Keywords: cisaillement ductile Fengning-Longhua, DNSZ: zone de cisaillement ductile Damiao-Niangniangmiao, UF: faille sans nom, JXT: chevauchement Jixian, MLYA: anticlinal Malanyu, XBCB: bassin de Xiabancheng, YZB: bassin de Yingzi, NDB:

I

Résumé étendu

). Depuis sa formation au Paléoprotérozoïque par le rassemblement des blocs « orientaux », « intermédiaires »

Chapter 1. General introduction 1.1. Background and scientific issues After its assembly through the collision of the Eastern, Intermediate (or Fuping), and Western blocks during the Paleoproterozoic (~1.8-1.9 Ga; [START_REF] Zhao | Thermal evolution of the Archean basement rocks from the eastern part of the North China Craton and its bearing on tectonic setting[END_REF]Zhao et al., , 2001;;[START_REF] Faure | Polyorogenic evolution of the Paleoproterozoic Trans-North China Belt, new insights from the in Lüliangshan-Hengshan-Wutaishan and Fuping massifs[END_REF][START_REF] Li | Mesozoic tectonics in the Eastern Block of the North China Craton: implications for subduction of the Pacific plate beneath the Eurasian plate[END_REF][START_REF] Li | Paleoproterozoic structural evolution of the southern segment of the Jiao-Liao-Ji Belt, North China Craton[END_REF][START_REF] Trap | Paleoproterozoic tectonic evolution of the Trans-North China Orogen: toward a comprehensive model[END_REF], the North China Craton formed a stable craton from Mesoproterozoic to Paleozoic. During the Cretaceous, the destruction of the craton or the large-scale lithosphere thinning occurred in the North China Craton. The thick (∼200 km) Archean lithosphere mantle beneath the eastern NCB was replaced by a thin (<80 km) juvenile one [START_REF] Fan | Destruction of aged lower lithosphere and accretion of asthenosphere mantle beneath eastern China[END_REF][START_REF] Griffin | Composition and thermal structure of the lithosphere beneath South Africa, Siberia and China: porton microprobe studies[END_REF][START_REF] Griffin | Phanerozoic evolution of the lithosphere subduction of the Paleo-Pacific Plate[END_REF][START_REF] Menzies | Palaeozoic and Cenozoic lithoprobe and the loss of >120km of Archean lithosphere, Sino-Korean craton, China. In Magmatic Processes and Plate Tectonic[END_REF][START_REF] Zhu | Timing of destruction of the North China craton[END_REF][START_REF] Wu | Destruction of the North China Craton in the Mesozoic[END_REF]. The destruction of the North China Craton has become a hot issue of international geoscientific research today and considerable progress has been made during the past two decades.

Before the destruction of the North China Craton in the Cretaceous, the North China Craton has undergone two orogenic cycles, including Paleozoic-Triassic continental collisions with Mongolian arc terranes and South China Block at block boundaries (Hacker et al., 2000;[START_REF] Mattauer | Tectonics of the Qinling belt: build-up and evolution of eastern Asia[END_REF][START_REF] Meng | Timing of collision of the North and South China blocks: controversy and reconciliation[END_REF][START_REF] Windley | Tectonic models for accretion of the Central Asian Orogenic Belt[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 | A tale of amalgamation of three Permo-Triassic collage systems in Central Asia: oroclines, sutures, and terminal accretion[END_REF][START_REF] Xu | Deformation characteristics and Tectonic evolution of the eastern Qinling orogenic belt[END_REF]B. Xu et al., 2013;Figure 1.1), and Jurassic-Early Cretaceous intracontinental orogeny (also called Yanshanian Orogeny, [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Dong | Late Jurassic-Early Cretaceous continental convergence and intracontinental orogenesis in East Asia: a synthesis of the Yanshan revolution[END_REF][START_REF] Faure | Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the NCC?[END_REF]Figure 1.1). Since the early 1900s, the Phanerozoic NCB has been studied from the standpoint of both structure and stratigraphy (e.g., [START_REF] Wong | The Mesozoic orogenic movement in eastern China[END_REF][START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF]. Especially in the Yinshan-Yanshan fold and thrust belt in the north, the alternating compressional and extensional deformations during the Mesozoic have been identified [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF]; [START_REF] Faure | Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the NCC?[END_REF][START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF]Figure 1.2). Although the destruction of the North China Craton occurred in the Cretaceous, this is controversial with various estimates as to the onset of destruction (Figure 1.3), i.e., Late Triassic (Han et al., 2004;[START_REF] Yang | Tracing magma mixing in granite genesis: in situ U-Pb dating and Hf-isotope analysis of zircons[END_REF]Yang et al., , 2010b[START_REF] Yang | Petrogenesis of silica-saturated and silica-undersaturated syenites in the northern North China Craton related to post-collisional and intraplate extension[END_REF], or Late Jurassic [START_REF] Gao | Recycling lower continental crust in the North China Craton[END_REF].

During the Late Triassic, the EW-trending alkaline intrusive complexes (e.g., nepheline syenite, quartz syenite, and A-type granite) and associated mafic rocks were widely developed along the northern NCB in an extensional setting [START_REF] Yang | Petrogenesis of silica-saturated and silica-undersaturated syenites in the northern North China Craton related to post-collisional and intraplate extension[END_REF][START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF]. Detrital zircon dating and sedimentological studies of the Late Triassic basin remnants showed a fining and deepening upward depositional system as well as abundant volcaniclastic rocks from the conformable Upper Triassic to Lower Jurassic strata, suggesting a Late Triassic extensional tectonic setting [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF]. A NE-SW trending regional extension in the northern NCB has been documented in the Sonid Zuoqi MCC in the vicinity of the Solonker zone [START_REF] Davis | Indosinian extension in the Solonker suture zone: the Sonid Zuoqi metamorphiccore complex, Inner Mongolia, China[END_REF]. During the Jurassic, two stages of magmatism have been identified, i.e., Early Jurassic-early Middle Jurassic and Early Jurassic (161-155 Ma) [START_REF] Zhu | Timing of destruction of the North China craton[END_REF][START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF]. During the Early Jurassic-early Middle Jurassic, the E-W trending extensional basins or normal faults were widely in the western NCB, e.g., the Ordos basin and its periphery [START_REF] Zhang | Changes of Late Mesozoic tectonic regimes around the Ordos Basin (North China) and their geodynamic implications[END_REF], the Daqingshan [START_REF] Darby | Paleozoic and Mesozoic tectonic evolution of central Asia: From continental assembly to intracontinental deformation[END_REF][START_REF] Ritts | Early Jurassic extensional basin formation in the Daqing Shan segment of the Yinshan belt, northern North China Block, Inner Mongolia[END_REF], and the Taihangshan (Li et al., 2015).

Meanwhile, the eruption of basalt (the Nadaling or Xinglonggou Formations) in the eastern NCB and the coal-bearing basins have been considered to occur in a backarc extensional setting [START_REF] Meng | Tectonic evolution of early Mesozoic sedimentary basins in the North China block[END_REF]Hao et al., 2020). During the early Late Jurassic, an early Late Jurassic extension was recorded by Kalaqin metamorphic core complex with top-to-the-NE shearing (156-150 Ma;[START_REF] Lin | Structural characteristics and formation mechanism of the Kalaqin metamorphic core complex in the Yanshan area, China (in Chinese)[END_REF], nearly N-S or NE trending Diaoe graben and Houcheng half-graben [START_REF] Qi | Mesozoic tectonic setting of rift basins in eastern North China and implications for destruction of the North China Craton[END_REF], Chengde graben (Davis et al., 2001), and Guojiadian half-graben [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF]. However, Late Triassic-Early Jurassic contractional tectonics was also proposed according to the unconformity between Triassic and Lower Jurassic strata, and Lower Jurassic syntectonic conglomerate [START_REF] Zhao | The Mesozoic orogenesis and tectonic evolution of the Yanshan area (in Chinese)[END_REF][START_REF] Liu | Rapid exhumation of basement rocks along the northern margin of the North China craton in the early Jurassic: Evidence from the Xiabancheng Basin, Yanshan Tectonic Belt[END_REF]. Therefore, the tectonic evolution of the NCB during early Mesozoic remains debated. Particularly, the extensional tectonics were almost documented in several basin remnants. The timing and duration of these extensional tectonics remain ambiguous (Figure 1.3).

Deciphering the interplay existing between tectonics and granitic pluton emplacement mechanisms is of fundamental importance for the understanding of the evolution of the continental crust (e.g., Bouchez & Gleizes, 1995;[START_REF] Gleizes | Variscan granites of the Pyrenees revisited: their role as syntectonic markers of the orogen[END_REF][START_REF] De Saint Blanquat | Multiscale magmatic cyclicity, duration of pluton construction, and the paradoxical relationship between tectonism and plutonism in continental arcs[END_REF][START_REF] Žák | Multistage magma emplacement and progressive strain accumulation in the shallow-level Krkonoše-Jizera plutonic complex, Bohemian Massif[END_REF]. The structural study of plutons is an effective and practical way to unravel regional tectonic setting coeval with the emplacement process (e.g., Bouchez & Gleizes, 1995;[START_REF] Bouchez | Granite is Never Isotropic: An Introduction to AMS Studies of Granitic Rocks[END_REF][START_REF] Sant'ovaia | Composite-laccolith emplacement of the post-tectonic Vila Pouca de Aguiar granite pluton (northern Portugal): a combined AMS and gravity study[END_REF][START_REF] De Saint Blanquat | Multiscale magmatic cyclicity, duration of pluton construction, and the paradoxical relationship between tectonism and plutonism in continental arcs[END_REF][START_REF] Lin | Late Mesozoic compressional to extensional tectonics in theYiwulüshan massif, NE China and its bearing on the evolution of the Yinshan-Yanshan orogenic belt part II: Anisotropy of magnetic susceptibility and gravity modeling[END_REF]. The early Mesozoic magmatism is conspicuous in the NCB, represented by E-W trending Late Triassic alkaline intrusive complexes in the northern NCB and Jurassic granites in the Liaodong and Jiaodong peninsulas and the eastern Yanshan Fold and Thrust Belt. The Late Triassic and Jurassic granitic plutons from the NCB present good opportunities to realize the tectonic regimes during the early Mesozoic. In this thesis, Late Triassic Dushan-Dashizhu pluton and Wangtufang pluton, and Jurassic Jianchang-Jiumen pluton were selected to provide regional tectonic information for the extensional episodes through an integrated multidisciplinary investigation (including structural geology, isotope chronology, geochemistry, Anisotropy of magnetic susceptibility (AMS), and gravity modeling). Then, the geodynamics of the NCB during the early Mesozoic was discussed.

Research contents and methodology

As the research targets, three representative plutons (Dushan-Dashizhu pluton, Wangtufang pluton, and Jianchang-Jiumen pluton) were chosen to clarify the extensional tectonics through an integrated multidisciplinary investigation (including structural geology, isotope chronology, geochemistry, Anisotropy of magnetic susceptibility (AMS), and gravity modeling).

Research purpose and contents

In the northern NCB, the Triassic strata are only exposed in few small remnant basins (i.e., Xiabancheng and Niuyingzi-Dengzhangzi basins). Detrital zircon dating and sedimentary studies suggest that the conformable Upper Triassic to Lower Jurassic strata were deposited in an extensional setting [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF].

The Late Triassic tectonic regime remains poorly constrained due to the difficulty of structural investigation in few small remnant basins. Therefore, two Late Triassic plutons (Dushan-Dashizhu pluton and Wangtufang pluton) as good targets were chosen to clarify Late Triassic tectonic regime. Jurassic-Early Cretaceous intracontinental orogeny, also termed the Yanshanian Movement in the Chinese literature [START_REF] Wong | The Mesozoic orogenic movement in eastern China[END_REF], was widespread and intense in the North China Craton [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF]. Albeit alternating contractional and extensional deformations have been recognized in the Yanshan fold-and-thrust belt, timing and duration of these events remain debated [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Dong | Late Jurassic-Early Cretaceous continental convergence and intracontinental orogenesis in East Asia: a synthesis of the Yanshan revolution[END_REF][START_REF] Faure | Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the NCC?[END_REF][START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF]. Particularly, Jurassic extensional deformations have not firmly constrained. Only sporadic grabens or half-grabens have been documented in the NCB during Early Jurassic-early Middle Jurassic [START_REF] Darby | Paleozoic and Mesozoic tectonic evolution of central Asia: From continental assembly to intracontinental deformation[END_REF]Li et al., 2015;[START_REF] Qi | Mesozoic tectonic setting of rift basins in eastern North China and implications for destruction of the North China Craton[END_REF][START_REF] Ritts | Early Jurassic extensional basin formation in the Daqing Shan segment of the Yinshan belt, northern North China Block, Inner Mongolia[END_REF][START_REF] Zhang | Changes of Late Mesozoic tectonic regimes around the Ordos Basin (North China) and their geodynamic implications[END_REF] and early Late Jurassic [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Qi | Mesozoic tectonic setting of rift basins in eastern North China and implications for destruction of the North China Craton[END_REF]. Therefore, Jurassic plutons from the NCB present good opportunities to realize this purpose, and, accordingly, the Jianchang-Jiumen pluton was chosen for this study.

Early Mesozoic tectonic evolution is a key element of the East Asian tectonics.

After the amalgamation of Paleo-Asian ocean, the Late Triassic tectonic regime in the northern NCB remains controversial. After the Paleozoic-Triassic amalgamation, multiphase deformation events in the welded East Asian continent related to Jurassic-Early Cretaceous intracontinental orogeny remain poorly constrained. It is crucial to clarify Early Mesozoic extensional tectonics in the NCB for establishing the detailed structural framework of the NCB and understanding the geodynamic mechanism of Early Mesozoic tectonics in East Asia.

