]unknown, true are

	expressed as:
	δ 7 Li L-SVEC = 1000*{cps ( 7 Li)/cps ( 6 Li) /12.0192-1}*1000	(4-1)
	if IMF = δ 7 Li SIMS -δ 7 Li true

= 1000*{{[cps ( 7 Li)/cps ( 6 Li) SIMIS -cps ( 7 Li)/cps ( 6 Li) true]/12.019-1} (4-2) δ 7 Li unknown, true = (δ 7 Li unknown, SIMS -IMF unknown) -(δ 7 Li Standard, SIMS -IMF Standard) + δ 7 Li Standard, true

Table 4 -

 4 1 The raw results of cpx standards for Li isotope analyzed by SIMS.

	Time	Standard No.	cp (7)/n Account A/conte 7 Li nt of tan dard	delta Liby err or by byiCP 8 Li 7 Li content SIMS 1 p (ppm)	Mg# IMF	SD
	2015 Aug 06JY06-CPX@ 1 29173	1711	24.4	0.9	1.3	1.1	90.0	23.1
		06JY06-CPX@2 28431	1657	24. 1	1.3	1.3	1.1	90.0	22.8
		06JY06-CPX@3 28736	1675	23.3	1.3	1.3	1.1	90.0	22.0
		06JY06-PX 4 28586	1666	22.7	1.1	1.3	1.1	90.0	21.4
		Mean							90.0	22.3	0.7
		06JY29-CPX@ 1 19870	1602	20.5	1.2 -2.6	0.8	91.9	23.1
		06JY29-CPX@2 15728	1277	19.9	1.9 -2.6	0.8	91.9	22.5
		06JY29-CPX@3 14768	1191	16.5	1.5 -2.6	O.	91.9	19. 1
		06JY29-CPX@4 13631	1099	17.2	1.2 -2.6	0.8	91.9	19.8
		Mean							91.9	21.1	1.7
		CPX25a@ l	89491	2221	16.9	0.6 -1.02 2.55	89.3	17.9
		CPX25a@2	89826	2229	19.0	0.7 -1.02 2.55	89.3	20.0
		CPX25a@3	90729	2252	18.6	0.6 -1.02 2.55	89.3	19.6
		CPX25a@4	88353	2193	18.1	0.6 -1.02 2.55	89.3	19.1
		Mean							89.3	19.2	0.8
		CPX35a@ 1	88833	1645	7.7	0.6 -5.68 3.44	82.9	13.4
		PX35a@2	7931	1469	7.0	0.7 -5.6	3.44	82.9	12.7
		CPX35a@3	79054	1464	9.0	0.8 -5.68 3.44	82.9	14.6
		Mean							82.9	13.6 0.8
	2016 Jan	06JY06-PX@ 1 29781	1793	43 .6	1.0	1.3	1.1	90.0	42.3
		06JY06-CPX@2 29050	1761	43.4	1.2	1.3	1.1	90.0	42.1
		06JY06-CPX@3 29996	1830	42.6	1.2	1.3	1.1	90.0	41.3
		Mean							90.0	41.9 0.4
		06JY29-PX@ 1 22799	1926	37.7	1.1	-2.6	o. 91.1 40.3
		06JY29-CPX@2 22657	1914	38.7	1.3 -2.6	0.8	91.1	41.3
		06JY29-CPX@3 22756	1922	40.2	1.5 -2.6	o. 91.1 42.
		Mean							91.1	41.5	1.0
		06JY31-CPX@ 1 20124	1351	42.0	1.1	-2.4	1.0	91.1	44.4
		06JY31-CPX@2 21397	1436	42.6	1.1	-2.4	1.0	91.1	45.0
		06JY3 1-CPX@3 21432	1448	38.3	1.5 -2.4	1.0	91.1	40.7
		Mean							91.1	43.4	1.9
		CPX25@ 1	82880	2167	35.9	0.6 -1.02 2.55	89.3	36.9
		CPX25@2	81364	2127	35.8	0.8 -1.02 2.55	89.3	36.8
		CPX25@3	82151	2148	34.5	0.6 -1.02 2.55	89.3	35.5
		CPX25@4	83500	2183	32.9	0.8 -1.02	2.55	89.3	33.9
		Mean							89.3	35.8	1.2

Table 4 -

 4 2 The raw and corrected Lithium result< analyud by S!MS from Fuj ian basalts.

	Location	Accoum 'u!PI
	MX	5.03E+I2 1.64E+ I2	26.2	1.5 80.9	1
		5.41 E+l2	22.8	1.3 79.5
		7.66E+I2	21.4	0.8 82 .0
		8. 19E+I2	19.5	1.8 82 .5
		7.22E+I2	19.2	1.1 81.5
		6.92E+I2	19.8	1.3 81.9
		6.5 1 E+l2	21.5	1.5 81.0
		6.70 E+I2	22.4	1.4 79.2
	MX	6.96E+I2	29. 1	0.7 79.8
		7.58E+I2	28.7	0.6 81.3
		1. 16E+I3	27.7	0.3 83.0
		6.47E+I2	26. 1	0.8 87.8
		2. 10E+I3	27.9	0.4 88.9
		5.86E+I3	24.9	0.3 89.6
		3.84E+I3	29.9	0.3 89.8
		3.07E+I3	28.6	0.4 88.9
		8.75E+I2	28.8	0.6 85.7
		1.08E+I3	24.9	0.5 84.9
		9.85E+I2	24.2	0.6 79.2
	MX	7. 19E+I2	21.7	1.4 82 .2
		7.38E+I2	21.1	1.0 79.2
		6.47E+I2	22.5	1.1 78. 1
		4.56E+I3	15.8	0.8 90.7
		4.96E+I3	16.9	0.8 90.7
		4.9 1 E+l3	15.9	0.8 91.2
		4.89E+I3	17.0	0.8 90.8
		5.27E+I3	15.9	1.4 91.2
	BL	1.40E+05	30.0	0.8 76.9
		8. 11 E+04	29.2	0.9 78.3
		5.26E+04	31.6	0.9 82 .6
		5. 17E+04	40.6	1.1 81.5
		4.3 1 E+04	36.7	1.7 81.6
		8.70 E+04	31.9	1.4 79.4
		5. 16E+04	30.9	1.4 81.0
		6.27E+04	28.4	1.9 80.2
		6.90E+04	24.7	0.8 81.2
		8.0 1 E+04	31.9	1.1 78. 1
		8.62E+04	32.2	1.2 76.0

Table 4

 4

	-3
	F	0=0.27

Continuous supply of recycled Pacific oceanic materials in the source of Cenozoic basalts in SE China: the Zhejiang case 5.1 Results

Table 5

 5 -3.

14 The watcr content of SC are the original calcul:ncd mu lis &om data.. and only lhe walcr content sc . . s is u.~ to saa.nd for thci" •mttial• water content