Methodology

Three granite plutons were selected as the targets to decipher the unclarified scientific problems, some methods have been utilized as follows:

(1) Detailed field observations in three areas, including Dushan-Dashizhu, Wangtufang, and Jianchang-Jiumen, to investigate the deformations of the plutons and their country rocks.

(2) Geochemical investigation of the Wangtufang pluton, which lack of geochemical data, aiming to reveal its origin and tectonic setting.

(3) Isotope chronology analysis on three granite plutons to constrain precise age of magmatism by a Cameca IMS 1280 large-radius SIMS (SIMS zircon U-Pb Dating).

(4) Measurement of the Anisotropy of Magnetic Susceptibility (AMS), to determine the fabrics of the plutons and the tectonic setting of pluton emplacement.

(5) Gravity modelling, to constrain the deep structures of the plutons (the geometry and possible feeder zones of pluton).

Workload of the study

Detailed workload can be listed in Table 1.1 1.4. Major findings and innovations 1. The Late Triassic Dushan pluton emplaced southwards through a northeastern feeder zone, beginning probably with a sill then evolving into the inflation of magma batches. This inflation deformed, and even recrystallized the former cool-down magma, forming a curved gneissic to mylonitic foliation delineating the pluton southwestern margin. Both mesoscopic and magnetic fabrics in the Dushan pluton were rather related to its building than the Late Triassic regional tectonics.

2. In the Late Triassic Wangtufang pluton, the diorite forms just thin remnants above the syenogranite. The syenogranite with a series of NW-SE trending dykes intruded into the diorite and its country rocks. The syenogranite, a lopolith-like intrusion, was likely emplaced by inflation of magma pulses from its central conduit and built up by floor depression under an extensional setting, considering: (1) the NE-SW striking magnetic lineation, (2) the NE-SW trending elongated subsurface pluton shape, and (3) the orthogonal NW-SE striking syenogranitic dykes considered as tension gashes during the NE-SW trending extension.

3. In the Jurassic Jianchang-Jiumen pluton, the phacolith-like Jiumen pluton (~190 Ma) with margin-parallel foliations emplaced by magma inflation in the anticlinal core, while the tabular-like Jianchang pluton (~158 Ma) with concentric foliations underlay the Jiumen pluton by inflation of conduit-fed magma from its feeder zone. Two patterns of magnetic lineations recorded Early Jurassic NW-SE extension and early Late Jurassic NE-SW extension in the eastern NCB, respectively. Chapter 2. Regional geological outline of North China 2.1. Tectonic setting of the North China Block and its adjacent area

The NCB is one of the most important continental terranes that form the East Asian continent (e.g. [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Yin | A Phanerozoic palinspastic reconstruction of China and its neighboring regions[END_REF]. It is separated from the Siberia Craton in the north by the Central Asian Orogenic Belt and from the South China Block in the south by the Qinling-Dabie-Sulu orogen, respectively (Figure 1.1). The North China Craton formed a stable craton from Mesoproterozoic to Paleozoic, after its assembly through the collision of the Eastern, Intermediate (or Fuping), and Western blocks during the Paleoproterozoic (Zhao et al., 2001;[START_REF] Faure | Polyorogenic evolution of the Paleoproterozoic Trans-North China Belt, new insights from the in Lüliangshan-Hengshan-Wutaishan and Fuping massifs[END_REF][START_REF] Li | Mesozoic tectonics in the Eastern Block of the North China Craton: implications for subduction of the Pacific plate beneath the Eurasian plate[END_REF][START_REF] Li | Paleoproterozoic structural evolution of the southern segment of the Jiao-Liao-Ji Belt, North China Craton[END_REF]. The basement of the stable craton was overlain by a Mesoproterozoic to Permian sedimentary cover, separated by a regional unconformity between the Middle Ordovician and Upper Carboniferous-Permian strata [START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF]. The northern NCB is located to the south of the eastern segment of the CAOB (Figure 1.1). The evolution of the eastern segment of the CAOB is dominated by the late Paleozoic Paleo-Asian Ocean domain in the south and Mesozoic Mongol-Okhotsk

Ocean domain in the north [START_REF] Wang | Paleoplate tectonics between Cathaysia and Angaraland in Inner Mongolia of China[END_REF]Sengör and Natal'in, 1996;[START_REF] Xu | Framework and evolution of the middle Paleozoic orogenic belt between Siberian and North China Plates in northern Inner Mongolia[END_REF][START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern 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] Donskaya | Late Paleozoic-Mesozoic subduction-related magmatism at the southern margin of the Siberian continent and the 150 million-year history of the Mongol-Okhotsk Ocean[END_REF]. The eastern segment of the CAOB is the result of a complex multi-period tectonic evolution during late Paleozoic to Mesozoic, with the subduction and closure of the Paleo-Asian Ocean and the Mongol-Okhotsk Ocean [START_REF] Zonenshain | Geology of the USSR: A Plate-Tectonic Synthesis[END_REF]Sengor and Natal'in, 1996;[START_REF] Yin | A Phanerozoic palinspastic reconstruction of China and its neighboring regions[END_REF][START_REF] Kravchinsky | Evolution of the Mongol-Okhotsk Ocean as constrained by new palaeomagnetic data from the Mongol-Okhotsk suture zone, Siberia[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] Windley | Tectonic models for accretion of the Central Asian Orogenic Belt[END_REF][START_REF] Zhang | Carboniferous granitic plutons from the northern margin of the North China block: implications for a late Paleozoic active continental margin[END_REF][START_REF] Xiao | Geodynamic processes and metallogenesis of the Central Asian and related orogenic belts: introduction[END_REF][START_REF] Zhang | Contrasting Late Carboniferous and Late Permian-Middle Triassic intrusive suites from the northern margin of the North China Craton: geochronology, petrogenesis, and tectonic implications[END_REF]Han et al., 2012;[START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF][START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF]. In the south, it is characterized by the amalgamation of several microcontinents including, from west to east, the Erguna, Xing'an, Songnen, Jiamusi, and Khanka massifs (Sengör et al., 1993;[START_REF] Xu | Middle Paleozoic convergent orogenic belts in western Inner Mongolia (China): framework, kinematics, geochronology and implications for tectonic evolution of the Central Asian Orogenic Belt[END_REF]. Timing and process of the closure of the Paleo-Asian Ocean are still debated, 1) the late Devonian closure of the Paleo-Asian ocean occurred during the middle Paleozoic, with two opposite subductions and collisions along Ondor Sum in the south and Sunid Zuoqi in the north [START_REF] Xu | Framework and evolution of the middle Paleozoic orogenic belt between Siberian and North China Plates in northern Inner Mongolia[END_REF][START_REF] Xu | Middle Paleozoic convergent orogenic belts in western Inner Mongolia (China): framework, kinematics, geochronology and implications for tectonic evolution of the Central Asian Orogenic Belt[END_REF], 2) a Late Permian to Early Triassic collision, between the Tuva-Mongolia microcontinent and NCB, occurred with long-lived multiple southward and northward subductions from 530 to 250 Ma [START_REF] Chen | Two contrasting Paleozoic magmatic belts in northern Inner Mongolia, China: Petrogenesis and tectonic implications[END_REF][START_REF] Chen | Evolution of the Solonker suture zone: Constraints from zircon U-Pb ages, Hf isotopic ratios and whole-rock Nd-Sr isotope compositions of subduction-and collisionrelated magmas and forearc sediments[END_REF], 3) the final amalgamation of the CAOB occurred during latest Permian to mid-Triassic by termination of the accretionary processes [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 | A tale of amalgamation of three Permo-Triassic collage systems in Central Asia: oroclines, sutures, and terminal accretion[END_REF], and 4)

an early to mid-Paleozoic paired orogens with a Permian intra-oceanic arc trench system and a sequence of tectono-magmatic events from 299 Ma to 260 Ma were responsible for the CAOB accretion [START_REF] Jian | Time scale of an Early to Mid-Paleozoic orogenic cycle of the long-lived Central Asian Orogenic Belt, Inner Mongolia of China: implications for continental growth[END_REF][START_REF] Jian | Evolution of a Permian intraoceanic arc-trench system in the Solonker suture zone, Central Asian Orogenic Belt, China and Mongolia[END_REF]. Numerous authors suggested the final closure of the Paleo-Asian Ocean was along the Solonker-Xra Moron-Changchun suture during Permian-Early Triassic (Sengör et al., 1993;[START_REF] Yin | A Phanerozoic palinspastic reconstruction of China and its neighboring regions[END_REF][START_REF] Chen | Two contrasting Paleozoic magmatic belts in northern Inner Mongolia, China: Petrogenesis and tectonic implications[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] Shang | Occurrences of Permian radiolarians in central and eastern Nei Mongol (Inner Mongolia) and their geological significance to the northern China Orogen[END_REF][START_REF] Li | Permian geodynamic setting of Northeast China and adjacent regions: closure of the Paleo-Asian Ocean and subduction of the Paleo-Pacific Plate[END_REF][START_REF] Lin | Permian-Triassic amalgamation of Asia: insights from Northeast China sutures and their place in the final collision of North China and Siberia[END_REF][START_REF] Jian | Evolution of a Permian intraoceanic arc-trench system in the Solonker suture zone, Central Asian Orogenic Belt, China and Mongolia[END_REF][START_REF] Eizenhöfer | Final closure of the Paleo-Asian Ocean along the Solonker Suture Zone: Constraints from geochronological and geochemical data of Permian volcanic and sedimentary rocks[END_REF]Li et al., 2014).

In the eastern CAOB, it is closely related to the closure of the Mongol-Okhotsk

Ocean in the north [START_REF] Xu | Triassic volcanism in eastern Heilongjiang and Jilin provinces, NE China: chronology, geochemistry, and tectonic implications[END_REF][START_REF] Wu | Geochronology of the Phanerozoic granitoids in northeastern China[END_REF][START_REF] Xiao | A tale of amalgamation of three Permo-Triassic collage systems in Central Asia: oroclines, sutures, and terminal accretion[END_REF]. The Mongol-Okhotsk Ocean subducted northward beneath the Siberia Craton, resulting in the collision between the Siberia Craton and the Amurian supertarrane [START_REF] Vander | Mesozoic subducted slabs under Siberia[END_REF]. The suture extends from the middle Mongolia to the Mongol-Okhotsk Sea [START_REF] Tomurtogoo | Zircon age and occurrence of the Adaatsag ophiolite and Muron shear zone, central Mongolia: constraints on the evolution of the Mongol-Okhotsk ocean, suture and orogen[END_REF]. This is controversial with various estimates as to the timing of its closure, i.e., Middle Jurassic [START_REF] Zorin | Geodynamics of the western part of the Mongolia-Okhotsk collisional belt, Trans-Baikal region (Russia) and Mongolia[END_REF][START_REF] Yarmolyuk | Stages of bimodal and alkaline granite magmatism in the western Transbaikal region: geochronological data on rocks from the Tugnui Depression[END_REF][START_REF] Tomurtogoo | Zircon age and occurrence of the Adaatsag ophiolite and Muron shear zone, central Mongolia: constraints on the evolution of the Mongol-Okhotsk ocean, suture and orogen[END_REF][START_REF] Sun | Geochronological and geochemical constraints on the Erguna massif basement, NE China-subduction history of the Mongol-Okhotsk oceanic crust[END_REF], Late Jurassic [START_REF] Zonenshain | Geology of the USSR: A Plate-Tectonic Synthesis[END_REF], and Late Jurassic-Early Cretaceous [START_REF] Parfenov | Problems of tectonics of the Mongol-Okhotsk orogenic belt[END_REF][START_REF] Kravchinsky | Evolution of the Mongol-Okhotsk Ocean as constrained by new palaeomagnetic data from the Mongol-Okhotsk suture zone, Siberia[END_REF][START_REF] Cogné | Late Jurassic-Early Cretaceous closure of the Mongol-Okhotsk Ocean demonstrated by new Mesozoic palaeomagnetic results from the Trans-Baikal area (SE Siberia)[END_REF][START_REF] Metelkin | Late Mesozoic tectonics of Central Asia based on paleomagnetic evidence[END_REF][START_REF] Pei | A paleomagnetic study from the Late Jurassic volcanics (155 Ma), North China: implications for the width of Mongol-Okhotsk Ocean[END_REF]. However, the collision between the Siberia Craton and the Amurian supertarrane occurred after the Middle Jurassic, evidenced by the Triassic-Middle Jurassic marine deposits [START_REF] Enkin | Paleomagnetic constraints on the geodynamic history of the major blocks of China from the Permian to the present[END_REF]. The majority of scholars suggested that the closure of the Mongol-Okhotsk Ocean was diachronous but generally became younger eastward [START_REF] Zonenshain | Geology of the USSR: A Plate-Tectonic Synthesis[END_REF][START_REF] Yin | A Phanerozoic palinspastic reconstruction of China and its neighboring regions[END_REF][START_REF] Kravchinsky | Evolution of the Mongol-Okhotsk Ocean as constrained by new palaeomagnetic data from the Mongol-Okhotsk suture zone, Siberia[END_REF][START_REF] Xiao | Geodynamic processes and metallogenesis of the Central Asian and related orogenic belts: introduction[END_REF][START_REF] Archanjo | Magnetic fabrics vs. magnetite and biotite shape fabrics of the magnetite-bearing granite pluton of Gameleiras (Northeast Brazil)[END_REF], for instance, the Middle Jurassic in the west [START_REF] Zorin | Geodynamics of the western part of the Mongolia-Okhotsk collisional belt, Trans-Baikal region (Russia) and Mongolia[END_REF][START_REF] Parfenov | Problems of tectonics of the Mongol-Okhotsk orogenic belt[END_REF] and the Late Jurassic or the Early Cretaceous in the east [START_REF] Yarmolyuk | Stages of bimodal and alkaline granite magmatism in the western Transbaikal region: geochronological data on rocks from the Tugnui Depression[END_REF][START_REF] Daoudene | Timing of exhumation of the Ereendavaa metamorphic core complex (north-eastern Mongolia)-U-Pb and 40 Ar/ 39 Ar constraints[END_REF].