	Group		Group 2														Gtoup2
	LoacWon Gaoping (GP, Xincbang) Gmt~pl Age 4.7•S.3Mo XiloosCXL> GPS N 29" 3'46.00" 2J. 7-26.4Mo N 29" J'-16.00" Analysis No. GP• I GP-2	E 118"S8'S2.40" E 118"SB'Sl.40" GP-3 GP-4	GP•S			GP-7	sbJa:ogcai esc. Xincbang) 8.4-9.3Mo N 29"20'9.40" SC•I SC-2	E 120"S1'15. 10" SC3 SC-4	se-s
	Rock 1)-pe		XL.I Basanite 83sanite XL,.2	XL,.] Basanite	)(L.4 AOB<	XL.S AOB<			XL,.7 A OB<	)(L.8	)(L.9 AOB<	XL.IO AOB<	XL-11 AOB<	XL-12 AOB<	XL-13 A OB<
						B.uanicc &sonne	Bzonile B.uanilc	Booanite			Boson ile	&sonite	&sonitc	S....Oilc	Basaoitc	B:uanile	8oslllli1C
	SiOJ			44.02		44. 15	44.39	45.68	45. 16	43.46	45.21		49.68	48.24	48.21	48.49	48.56
	Tiû>				2.7S	41.76	42.58 2.83	41 .44 3.06	.0.22 2. 84	42.70 3.01	40.70 3.02	40.04 2.91	42.57	41 .81 2.37	40.34 2.39	41.SS 2 . .30	42.19 2.43	41.43 2.48
	AJ,O, f~ MnO MgO			2.68 8.91 14.0S 0.20 12Jl 14.08 10.61 0.17 IOJS	2.SO 7.61 14.4S 0.19 14.48 10.80 14.28 0. 17 10.04	2.73 7.08 14,74 0.20 14.82 10.87 14.69 0.18 10.67	2.44 8.76 13.83 0.18 13.20 11.11 14. 19 0. 17 9.93	2.S6 8. 73 14.22 0 .19 1 10 11.21 13.82 0. 17 10.46	2.90 7.95 15.06 0.22 14.57 ll.SS 13.9S 0.17 10.43	2.94 7.52 15.34 0.23 15.27 11.31 13.72 0. 17 10.31	2.77 9.41 13.82 0.21 12.62	2.73 9.66 1) ,64 0.21 12.47 12.S4 12.80 O. IS 7.4S	2.87 12.69 1.n 15.09 0.22 14.96 12.58 O. IS 7.71	2.85 12.77 8.65 IUl 0.22 13. 13 12. 12 0. 15 1.05	2.43 12.96 9.96 12.66 0. 18 13.02 12.8S 0. 15 7.88	2.64 12.82 8.80 12.35 13.89 0. 16 0.21 14.2 1 7.88
	ûO				10.36 10.23	10.41 10.08	10.96 IO.S2	IO.IS 9.76	IO.OS 10.49	11.32 10.47	10.90 IO.S6	9.4S	9.10 8.41	10.82 8.89	10.02 8.77	9.61 8.68	9.65 9.31
	~			2.02		4.50	3.82 2.01	3.67 2.03	4.52 2.79	4 .80 2.20	3.28 2.27	2.7S 2.08	4.04	4.18 3.22	3.26 2.89	3.65 3. 13	4.06 2.99	3. 16 3.22
	K...O				1.47	2.27	1.37 1.61	1.10 t.n	1.40 1.67	2. 19 1.80	1.93 1.73	1.88 1.69	3.08	3.02 1.27	1.90 1.27	2.76 1.28	2.64 1.32	2.51	U9
	P:Os				0.48		1.23	1.08 0.49	1.18 0.52	1.11 0.51	1.19 0.51	1.18 0.62	1.14 o.ss	1.01	1.06 0.38	1.16 0.38	1.01 0.37	1.17 0.38	1.02 O.SI
	LOI T01al Mgr		0.81 99.07 67.4 2. 16 9&.34 63.4	1.20 99.69 70.2 1.88 9&.34 62.3	1.10 99.02 70.3 1.42 100.09 63.1	I.SJ 100.34 69.2 l.S3 100.17 62.2	0.70 99.44 66.7 0.93 99.81 64.0	0.29 99.40 69.5 0.97 98.64 63.8	1.21 1.14 99.22 70. 1 99.76 63.9	0.93 99.91 68.2	1.07 1.80 98.9S 68.3 100.06 S7.8	0.78 2.33 99. 17 70.0 99.S2 S9.1	0.66 2. 19 98.93 98.34 68.2 S7.8	O.Sl 2.03 98.4S 100. 16 70.8 S9. 1	1.99 1.32 99.SI 100.00 70.6 60.0
								1282		900	594	952	llS7	870	900		1490	ISJO	880	1390	1266	1160
	Ba				649		3.4	643	2.6	2.3 687	3.0 680	JJ 656	1.8 663	2.0 6 18	2.7	2.9 478	2.0 SOl	2.6 481	3.1 488	2.6	496
	Be				1.7		166	1.7		144	147 1.7	156 1.8	171 1.9	141 1.9	142 1.8	143	ISI 1.4	137 1.3	138 1.4	161 1..3	143	l .S
	Ce				60		62	62		69	71 62	64 64	61 71	68 74	74	67	57	59 46	70 43	61 44	62	42	64	S2
	Co				6 1		440	60	S77	606 62	S24 60	424 66	S70 6S	640 65	490	430 so	S90 46	460 47	SOl 48	530	S I
	Cr				300		1.8	293	1.8	2.6 281	2.6 278	1.6 3 10	1.2 287	0.8 280	1.4	1.6 IS4	1.1 169	1.3 173	2.3 152	1.1	174
	Cs Cu Dy	Er Eu		0.6 as 5.6		54 7.7 2.9 4.3	0.6 78 S.7	51 6.9 2.6 3.9	53 6.9 2.S 4.0 0.5 68 5.1	52 1.2 2.7 4.0 0.5 78 5.8	54 8.0 3.0 4.4 0.6 78 6. 1	61 6.5 2 .4 3.8 0.5 79 6. 1	50 6.5 2.3 3.6 0.6 91 ~0	45 6.9 2.7 3.7	64 6.9 2.7 3.7 o.s 61 4.9	56 6.5 2.2 3.7 0.4 61 4.6	54 6.6 2.3 J.S 0.2 SB 4.7	48 6.8 2.5 3.9 0.4 SB 4.7	42 6.5 2.4 3.S	0.2 6S 4.9
	Er	Ga		2.3		21	2.3	19	19 2.4	20 2.4	22 2.5	20 2.S	21	2.S	22	24 2.2	19 2. 1	22 2.1	21	2. 1	21	2.1
	Eu	Gd		2.7		12	2. 7		Il	Il 2.8	Il 2.8	12 2.9	Il 2.9	10	2.8	10	10 2.3	10 2.2	10 2.2	Il	2.2	10	2.3
	Ga	Ge		2 1		1.4	22		I.S	I.S 20	1.4 22	1.4 22	0.2 22	0.2	2 1	0.2	0.2 22	0.2 21	0.2 22	1.4	22	0 .2	22
	Gd	Hf		7		7.9	7		6.9	8	6.4	7.2 8	8.0 8	6.8 8	7.0	8	7.9	8.2 6	6.6 6	7.8 6	6.6	6	7.0	6
	Ge	Ho		l .S		1.2	1.4	1.1	1.1 1.5	1.2 1.4	1.3 1.6	1.1 l.S	1.1		1.6	1.2	1.2 1.4	1.1 1.4	1.1 1.4	1.1	1.4	1.1	l .S
	Hf Ho la	Lo li Lu Nb		S.l 1.0 3 1		93 22 0.22 194	79 21 0.21 139 5J 1.0 31	81 26 0.19 106 s.s 1.0 32	86 14 0.21 ISS S.4 1.0 33	96 20 0.23 196 .5J 1.0 3S	72 14 0.18 127 S.l 1.0 38	73 15 0.20 131 5.3 1.0 33	7S 19 0.22 2 11	80 20 0.22 218 4.5 0.9 24	71 IS 0. 18 131 4.3 0.8 22	72 16 0.20 198 4.4 0.8 22	89 21 0.22 157 4.S 0.8 22	7S 17 0.20 173	4.2 0.9 26
	ü		Nd		10		74	Il		65	9	68	69 9	76 9	61 10	59		9	S9	60 7	S9 7	56 6	65	6	sa	6
	Lu	Ni		0.21	364	492 0.21	488 0.21	435 0.21	360 0.22	SOl 0.22	S3S 0.22	428	4SI 0.22	SH 0.21	454 0.21	440 0.21	S10 0.21
	Nb	Pb		66		4.89	68	3.58	2.99 71	4.21 70	5.44 71	3.70 70	3.20 70	4.90	5.20 so	3.40 47	4.80 48	5.32 so	4.20	47
	Nd		Pr		32		19	33		16	17 34	17 34	19 37	16 39	16		36	16	17 25	16 23	IS 23	17	23	16	25
	Ni	Rb		268		84	246	84	69 249	58 238	86 283	48 273	54	269	102	83 131	41 117	99 120	187 127	77	132
	Pb Pr Rb Sc	Sc Sm Sr Ta Tb		2.36 7 71 22		16 14 1439 10.1 1.55	18 13 1209 2.41 7.6 1.40 8 74 22	19 2.53 13 1200 6.0 1.42 8 80 22	17 2.54 13 1316 8.3 1.47 70 21	16 2.51 IS 1486 10.3 1.63 8 84 22	17 2.55 12 1300 6.3 I.JS 9 89 22	19 2.SO 12 1180 6.4 1.35 8 84 23	14 Il 14SO 10.3 1.39	14 2.73 Il ISOO 10.7 1.40 6 53 21	16 2.32 12 1270 6.8 1.25 s S2 21	IS 2.43 12 1420 9.6 1.29 s 49 22	16 2.66 13 1343 7.8 1.41 s 53 21	IS 12 1290 2.34 6 76 8.6 1.31 22
	Sm	Tb		8		16	8		12	8	9	14 8	17 9	Il	9	10		8	17	18 6	Il 6	IS 6	14	6	14	7
	St		Tm		892		0.33	0.29 1133	0.27 991	0 .31 1044	0.34 939	0.25 1021	0.25 979	0.32	0.30 676	0.25 929	0.29 606	0.30 666	0.28	581
	Ta		u		3.6		3.9	3.7	2.8	2.0 3.9	3.3 3.8	4.0 3.8	2.4 3.7	2.3 3.7	3.8	4.1 2.7	2.4 2.6	3.7 2.6	3.4 2.7	3.4	2.4
	Tb		v		1.06	174	181 1.07	194 1.09	180 1.09	171 1.16	182 U9	180 1.14	160	161 0.90	173 0.86	174 0.87	IS9 0.8S	IS7 0.93
	Th		y		4		34	4		30	5	29	JI 5	JS 5	25	5	26		5	27	29 4	25 3	27 3	31	3	27	4
	Tm u v	Yb Zn 'h:		0.29 0.7 231	1.8 160 397	1.6 1S1 326 0.29 0.7 224	I.S 1S1 284 0.29 0.7 224	1.7 148 346 0.29 1.3 220	1.9 IS9 401 0.30 0.7 228	I.S 172 331 0.3 1 0.7 223	1.4 172 329 0.31 0.6 232	1.7 171 429	1.7 169 421 0.28 0.9 178	I.S 174 334 0.2S 0.8 19S	1.7 181 416 0.26 0.7 197	1.7 140 332 0.26 0.9 191	I.S 162 0.26 0.8 370 193
	y	H>O'(wt%)	26		1.7	26		2.2	2.9 27	2.1 27	1.6 28	1.4 29	2. 1	28	1.7	1.9 24	1.6 23	2.0 23	2.2	23	2.0	24
	H,Q'(wt%) Yb	1.6		1.3	1.6		1.7	2.7 1.6	1.7 1.6	1.4 1.6	1.1 1.7	1.9	1.7	1.7	1.7 1.6	1.4 1.5	1.8 1.6	2.0	1.6	1.6	1.6
	z..				140			140		146	140	ISI	151		148		127	120	122	123	124
	Zr	17 Sr,OOS,	227			231		0.703692 241	238	0.703734 0.703664 234 231		230		198	189	0.703713 194	198	0.703697 184
			2o									s		9	s							4
	14lNdf1.,.Nd 2o ,..f'bi'O'Pb th~(wt%) H.ooO' (wt"/o)	2.6 2.4			2 . . 0 2.1		0.51 2905 13 2.2 2.5	l.S 1.3	0.512896 0.512896 16 13 2.6 2.6 2.3 1.6			1.7 1.7		0.31 0.31	0.3' 0.4 r	0.51 2894 0.2 r 14 0.3 r	0.4 r 0.3 r	0.51 2896 1.3' 1.1 '
		'"'Phi'"' Pb
	""Pbi""Pb "'Sti"'St 0.703340 0.703233 0.703292 0.703303 0.703307 0.703290 0.703262	0.703664 0.703667	0.703499 0.703486
	2a				The data of age arc from che Ho ct al. (2003) ard Zou ct al (2000) 7 Il 14 9 10 Il			8		6	12	9	Il
	b "'Ndi 164 Nd 1	MgN-Mg'"/(Mg 2 '+!Fc''). values wcre cakulalcd assuming Fc''IIFc • 0.85. 0.513048 0.512978 0.513007 0.512968 0.512960 0.512964 O.SI2988	0.512950 0.512928	O.SI 29S9 0.512931
	2o				The average ofH,O conlef< calculatcd fromcpx phcnocrysts with Mg* >80 (Mg* >77 for GP samples). s 8 8 7 8 9 6 14	10	8	7
	lOOJ>bi*Pb	d	The a venge of H,O conter< calculatcd from cp x phcnocrysls wich Mg* > 75. 18.398 18.413 111.451 18.447 18.479 18.46S			18.49S	18.48S	18.394
	lOTJ>bi!'O' Pb		AOB: Alltali olivine b:uah. 15.496 15.502		15.514	15.551	15.571	15.568			IS.S62	15.SS8	15.525
	~Pb		38.453	38.4SI			38.463	38.546	38.599	38.573			38.675	38.646	38.467