Paleomagnetic studies suggested that the Mongol-Okhotsk Ocean subducted southward and collided with the Amurian supertarrane [START_REF] Enkin | Paleomagnetic constraints on the geodynamic history of the major blocks of China from the Permian to the present[END_REF].

In the south of the NCB, it is separated the South China Block by the Qinglin-Dabie-Sulu Orogenic belt (Figure 1.1), which underwent a complex multi-period tectonic evolution related to the Proto-Tethys Ocean and the Paleo-Tethys Ocean (e.g., [START_REF] Mattauer | Tectonics of the Qinling belt: build-up and evolution of eastern Asia[END_REF]Hacker et al., 1995Hacker et al., , 1996Hacker et al., , 1998Hacker et al., , 2000;;[START_REF] Wang | Top boundary of the Dabie UHPM rocks, central China[END_REF][START_REF] Faure | Tectonics of the Dabieshan (eastern China) and possible exhumation mechanism of ultra high-pressure rocks[END_REF][START_REF] Faure | Continental subduction and exhumation of UHP rocks. Structural and geochronological insights from the Dabieshan (East China)[END_REF]Meng and Zhang 2000;[START_REF] Ratschbacher | Tectonics of the Qinling (Central China): tectonostratigraphy, geochronology, and deformation history[END_REF][START_REF] Ratschbacher | The Sino-Korean-Yangtze suture, the Huwan detachment, and the Paleozoic-Tertiary exhumation of (ultra) high-pressure rocks along the Tongbai-Xinxian-Dabie Mountains[END_REF][START_REF] Lin | Tectonic evolution of Dabie orogen: in the view from polyphase deformation of the Beihuaiyang metamorphic zone[END_REF][START_REF] Lin | Exhumation tectonics of the HP-UHP orogenic belt in Eastern China: new structural-petrological insights from the Tongcheng massif, Eastern Dabieshan[END_REF][START_REF] Dong | Tectonic evolution of the Qinling orogen, China: review and synthesis[END_REF][START_REF] Wu | Tectonic evolution of a composite collision orogen: an overview on the Qinling-Tongbai-Hong'an-Dabie-Sulu orogenic belt in central China[END_REF][START_REF] Dong | Tectonic architecture and multiple orogeny of the Qinling Orogenic Belt, Central China[END_REF]. Generally, the amalgamation of the South Qinling and the NCB occurred in the middle Paleozoic, forming the North Qinling (e.g., [START_REF] Mattauer | Tectonics of the Qinling belt: build-up and evolution of eastern Asia[END_REF]Meng and Zhang 2000). In the Late Triassic, the final amalgamation of the North and South China Blocks was along the Mianlue suture (e.g., [START_REF] Mattauer | Tectonics of the Qinling belt: build-up and evolution of eastern Asia[END_REF]Hacker et al., 1995Hacker et al., , 1996Hacker et al., , 1998Hacker et al., , 2000;;[START_REF] Wang | Top boundary of the Dabie UHPM rocks, central China[END_REF]Meng and Zhang 2000;[START_REF] Ratschbacher | Tectonics of the Qinling (Central China): tectonostratigraphy, geochronology, and deformation history[END_REF][START_REF] Ratschbacher | The Sino-Korean-Yangtze suture, the Huwan detachment, and the Paleozoic-Tertiary exhumation of (ultra) high-pressure rocks along the Tongbai-Xinxian-Dabie Mountains[END_REF]. The continental deep subduction of the Yangtze Block occurred beneath the NCB, forming the HP-UHP Dabie-Sulu orogenic belt [START_REF] Okay | Coesite from the Dabie Shan eclogites, central China[END_REF][START_REF] Wang | Coesite-bearing eclogite from the Dabie Mountains in central China[END_REF]Xu et al. 1992;[START_REF] Faure | Tectonics of the Dabieshan (eastern China) and possible exhumation mechanism of ultra high-pressure rocks[END_REF][START_REF] Faure | Continental subduction and exhumation of UHP rocks. Structural and geochronological insights from the Dabieshan (East China)[END_REF][START_REF] Lin | Tectonic evolution of Dabie orogen: in the view from polyphase deformation of the Beihuaiyang metamorphic zone[END_REF][START_REF] Lin | Exhumation tectonics of the HP-UHP orogenic belt in Eastern China: new structural-petrological insights from the Tongcheng massif, Eastern Dabieshan[END_REF][START_REF] Dong | Tectonic evolution of the Qinling orogen, China: review and synthesis[END_REF][START_REF] Wu | Tectonic evolution of a composite collision orogen: an overview on the Qinling-Tongbai-Hong'an-Dabie-Sulu orogenic belt in central China[END_REF][START_REF] Dong | Tectonic architecture and multiple orogeny of the Qinling Orogenic Belt, Central China[END_REF]. (198-195Ma;[START_REF] Xu | Tracing an early Jurassic magmatic arc from South to East China Seas[END_REF]. In the Korean Peninsula, the Early Jurassic synorogenic foreland deposits and high-k calc-alkaline volcanic rocks were supposed to a result of the Paleo-Pacific Plate subduction in the active continental margin (184~167 Ma;Han et al., 2006;[START_REF] Kim | Geochronological and geochemical constraints on the petrogenesis of Mesozoic high-K granitoids in the central Korean peninsula[END_REF]. The Early Jurassic volcanics in the Yanshan belt of the NCB recorded the onset of the Paleo-Pacific Plate subduction (Hao et al., 2020). The Middle-Late Jurassic fold and thrust belt, and extensive Jurassic magmatism was also considered as a result of the Paleo-Pacific Plate subduction [START_REF] Zhou | Origin of Late Mesozoic igneous rocks in Southeastern China: implications for lithosphere subduction and underplating of mafic magmas[END_REF]Li and Li, 2007;Li et al., 2018).

During the late

2.2. Tectonic evolution of the Triassic-earliest Cretacous basins 2.2.1. Triassic In the NCB, the Triassic strata are mainly distributed in the Ordos Basin, e.g., the Helanshan, the Liupanshan, and the Alxa Block in its west [START_REF] Deng | New knowledge of Triassic in Liupanshan Basin, Ningxia and its significance[END_REF]. The Ordos Basin was a cratonic basin with convergence plate margins during the late Paleozoic-Early Triassic (Yang et al., 2015). In the Early Triassic, sand and mudstone in fluvial and lacustrine facies were deposited in the Ordos Basin. During the Middle Triassic, red conglomerate and mudstone were deposited in its eastern margin, and gray green mudstone with intercalated coal seams was deposited in the middle. The Triassic structural deformation was sporadically documented in the Yanshan belt. In the Yanshan belt, the ductile shear zone concerns the E-W trending Chicheng-Fengning, Fengning-Longhua, and Damiao-Niangniangmiao ductile shear zones in the north [START_REF] Wang | Cratonic reactivation and orogeny: an example from the northern margin of the North China Craton[END_REF][START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF]Figure 2.1), and the E-W trending folds and thrusts include the Unnamed fault, Malanyu anticline, and Jixian thrust fault in the south [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Ma | SHRIMP U-Pb dating of zircon from Panshan granitoid pluton in Yanshan orogenic belt and its tectonic implications (in Chinese with English abstract)[END_REF].

During the Late Triassic, the Ordos Basin was gener ally a cratonic basin, characterized by the nature of the foreland depression in its southwest and rift in its northwest [START_REF] Li | Paleoproterozoic structural evolution of the southern segment of the Jiao-Liao-Ji Belt, North China Craton[END_REF]. Several small-sized half-grabens were documented in the Helanshan and Zhuozishan to the southwest of the Ordos basin [START_REF] Darby | Mesozoic contractional deformation in the middle of the Asian tectonic collage: the intraplate Western Ordos fold-thrust belt, China[END_REF][START_REF] Ritts | Sedimentary record of Triassic intraplate extension in North China: evidence from the nonmarine NW Ordos Basin, Helan Shan and Zhuozi Shan[END_REF]Figure 2.1). Besides, only few small remnants of Late Triassic [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF][START_REF] Meng | Tectonic evolution of early Mesozoic sedimentary basins in the North China block[END_REF]. In the Xiabancheng basin, it was usually considered as a contractional tectonic setting during the Late Triassic-Early Jurassic according to the unconformity between Triassic and Lower Jurassic strata, and Lower Jurassic syntectonic conglomerate [START_REF] Zhao | The Mesozoic orogenesis and tectonic evolution of the Yanshan area (in Chinese)[END_REF][START_REF] Liu | Rapid exhumation of basement rocks along the northern margin of the North China craton in the early Jurassic: Evidence from the Xiabancheng Basin, Yanshan Tectonic Belt[END_REF]. Detrital zircon dating and sedimentary studies suggest that the conformable Upper Triassic strata were deposited in an extensional setting [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF][START_REF] Meng | Tectonic evolution of early Mesozoic sedimentary basins in the North China block[END_REF]. In addition, both the Shuiquangou Formation and Dengzhangzi Formation belong actually to the Upper Triassic strata [START_REF] Zhang | Timing of deposition in the Dengzhangzi and Guojiadian Basins of the Yanshan fold-thrust belt, North China[END_REF]Figure 2.2). The Shuiquangou Formation and Dengzhangzi Formation are controlled by the boundary normal faults [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF]. The gravity slide collapse deposits related to the extensional deformation was extensively identified in these areas (e.g., [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Hu | Early Mesozoic deformations of the eastern Yanshan thrust belt, northern China[END_REF].

Early-Middle Jurassic

The Upper-Lower Jurassic strata were distributed in the Ordos Basin, the Taihangshan, the Helanshan-zhuozishan, the Yinshan-Yanshan fold and thrust belt Liaoning . The Lower Jurassic strata contain abundant volcanic rock or pyroclastic rock in the Yanshan belt, and coal-bearing series in the whole North China (Figure 2.4). The structural and sedimentary studies suggested that the North China Craton was in an extensional setting during the Early-early Middle Jurassic [START_REF] Darby | Paleozoic and Mesozoic tectonic evolution of central Asia: From continental assembly to intracontinental deformation[END_REF][START_REF] Ritts | Early Jurassic extensional basin formation in the Daqing Shan segment of the Yinshan belt, northern North China Block, Inner Mongolia[END_REF][START_REF] Meng | Tectonic evolution of early Mesozoic sedimentary basins in the North China block[END_REF]. The NNE-SSW or nearly N-S extensional normal faults were identified in the Upper Triassic-Lower Jurassic strata in the central and northeastern Ordos Basin [START_REF] Zhang | Changes of Late Mesozoic tectonic regimes around the Ordos Basin (North China) and their geodynamic implications[END_REF]Figure 2.3). In the Yungang and Guangling Basins, the normal faults cut the conglomerates in the lower Lower Jurassic, covered by the upper Lower Jurassic strata (Li et al., 2015;Figure 2.3).

The sedimentary studies showed a fining and deepening upward depositional system from the Upper Triassic to Lower Jurassic strata, suggesting a Late Triassic extensional tectonic setting in the Lingwu-Jingle Basin [START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF]Li et al., 2015). In the southwestern Daqingshan, the E-W trending normal faults cut the unconformity between the Lower Jurassic and Archeozoic [START_REF] Darby | Paleozoic and Mesozoic tectonic evolution of central Asia: From continental assembly to intracontinental deformation[END_REF]Figure 2.4). The smallsized grabens were developed, dominated by the growth normal faults.

Event A of the Yanshanian Orogeny

Wong (1927) suggested that the unconformity at the bottom of Jurassic Tiaojishan Formation in Western Hill of Beijing is of regional tectonic significance, named Afterward, Previous studies suggested that it is comformable between the Tiaojishan Formation and the Jiulongshan Formation in large area of the North China (Li et al., 2014). Recently, the prospecting trench and drilling indicated that the Tiaojishan Formation, the Jiulongshan Formation, and the Longmen Formation all converge to an unconformity in space (Li et al., 2014). The Jiulongshan-Longmen Formations are a set of conglomerates as a molasse below the volcanics in the Tiaojishan Formation [START_REF] Zhao | The Mesozoic orogenesis and tectonic evolution of the Yanshan area (in Chinese)[END_REF], corresponding to the Haifanggou Formation in the western Liaoning (Figure 2.4). The Jiuongshan Formation consists of the thick terrestrial clastic rocks intercalated with the volcanic rocks, and conglomerates and tuff at the bottom (Figure 2.4). The Longmen Formation is absent in the Chengde area. Previous studies suggested there is no distinction between the Longmen Formation and the Jiulongshan Formation in the lithology (Li et al., 2014). It exists obvious sedimentary discontinuity between the Yaopo Formation and the Longmen Formation [START_REF] Zhao | The Mesozoic orogenesis and tectonic evolution of the Yanshan area (in Chinese)[END_REF]Li et al., 2014). The Event A is indicated by the parallel unconformity between the conglomerates in the Longmen Formation and the coal-bearing series in the Yaopo Formation in the Western Hill of Beijing (Li et al., 2014;Hao et al., 2019;Figure 2.4). The volcanics in the Tiaojishan Formation was only distributed in the Yanshan belt. However, the conglomerates below the volcanics in the Tiaojishan Formation were widely distributed in the North China (Figure 2.4), e.g., the Yungang Formation and the Tianchihe Formation in the Ningwu-Jingle Basin, Taihanshan (Li et al., 2015), the Changhangou Formation in the Shiguai Basin, Yanshan belt [START_REF] Wang | The Jurassic structural evolution of the western Daqingshan area, eastern Yinshan belt, North China[END_REF], and the Zhiluo Formation in the Ordos Basin [START_REF] Zhang | Changes of Late Mesozoic tectonic regimes around the Ordos Basin (North China) and their geodynamic implications[END_REF]. Therefore, the Event A is presented by the unconformity between the conglomerates below the volcanics and underlying coal-bearing series (Figure 2.4).

Due to the discontinuous distribution of the conglomerates, the Event A was presented as different contact relationships in different areas (Figure 2.4), e.g., parallel unconformity between the Longmen Formation and the Yaopo Formationin the Western Hill (Li et al., 2014;Hao et al., 2019), angular unconformity between the Jiulongshan Formation and the Xiahuayuan Formation (Liu et al., 2018), and angular unconformity between the Haifanggou Formation and the Beipiao Formation [START_REF] Meng | Tectonic evolution of early Mesozoic sedimentary basins in the North China block[END_REF]. In the Shiguai Basin, Yinshan, the Event A is suggested by the angular unconformity between the Changhangou Formation and the underlying Zhaogou Formation (Wang et al., 2017). The intense fold and thrust deformations in the coal-bearing series in the Wudanggou and Zhaogou Formations was covered by the growth strata in the Changhangou Formation [START_REF] Wang | The Jurassic structural evolution of the western Daqingshan area, eastern Yinshan belt, North China[END_REF]. In the Yungang Basin, Taihangshan, it is angular unconformity between the Permian Shanxi Formation and the overlying Jurassic Tiaojishan Formation (Li et al., 2015). It is it is angular unconformity between the Tianchihe Formation and the underlying Datong Formation in the Ningwu-Jingle Basin, Taihangshan, presenting as the great changes in the Lithology, heavy minerals, sediment source and detrital zircon (Li et al., 2015).

However, [START_REF] Wong | Crustal movements and igneous activities in Eastern China since Mesozoic time[END_REF] suggested that the volcanics in the Tiaojishan Formation overlay the different strata, indicating the intense deformation and erosion before the deposition of the the Tiaojishan Formation (Figure 2.3). The conglomerates below the Tiaojishan Formation are locally distributed in the Yanshan belt. In fact, the Event A was presented as the unconformity between the volcanics in the Tiaojishan Formation and the different underlying strata [START_REF] Faure | Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the NCC?[END_REF]. The extensive deformations related to Event A have been overlaid by the volcanics in the Tiaojishan Formation. For instance, the fold and thrust belt in the Proterozoic-Paleozoic strata were covered by the he volcanics in the Tiaojishan Formation, e.g., Mengjiazhuang anticline and Duanshuao-Jianbaoshan thrust fault ( Li et al., 2016), Miyun-Xifengkou fault, Zhujiagou fault, Qingshuihu fault, Xinglong fault, Gaobanhe fault, Sanpo fault, Banbishan fault, and Lengkou fault [START_REF] Chen | Geometric and kinematic evolution of basement-cored structures: intraplate orogenesis within the Yanshan Orogen, northern China[END_REF], Davis et al., 2001;[START_REF] Zhang | Mesozoic tectonic framework of the intraplate and evolution in the central segment Yanshan orogenic belt (in Chinese)[END_REF].

This event was considered as northward thrust that occurred during post-161 Ma, pre-148 Ma?, pre-131 Ma according to the isotope chronology [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF]. [START_REF] Faure | Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the NCC?[END_REF] and [START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF] suggested the Event A was related to the unconformity below the volcanics in the Tiaojishan Formation (172-164 Ma).

Intermediate phase of the Yanshanian Orogeny

Wong (1928) firstly described "Intermediate phase" as the volcanism stage, characterized by the volcanics in the upper and the conglomerates in the lower (Figure 2.4). As mentioned above, the Longmen Formation and Jiulongshan Formation, distributed locally in the Yanshan belt, might be the molasse after the Event A of the Yanshanian Orogeny. Alternatively, both the Longmen Formation and the Jiulongshan Formation belong to one set of conglomerates beneath the volcanics (Zhang et al., 2013).

The Intermediate phase has been defined as the volcanism stage of the Tiaojishan Formation. The Tiaojishan Formation consists of dark purple, purple-brown, and graygreen andesite, amphibole andesite, pyroxene andesite, andesitic lava breccia, andesitic breccia, andesite agglomerate with purplish red, grayish brown and grayish-green sandstone, conglomerate, siltstone and mudstone (Li et al., 2014). Several rifts have been distinguished in the Yanshan belt, e.g., Diaoe graben and Houcheng half-graben [START_REF] Qi | Mesozoic tectonic setting of rift basins in eastern North China and implications for destruction of the North China Craton[END_REF]. A N-S striking graben was developed in the Jurassic strata in the hanging wall of the Chengde thrust [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF]. In the Niuyingzi-Dengzhangzi basin, the Middle Jurassic Guojiadian half-graben was dominated by the normal fault [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF]. Besides, the top-to-the NE detachment fault was developed in the Kalaqin MCC (156-150 Ma;[START_REF] Lin | Structural characteristics and formation mechanism of the Kalaqin metamorphic core complex in the Yanshan area, China (in Chinese)[END_REF]. However, the volcanics of the Tiaojiashan Formation are only distributed in the Yanshan belt and the north of the Taihangshan (Figure 2.3). In the western Liaoning, it corresponds to the Lanqi Formation (Figure 2.4). The coeval extensional basins are also distributed in the Yanshan belt (Figure 2.3).

As mentioned above, the conglomerates below the volcanics are widely distributed in other areas (Figure 2.4). In the Shiguai basin of the Daqingshan, the Event A of the Yanshanian orogeny is characterized by the unconformity between the Zhaogou Formation and the Changhangou Formation (Figure 2.4), and the growth strata of the Changhangou Formation. Above it, the growth strata of the Daqingshan Formation overlie the Changhangou Formation [START_REF] Wang | The Jurassic structural evolution of the western Daqingshan area, eastern Yinshan belt, North China[END_REF]Figure 2.4). Therefore, the volcanism and coeval extensional basins in the intermediate phase could only occur in the eastern NCB (Figure 2.3).

Event B of the Yanshanian Orogeny

The Event B of the Yanshanian Orogeny occurred after the volcanism of the Tiaojishan Formation, characterized by the large-scale fold-and-thrust belts [START_REF] Wong | Study on geological structure near Beipiao and Rehe (in Chinese)[END_REF]. In the Yanshan belt, the widely distributed conglomerates in the Tuchengzi/Houcheng Formation overlie the volcanics [START_REF] Zhao | The Mesozoic orogenesis and tectonic evolution of the Yanshan area (in Chinese)[END_REF][START_REF] Cope | Detrital record of Mesozoic shortening in the Yanshan belt, NE China: testing structural interpretations with basin analysis[END_REF][START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF]Figure 2.4). The Event B corresponds to the unconformity between the Tuchengzi/Houcheng Formation and the overlying Zhangjiakou Formation (Figure 2.4). The growth strata of Tuchengzi/Houcheng Formation consist of syn-tectonic conglomerates during the Event B of the Yanshanian orogeny [START_REF] Fu | Revisiting of the Yanshanian basins in western and northern Beijing, North China[END_REF]Liu et al., 2018).

The deformation of the Event B was widely distributed in the Yanshan belt. E-W striking fold and thrust belts were widely developed in the middle and western segments of the Yanshan belt, for instances, the Xuanhua fault, the Xiahuayuan fault, and the Jimingshan fault in the Xiaohuayuan basin (Zhang et al., 2006), the Xiaosuangou-Jiuchaigou fault and the Shangyi fault in the southeastern Shangyi basin [START_REF] He | A preliminary research on sedimentary features and genetic mechanism of frontal basins before Jurassic large-scale nappe in the northern region of North China (in Chinese)[END_REF], the Qianjiadian fault, the Shaliangzi fault, and the Tanghekou fault (<158Ma), the thrust nappe in the Shisanling (151-127Ma; [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF], the Sihetang thrust (151-143Ma) and Shanggu-pingquan fault (145-135Ma) and the Gubeikou fault (148-132Ma) [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF]. The paleostress along the dextral strike-slip faults is NW-SE direction [START_REF] Lin | From dextral contraction to sinistral extension of intracontinental transform structures in the Yanshan and northern Taihang Mountain belts during Early Cretaceous: Implications to the destruction of the North China Craton[END_REF]. It is characterized by NE or NNE striking thrust and fold belts in the western Liaoning, e.g., the Lingyuan-Dongguanyingzi fault, the Nangongyingzi-Beipiao fault, the Jianchang-chaoyang fault and the Jingzhougou fault. These faults thrust onto the Lanqi/Tuchengqi Formation, and were overlaid by the Early Cretaceous Yixian Formation [START_REF] Zhang | Thrust tectonics in the eastern segment of the intraplate Yanshan Orogenic belt, western Liaoning, North China (in Chinese)[END_REF][START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Hu | Early Mesozoic deformations of the eastern Yanshan thrust belt, northern China[END_REF].

Although the Tiaojishan/Lanqi Formation was only distributed in the Yanshan belt, the conglomerates in the Tuchengzi/Houcheng Formation and their counterparts were distributed in the whole NCB (Figure 2.4). In the Shiguai basin of the Daqingshan, the Late Jurassic Daqingshan Formation, synchronous with the NW-SE compression, underlay the growth strata of the Changhangou Formation related to the Event A [START_REF] Wang | The Jurassic structural evolution of the western Daqingshan area, eastern Yinshan belt, North China[END_REF]. In the western margin of the Ordos basin, the Middle Jurassic Anding Formation, involved in fold and thrust belt, was covered by the syntectonic conglomerates in the Fenfanghe Formation [START_REF] Zhang | Changes of Late Mesozoic tectonic regimes around the Ordos Basin (North China) and their geodynamic implications[END_REF]. In the northern segment of the Taihangshan, the syn-tectonic conglomerates were developed in the footwall of the NNE striking Nanyangzhai-Heishiling fault [START_REF] Wang | An Analysis of Late Mesozoic Tectonic Evolution Process in Northern China: Based on Basin Sedimentary Records in Northern Taihang Mountains (in Chinese)[END_REF].

The unconformity between the Upper Jurassic Tuchengzi Formation and the lower Cretaceous Zhangjiakou Formation was developed in the Hunyuan basin (Li et al., 2015).

Triassic-Jurassic magmatism

The Triassic-Jurassic igneous rocks were widely distributed in the NCB.

According to the isotope chronology, four stages of magmatism have been identified, [START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF]. Some volcanics were developed in the Yanshan belt, e.g., the andesitic volcanic rocks in the Shuiquangou Formation. Late Permian-Middle Triassic intrusive rocks were derived from mixing of coeval mantle-and crust-derived melts, linked to the postcollisional/postorogenic lithospheric extension and asthenospheric upwelling after the final collision of the Mongolian arc terranes with the North China craton (e.g., [START_REF] Zhang | Contrasting Late Carboniferous and Late Permian-Middle Triassic intrusive suites from the northern margin of the North China Craton: geochronology, petrogenesis, and tectonic implications[END_REF][START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF].

The EW-trending Late Triassic alkaline intrusive complexes (e.g., nepheline syenite, quartz syenite, and A-type granite) and associated mafic rocks were widely developed along the northern NCB [START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF]. The Late Triassic alkaline intrusive complexes were mainly derived from the melts of subduction-modified enriched lithospheric mantle and ancient lower crust with some depleted asthenospheric mantle components during an intracontinental extensional setting [START_REF] Yang | Petrogenesis of silica-saturated and silica-undersaturated syenites in the northern North China Craton related to post-collisional and intraplate extension[END_REF][START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF]. It points to an upwelling of the asthenospheric mantle during the early lithospheric thinning or modification of the northern NCB. In the southern NCB, the Late Triassic igneous rocks, including Hornblende monzonite, quartz monzonite, quartz diorite, syenite and monzogranite, are mainly distributed in the Xiaoqingling area [START_REF] Ding | Timing and genesis of the adakitic and shoshonitic intrusions in the Laoniushan complex, southern margin of the North China Craton: implications for post-collisional magmatism associated with the Qinling Orogen[END_REF][START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF]. These rocks were originated from the partial melting of thickened lower crust, suggesting the postcollisional lithospheric extension after the collision of the South and North China blocks.

Early Jurassic-earliest Middle Jurassic igneous rocks are mainly distributed in the eastern NCB, including the Liaodong and Jiaodong peninsulas and the eastern Yanshan belt [START_REF] Wu | Geochronology, petrogenesis and tectonic implications of Jurassic granites in the Liaodong Peninsula, NE China[END_REF][START_REF] Wu | Geochronology of the Phanerozoic granitoids in northeastern China[END_REF]Figure 2.3). The main rock types include granite, monzodiorite, monzonite, and syenite, as well as the volcanics in the Nandaling/Xinglonggou Formation. The volcanics are composed of basalt, andesite, andesite, dacite and a small amount of trachyte. The intrusive rocks were mainly produced by partial melting of the ancient lower crust, whereas the volcanics were derived mainly from the ancient enriched lithospheric mantle [START_REF] Wu | Geochronology, petrogenesis and tectonic implications of Jurassic granites in the Liaodong Peninsula, NE China[END_REF][START_REF] Yang | Diachronous decratonization of the Sino-Korean craton: geochemistry of mantle xenoliths from North Korea[END_REF]. One group of researchers considers that the Early Jurassic-earliest Middle Jurassic igneous rocks are related to the subduction of the Paleo-Pacific plate, and the volcanic rocks are originated from the back-arc extension [START_REF] Wu | Geochronology, petrogenesis and tectonic implications of Jurassic granites in the Liaodong Peninsula, NE China[END_REF][START_REF] Gao | Recycling lower continental crust in the North China Craton[END_REF][START_REF] Yang | Diachronous decratonization of the Sino-Korean craton: geochemistry of mantle xenoliths from North Korea[END_REF]. Some scholars believe that it is an ongoing postcollisional lithospheric extension after the Mongolia arc terranes and the NCB (e.g., [START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF].