Table 5 -

 5 2. The calculated H20 contents of mantle source for Zhejiang basalts.

			D• Hzû in source =0.005			D-HzO in source =0.0 13
	F( 0 o)	1.00 2.00 5.00 10.00 15.00	1.00 2.00	5.00 10.00 15.00
	XL-I	197	348	854	1707 2561	317	433	870		2561
	XL-2	254	449	1102 2203 3305	409	559	1123 3305
	Xl-3	332	585	1436 2872 4308	533	728	1464 4308
	XL-4	237	418	1027 2054 3081	381	52 1 1047 3081
	XL-5	189	334	820	1639 2458	304	416	836		2458
	XL-6	165	29 1	714	1428 2142	265	362	728		2142
	XL-7	240	422	1038 2075 311 3	385	526	1058 3113
	XL-8	200	352	864	1728 2592	32 1	438	88 1 2592
	XL-9	219	387	950	1899 2849	353	482	968		2849
	XL-JO	182	320	786	1573 2359	292	399	802		2359
	XL-JI	235	414	1018 2036 3054	378	516	1038 3054
	XL-12	259	457	11 22 2243 3365	417	569	1144 3365
	XL-13	232	409	1005 2010 3015	373	510	1025 3015
	GP-1	302	532	1307 2614 3921	486	663	1333 392 1
	GP-2	230	405	996	1991 2987	370	505	1015 2987
	GP-3	253	447	1098 2195 3293	408	557	11 19 3293
	GP-4	169	298	732	1464 2197	272	371	747		2197
	GP-5	300	529	1299 2599 3898	483	659	1325 3898
	GP-6	297	523	1286 257 1 3857	478	652	131 1 3857
	GP-7	200	353	866	1732 2598	322	439	883		2598
	SC-1	38	67	166	332	497	62	84	169	332	497
	SC-2	46	81	200	400	600	74	101	204	400	600
	SC-3	39	69	170	340	510	63	86	173	340	510
	SC-4	47	83	205	410	615	76	104	209	410	615
	SC-5	150	265	650	1300 1950	241	330	663

Table 5

 5

	-3	EPMA and FTIR data for the CPX phenocrysts of the Zhejiang basalts.
	Sample No. XL-1
	Section No.	1			2			8
	Point No.	1	2	3	1	2	3	1	2
	SiO 2	49.87	51.47	48.01	50.45	53.90	51.03	47.95	49.29
	TiO 2	1.24	1.19	2.51	1.05	0.06	1.61	2.65	2.27
	Al 2 O3	5.91	3.26	4.45	7.55	3.23	1.99	4.77	3.71
	Cr 2 O3	0.56	0.82	0.03	0.00	1.40	0.01	0.11	0.00
	FeO	5.51	5.54	7.10	6.45	3.05	5.86	6.76	6.63
	MnO	0.10	0.09	0.11	0.10	0.11	0.11	0.09	0.06
	MgO	12.36	13.93	12.90	14.42	18.36	14.05	12.73	12.94
	CaO	22.34	23.33	23.92	17.23	20.05	23.84	23.69	24.07
	Na 2 O	1.24	0.53	0.48	1.66	0.43	0.69	0.47	0.51
	K 2 O	0.01	0.00	0.00	0.02	0.02	0.01	0.01	0.01
	NiO	0.01	0.00	0.01	0.05	0.06	0.02	0.01	0.03
	Total	99.14	100.15	99.51	98.97	100.66	99.21	99.22	99.50
	Si	1.86	1.90	1.81	1.86	1.93	1.91	1.81	1.85
	Ti	0.03	0.03	0.07	0.03	0.00	0.05	0.08	0.06
	Al	0.26	0.14	0.20	0.33	0.14	0.09	0.21	0.16
	Cr	0.02	0.02	0.00	0.00	0.04	0.00	0.00	0.00
	Fe	0.17	0.17	0.22	0.20	0.09	0.18	0.21	0.21
	Mn	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
	Mg	0.69	0.77	0.73	0.79	0.98	0.78	0.72	0.72
	Ca	0.89	0.92	0.97	0.68	0.77	0.96	0.96	0.97
	Na	0.09	0.04	0.04	0.12	0.03	0.05	0.03	0.04
	K	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
	Ni	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
	Total	4.01	4.00	4.04	4.01	3.99	4.02	4.02	4.02
	Mg#	79.99	81.75	76.43	79.94	91.48	81.03	77.05	77.67
	D (cpx-melt) H2O	0.0154	0.0113	0.0195	0.0191	0.0107	0.0102	0.0199	0.0149
	Absorbance of cpx (cm -1 )	3.30	3.69	4.95	3.10	3.50	4.30	2.90	2.30
	Thickness of cpx (0.001mm)	96	110	75	105	103	100	54	59
	Absorbance
	normalized to 1	344	335	660	295	340	430	537	390
	cm (cm -1 )
	H 2 O-cpx (ppm)	145	142	279	125	144	182	227	165
	H 2 O-melt (wt%)	0.95	1.25	1.43	0.65	1.35	1.78	1.14	1.10

Table 5 -

 5 4. Source materials calculation for rthe Zhej iang basalts

		Start Materials			Mobility		Using Values
	Sed	TABs	DMM	Sed"	Sedb	TABsc	TABsd	Sed	TABs
				900	900	900	800
				5.5	4.0	5.5	4
		(ppm)
	6.94	15.9			4.5	0.3	0.33	6.63	15.85
	90	150			23.2	2.6		69.09	146.10
	164.5	76.4				3.2			73.96
	2 1.6	24.5			18.9	-1.7		17.53
	99.5	61				2.5			59.48
	68.4	41.5		4		50.4		65.66	20.58
	64.2	69.9				0.9			6927
	57	43.5	0.05	18	27.9	63	92	46.74	16.10
	1.32	0.716		30	32.7	50.8	98	0.92	0.35
	327	324	7.664	9.2	31.9	40.8	30.1	259.82 226.53
	776	383	0.563	12	29.0	52.5	76	616.78 136.26
	25.9	27.2	3.328		6.6	-0.5	0.21	2420	27.14
	86	22 1	5.082		8.3		1.01	78.89 218.76
	1.9	4.73	0.157		11.5		1.42	1.68	4.66
	11.04	40.3	0. 1485	4	9.3	3.6	7.9	10.60	38.85
	0.758	2.42	0.0096		5. 1	-0.4	2.35	0.72	2.36
	20.78	22.2	0.192	7.5	3. 1	56.1	19.3	19.22	9.75
	31.54	51.9	0.55	7.3	10.1	50.7	11.1	2924	35.87
		6.81	0.107			42.4			3.92
	21.03	27	0.58 1	8.3	7.0	30.7	3.20	19.55	22.42
	4.62	5.87	0.239	5.2	3.9	13.6	1.45	4.44	5.43
	1.15	1.92	0.096		-0.1	8.3	1.07		1.83
	4.2	5.95	0.358		6.9	5	0.67	3.91	5.78
		0.944	0.07			1.4			0.93
	3.81	5.17	0.505		5.5	3.6	0.23	3.60	5.o7
		0.959	0.1 15			2.8			0.93
	2.12	2.55	0.348		3.5	0.6	0.1 1	2.04	2.54
	1.86	2.21	0.365	0	28.1	1.4	0.09	1.34	2.19
	0.268	0.337	0.058		1. 1	-0.4	0.12	0.27	0.34
	6	1.74	0.0 18	51	48.8	84.6	81	2.94	0.30
	2.62	2.44	0.0079	14	18.5	37.7	9.1	2.25	2.22
	0.58	0.922	0.0032	12	26.4	29.1	18.8	0.43	0.65
		157
	0.706 170	o. 704259 o. 702190
	0.5 12520	0.512941	0.513130
	18.9 17	19.363	18.275
	15.646	15.553	15.486
	38.918	38.622

Table 5 -

 5 5. Modeling Source calculation for the Zhejiang basalts.