The Late Jurassic intrusive rocks are widely distributed in the Yanshan belt, the Liaodong area and Jiaodong Peninsulas in the eastern NCB, and the southern Yanbian-Liaobei area in the northeastern NCB and the northern North Korea [START_REF] Wu | Geochronology of the Phanerozoic granitoids in northeastern China[END_REF]Figure 2.3). These intrusive rocks include monzogranite, syenite, diorite, monzonite and granite. The simultaneous volcanics are composed of the Tiaojishan Formation in the mid-western Yanshan belt and the Lanqi Formation in the eastern Yanshan belt, including andesite, basaltic andesite, andesitic tuff and trachyandesite, and minor rhyolite. Both the intrusive rocks and the volcanics were derived from partial melting of the ancient lower crust (e.g., [START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF]. It was considered that the Late Jurassic igneous rocks are related to the subduction of the Paleo-Pacific plate (e.g., [START_REF] Wu | Destruction of the North China Craton in the Mesozoic[END_REF].

Chapter 3. Emplacement of the Late Triassic granitic Dushan pluton

Introduction

The NCB is located on the southern border of the longest Paleozoic Central Orogenic Belt (CAOB), and this latter has been the target of numerous studies over the past decades, however, no common consensus has been reached on its time of formation among the geologists. One opinion considers that the Paleo-Asian Ocean had closed since the Devonian to form the CAOB (e.g., [START_REF] Xu | Framework and evolution of the middle Paleozoic orogenic belt between Siberian and North China Plates in northern Inner Mongolia[END_REF][START_REF] Xu | Middle Paleozoic convergent orogenic belts in western Inner Mongolia (China): framework, kinematics, geochronology and implications for tectonic evolution of the Central Asian Orogenic Belt[END_REF][START_REF] Zhao | Did the Paleo-Asian Ocean between North China Block and Mongolia Block exist during the late Paleozoic? first paleomagnetic evidence from central-eastern Inner Mongolia, China[END_REF]. Another argues that this event occurred along the Solonker zone during the Permo-Triassic time (e.g., [START_REF] Chen | Two contrasting Paleozoic magmatic belts in northern Inner Mongolia, China: Petrogenesis and tectonic implications[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] Jian | Evolution of a Permian intraoceanic arc-trench system in the Solonker suture zone, Central Asian Orogenic Belt, China and Mongolia[END_REF][START_REF] Eizenhöfer | Final closure of the Paleo-Asian Ocean along the Solonker Suture Zone: Constraints from geochronological and geochemical data of Permian volcanic and sedimentary rocks[END_REF][START_REF] Xiao | A tale of amalgamation of three Permo-Triassic collage systems in Central Asia: oroclines, sutures, and terminal accretion[END_REF]Figure 3.1). Therefore, the recognition of the Late Triassic tectonic context in the northern part of the NCB becomes essential to understand the evolution of the CAOB. Meanwhile, the North China Craton is often considered to be destroyed during the Late Mesozoic when it experienced extensive magmatism and deformation, characterized by metamorphic core complexes, detachment faults, fault-bounded half-grabens and a general thinning of the cratonic lithospheric mantle (e.g., [START_REF] Zhu | Timing of destruction of the North China craton[END_REF][START_REF] Wu | Destruction of the North China Craton in the Mesozoic[END_REF]. However, the onset of cratonic modification was considered to occur in an early time, for instance, in the Late Triassic (e.g., Han et al., 2004;[START_REF] Yang | Diachronous decratonization of the Sino-Korean craton: geochemistry of mantle xenoliths from North Korea[END_REF] or the Late Jurassic (e.g., [START_REF] Gao | Recycling lower continental crust in the North China Craton[END_REF]. Consequently, the Late Triassic tectonic setting is also crucial to improve our understanding of the evolution of the NCB.

In the Late Triassic, the EW-trending alkaline intrusive complexes (e.g., nepheline syenite, quartz syenite, and A-type granite) and associated mafic rocks were widely developed along the northern NCB [START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF]Figure 3.1). Over the past decades, isotope chronology and geochemical works suggested that the Late Triassic alkaline intrusive complexes were mainl y derived from the mel ts of subduction -modified enri ched lithospheric mantle and ancient lower crust with some depleted asthenospheric mantle components during an intracontinental extensional setting [START_REF] Yang | Petrogenesis of silica-saturated and silica-undersaturated syenites in the northern North China Craton related to post-collisional and intraplate extension[END_REF][START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF]. It points to an upwelling of the asthenospheric mantle during the early lithospheric thinning or modification of the northern NCB. Nevertheless, the Triassic strata in the northern NCB are only exposed in few small remnant basins (i.e., Xiabancheng and Niuyingzi-Dengzhangzi basins; Figure 3.1).

Detrital zircon dating and sedimentary studies suggest that the conformable Upper Triassic to Lower Jurassic strata were deposited in an extensional setting [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF]. The Late Triassic tectonic regime remains poorly constrained due to the difficulty of structural investigation in few small remnant basins.

Deciphering the interplay existing between tectonics and granitic pluton emplacement mechanisms is of fundamental importance for the understanding of the evolution of the continental crust (e.g., Bouchez & Gleizes, 1995;[START_REF] Gleizes | Variscan granites of the Pyrenees revisited: their role as syntectonic markers of the orogen[END_REF][START_REF] De Saint Blanquat | Multiscale magmatic cyclicity, duration of pluton construction, and the paradoxical relationship between tectonism and plutonism in continental arcs[END_REF][START_REF] Žák | Structure, emplacement, and tectonic setting of Late Devonian granitoid plutons in the Teplá-Barrandian unit, Bohemian Massif[END_REF]. During the emplacement of granitic plutons, magmatic fabrics could not only record mineral shape preferred orientation in the magma flow but also retain information on strain field to which the magma was subjected [START_REF] Paterson | A review of criteria for the identification of magmatic and tectonic foliations in granitoids[END_REF][START_REF] Bouchez | Granite is Never Isotropic: An Introduction to AMS Studies of Granitic Rocks[END_REF][START_REF] Žák | Magmatic to solid state fabrics in syntectonic granitoids recording early Carboniferous orogenic collapse in the Bohemian Massif[END_REF]2013). The solid-state fabrics record structural deformation after complete crystallization of the magma [START_REF] Paterson | A review of criteria for the identification of magmatic and tectonic foliations in granitoids[END_REF]. Consequently, structural studies of granite plutons have been used for their potential in recording the tectonic regime coeval with their emplacement (e.g., Bouchez & Gleizes, 1995;Žák et al., 2008;[START_REF] Lin | Late Mesozoic compressional to extensional tectonics in theYiwulüshan massif, NE China and its bearing on the evolution of the Yinshan-Yanshan orogenic belt part II: Anisotropy of magnetic susceptibility and gravity modeling[END_REF].

Up to now, the Late Triassic plutons in the northern NCB have not been the subject of structural studies that would shed light on Late Triassic tectonic regime. To offer direct structural evidence on the Late Triassic granite emplacement, the Dushan pluton in the Yanshan fold-and-thrust belt (YFTB) was chosen for this study. On the basis of a multidisciplinary investigation, including structural geology, isotope chronology, AMS measurement, and gravity modeling, this study reveals the emplacement mechanism of the Late Triassic Dushan pluton and coeval tectonic regime.

Geological overview of the YFTB

After its cratonization during the Paleoproterozoic (Zhao et al., 2001), the NCB was overlain by a Mesoproterozoic to Permian sedimentary cover, separated by a regional unconformity between the Middle Ordovician and Upper Carboniferous-Permian strata (Li et al., 2016). The geological evolution of the YFTB began in the Late Paleozoic-Early Mesozoic, resulting possibly from the closure of the Paleo-Asian Ocean [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern 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] Xu | Middle Paleozoic convergent orogenic belts in western Inner Mongolia (China): framework, kinematics, geochronology and implications for tectonic evolution of the Central Asian Orogenic Belt[END_REF]. The related deformation was featured by the E-W trending ductile shear zones (e.g., Chicheng-Fengning, Fengning-Longhua, and Damiao-Niangniangmiao ductile shear zones) and thick-and thin-skinned folds and faults (e.g., Unnamed fault, Malanyu anticline, and Jixian thrust) [START_REF] Wang | Cratonic reactivation and orogeny: an example from the northern margin of the North China Craton[END_REF]Figure 3.1). The Late Paleozoic-Early Mesozoic magmatism is widely developed in the YFTB [START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF]Figure 3.1c).

The intra-continental deformation and magmatism, traditionally referred to as the Yanshanian movement, occurred during the Jurassic to Cretaceous. The NE-and E-Wtrending thrust faults are distributed throughout the YFTB (e.g. [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Faure | Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the NCC?[END_REF]Figure 3.1). The YFTB generally trends E-Wwards, but NE-SWwards in the east.

Several generations of out-of-sequence thrusts took place during the Middle Jurassic to

Cretaceous and crosscut preexisting southward verging E-W trending fold-and-thrust belt [START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF]. Several Jurassic to Cretaceous fault-bounded basins, related to multi-phase thrusting events, are widely distributed in the YFTB, whereas the Triassic strata are only exposed in few small remnant basins as mentioned above (Figure 3 There is no clear contact between them. Mineral fabrics are well developed in the southwest southwestern border of the Dushan pluton (Figure 3.4d), without evident stretching lineations.

Close to the southeastern contact with the country rocks, the foliation dips toward the interior of the pluton (Figure 3.2). This southwestern part of the pluton also reveals a mylonitic fabric with a well-defined lineation that locally develops ( Figures 3.2 and3.4e-3

Microscopic Observation

Microstructural investigations of the plutons provide insights into the crystallizationdeformation relationships from magma cooling to post-solidus fabrics [START_REF] Paterson | A review of criteria for the identification of magmatic and tectonic foliations in granitoids[END_REF].

Magmatic fabric is recorded when the pluton does not suffer solid-state deformation, whereas a solid-state fabric characterizes a deformation after magma full crystallization (e.g., [START_REF] Talbot | Emplacement in an extensional setting of the Mont Lozère-Borne granitic complex (SE France) inferred from comprehensive AMS, structural and gravity studies[END_REF]. In the Dushan pluton, microscopic observations were performed to establish the relationships between the minerals and magnetic fabrics. Through observations of more than sixty thin-sections, three microscopic fabric types can be distinguished in the Dushan pluton (Figure 3.5).

( contact with the country rocks.

New Dating Results

Several isotope chronology data have been documented in the Dushan pluton and its neighboring Dashizhu pluton (Figure 3.2). Late Triassic ages are rather consistent for the Dushan pluton (223-215 Ma;[START_REF] Luo | SHRIMP U-Pb zircon dating of the Dushan granitic pluton and related granite-porphyry dyke, eastern Hebei province, China, and their geological significance[END_REF][START_REF] Ye | Petrogenesis and emplacement deformation of the Late Triassic Dushan composite pluton in the Yanshan fold and thrust belt: Implications for the tectonic settings of the northern margin of the North China Craton during the Early Mesozoic (in Chinese with English abstract)[END_REF][START_REF] Xu | Petrogenesis and geological implications for the Mesozoic granites in Qinglong area, eastern Hebei Province[END_REF][START_REF] Jiang | Geochronology and petrogenesis of the granites in Malanyu anticline in eastern North China Block[END_REF], and they are relatively close to those of the Dashizhu pluton ranging from 266 to 224

Ma [START_REF] Ye | Petrogenesis and emplacement deformation of the Late Triassic Dushan composite pluton in the Yanshan fold and thrust belt: Implications for the tectonic settings of the northern margin of the North China Craton during the Early Mesozoic (in Chinese with English abstract)[END_REF][START_REF] Xiong | Geochronology, petrology and geochemistry of the Mesozoic Dashizhu granites and lamprophyre dykes in eastern Hebei -western Liaoning: implications for lithospheric evolution beneath the North China Craton[END_REF]. To clarify temporal precedence between two plutons, new zircon U-Pb dating was performed by a Cameca IMS 1280 large-radius SIMS at IGGCAS. anisotropic rocks where macro and microscopic features cannot be observed [START_REF] Archanjo | Magnetic fabrics vs. magnetite and biotite shape fabrics of the magnetite-bearing granite pluton of Gameleiras (Northeast Brazil)[END_REF]Bouchez & Gleizes, 1995;[START_REF] Bouchez | Granite is Never Isotropic: An Introduction to AMS Studies of Granitic Rocks[END_REF][START_REF] Benn | Magmatic fabrics in plutons as markers of regional strains and plate kinematics: Example of the Cretaceous Mt. Stuart pluton[END_REF]). An AMS study has been therefore carried out on the Dushan pluton in order to reveal its magnetic fabrics and set up the surface structure of the pluton. It is worthy to notice that the AMS study has not been performed in the neighboring coeval Dashizhu pluton due to the poor outcrop conditions.

Sampling and Measurements

A total of 252 cores from 41 sampling sites have been collected in the Dushan pluton. Five to eight cores of 2.5 cm in diameter have been sampled from each site. In the laboratory, each core was cut into cylindrical specimens of 2.2 cm in length. A KLY4 susceptometer was used to measure both the anisotropy magnetic susceptibility and the bulk susceptibility (Figure 3.7).

The statistical analysis of the AMS data was carried out using the ANISOFT package [START_REF] Jelinek | Characterization of the magnetic fabric of rocks[END_REF] that calculates the mean orientation of three principal axes of the AMS ellipsoid (K1 ≥ K2 ≥ K3), the shape parameter (T), and the anisotropy degree (PJ). To identify the magnetic carriers, the magnetic mineralogy was investigated with the following measurements (Figure

Magnetic Susceptibility Carrier

The mean magnetic susceptibility, Km = (K1 + K2 + K3)/3, of 41 sampling sites displays a rather large range of values in the Dushan pluton, from 397 to 25,800×10 -6 SI (Figure 3.7a and Table 3.2). 27 out of 41 AMS (more than 66%) sites reveal high Km values (>500×10 -6 SI),

indicating that ferromagnetic minerals are the principal magnetic carriers (Figure 3.7a, Table Table 3. According to the ratios of hysteresis parameters Mr/Ms and Hcr/Hc, the mean grain size of the magnetite is within the pseudo-single domain (PSD) range [START_REF] Dunlop | Theory and application of the day plot (Mrs/Ms versus Hcr/Hc) 1. Theoretical curves and tests using titanomagnetite data[END_REF]Figure 3.7b).

In conclusion, despite the presence of abundant biotite, the magnetite is likely the dominant contributor to the magnetic susceptibility of more than 96% AMS sites in the Dushan pluton. For 2 sites (DS17 and DS20), biotite may be a significant magnetic susceptibility carrier.

The magnetic susceptibility seems to vary according to petrofacies type and the relative contents of magnetite. Moreover, the paramagnetic and ferromagnetic minerals often carry compatible magnetic fabrics [START_REF] Archanjo | Magnetic fabrics vs. magnetite and biotite shape fabrics of the magnetite-bearing granite pluton of Gameleiras (Northeast Brazil)[END_REF][START_REF] Martín-Hernández | Paramagnetic anisotropy of magnetic susceptibility in biotite, muscovite and chlorite single crystals[END_REF]. Since there is no magnetite in single-domain (SD) that could bring inverse fabrics, the principal axis of the magnetic susceptibility ellipsoid (i.e., K1 and K3 axes) can be correlated to the lineation and the pole of foliation, respectively (e.g. [START_REF] Hargraves | Distribution anisotropy: the cause of AMS in igneous rocks?[END_REF][START_REF] Tarling | Magnetic Anisotropy of Rocks[END_REF].

3.6.3. Anisotropy Degree and Shape Parameter Figure 3.7c shows that more than 58% of sampled sites in the Dushan pluton display an anisotropy degree higher than 1.2 with a positive correlation between PJ and Km. In the arcshaped gneissic and locally mylonitic zones where moderate to strong solid-state deformation occurred, the PJ values are not higher than elsewhere (Figure 3.9b). Therefore, it seems that the higher PJ values have no correlation with strain intensity. The shape parameter T varies from -0.728 to 0.733 (Figures 3.7d [START_REF] Jelinek | Characterization of the magnetic fabric of rocks[END_REF], cannot constrain strain patterns in this study.

Fabric Pattern and Comparison with Mesoscopic Fabric

For each site, the site-average orientation with corresponding 95% confidence level (α95max and α95min) was calculated for K1 and K3 axes [START_REF] Jelinek | Statistical processing of anisotropy of magnetic susceptibility measured on groups of specimens[END_REF]Figure 3.10). Note that for a confidence level larger than 25°, the direction of corresponding magnetic axis is considered as poorly defined; when lower than 25°, it is considered as well-defined or reliable. The latter is the case for more than 74% of the AMS sites for both K1 and K3. Figure 3.11 shows that the magnetic foliations measured in the laboratory are rather consistent with the mesoscopic fabrics observed in the field.

In the Dushan pluton, both mesoscopic and magnetic foliations with moderate to steep outward dipping display a well-defined elliptic pattern with a NE-SW oriented long axis (Figure 3.11a). In the northeastern part of the pluton, the foliations are sub-vertical and close to the southeastern border, they dip inward and strike sub-parallel to the contact with the country rocks. The magnetic lineations display gentle to moderate NE-SW plunging throughout the pluton except in its northeastern part where they become more scattered in trends and locally steeper dipping (Figure 3.11b).

Gravity Modeling

Gravity modeling has been proved its efficiency to depict the architecture of deep structures, especially for granitic plutons [START_REF] Améglio | Geophysical imaging of the shape of granitic intrusions at depth: a review[END_REF][START_REF] Vigneresse | Use and misuse of geophysical data to determine the shape at depth of granitic intrusions[END_REF]. In order to constrain the geometry of the Dushan pluton, its shape, and possible feeder zones, a gravity modeling study has been performed. Meanwhile, the Dashizhu pluton has also taken into account to clarify its relationship with the Dushan pluton in the gravity modeling study.

The available Bouguer anomaly map (1: 200,000) was derived from the Chinese regional gravity survey. The short wavelengths of the gravity anomaly originate from the upper crust (down to a few kilometers). The long wavelengths of the gravity anomaly, due to deeper structures, must be removed from the complete Bouguer anomaly to highlight the Dushan pluton related anomalies. The filtered regional Bouguer anomaly has been computed from a lower-resolution (2′×2′) Bouguer grid, which was acquired from the International Gravimetric Bureau database [START_REF] Bonvalot | World gravity map[END_REF]. The long wavelengths of the gravity anomaly were extracted using a 380 km low-pass Butterworth filter after several attempts. The residual Bouguer anomaly map was obtained by subtracting the filtered regional Bouguer anomaly (Figure 3.12a). The negative anomalies show a NE-SW trending elliptical shape that more or less correlates with the main geological boundary of the Dushan pluton (Figure 3.12a). The Dushan pluton shows a negative anomaly with an anomaly center in its northeastern part, suggesting corresponds to the root of the pluton. In its north, the negative anomaly beyond the contact is likely related to the outward extension of the pluton below its country rocks. A maximal thickness of ~7 km in the southeastern part progressively decreases southwestward to a minimum of ~1 km. However, it exists a higher negative anomaly close to the southwestern border, indicating local thickening of the pluton. The Dushan pluton presents an overall southwestward thinning tabular or tongue-like shape with a feeder zone in its northeast. In the Dashizhu pluton, the negative anomaly, located in the west of the current exposure, is beyond the contact with cover rocks. The NE trending highest negative anomaly, that likely represents its root, is located in the western corner of the current exposure. In its current exposure, it changes into a positive anomaly away from the western corner. It seems that the Dashizhu pluton presents a funnel shape that sharply thins outward from a feeder zone in its western corner. Combining this dome geometry with the absence of top-to-the-SW ductile shearing in the country rocks, it undoubtedly argues for the contemporaneity between the pluton emplacement and solid-state deformation. Our field and microscopic observations, together with AMS data, allow us to recognize a continuum of fabric variation from magmatic to solid-state conditions during the pluton emplacement.

Emplacement mode

The Dashizhu pluton presents a funnel-shaped architecture with a feeder zone in the northwestern corner of its current exposure (Figures 3.12b The Dushan pluton has a NE-SW trending tabular or tongue-like shape with a feeder zone in its northeast. The roof is estimated as a dome-like structure due to the moderate to high outward dipping foliations parallel to the border (Figure 3.12a), except that the biotite-rich marginal facies. Close to the southeastern border, the foliations present inward dipping and strike sub-parallel to the contact with the country rocks. These foliations roughly conform to the overall attitude of the country rocks near the pluton (Figure 3.2). Taking the geochronological uncertainties into account, it seems that the biotite-rich magma batch probably firstly made it ascent via the feeder zone and injected as a sill into the Malanyu anticline (Figure 3.13). Following monzogranite magma may relatively upwell to inflate and push aside the country rocks to build the Dushan pluton. No internal petrographic zoning of pluton with sharp facies boundaries can be observed, although a progressive mineral fabric change is observed. As no related ductile deformation has been observed in the country rocks along the contact between the pluton and the country rocks, it seems that the emplacement of the Dushan pluton could not be interpreted as a nested diapir of expanded plutons that implies rising of large magma batches, but inflation of small conduit-fed magma batches [START_REF] Paterson | Bursting the bubble of ballooning plutons: A return to nested diapirs emplaced by multiple processes[END_REF].

The following lines of evidence suggest that the inflation occurred not only upwards and downwards, but also laterally: (1) a dome-like roof, confined by outward dipping foliations;

( The magma spreads southwestwards from the feeder zone until loss of heat and its crystallization, while the later magma continues to expand the already crystallized southwestern margin. This inflation formed an arc-shaped, gneissic to mylonitic foliation in

Tectonic implication

The fabrics of the Dushan pluton may be mainly explained by magma intrusion, pluton inflation, and syn-emplacement solid-state deformation. The fabrics recorded a continuum of fabric variation from magmatic to solid-state conditions during the pluton emplacement. In the study area, a syn-magmatic ductile shearing coeval with the fabrics observed within the Dushan pluton is absent in the country rocks. Moreover, in the regional scale, no syn-magmatic tectonic phenomenon can be documented. Therefore, the pluton emplacement was probably mainly driven by magma buoyancy without significant influence of regional tectonics. In other words, both mesoscopic and magnetic fabrics in the Dushan pluton were rather related to its building than the Late Triassic regional tectonics, if there existed any. Alternatively, the Late Triassic was a period of relative "tectonic quiescence" in the northern NCB after the final formation of the CAOB.

However, a Late Triassic extensional setting for the northern NCB has been proposed according to the geochemistry of the E-W trending alkaline intrusive complexes [START_REF] Yang | Petrogenesis of silica-saturated and silica-undersaturated syenites in the northern North China Craton related to post-collisional and intraplate extension[END_REF][START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF]. The geochemistry of the Dushan pluton, similar to the Late Triassic alkaline intrusive complexes, indicates that it originated from partial melting of the lower crust with a contribution of mantle-derived materials during an extensional setting [START_REF] Ye | Petrogenesis and emplacement deformation of the Late Triassic Dushan composite pluton in the Yanshan fold and thrust belt: Implications for the tectonic settings of the northern margin of the North China Craton during the Early Mesozoic (in Chinese with English abstract)[END_REF][START_REF] Jiang | Geochronology and petrogenesis of the granites in Malanyu anticline in eastern North China Block[END_REF]. Fining and deepening upward depositional system and abundant volcaniclastic rocks in the remnant basins suggest a Late Triassic extensional setting in the northern NCB [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF]Figure 3.1). In the south of Sonid Zuoqi in the vicinity of the Solonker zone, a NE-SW trending extension has been also documented in a Late Triassic metamorphic core complex [START_REF] Davis | Indosinian extension in the Solonker suture zone: the Sonid Zuoqi metamorphiccore complex, Inner Mongolia, China[END_REF]Figure 3.1b). Nevertheless, the Dushan pluton did not record any regional extension feature, coeval with its emplacement process. To clarify the Late Triassic tectonic and geodynamic setting of the NCB, more detailed structural studies are needed. The early Mesozoic magmatism, represented by E-W trending Late Triassic alkaline intrusive complexes, is conspicuous in the northern NCB. However, their tectonic and geodynamic settings are still debated [START_REF] Yang | Petrogenesis of silica-saturated and silica-undersaturated syenites in the northern North China Craton related to post-collisional and intraplate extension[END_REF][START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF][START_REF] Zhao | A new Triassic shortening-extrusion tectonic model for Central-Eastern Asia: Structural, geochronological and paleomagnetic investigations in the Xilamulun Fault (North China)[END_REF].

Based on structural observations and paleomagnetic studies, one group of researchers considers that these Late Triassic granitic and syenitic plutons were due to large-scale Triassic thrusting and strike-slip faulting in the northern margin of the NCB and produced in the local extensional areas by the pull-apart of the strike-slip faults (e.g., [START_REF] Zhao | A new Triassic shortening-extrusion tectonic model for Central-Eastern Asia: Structural, geochronological and paleomagnetic investigations in the Xilamulun Fault (North China)[END_REF]. According to geochemical studies, another group proposes that the Late Triassic alkaline complexes in the northern NCB, especially silica-undersaturated syenites, occurred in an intracontinental extensional tectonic setting (e.g., [START_REF] Yang | Petrogenesis of silica-saturated and silica-undersaturated syenites in the northern North China Craton related to post-collisional and intraplate extension[END_REF][START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF], implying the early timing of cratonic destruction during the Late Triassic (Han et al., 2004). The Late Triassic tectonic regime is important to understand the tectonic and geodynamic evolution of the NCB.

However, only few small remnants of Late Triassic sedimentary basins can be observed and offer little coeval structural information in the northern NCB due to the intense post-Triassic tectonics (i.e., Xiabancheng basin and Niuyingzi-Dengzhangzi basin in the Yanshan Fold-and-Thrust Belt (YFTB); Figure 4.1; [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF]. Moreover, it is difficult to recognize the regional tectonic framework from these few small remnant basins. Due to less impressive and controversial evidence, the nature of the Triassic regime is in debate since long time with different hypotheses. Late Triassic contractional tectonics was proposed according to the unconformity between Triassic and Lower Jurassic strata, and Lower Jurassic syntectonic conglomerate [START_REF] Zhao | The Mesozoic orogenesis and tectonic evolution of the Yanshan area (in Chinese)[END_REF][START_REF] Liu | Rapid exhumation of basement rocks along the northern margin of the North China craton in the early Jurassic: Evidence from the Xiabancheng Basin, Yanshan Tectonic Belt[END_REF]. Detrital zircon dating and sedimentary studies suggest that the conformable Upper Triassic strata were deposited in an extensional setting [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF][START_REF] Meng | Tectonic evolution of early Mesozoic sedimentary basins in the North China block[END_REF]. Consequently, the paucity of structural data makes difficult to assess the Late Triassic tectonic regime.