		OMM	RTABs	RSed	XL	GP	sc	sc•
				OMM	96.05%	98.70%	98.58%	97.61%
				RTABs	3.95%	1.02%	0.47%	1.77%
				RSed		0.29%	0.95%	0.62%
	Trace Elements	(ppm)
	Rb	0.05	16. 10	46.74	0 .68	0.35	0.57	0.62
	Ba	0.56	136.26	616.78	5.92	3.7 1	7.08	6.79
	Th	0.01	2.22	2.25	0. 10	0.04	0.04	0.06
	u	0.00	0.65	0.43	0.03	0.01	0.01	0.02
	Nb	0. 15	38.85	10.60	1.68	0.57	0.43	0.90
	K			994
	La	0. 19	9.75	19.22	0.57	0.34	0.42	0.48
	Cc	0.55	35.87	29.24	1.95	0.99	0.99	1.35
	Pb	0.02	0.30	2.94	0.03	0.03	0.05	0.04
	Pr	0. 11	3.92		0.26	0.15	0.12	0. 17
	Sr	7.66	226.53	259.82	16.3 1	10.61	11.10	13.10
	Nd	0.58	22.42	19.55	1.44	0.86	0.86	1.09
	Zr	5.08	2 18.76	78.89	13.53	7.47	6.79	9.32
	Hf	0. 16	4.66	1.68	0.34	0.21	0.19	0.25
	Sm	0.24	5.43	4.44	0.44	0.30	0.30	0.36
	Eu	0.10	1.83		0. 16	0. 11	0.10	0. 13
	Ti	7 16	13860	3993	1236	859.34	809.28	969.25
	Gd	0.36	5.78	3.9 1	0.57	0.42	0.42	0.48
	Tb	0.07	0.93		0 .10	0.08	0.07	0.08
	Dy	0.51	5.07	3.60	0.69	0.56	0.56	0.6 1
	Ho	0. 12	0.93		0 .15	0.12	0.12	0.13
	y	3.33	27. 14	2420	4.27	3.63	3.64	3.88
	Er	0.35	2.54	2.04	0.43	0.38	0.37	0.40
	Tm
	Yb	0.37	2.19	1.34	0.44	0.39	0.38	0.40
	Lu	0.06	0.34	0.27	0 .07	0.06	0.06	0.06
	87 Srf86Sr	0.70260	0.70449	0.706 19
	143Ndf'44Nd	0.51310	0.51289	0.51252
	206 Pbf20"Pb	18.27	2 1.38	18.97
	l07pbf20" Pb	15.49	15.65	15.65
	87 Srf86Sr				0.70364	0.70326	0.70358	0.70362
	I43Ndf'44Nd				0.51293	0.5 1301	0.51295	0.51296
	206 Pbf20" Pb				19.53	18.79	18.78	18.98
	207pbf20" Pb				15.55	15.55	15.59	15.58

Table 5 -

 5 5 ( continued)

			Panition coefficient				XL
		ol	op x	cp x	gn		Melting Degree
	Mineral modes	0.73	0.15	0.06	0.06	0. 10%	0 .50%	1.00%	1.50%	10.00%
	Melt reaction	-0.0005	0.0049	-0.013 1	-0.00 13
	Rb	3E-4	2E-4	4E-4	2E-4	534.35	129.57	66.55	44.78	6.82
	Ba	5E-6	6E-6	4E-4	7E-5	5766.62	1178.51	590.87	394.27	59.23
	Th	5E-5	2E-3	5.7E-3	9E-3	44.5 1	15.52	8.55	5.90	0.94
	u	3.8E-4	2E-3	1.1 E-2	2.8E-2	7.69	3.73	2.27	1.63	0.28
	Nb	5E-4	4E-3	1E-2	1.5E-2	503.59	229.13	136.28	96.98	16.43
	K	2E-5	1 E-4	1E-3	1.3E-2
	La	5E-4	4E-3	1.5E-2	7E-4	208.82	84.74	48.63	34.10	5.61
	Ce	5E-4	4E-3	8.6E-2	2. 1E-2	268.9 1	173.55	120.25	92.00	18.42
	Pb	3E-3	9E-3	9E-3	5E-3	5.49	3.13	2.04	1.51	0.28
	Pr
	Sr	4E-5	7E-4	9. 1E-2	7E-4	2997.4 1	1730.87	11 32.64	841.72	156.85
	Nd	4.2E-4	1.2E-2	1.9E-1	8.7E-2	84.12	68.43	55.50	46.67	12.60
	Zr
	H f	1.1 E-3	2.4E-2	1.4E-1	4E-1	9.43	8.51	7.58	6.83	2.56
	Srn	1.1 E-3	2E-2	1.5E-1	2.3E-1	17.45	15.13	12.97	11 .35	3.64
	Eu
	Ti	1.5E-2	8.6E-2	3.8E-1	2E-I	22559.63 2 11 01.53	19524. 15	18166.20 8323.97
	Gd	1.1 E-3	6.5E-2	1.6E-l	5E-1	11.79	10.93	10.02	9.25	4.0 1
	Th
	Dy	2.7E-3	6.5E-2	1.7E-1	2E+OO	4.96	4.84	4.69	4.56	3.06
	Ho
	y
	Er	1.3E-2	6.5E-2	1.8E-I	3	2. 12	2.09	2.05	2.01	1.53
	Tm
	Yb	2E-2	8E-2	2.5E-I	5.5	1.21	1.20	1.19	1.18	1.03
	Lu	2E-2	1.2E-l	2.8E-l	7	0. 15	0.15	0.15	0. 15	0. 13

Table 6 -

 6 The ratios of206 Pb/ 204 Pb, 207 Pb/ 204 Pb, and 208 Pb/ 204 Pb of the SH samples are 18.301-18.377, 15.487-15.570 and 38.328-38.606, respectively. The BL diabases have the ratios of 87 Sr/ 86 Sr, 143 Nd/ 144 Nd, 206 Pb/ 204 Pb, 207 Pb/ 204 Pb, and 208 Pb/ 204 Pb from 0.703847

	703601 to 0.703745,

1 and plotted in Fig. 6-4. The MX basanites have homogeneous 87 Sr/ 86 Sr ratios from 0.703596 to 0.703676, 143 Nd/ 144 Nd ratios from 0.512849 to 0.512909 (εNd(t) values range from 4.1 to 5.3), 206 Pb/ 204 Pb ratios from 18.243 to 18.308, 207 Pb/ 204 Pb ratios from 15.503 to 15.591, and 208 Pb/ 204 Pb ratios of 38.320 to 38.620. Zou et al. (2000) has reported some Sr-Nd-Pb isotopic data for the MX basalts from 0.

  .

	.	•	.	.	.	.
	74		76	78	80	82
				Mg#
	Water content
	ofmelts

  MX, but significantly in SH and BL. The water contents of the cpx phenocrysts in the MX basalts are relatively low, suggesting H loss at first glance. It can be inferred whether the relative low water content is the natural feature of these cpx phenocrysts or a result of diffusion-driving H-loss, from following: (1) a large number of peridotite

, which can index to the H diffusion in cpx phenocryst, indirectly. The Li isotopic data suggest limited diffusion of Li occurred in Chapter 6

  ). At the same time, the high δ 18 O values are not correlated with the LOI (loss on ignition) values of the bulk rocks. The SH have the highest LOI, but share the similar range of δ 18 O values as the MX and BL samples.

Table 6 -

 6 1 Major and trace element compo ition and isotopie ratios of the Fujian ba ait and the calculated H 2 0 content of the basaltic melts.

	Location		Bail in
	p	27"9'38.4 E 120°10'4.44"
	A e	Pleistocene
	Rock type	Dia base	Diaba e	Dia base	Dia base	Dia base	Diabase	Dia base	Diabase	Dia base
	Samole o.	BL-3	BL-4	BL-5	BL-6	BL-7	BL-8	BL-9	BL-10	BL-11
	i02	46.66	48.34	46. 3	47.25	46.62	47.02	46.82	46.70	46.90
	TiO,	2.18	1.94	2.08	2. 13	2. 11	2. 19	2.14	2. 10	2.14
	Al 2 0 3 Fe,0 1	11 .92 12.08	10.40 11.20	12. 12 11 .86	12.21 11 .80	11 .50 12.05	11 .96 11.79	12.16 11.77	12. 11 11.76	11 .96 11 .87
	MnO	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.2
	MgO	10. 10	10.89	10. 8	10. 11	10.72	10. 13	9.99	10.13	10.21
	CaO	10.04	11.35	10.25	10.33	10.31	10.32	10.14	10.29	10.26
	a, O	3.03	2.60	2.49	2.76	2.60	2.99	2.84	2.96	2.73
	K, O	2.15	1.52	1.79	2.02	1.96	2. 12	2.11	1.98	2.06
	P,O ,	0.56	0.39	0.47	0.59	0.54	0.58	0.60	0.57	0.57
	LOI (%)	0.07	0.40	0.72	0.43	0.32	0.40	0.37	0. 16	0.41
	Total Mg# •	9 .95 0.69	99. 1 0.72	99.64 0.71	99.7 0.69	9 .89 0.70	99.66 0.69	99 .10 U.O::t	9 .92 0.69	99.27 0.69
	Ti	13066	11621	12460	12736	12616	13120	12796	12598	12 32
	K	17893	12650	14897	168 11	16312	17643	17560	16478	17144
	Li	8.2	5.8	6.2	7.3	7. 1	7.2	7.4	7.2	6.9
	Be	1.6	1.1	1.3	1.4	1.3	1.5	1.5	1.4	1.4
	Sc v	28.22 215	35.49 237	29.48 214	27.56 202	28 .29 204	28.15 207	27 .55 205	27.40 202	27.48 201
	Cr	321	515	341	302	324	310	305	315	309
	Co	62.3	56.5	57.5	58.0	59.7	57 .0	60.0	58.5	57.
		i	207	202	190	196	205	193	199	197	191
	Cu	66.6	50.0	54.1	60.3	58 . 1	62.1	62.6	59.6	55 .6
	Zn	Il	99	107	109	108	109	112	108	107
	Ga	19.5	16.9	1 .2	19.3	1 .5	19.2	19.8	19.0	1
	Ge	1.6	1.5	1.5	1.5	1.5	1.5	1.5	1.5	1.5
	Rb	169	74	86	153	148	155	153	142	147
	y	r	57 22.8	632 21.9	732 22.0	46 22.2	787 21.4	Il 22.6	862 23 .0	38 21.9	821 22.0
	Zr	212	186	208	203	195	209	20	196	200
		b	69. 1	55.7	65 .2	65 .	62.9	67.5	67.6	62.7	63 .2
	Cs	1.1	0.8	1.0	1.3	1.2	1.4	1.2	1.1	1.1
	Ba	806	572	678	765	728	775	783	739	733
	La	46.2	33 .3	38.7	45.3	41.5	45 . 1	48.2	44. 1	43 .7
	Ce	84.7	64.0	71.4	83 .4	77.0	83 .3	88. 1	81.0	80.9
	Pr	.9	7.3	. 1	8.7	.1	8.7	9.1	.5	.5
		d	35. 1	30.6	32.9	34.2	32.2	34.7	35.8	33.5	33 .6
	Sm	7.6	6.7	7.0	7.4	7.1	7.4	7.7	7.2	7.2
	Eu	2.5	2.2	2.3	2.4	2.3	2.5	2.5	2.4	2.4
	Gd	6.6

Table 6 -

 6 2EPMA and FTIR data for the CPX phenocrysts of the Fujian basalts.