During pluton emplacement, magma fabrics can potentially record information on both magma dynamics and regional strain fields to which the magma was subjected (e.g., [START_REF] Bouchez | Granite is Never Isotropic: An Introduction to AMS Studies of Granitic Rocks[END_REF]Paterson et al., 1998;[START_REF] Sant'ovaia | Composite-laccolith emplacement of the post-tectonic Vila Pouca de Aguiar granite pluton (northern Portugal): a combined AMS and gravity study[END_REF]. The solid-state fabrics present structural deformation after magma full crystallization [START_REF] Paterson | A review of criteria for the identification of magmatic and tectonic foliations in granitoids[END_REF]. Therefore, the fabric pattern and shape of pluton are crucial to decipher the pluton emplacement process. The structural study of plutons is an effective and practical way to unravel regional tectonic setting coeval with the emplacement process (e.g., [START_REF] Bouchez | Granite is Never Isotropic: An Introduction to AMS Studies of Granitic Rocks[END_REF][START_REF] De Saint Blanquat | Multiscale magmatic cyclicity, duration of pluton construction, and the paradoxical relationship between tectonism and plutonism in continental arcs[END_REF]. Numerous studies have proven that the fabrics of granitic plutons may provide signatures of the local and regional constraints on the pluton emplacement (e.g., Paterson et al., 1998;[START_REF] De Saint Blanquat | Multiscale magmatic cyclicity, duration of pluton construction, and the paradoxical relationship between tectonism and plutonism in continental arcs[END_REF]Lin et al., 2013b). Therefore, Late Triassic plutons from the NCB present good opportunities to realize this purpose, and, accordingly, the Wangtufang pluton was chosen for this study (Figure 4.1). Indeed, such studies have been rarely performed on Late Triassic plutons of the northern NCB. An integrated multidisciplinary investigation, including structural geology, geochronology, geochemistry, Anisotropy of magnetic susceptibility (AMS), and gravity modeling, has been conducted to decipher the Late Triassic tectono-magmatic setting in the northern NCB. Given the correlation with other contemporaneous plutons or tectonics, the proposed model may have regional implications for the Late Triassic tectonic setting in the northern NCB.

Geological setting

After its assembly through the collision of the Eastern, Intermediate (or Fuping), and

Western blocks during the Paleoproterozoic (Zhao et al., 2001;[START_REF] Faure | Polyorogenic evolution of the Paleoproterozoic Trans-North China Belt, new insights from the in Lüliangshan-Hengshan-Wutaishan and Fuping massifs[END_REF][START_REF] Li | Mesozoic tectonics in the Eastern Block of the North China Craton: implications for subduction of the Pacific plate beneath the Eurasian plate[END_REF][START_REF] Li | Paleoproterozoic structural evolution of the southern segment of the Jiao-Liao-Ji Belt, North China Craton[END_REF], the NCB formed a stable craton from Mesoproterozoic to Paleozoic.

Archaean and Paleoproterozoic gneiss, migmatites and granites were overlain by a Mesoproterozoic to Permian sedimentary cover, separated by a widespread disconformity between the Middle Ordovician and Upper Carboniferous sequences [START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF]. The closure time of the Paleo-Asian Ocean to the north of the NCB is still controversial. Some authors argue for a Late Permian to the Early Triassic age (e.g., [START_REF] Windley | Tectonic models for accretion of the Central Asian Orogenic Belt[END_REF][START_REF] Xiao | A tale of amalgamation of three Permo-Triassic collage systems in Central Asia: oroclines, sutures, and terminal accretion[END_REF], whereas others propose the Paleo-Asian Ocean closed during the Late Devonian, followed by the Late Carboniferous-Triassic intracontinental tectonics [START_REF] Xu | Middle Paleozoic convergent orogenic belts in western Inner Mongolia (China): framework, kinematics, geochronology and implications for tectonic evolution of the Central Asian Orogenic Belt[END_REF][START_REF] Zhao | Did the Paleo-Asian Ocean between North China Block and Mongolia Block exist during the late Paleozoic? first paleomagnetic evidence from central-eastern Inner Mongolia, China[END_REF]. In the south, the NCB collided with the South China Block before the Middle Devonian (e.g., [START_REF] Mattauer | Tectonics of the Qinling belt: build-up and evolution of eastern Asia[END_REF][START_REF] Xu | Deformation characteristics and Tectonic evolution of the eastern Qinling orogenic belt[END_REF] or in the Triassic (e.g., [START_REF] Meng | Timing of collision of the North and South China blocks: controversy and reconciliation[END_REF]Hacker et al., 2000;Li et al., 2010Li et al., , 2011[START_REF] Li | Triassic southeastward subduction of North China Block to South China Block: insights from new geological, geophysical and geochemical data[END_REF]Li et al., , 2018)). In the YFTB, the E-W trending ductile shear zone and thick-and thin-skinned folds and faults occurred progressively from the northern margin toward the interior [START_REF] Wang | Cratonic reactivation and orogeny: an example from the northern margin of the North China Craton[END_REF]. The ductile shear zone concerns the E-W trending Chicheng -Fengning, Fengning -Longhua, and Damiao -Niangniangmiao ductile shear zones in the north [START_REF] Wang | Cratonic reactivation and orogeny: an example from the northern margin of the North China Craton[END_REF][START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF]Figure 4.1), and the E-W trending folds and thrusts include the Unnamed fault, Malanyu anticline, and Jixian thrust fault in the south [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Ma | SHRIMP U-Pb dating of zircon from Panshan granitoid pluton in Yanshan orogenic belt and its tectonic implications (in Chinese with English abstract)[END_REF]. Few Triassic remnant basins and a large number of contemporaneous plutons are exposed in the northern NCB [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF][START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF].

During the Jurassic to earliest Cretaceous, the Mongol-Okhotsk Ocean closed progressively from west to east in the north of the East Asian continent [START_REF] Zorin | Geodynamics of the western part of the Mongolia-Okhotsk collisional belt, Trans-Baikal region (Russia) and Mongolia[END_REF][START_REF] Daoudene | Timing of exhumation of the Ereendavaa metamorphic core complex (north-eastern Mongolia)-U-Pb and 40 Ar/ 39 Ar constraints[END_REF]. Meanwhile, the subduction of the Paleo-Pacific Ocean plate occurred in the southeast of the East Asian continent [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF]. A large scale intra-continental deformation and magmatism, traditionally referred to as the Yanshanian movement, occurred in the NCB [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Faure | Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the NCC?[END_REF][START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF][START_REF] Dong | Late Jurassic-Early Cretaceous continental convergence and intracontinental orogenesis in East Asia: a synthesis of the Yanshan revolution[END_REF]. The YFTB is a typical intracontinental orogen, formed in the northern part of the NCB (Davis et al., 2001). The thrust faults, which strike E-W in the west and NE-SW in the east, are distributed throughout the YFTB (e.g., [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Faure | Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the NCC?[END_REF]Figure 4.1). As mentioned above, due to the intense deformation during the Jurassic Yanshanian contractional events, only few pre-Jurassic structures could be surely recognized in the YFTB (e.g., [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF][START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF][START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF]Figure 4.1). In the Early Cretaceous, the NCB was dominated by extensional tectonics (i.e., metamorphic core complexes (MCCs), A-type magmatism, graben or half-graben basins; [START_REF] Li | Paleoproterozoic structural evolution of the southern segment of the Jiao-Liao-Ji Belt, North China Craton[END_REF][START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF], Lin et al., 2018). Analyses of whole-rock major and trace elements were carried out at the IGGCAS. Major elements were analysed by X-ray spectrometry. Analytical precision is estimated at 1-5% for major elements. Trace elements were determined by inductively coupled plasma mass spectrometry (ICP-MS). The major-and trace-element data are documented in

Anisotropy of magnetic susceptibility

Field and microscopic observations suggest that both planar and linear fabrics cannot be directly observed in the Wangtufang pluton. Magnetic fabrics can often record the fabric elements of anisotropic rocks where macro and microscopic features fail to do it [START_REF] Archanjo | Magnetic fabrics vs. magnetite and biotite shape fabrics of the magnetite-bearing granite pluton of Gameleiras (Northeast Brazil)[END_REF]Bouchez and Gleizes, 1995;[START_REF] Bouchez | Granite is Never Isotropic: An Introduction to AMS Studies of Granitic Rocks[END_REF]. In order to assess the fabric elements, an AMS study has been carried out. Two hundred and four cores from 36 sites have the anisotropy degree (PJ) were calculated by the ANISOFT package [START_REF] Jelinek | Characterization of the magnetic fabric of rocks[END_REF]. The magnetic mineralogy was investigated to identify the magnetic susceptibility carriers by several methods, including: (1) Isothermal Remanent Magnetization (IRM); ( 2) thermomagnetic (K-T) curves, and (3) hysteresis loops.

Magnetic mineralogy

The histogram of mean magnetic susceptibility, Km = (K1 + K2 + K3)/3, displays a large range of values in 36 sites, from 90 to 95,900×10 -6 SI (Figure 4.10a and Table 4.4). In the diorite, all 16 sites exhibit Km values higher than 7,000×10 -6 SI (7,540 to 95,900×10 -6 SI), demonstrating the predominance of ferromagnetic minerals. In the syenogranite, Km mainly varies from about 90 to 15,400×10 -6 SI, and 7 out of 20 sites show Km values lower than 500×10 -6 SI, implying that the paramagnetic minerals (biotite) may be the main carriers of the magnetic susceptibility (e.g., [START_REF] Tarling | Magnetic Anisotropy of Rocks[END_REF]. In 13 out of 20 sites, Km values are higher than 500×10 -6 SI, suggesting the presence of ferromagnetic minerals. It seems that both paramagnetic and ferromagnetic minerals are the contributors to the magnetic fabrics in the syenogranite.

All hysteresis curves of six representative samples display nonlinear variations . Sudden saturation of the isothermal magnetic remanence below 300 mT occurs in all samples . Thermomagnetic measurements show a rapid drop of magnetic susceptibility at ~580°C . All these results suggest that magnetite is likely an overwhelming contributor to the magnetic carriers in the Wangtufang pluton despite the presence of biotite. The ratios of hysteresis parameters Mr/Ms and Hcr/Hc display the mean grain size of the magnetite of the analyzed samples is within the pseudo-single domain (PSD) zone [START_REF] Dunlop | Theory and application of the day plot (Mrs/Ms versus Hcr/Hc) 1. Theoretical curves and tests using titanomagnetite data[END_REF]Figure 4.12), indicating that the principal axes of the magnetic susceptibility ellipsoid (K1 and K3 measured in this study) correspond to the major morphological axes of minerals, representing magnetic lineation and the pole of magnetic foliation, respectively. observations, and the remaining sites come from the diorite, implying that their higher PJ value may be due to the high concentration of magnetite [START_REF] Cruden | Magnetic fabric evidence for conduit-fed emplacement of a tabular intrusion: Dinkey Creek Pluton, central Sierra Nevada batholith, California[END_REF]. The shape parameter (T) mainly ranges between -0.551 and 0.829, showing a dominant oblate shape (~86%) for magnetic fabrics (Figures 4.10c and 4.10d). Obvious correlations between PJ, T, and Km is lacking, implying that AMS varies independently from the magnetic minerals [START_REF] Borradaile | Tectonic applications of magnetic susceptibility and its anisotropy[END_REF]Figures 4.10b-4.10d).

AMS results

The site-average orientation with corresponding 95% confidence level (α95max and α95min)

was calculated for K1 and K3 axes of each site [START_REF] Jelinek | Statistical processing of anisotropy of magnetic susceptibility measured on groups of specimens[END_REF]Figure 4.13). For a confidence level larger than 25°, the direction of the corresponding magnetic axis is considered as poorly

Gravity modeling

Gravity modeling has been long proved its efficiency to constrain the geometry and possible feeder zones of pluton (e.g., [START_REF] Vigneresse | Use and misuse of geophysical data to determine the shape at depth of granitic intrusions[END_REF]Amé glio and Vigneresse, 1999;Lin et al., 2013b). We carried out a gravity study to characterize the shape of the Wangtufang pluton at depth.

Residual Bouguer anomaly and 2D modeling

The short wavelengths of the gravity anomaly originate from upper crust (down to a few kilometers). The long wavelengths of the gravity anomaly, which reflect the deep structures, must be removed from the complete Bouguer anomaly to highlight the Wangtufang pluton related anomalies. Available Bouguer anomaly map (1: 200,000) in the Wangtufang pluton and its surrounding area was derived from the Chinese regional gravity survey. A regional lower-resolution (2′×2′) Bouguer grid acquired from the International Gravimetric Bureau database [START_REF] Bonvalot | World gravity map[END_REF]. The long wavelengths of the gravity anomaly were extracted using a 200 km low-pass Butterworth filter from a lower-resolution (2′×2′) Bouguer grid after several attempts. The residual Bouguer anomaly map was obtained from the complete Bouguer anomaly by subtracting the filtered regional Bouguer anomaly related to the long wavelengths (Figure 4.15a).

2D gravity modeling was also performed to characterize the geometry of the Wangtufang pluton. To build these models, several constraints have been taken into account, including (1) geological contacts, lithological units, and structural data from geological maps and our field observations; (2) geometrical constraints, derived from indirect analysis of gravity anomaly, and (3) densities of geological units, determined by the laboratory measurements.

The residual gravity anomaly has been modelled along three profiles across the center of the pluton (Figure 4.15b).