	Sample No.	MX-1
	Section No.	6
	Point No.	1	4	5	6	7	8	9	10
	SiO 2	50.55	48.73	47.07	48.86	46.71	47.13	46.65	46.23
	TiO 2	1.88	2.20	3.02	2.03	2.86	2.83	3.11	3.06
	Al 2 O3	3.53	4.33	5.09	4.75	5.39	6.10	5.35	6.48
	Cr 2 O3	0.19	0.18	0.00	0.00	0.13	0.23	0.00	0.28
	FeO	5.80	5.89	7.24	6.91	6.76	6.63	6.75	6.39
	MnO	0.05	0.07	0.07	0.08	0.02	0.05	0.08	0.06
	MgO	14.31	13.74	12.51	13.52	12.91	12.67	12.76	12.49
	CaO	23.43	23.40	23.37	22.93	23.23	23.35	23.38	23.37
	Na 2 O	0.38	0.37	0.36	0.62	0.69	0.49	0.45	0.54
	K 2 O	0.01	0.00	0.01	0.01	0.05	0.00	0.00	0.00
	NiO	0.00	0.00	0.06	0.02	0.00	0.00	0.02	0.03
	Total	100.12	98.91	98.80	99.73	98.73	99.46	98.55	98.94
	Si	1.87	1.83	1.79	1.83	1.77	1.77	1.78	1.75
	Ti	0.05	0.06	0.09	0.06	0.08	0.08	0.09	0.09
	Al	0.15	0.19	0.23	0.21	0.24	0.27	0.24	0.29
	Cr	0.01	0.01	0.00	0.00	0.00	0.01	0.00	0.01
	Fe	0.18	0.19	0.23	0.22	0.21	0.21	0.21	0.20
	Mn	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
	Mg	0.79	0.77	0.71	0.75	0.73	0.71	0.72	0.71
	Ca	0.93	0.94	0.95	0.92	0.95	0.94	0.95	0.95
	Na	0.03	0.03	0.03	0.04	0.05	0.04	0.03	0.04
	K	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
	Ni	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
	Total	4.01	4.02	4.02	4.03	4.05	4.03	4.03	4.03
	Mg#	81.47	80.62	75.50	77.71	77.29	77.33	77.12	77.70
	D (cpx-melt) H2O	0.0137	0.0173	0.0229	0.0183	0.0251	0.0256	0.0249	0.0294
	Absorbance of cpx (cm -1 )	1.3	1.1	0.8	0.8	2.6	0.8	1.1	0.7
	Thickness of cpx (0.001mm)	63	83	77	73	71	72	77	76
	Absorbance
	normalized to 1	206	133	104	110	366	117	143	92
	cm (cm -1 )
	H 2 O-cpx (ppm)	87	56	44	46	155	49	60	39
	H 2 O-melt (wt%)	0.64	0.32	0.19	0.25	0.62	0.19	0.24	0.13

Table 6 -

 6 3 Lithium isotope and content ofCPX phenocrysts and xenocry tin the Fujian basalts.

	ample o.	Anlysi o.	Account 7 Li/PI

  Li l) Lie..

			cps(7)/nNL 1 iof standard li LisiMS	error		SlopM• Li	Li content	error
		7.66E+ I2	1.64E+ I2	21.4	0.8	S2.0	1.06	4.7	0.6
		5.03 E+ 12		20.2	1.5	80.9	1.06	3.1	0.7
		5.41 E+ 12		19.S	1.3	79.5	1.06	3.3	0.9
		6.51E+ 12		21.5	1.5	81.0	1.06	4.0	0.9
		6.70 E+ 12		20.4	1.4	79.2	1.06	4.1	o.
		6.92E+ 12		19.8	1.3	81.9	1.06	4.2	O.S
		S.I9E+ I2		19.5	1.8	82.5	1.06	5.0
		7.22 E+ I2		19.2	1.1	81.5	1.06	4.4
		S.36E+ 12		20.7	1.9	0.6	1.06	5.1
		6.59E+ I2		21.5	1.0	S2.7	1.06	4.0
		4.95 E+ I2		27.4	1.4 S3.0	1.06	3.0	0.6
		5.96E+ I2		26.7	2.0 83.0	1.06	3.6	0.7
		4.96 E+ 12		24.4	1.3 S3.0	1.06	3.0	0.6
		5.25E+ I2		26.0	1.1 83.0	1.06	3.2	0.6
		6.96E+ 12		29. 1	O. 7 79.	1.06	4.2	o.s
		7.5 E+ l2		28.7	0.6	1.3	1.06	4.6	0.9
		1.16E+ 13		27.7	0.3 S3.0	1.06	7.1	1.4
		6.47E+ 12		26. 1	0.8 87.	1.06	3.9	0.8
		2.10E+ I3		27.9	0.4 8 .9	1.06	12.8	2.6
		5.86E+ I3		24.9	0.3 89.6	1.06	35.7	7.1
		3. E+ l3		29.9	0.3	9.	1.06	23.4	4.7
		3.07E+ 13		28.6	0.4 8S.9	1.06	18.7	3.7
		8.75E+12		28.8	0.6 85.7	1.06	5.3	1.1
		1.0 E+ l3		24.9	0.5 84.9	1.06	6.6	1.3
		9.S5E+ 12		24.2	0.6 79.2	1.06	6.0	1.2
		4.0 E+ 13		31.8	0.4 79.	1.06	24.	5.0
		3.57E+ I3		36.7	0.3 79.S	1.06	21.S	4.4
		4.92E+ I3		33.3	0.5 79.8	1.06	29.9	6.0
		4.62E+ I3		30.0	0.4 79.	1.06	2 .1	5.6
		6.62E+ I2		28.8	0.5 80.9	1.06	4.0	0.8
		5.96E+ 12		29.2	0.6 80.9	1.06	3.6	0.7
		9.46E+ I2		25.3	1.4 S0.9	1.06	5.8	1.2
		6.43E+ 12		27.6	0.7 80.9	1.06	3.9	0.8
		1.15E+ 13		26.2	1.4 76.	1.06	7.0	1.4
		5.39E+ I2		24.8	0.9 75.1	1.06	3.3	0.7
		5.40 E+ I2		28.6	1.3 74.9	1.06	3.3	0.7
		6.46 E+ 12		27.0	1.0 78.4	1.06	3.9	0.8
		7.06E+12		24.0	1.2 80.0	1.06	4.3	0.9
		5.31 E+ 12		25.3	1.3 7S.4	1.06	3.2	0.6
	IIMX-B-1-3-7 5-11-7a@ l	7.19E+ I2		21.7	1.4 82.2	1.06	4.4
	5-l l-7a 2	7.3 E+ 12		21. 1	1.0 79.2	1.06
	5-l l-7a 3	6.47E+ 12		22.5	1.1	78. 1	1.06
	1	4.56E+ I3		15.8	0.8 90.7	1.06
		4.96E+ 13		16.9	0.8 90.7	1.06
		4.91E+ 13		15.9	0. 8 91.2	1.06
		4. 9E+13		17.0	0.8 90.	1.06
		5.27E+ 13		15.9	1.4 91.2	1.06
	IIMX-B-1 -3-2 5-I0-2b@ l	S.I4E+ I2		24.3	1.1	77.3	1.06
	5-I0-2b	6.09E+ 12		23. 1	1.4 77.6	1.06
	5-10-2b@3	7.91E+ 12		23. 1	0.8 7 .9	1.06
	5-10-2b@4	7.06E+ 12		24.1	1.6 78.8	1.06
	5-10-2b	7.35E+ 12		22.4	1.5 79.2	1.06
	5-10-2b	7.56E+ I2		23.9	1.0 79.5	1.06
	5-1 0-2b	6.50E+ 12		21.9	1.1 79.5	1.06

1 Mg# r interceptMg.

Table 7

 7

	-2. The

Table 7 - 1

 71 The data of Major and trace elements comeo ition are from Zou et al. ~20 102Major element compositions and the H 2 O content of cpx phenocrysts for the Hainan basalts.

	Location

Table 7 - 3

 73

Table 7 -

 7 4 Oxygen isOtopie ratios of epx phcnoerysts for the Hainan ba.~lts.

				crror Mg#		intcrccptM 1 • u () 7 Li..,.	Li content	crror
	1.68E-08 3.62E+{)4 1.72E+ 12	32.4	1.1	83.7	1.18	-71.7	5.4	0.8	0.2
	1.64E-O	4.96E+{)4	25.9	0.9	3.7			-1.1	0.6	0.
	1.55E-O	8.57E+{)4	31.2	1.1	83.7			4.2	0.3	0.
	1.43E-O	3.14E+{)4	41.1	1.2 83.7			14.1	0.8	0.2
	1.36E-O	8. 2E+{)4	2 .6	o.	3.7			1.6	0.3	0.
	1.30E-O	7.63E+{)4	28.6	0.9 84.4			0.7	0.3	0.
	1.24E-0	2.66E+{)4	36.2	1.0	4.4			.2	o.	0.2
	1.26E-O	4.94E+{)4	29.0	1.0 84.4			1.0	0.4	0.1
	1.29E-08 9.31 E+{)4	23.8	1.1	84.4			-4. 1	0.2	0.0
	1.09E-O	2.1 E+{)4	36.9	1.5	4.4			9.0	0.9	0.2
										0.0
	1.09E-O	1.9 E+{)4	34.8	1.6 82.3			9.3	0.9	0.2
	1.09E-O	2.06E+{)4	25.6	1.5 82.3			0.2	0.9	0.2
	1.1 OE-0	1.76E+{)4	48 .1	1.9 82.3			22.7	1.1	0.2
	1.09E-O	1.42E+{)4	47.9	1.6 82.3			22.4	1.3	0.3
	1.05E-O	2.52E+{)4	26.9	1.	82.3			1.5	0.7	0.
										0.0
	8.41 E-09 1.83E+{)4	44.4	1.7 80.7			20.8	0.8	0.2
	.33E-09	1.61 +{)4	27.1	1.2	0.7			3.5	0.9	0.2
	8.49E-09 1.41 E+{)4	44.3	2.0 80.7			20.8	1.0	0.2
	.66E-09 1.54E+{)4	39.	2.0	0.7			16.2	1.0	0.2
	8.82E-09 8. 17 E+{)4	32.6	2. 1	0.7			9. 1	0.2	0.0
										0.0
	8.76E-09 3.03E+{)4	48.8	1.6 82.5			23.2	0.5	0.
										0.0
	1.16E-08 4.52E+{)4	59.9	1.1				35.1	0.4	0.
	1.16E-O	4.94E+{)4	48.6	1.2				23.	0.4	0.1
	1.18E-O	4.79E+{)4	40.	2.9				15.9	0.4	0.
	1.21 E-0	4.69E+{)4	44.8	1.2 81.8			20.0	0.4	0.1
	1.23E-O	6.37E+{)4	50.2	1.2	1.			25.3	0.3	0.
										0.0
	1.37E-O	7.14E+{)4	44.5	1.1	78.1			19.7	0.3	0.1
	1.39E-08 5.16E+{)4	43.7	1.1	78.1			18.	0.5	0.
	1.41 E-0	6.3 E+{)4	39. 1	o. 7 .1			14.2	0.4	0.1
										0.0
	1.42E-O	3.22E+{)4	50.6	1.7 79.0			25.	0.8	0.2
	1.42E-O	1.5 E+{)4	76.3	2.3 79.0			51.5	1.5	0.3
	1.43E-O	2.42E+{)4	29.6	1.3 79.0			4.7	1.0	0.2
	1.42E-O	2.33E+{)4	32.9	1.4 79.0			.0	1.0	0.2
	1.42E-O	2.10 +{)4	41.0	1.3 79.0			16.2	1.2	0.2
	1.41 E-0	3.21 E+{)4	43.3	1.2 82.2			18.4	0.8	0.2
	1.40E-O	2. 5E+{)4	22.5	1.3	2.2			-2.3	O.	0.2
	1.38E-O	2.34E+{)4	3 .4	1.4	1.4			13.6	1.0	0.2
	1.36E-O	2.1 E+{)4	33.	1.4 81.4			9.0	1.1	0.2
	1.39E-O	1.64E+{)4	53.6	2.3 8 1.4			2 .	1.5	0.3
			36.7	1.2 81.4			11.9	1.1	0.2
			42.9	1.5	1.4			1 .1	1.0	0.2

  variations of Sr/Ca and Mg/Ca, we examined the carbonate compositions ofvarious bedrocks (silicate and carbonate rocks) and sediments ( eolian and fluvial sediments, sand, and topsoil) found in the NE Tibetan Plateau (TP) region. A combined carbonate composition dataset based on our results and other reported data

	ABSTRACT
	Using co-
	L Introduction
	•	SCIENCE CHINA PRESS

? 1994-2016 Ch ma Academie Journal f<.lcctronic Puhltshmg Il ouse. Ail rights rcscrvcd. http: \\\\\\.en kt. net

•

  Correspooding author. Tel.: + 86 5513607008: fax: + 86 551 3607656. E-mail address: qkxia@ustc.edllcn ( Q-K. Xia). 1342-937XJ$-see front matter © 2012 International Association for Gon<lwana Research. Published by Elsevier B.V. Ali rights reserved.

	water
	clinopyroxene phenocrys[
	basait
	lithospheric man[le
	Nonh China Cramn
	doi:10.1016/j.gr.2012.01 .010

  Corresponding aurhor at No. 96, jin>hai Road, 230026. Hefei, Anhui. PR China. Tel.: + 86 551 3607008: fax: + 86 551 3607386. E-mail address: qkxia@ustc.edllcn ( Q Xia). 0024-4937/$ -see front matter C> 2012 Elsevier B. V. Ali righrs reserved . doi :10.1 016/j.l irhos.2012.03.013

Li values. The data are from: seawater[START_REF] Chan | Variation of lithium isotope composition in the marine environment: a preliminary report[END_REF][START_REF] You | Precise determination of lithium isotopic composition in low concentration natural samples[END_REF], river water(Huh et al., 1998[START_REF] Huh | Lithium isotopes as a probe of weathering processes: Orinoco River[END_REF][START_REF] Millot | Behaviour of lithium and its isotopes during weathering in the Mackenzie Basin, Canada[END_REF][START_REF] Dellinger | Riverine Li isotope fractionation in the Amazon River basin controlled by the weathering regimes[END_REF], arc lavas[START_REF] Moriguti | Across-arc variation of Li-isotopes in lavas and implications for crust /mantle recycling at subduction zones[END_REF][START_REF] Tomascak | The control of lithium budgets in island arcs[END_REF] Chan et al., 2002a; Agostini et a., 2008; Košler et al., 2009), Fresh N-MORB[START_REF] Tomascak | Lithium isotopes in global mid-ocean ridge basalts[END_REF], OIB[START_REF] Tomascak | The absence of lithium isotope fractionation during basalt differentiation: new measurements by multicollector sector ICP-MS[END_REF][START_REF] Chan | Lithium isotope geochemistry of the Hawaiian plume: results from the Hawaii Scientific Drilling Project and Koolau volcano[END_REF][START_REF] Kobayashi | Lithium, boron, and lead isotope systematics of glass inclusions in olivines from Hawaiian lavas: evidence for recycled components in the Hawaiian plume[END_REF][START_REF] Ryan | Lithium abundance and lithium isotope variations in mantle sources: insights from intraplate volcanic rocks from Ross Island and Marie Byrd Land (Antarctica) and other oceanic islands[END_REF][START_REF] Nishio | Lithium, strontium, and neodymium isotopic compositions of oceanic island basalts in the Polynesian region: constraints on a Polynesian HIMU origin[END_REF][START_REF] Jeffcoate | Li isotope fractionation in peridotites and mafic melts[END_REF][START_REF] Chan | Lithium isotope systematics of lavas from the Cook-Austral Islands: constraints on the origin of HIMU mantle[END_REF], altered oceanic crust[START_REF] Chan | Lithium isotopic composition of submarine basalts: implications for the lithium cycle in the oceans[END_REF](Chan et al., , 2002b)), marine sediments[START_REF] Chan | Lithium isotope geochemistry of sediments and hydrothermal fluids of the Guaymas Basin, Gulf of California[END_REF][START_REF] Chan | Lithium isotopic composition of marine sediments[END_REF][START_REF] Chan | Lithium isotopic compositions of pore fluids and sediments in the costa rica subduction zone: implications for fluid processes and sediment contribution to the arc volcanoes[END_REF][START_REF] Bouman | Lithium inputs to subduction zones[END_REF], upper continental crust[START_REF] Teng | Lithium isotope composition and concentration of the upper continental crust[END_REF], lower continental crust[START_REF] Teng | Lithium isotopic composition and concentration of the deep continental crust[END_REF], normal upper mantle[START_REF] Von Strandmann | Variations of Li and Mg isotope ratios in bulk chondrites and mantle xenoliths[END_REF], eclogite[START_REF] Zack | Extremely light Li in orogenic eclogites: the role of isotope fractionation during dehydration in subducted oceanic crust[END_REF][START_REF] Marschall | The lithium isotopic composition of orogenic eclogites and deep subducted slabs[END_REF][START_REF] Penniston-Dorland | Lithium isotopes as a tracer of fluids in a subduction zone mélange: Franciscan Complex, CA[END_REF].

), which is

times the integral area of unpolarized absorption[START_REF] Kovacs | Quantitative absorbance spectroscopy with unpolarized light: Part II. Experimental evaluation and development of a protocol for quantitative analysis of mineral IR spectra[END_REF][START_REF] Sambridge | Quantitative absorbance spectroscopy with unpolarized light: Part I. Physical and mathematical development[END_REF], I is the integral specific absorption coefficient (7.09 ppm -1 cm - 2[START_REF] Bell | Quantitative analysis of trace OH in garnet and pyroxenes[END_REF]), and t is the sample thickness (cm). Analytical uncertainty in the H2O content of a single cpx phenocryst is less than 50%(Liu et al., 2015; Xia et al., 2013).Picture of the Nicolet 5700 FTIR spectrometer coupled with a microscope, located at USTC

Acknowledgements I Acknowledgements II Yu, Piaoyi Wang, and Hui Chen.

Finally yet most importantly, I would like to give my unfeignedly gratitude to my parents for their kindness in raising and educating me. I also would like to thank my wife, who always supports me and tolerates my defects.

Chapter 4

The correlation between the Mg# raw data vs. IMF for Lithium isotope in each session.

The correlation between mean Mg# vs. IMF for Lithium isotope in each session.

Such linear fitting requires the precisely known Li isotopic and chemical

Chapter 4

The correlation between mean Si (afu) vs. IMF for Lithium isotope in each session.

The correlation between mean Cr (afu) vs. IMF for Lithium isotope in each session.

Chapter 4

The correlation between mean Ti (afu) vs. IMF for Lithium isotope in each session.

The correlation between mean Al (afu) vs. IMF for Lithium isotope in each session.

Chemical and isotopic composition of cpx phenocrysts

Major elements of cpx phenocrysts

The cpx phenocrysts in the Fujian samples range from the augitic to the diopsidic, with Mg# varying from less than 70 to higher than 84, which are [68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83]in SH,MX and BL,respectively. Most of the SH cpx phenocrysts have homogenous composition from core and rim, and the difference of Mg# in the same cpx phenocryst usually are less than 3 (Table 3). Some MX cpx phenocrysts have the xenocryst core inside the phenocryst rim. The MX cpx phenocrysts mostly are homogenous, while very few zonation are observed in a few MX cpx phenocrysts basalts showing relative high difference of Mg# between core and rim, which can be as high as 7, despite the xenocryst core. The BL cpx phenocrysts usually have growth zoning and show a relatively high difference between core and rim, ranging from 2 to 7, mostly about 5.

The cpx phenocrysts show relatively low Cr2O3 and lower Mg#, in common, which are distinct from those of the cpx xenocrysts. The detailed cpx phenocryst major element compositions are listed in Table 6-2. (a) Representative OH IR absorption spectrum of the Fujian cpx phenocrysts.

Water content of cpx phenocrysts and equilibrated melts

The cpx phenocrysts of the Fujian samples have OH-typical IR absorption spectra in its stretching vibration region (3000-3800 cm -1 ), and their IR bands are centered at 3630 cm -1 and 3540 cm -1 (Fig. 6-5), which consist with typical structural OH bands of cpx in previous studies [START_REF] Bell | Quantitative analysis of trace OH in garnet and pyroxenes[END_REF][START_REF] Denis | Evidence of dehydration in peridotites from Eifel Volcanic Field and estimates of the rate of magma ascent[END_REF][START_REF] Ingrin | Hydrogen in nominally anhydrous upper-mantle minerals: concentration levels and implications[END_REF][START_REF] Kovacs | An Experimental Study of Water in Nominally Anhydrous Minerals in the Upper Mantle near the Water-saturated Solidus[END_REF][START_REF] Li | Water contents in mantle xenoliths from the Colorado Plateau and vicinity: Implications for the mantle rheology and hydration-induced thinning of continental lithosphere[END_REF][START_REF] Peslier | Low water contents in pyroxenes from spinelperidotites of the oxidized, sub-arc mantle wedge[END_REF][START_REF] Skogby | Hydroxide in pyroxene: Variations in the natural-environment[END_REF][START_REF] Sundvall | Water in upper mantle pyroxene megacrysts and xenocrysts: A survey study[END_REF][START_REF] Xia | Low water content of the Cenozoic lithospheric mantle beneath the eastern part of the North China Craton[END_REF]Xia et al., 2013;[START_REF] Xia | Early Paleozoic crust-mantle interaction and lithosphere delamination in South China Block: Evidence from geochronology, References geochemistry, and Sr-Nd-Hf isotopes of granites[END_REF]. The H2O contents of the cpx phenocrysts for the MX samples range from 20 to 174 ppm, those of the SH samples range from 410 to 1079 ppm, and those of the BL samples range from 101 to 462 ppm. The detailed major element contents, absorbance of OH bands, section thicknesses, and the calculated H2O content of the cpx phenocrysts are listed in Table 6-2. Some xenocrysts in the MX basalts have more enriched water contents (from 128 to 221 ppm) than those of the cpx phenocrysts, their IR absorption spectra are shown in Fig. 6-6, which fall within the range of cpx water content from the MX xenoliths (from 118 to 488 ppm) reported by [START_REF] Yu | H2O contents and their modification in the Cenozoic subcontinental lithospheric mantle beneath the Cathaysia block, SE China[END_REF].

The partition coefficient (D cpx-melt ) of H2O between cpx phenocryst and basaltic melt can be calculated using the equation provided by O'Leary (2010) O'Leary et al.

(2010) which depend on cpx phenocryst chemistry. Therefore, the H2O content of a corresponding equilibrated melts for each cpx phenocryst can be deduced from its H2O content and its corresponding partition coefficient (D cpx-melt ) of H2O between cpx phenocryst and basaltic melt. The preliminary results of the H2O content of corresponding equilibrated basaltic melts range from less than 0.1% upto 1.2% for the MX samples, from 2.4% to 5.5% for the SH samples and from 1.7% to 4.0% for the BL samples. The detailed calculated data of water content for cpx grains and corresponding equilibrated basaltic melts are presented in Table 6-2. Chapter 6 CaO/Al2O3 with Mg# decrease [START_REF] Spath | Plume-lithosphere interaction and the origin of continental rift-related alkaline volcanism -the Chyulu Hills Volcanic Province, southern Kenya[END_REF]. In the plot of CaO/Al2O3 vs. Mg# (Fig. 6-11c), such a clear trend are found in the BL diabases, and the weaker trend in the NTS, MX and SH is noticed. It suggests the fractional crystallization of cpx is limited in SH and NTS samples and certain proportion of cpx fractional crystallization occurred in BL diabases. Because of potential xenocryst assimilation in some MX samples, it is hard to make sure that such disorder CaO/Al2O3 vs. Mg# in the MX samples is caused by either the xenocryst assimilation together with fractional crystallization of cpx or no fractional crystallization of cpx. The Cr in cpx phenocrysts ranging from 0 to 0.6% with an average of about 0.15% (1500 ppm) is higher than the Cr content in basaltic rocks, and the CaO is about 20%. When the basaltic rocks have undergone significant fractional crystallization of cpx, they will exhibit a positive trend in the plot of Cr vs. CaO. All the MX samples have high CaO content, suggesting the cpx fractional crystallization is insignificant. In addition, positive Ba and Eu anomalies of all the Fujian basalts (Fig. 6-3) exclude a significant fractional crystallization of pl.

In no case, the ratios of incompatible trace elements and Sr-Nd-Pb isotope are not sensitive to fractional crystallization of ol even cpx and the assimilation of peridotite, due to the relative low trace elements contents in conglomerates and peridotites to basaltic magma.

Chapter 6 re-equilibrium and later Li diffusion after crystallization. Distribution of measured water contents for clinopyroxene crystals from this study before and after thermal annealing at 1 atm and under pressure modified from Fig. 3 and Table 4 in [START_REF] Weis | Experimental hydration of natural volcanic clinopyroxene phenocrysts under hydrothermal pressures (0.5-3 kbar)[END_REF]. Error bars represent the 20% uncertainty in the FTIR analysis.

Chapter 6 6-2). The high EuN/Eu* and Srn/Sr* (Fig. 6-16d), high Zr, Hf, and Ti all suggest original fsp-rutile-zircon-sphene-like component melting. These component in Fig. 6-16b andc suggest that the NTS samples share the similar source lithology to other Fujian basalts, but the unlike source trace elements compositions in the source. The NTS melts generated are dominantly from the earlier melting residue of lower oceanic crust and some recycled sediments, accounting for their relatively high Eu/Eu*, Srn/Sr* and more enrichment radiogenic isotopic data.

Plots of Zr/Hf vs. 143 Nd/ 144 Nd for the Fujian basalts.

Implications for the mantle source

Two candidates are considered to reserve the enrichments: one is the metasomatic lithosphere/asthenosphere by upwelling melts generated from disappeared recycled oceanic slabs, another is the odd "pudding"-like fragments distributed in upper mantle separated from disappeared recycled oceanic slabs. The metasomatic lithosphere were involved to explain the genesis of some Cenozoic basalts in the NCC and in the Guangdong region (Xu et al. 2012b;[START_REF] Huang | Geochronology and geochemistry of Cenozoic basalts from eastern Guangdong, SE China: constraints on the lithosphere evolution beneath the northern margin of the South China Sea[END_REF]. Due to the large number of high δ 18 O cpx phenocrysts, it is too hard to image the large-scale lithospheric rock replacement by limited recycled melts, otherwise the high δ 18 O anomalies usually are buffered by large volume of ambient lithosphere rocks. The pudding-like fragments distributed in upper mantle from disappeared recycled oceanic slabs are more like to serve as the enrichment source. In fact, it is hard to identify exactly from which subducted slab the enrichment was divided. Because of the moderate radiogenic Sr-Nd-

Water content of cpx phenocrysts

The cpx phenocrysts of the Hainan samples have OH-typical IR absorption spectra in its stretching vibration region (3000-3800 cm -1 ), and their IR bands are centered at 3630 cm -1 and 3540 cm -1 (Fig. 7-3), which consist with typical structural OH bands of Chapter 7 cpx in previous studies [START_REF] Bell | Quantitative analysis of trace OH in garnet and pyroxenes[END_REF][START_REF] Denis | Evidence of dehydration in peridotites from Eifel Volcanic Field and estimates of the rate of magma ascent[END_REF][START_REF] Ingrin | Hydrogen in nominally anhydrous upper-mantle minerals: concentration levels and implications[END_REF][START_REF] Kovacs | An Experimental Study of Water in Nominally Anhydrous Minerals in the Upper Mantle near the Water-saturated Solidus[END_REF][START_REF] Li | Water contents in mantle xenoliths from the Colorado Plateau and vicinity: Implications for the mantle rheology and hydration-induced thinning of continental lithosphere[END_REF][START_REF] Peslier | Low water contents in pyroxenes from spinelperidotites of the oxidized, sub-arc mantle wedge[END_REF][START_REF] Skogby | Hydroxide in pyroxene: Variations in the natural-environment[END_REF][START_REF] Sundvall | Water in upper mantle pyroxene megacrysts and xenocrysts: A survey study[END_REF][START_REF] Xia | Low water content of the Cenozoic lithospheric mantle beneath the eastern part of the North China Craton[END_REF]Xia et al., 2013;[START_REF] Xia | Early Paleozoic crust-mantle interaction and lithosphere delamination in South China Block: Evidence from geochronology, References geochemistry, and Sr-Nd-Hf isotopes of granites[END_REF]. The ML, LH, and SJY basalts except HN9910 have almost totally dry cpx phenocrysts (Fig. 7-3a). The typical structural OH bands of HN9910, DY, and FJT samples are presented in Fig. 7-3b, c, and d, respectively. The H2O contents of the cpx phenocrysts for the HN9910 samples range from 174 to 850 ppm, those of the DY-4 and DY-7 samples range from 36 to 588 ppm, and those of the FJT samples range from 28 to 321 ppm. Other DY and FJT samples failed to provide measurable cpx phenocryst. The detailed major element contents, absorbance of OH bands, section thicknesses, and the calculated H2O content of the cpx phenocrysts are listed in Table 7-2. The -OH profiles in the FJT cpx phenocrysts display various absorbance from the core to the rim, as shown in Fig. 7-3d.

The xenocryst core have higher water contents than those in the phenocryst rim, while the phenocryst also can be observed slight H-loss from the core the rim in FJT-6-1-5 grain. The suspected crust xenocryst with very low Mg# has different -OH absorption spectrum among different measured point in one grain.

Li and O isotopic compositions of cpx phenocrysts

The Li and O isotope of cpx phenocrysts are analyzed for the LH samples, with associated chemical composition matrix effect, as we discussed in Chapter 6.

The matrix effect in the Li analysis through SIMS with various cpx element composition are similar as the discussion in Chapter 6. The slopes of δ 7 Li IMF line to Mg# for cpx phenocrysts are approximately 1.18 on IMS 1270. All the number of the measured samples are listed and presented in the Table 7-3. The IMF has been discussed in detail in the Chapter 4 and Chapter 6. The corrected δ 7 Li values of the LH cpx phenocrysts range from -4 to +5.1‰, and Li content range from 0.2 to 1.5 ppm. The intra-granular Li content and δ 7 Li profiles of the cpx phenocrysts are displayed in Fig. 7-4a. The Li content and δ 7 Li vs. Mg# for the cpx phenocrysts are plotted in Fig. 7-4b.

The detailed intra-granular profiles of these cpx phenocrysts are complex and can be divided into multiple kinds (Fig. 7-4a): a) some cpx phenocrysts display "V"-like δ 7 Li, but almost homogeneous Li content. The lightest 7 Li are found in the core of phenocrysts; b) some cpx phenocrysts have "W"-like δ 7 Li, and corresponding Li content variation. The lightest 7 Li are found in the mantle of phenocrysts, while the core of phenocryst have the heaviest 7 Li; c) some cpx phenocrysts have "M"-like δ 7 Li, and Chapter 7

Discussions

A large number of studies have been conducted on the Hainan Island basalts in the past, because of the suspicion of the mantle plume beneath the Hainan Island (Fig. 1

Crust contamination and fractional crystallization

The continental crust contamination may potentially effect the chemical

Water contents of the Hainan basalts

All the LH, ML, and SJY cpx phenocrysts are totally "dry" (Fig. 7

The abnormal Oxygen isotope in Hainan basalts.

The Haina cpx phenocrysts with the high δ 18 O values can provide insights into the mixture within the magma system. The δ 18 O values in the ML, LH, DY, and FJT cpx phenocrysts are considerably higher than the expected typical mantle values (e.g., [START_REF] Sheppard | Hydrogen and oxygen isotope geochemistry of Ascension Island lavas and granites: variation with crystal fractionation and interaction with seawater[END_REF][START_REF] Hoefs | Stable Isotopes[END_REF][START_REF] Bindeman | Oxygen isotopes in mantle and crustal magmas as revealed by single crystal analysis[END_REF]; the δ 18 O values of average Chapter 7

Indian Ocean type MORBs is about +5.7±0.2‰ [START_REF] Ito | The O, Sr, Nd and Pb isotope geochemistry of MORB[END_REF], while mafic arc melts have δ 18 O from +5.2 to +6.2‰ [START_REF] Eiler | Oxygen isotope geochemistry of oceanic arc lavas[END_REF], if the difference between mineral and magma follow ΔO cpx-melt = -0.1‰, as suggested in Chapter 6. The ML, LH, DY, and FJT cpx phenocryst δ 18 O values are similar to the values previously reported by Liu et al. (2016) in the NCC Mesozoic basalts and the Merapi basalts (+5.1 to +7.2‰) reported by [START_REF] Gertisser | Trace element and Sr, Nd, Pb and O isotope variations in medium-K and high-K volcanic rocks from Merapi Volcano, Central Java, Indonesia: evidence for the involvement of subducted sediments in Sunda Arc magma genesis[END_REF]. [START_REF] Gertisser | Trace element and Sr, Nd, Pb and O isotope variations in medium-K and high-K volcanic rocks from Merapi Volcano, Central Java, Indonesia: evidence for the involvement of subducted sediments in Sunda Arc magma genesis[END_REF] and [START_REF] Troll | Magmatic differentiation processes at Merapi Volcano: inclusion petrology and oxygen isotopes[END_REF] suggested the high δ 18 O values in Merapi cpx phenocrysts are the results of the crustal contamination due to their relative low crystallization pressure and depth. However, the εNd and 230 Th excesses disagree with the significant crustal contamination during the magma upwelling [START_REF] Zou | U-Th isotopes in Hainan basalts: Implications for subasthenospheric origin of EM2 mantle endmember and the dynamics of melting beneath Hainan Island[END_REF]. The high δ 18 O values (high to +8.3‰ for cpx and +8.4‰ for the melting) cannot be the result of fractional crystallization but may be inherited from the recycled materials. If so, the δ 18 O of cpx phenocrysts would represent the recycled material derived magma. The high δ 18 O values but asthenosphere-like bulk rock geochemical composition suggest the involvement of recycled components occurred in their mantle source. However, four extreme δ 18 O values of cpx phenocrysts are observed in LH and FJT basalts (Fig. 7-4c). Two cpx with extremely high δ 18 O values have very low Mg# of 58, suggesting not phenocrysts but crustal crystals. The Two cpx with low δ 18 O values have normal Mg# of 79 and 83, therefore these two cpx may be the phenocrysts crystallized from basalts.

The recycled materials in Hainan basalts

The recovered water content for the Hainan basalts is 1.3-2.7 wt. % falling within the range of MORBs to IABs (Dixon et al., 2004), i.e. the ratios of H2O/Ce range from 215 to 350, almost similar to the MORBs H2O/Ce ratios. However, the Ba/Th, Ce/Pb and Nb/La of LH is about from 70 to 140, from 19 to 27, and from 1.3 to 2.2 (Fig. 7-5), respectively. The positive relationship in the plots of Ba/Th vs. Nb/La suggests the existence of recycled oceanic crust component (Fig. 7-5). The higher Nb/La ratios reveal the potential recycled oceanic crust material existence. However, the plots of H2O/Ce and Nb/La vs. Ba/Th imply the most Ba/Th enriched sample from FJT and DY involved recycled sediments component. The recycled sediment component may have undergone various dehydration. The MORB-like H2O/Ce ratios suggest the upwelling plume under the Hainan Island may be not a wet buoyancy plume, but a hot plume.

These observations also accord with the trace patterns in Fig. 7-2a. The LH samples mainly involved the recycled oceanic crust component, whereas the DY and FJT Chapter 7 samples require more recycled oceanic sediment component.

The comparison of δ 18 O of cpx with the bulk rock Nb/La ratios for the Hainan basalt samples. The modeled mixing are among the DMM [START_REF] Workman | Major and trace element composition of the depleted MORB mantle (DMM)[END_REF] and GLOSS [START_REF] Plank | The chemical composition of subducting sediment and its consequences for the crust and mantle[END_REF], partial melts of altered upper oceanic crust and altered lower oceanic crust [START_REF] Gregory | An oxygen isotope profile in a section of Cretaceous oceanic crust, Samail ophiolite, Oman: evidence for δ 18 O buffering of the oceans by deep (>5 km) seawater-hydrothermal circulation at mid-ocean ridges[END_REF]. The recycled material trace element composition are recalculated based on the mobility from Jonhson and [START_REF] Johnson | Dehydration and melting experiments constrain the fate of subducted sediments[END_REF] and [START_REF] Kessel | Trace element signature of subduction-zone fluids, melts and supercritical liquids at 120-180 km depth[END_REF].

The high δ 18 O values may be inherited from the recycled materials undergone low-T reaction, such as low temperature water-rock altered oceanic crust or the marine limestone. Wang et al. (2013) suggest the Hainan basalts may contain as much as 20%-40% recycled oceanic crust in its mantle source, also consistent with high δ 18 O data of Hainan samples (Fig. 7-6 [START_REF] Sengör | Evolution of the Altaid tectonic collage and Palaeozoic crustal growth in Eurasia[END_REF][START_REF] Windley | Delamination/thinning of subcontinental lithospheric mantle under Eastern China: the role of water and multiple subduction[END_REF], these subduction caught lots of ascent subducted oceanic sediments and these ascent sediments may stay and be kept • Regional heterogeneity in water content exists in Eastern China lithosphere

• Regional heterogeneity is related to distinct origins and geodynam c processes Supporting Information:

• Tables 515253• Text 51 Ali Rights Reserved.

HAO ET AL.

Regional heterogeneity in the water content of the Cenozoic lithospheric mantle of Eastern China

Yan-Tao Hao