Results

In the residual Bouguer gravity anomaly map, the Wangtufang pluton displays a NE-SW trending elongated negative anomaly with a highest value in its center (Figure 4.15a). The negative anomalies decrease, even change into positive anomalies outwards. Particularly, the diorite shows a less negative anomaly in its northwest and a higher positive anomaly in its southeast, suggesting its thin thickness. The Wangtufang pluton becomes thinner outwards, presenting an overall funnel-shaped geometry. The country rocks display high positive anomalies in its east. To the southwest, the country rocks show a high negative anomaly, indicating the possible continuity of the pluton underlain the country rocks. The highest negative anomaly is located in its northwest due to a large area of Archaean migmatitic granite.

Three 2D modeling profiles image the detailed geometry of the two major intrusions (Figure 4.9). Considering that the Wangtufang pluton intrudes into Archaean gneiss and migmatitic granite (>2.5 Ga), the sources should be derived from the partial melting of Archean TTG in the lower crust with a contribution from a depleted mantle source.

The ɛHf(t) values for the syenogranite range from -9.78 to -6.54 and those of the diorite from -3.42 to -0.01 (Figure 4.9). Although the diorite was mainly derived from melting of ancient lower crust, εHf(t) values of the diorite are much higher than normal crustal melting (Figure 4.9), requiring some input of depleted asthenospheric mantle components. The εHf(t) values of the syenogranite are higher than those of the Archean lower crust (-28 ~ -13; Jiang et al., 2013).

It suggests that the syenogranite has a contribution from an enriched subcontinental lithospheric mantle. Therefore, the Wangtufang pluton was mainly derived from partial melting of the ancient lower crust of the NCB with some involvements of enriched subcontinental lithospheric mantle and depleted asthenospheric mantle components. Coeval with the Wangtufang pluton, Late Triassic silica-undersaturated syenites in the alkaline complexes in the northern NCB were derived from partial melting of an enriched lithospheric mantle, coupled with crustal assimilation and crystal fractionation in an intracontinental extensional setting (i.e., rift; [START_REF] Yang | Petrogenesis of silica-saturated and silica-undersaturated syenites in the northern North China Craton related to post-collisional and intraplate extension[END_REF]. Its similarity with the contemporaneous alkaline complexes may indicate an asthenosphere-lithospheric mantle interaction in the northern NCB during the Late Triassic [START_REF] Yang | Petrogenesis of silica-saturated and silica-undersaturated syenites in the northern North China Craton related to post-collisional and intraplate extension[END_REF][START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF]. Briefly, the Wangtufang pluton was derived from the mixing of magmas from asthenospheric upwelling-induced melting of subcontinental lithospheric mantle and ancient lower crust during an intracontinental extensional setting.

Emplacement model

Geochronology data suggest that both the syenogranite and the diorite were emplaced in the Late Triassic (both at ~209 Ma; et al., 2000). A dominant gentle magnetic fabric could be formed by flattening of magma mush against its roof, driven by later magma pulses [START_REF] Mcnulty | Multistage emplacement of the mount givens pluton, central Sierra Nevada batholith, California[END_REF]. The arrivals of later magma batches resulted in downward inflation of magma chamber against the roof. Floor depression occurred and created space for the pluton building (Figure 4.16). Close to the pluton, the country rocks were pushed aside and it resulted in the border-parallel foliations in the surrounding gneiss (Figure 4.2). We suggest that the diorite made a first intrusion, probably with a thin thickness, and then the syenogranite intruded and possibly dismembered the former with a series of dykes after the diorite had fully crystallized (Figure 4.16).

Relationships between the pluton emplacement and regional tectonics

The microstructures observed in the Wangtufang pluton are typical of magmatic or sub magmatic fabrics that developed during, or just after, the full crystallization of the magma.

However, the lack of significant emplacement-related ductile deformation in both the pluton and its country rocks does not preclude that a regional tectonic event, dominated by brittle deformation occurred during the Wangtufang pluton emplacement. The syenogranite intruded the diorite after its full crystallization as shown by the dyke swarm containing diorite xenoliths (Figure 4.4b). All the syenogranitic dykes are steeply dipping and striking NW-SE. We interpret these syenogranite dykes as tension gashes developed in the brittle upper crust, and controlled by a NE-SW stretching. This view implies a possible NE-SW trending regional extension (Figure 4.16).

Moreover, the plutons shape and internal fabric can record some increments of the regional strain to which the magma was subjected (e.g., Paterson et al., 1998;[START_REF] Sant'ovaia | Composite-laccolith emplacement of the post-tectonic Vila Pouca de Aguiar granite pluton (northern Portugal): a combined AMS and gravity study[END_REF]. Because mineral fabrics are easily reset, they reflect only the last strain increment developed in soft material such as magmatic rocks before their full crystallization. Furthermore, without any regional strain or pre-existing structural control, the magmatic lineation that reflects the magma flow within the pluton would have variable orientations and plunges (e.g., [START_REF] Paterson | A review of criteria for the identification of magmatic and tectonic foliations in granitoids[END_REF]Liu et al., 2018). Thus, we argue that the syenogranite, presenting a general NE-SW magnetic lineation, may have recorded a NE-SW trending regional extension (Figure 4.16). Meanwhile, the pluton growth could have been guided by the NE-SW trending regional tectonic regime, suggested by a NE-SW trending elongated subsurface shape of the pluton (Figure 4.15a).

Geochemical data suggest that the Wangtufang pluton was derived from the partial melting of Archaean TTG in the lower crust with a contribution from a depleted mantle source.

This feature is consistent with the geochemical characteristics of the E-W trending alkaline intrusive complexes along the northern NCB [START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF]Figure 4.17). Especially, the silica-undersaturated syenites comply with a Late Triassic intracontinental extensional setting after the final formation of the Central Asian Orogenic Belt [START_REF] Yang | Petrogenesis of silica-saturated and silica-undersaturated syenites in the northern North China Craton related to post-collisional and intraplate extension[END_REF]Figure 4.17).

Besides, a NE-SW trending regional extension in the northern NCB has been documented in the Sonid Zuoqi MCC in the vicinity of the Solonker zone [START_REF] Davis | Indosinian extension in the Solonker suture zone: the Sonid Zuoqi metamorphiccore complex, Inner Mongolia, China[END_REF]Figure 4.17).

The 40 Ar/ 39 Ar ages of muscovite in the detachment fault were 224~208 Ma. Detrital zircon dating and sedimentological studies of these basin remnants showed a fining and deepening upward depositional system as well as abundant volcaniclastic rocks from the conformable Upper Triassic to Lower Jurassic strata, suggesting a Late Triassic extensional tectonic setting [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF]Figure 4.1). The emplacement of the Wangtufang pluton provides new structural constraints on the Late Triassic NE-SW trending extensional setting in the northern NCB. Chapter 5. Emplacement of the Jurassic Jianchang-Jiumen pluton

Introduction

The NCB is one of the most important continental terranes that form the East Asian continent (e.g. [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Yin | A Phanerozoic palinspastic reconstruction of China and its neighboring regions[END_REF]. It is separated from the Siberia Craton in the north by the Central Asian Orogenic Belt and from the South China Block in the south by the Qinling-Dabie-Sulu orogen (Figure 5.1). The NCB is considered to be a stable craton after the Paleoproterozoic amalgamation of the Eastern, Intermediate (or Fuping) and Western blocks [START_REF] Faure | Polyorogenic evolution of the Paleoproterozoic Trans-North China Belt, new insights from the in Lüliangshan-Hengshan-Wutaishan and Fuping massifs[END_REF][START_REF] Trap | Paleoproterozoic tectonic evolution of the Trans-North China Orogen: toward a comprehensive model[END_REF]Zhao et al., 2001). The Phanerozoic tectonic evolution of the NCB is related to two orogenic cycles, including Paleozoic-Triassic continental collisions with Mongolian arc terranes and South China Block at block boundaries (Hacker et al., 2000;[START_REF] Mattauer | Tectonics of the Qinling belt: build-up and evolution of eastern Asia[END_REF][START_REF] Meng | Timing of collision of the North and South China blocks: controversy and reconciliation[END_REF][START_REF] Windley | Tectonic models for accretion of the Central Asian Orogenic Belt[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 | A tale of amalgamation of three Permo-Triassic collage systems in Central Asia: oroclines, sutures, and terminal accretion[END_REF][START_REF] Xu | Deformation characteristics and Tectonic evolution of the eastern Qinling orogenic belt[END_REF]B. Xu et al., 2013), and Jurassic-Early Cretaceous intracontinental orogeny [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Dong | Late Jurassic-Early Cretaceous continental convergence and intracontinental orogenesis in East Asia: a synthesis of the Yanshan revolution[END_REF][START_REF] Faure | Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the NCC?[END_REF].

Jurassic-Early Cretaceous intracontinental orogeny, also termed the Yanshanian Orogeny in the Chinese literature [START_REF] Wong | The Mesozoic orogenic movement in eastern China[END_REF], was widespread and intense in the North China Craton [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF]. It gave rise to a complicated assemblage of folds, thrust and reverse faults, normal faults, and Mesozoic plutons in the NCB. Alternating contractional and extensional deformations have been recognized in the Yanshan fold-and-thrust belt [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Faure | Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the NCC?[END_REF]. Two phases of shortening, including late Middle Jurassic (172-164 Ma) and late Late Jurassic-earliest Cretaceous (152-135 Ma) are quite evident, albeit timing and duration of these events remain debated [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Dong | Late Jurassic-Early Cretaceous continental convergence and intracontinental orogenesis in East Asia: a synthesis of the Yanshan revolution[END_REF][START_REF] Faure | Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the NCC?[END_REF][START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF]. However, Jurassic extensional deformations have not widely constrained except Early Cretaceous large-scale crustal extension implying the destruction of the North China Craton [START_REF] Lin | Late Mesozoic extensional tectonics in the North China Craton and its adjacent regions: a review and synthesis[END_REF][START_REF] Wang | Pattern and kinematic polarity of late Mesozoic extension in continental NE Asia: Perspectives from metamorphic core complexes[END_REF]. Only sporadic grabens or half-grabens have been documented in the NCB during Early Jurassic-early Middle Jurassic [START_REF] Darby | Paleozoic and Mesozoic tectonic evolution of central Asia: From continental assembly to intracontinental deformation[END_REF]Li et al., 2015;[START_REF] Qi | Mesozoic tectonic setting of rift basins in eastern North China and implications for destruction of the North China Craton[END_REF][START_REF] Ritts | Early Jurassic extensional basin formation in the Daqing Shan segment of the Yinshan belt, northern North China Block, Inner Mongolia[END_REF][START_REF] Zhang | Changes of Late Mesozoic tectonic regimes around the Ordos Basin (North China) and their geodynamic implications[END_REF] and early Late Jurassic [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Qi | Mesozoic tectonic setting of rift basins in eastern North China and implications for destruction of the North China Craton[END_REF]. Particularly, Early Jurassic contractional tectonics were also proposed according to the unconformity between Triassic and Lower Jurassic strata, and Lower Jurassic syntectonic conglomerate [START_REF] Zhao | The Mesozoic orogenesis and tectonic evolution of the Yanshan area (in Chinese)[END_REF][START_REF] Liu | Rapid exhumation of basement rocks along the northern margin of the North China craton in the early Jurassic: Evidence from the Xiabancheng Basin, Yanshan Tectonic Belt[END_REF]. Therefore, Jurassic extensional tectonics of the NCB remains ambiguous. Early Cretaceous intracontinental orogeny. The Jurassic-Early Cretaceous intracontinental orogeny in the NCB, named the Yanshanian Orogeny, was variously interpreted to be related to i) the closure of the Mongol-Okhotsk Ocean [START_REF] Yin | A Phanerozoic palinspastic reconstruction of China and its neighboring regions[END_REF][START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF], ii) the subduction of the Paleo-Pacific plate (G. [START_REF] Zhu | Destruction of the eastern North China Craton in a backarc setting: evidence from crustal deformation kinematics[END_REF]R. Zhu et al., 2011;[START_REF] Xu | Geotectonic features of Yanshan area in Hebei province[END_REF], iii) the interactions of north-south Eurasian intraplate deformation and northwestward Pacific Paleo-Pacific plate [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF] or iv) multiple plate convergence of the Mongolo-Okhotsk Ocean, Bangong-Nujiang Ocean, and the Paleo-Pacific Ocean [START_REF] Dong | Late Jurassic-Early Cretaceous continental convergence and intracontinental orogenesis in East Asia: a synthesis of the Yanshan revolution[END_REF]. Due to poor understanding of multiphase deformation events, especially extensional tectonics, the external driving force for the Jurassic-Early Cretaceous intracontinental orogeny in East China remains controversial.

Jurassic-Early

To understand the Jurassic-Early Cretaceous intracontinental orogeny of the NCB, it is crucial to clarify Jurassic extensional tectonics and its relationship to the dynamics of plate subduction/collision along active boundaries. Pluton emplacement processes potentially contain significant information on both magma internal dynamics and external strain fields to which the magma was subjected (e.g., [START_REF] Bouchez | Granite is Never Isotropic: An Introduction to AMS Studies of Granitic Rocks[END_REF]Paterson et al., 1998). The structural study of plutons is an effective and practical way to unveil regional tectonic setting coeval with the emplacement process (e.g., [START_REF] Bouchez | Granite is Never Isotropic: An Introduction to AMS Studies of Granitic Rocks[END_REF][START_REF] De Saint Blanquat | Multiscale magmatic cyclicity, duration of pluton construction, and the paradoxical relationship between tectonism and plutonism in continental arcs[END_REF][START_REF] Lin | Late Mesozoic compressional to extensional tectonics in theYiwulüshan massif, NE China and its bearing on the evolution of the Yinshan-Yanshan orogenic belt part II: Anisotropy of magnetic susceptibility and gravity modeling[END_REF]. In this study, we selected Jurassic Jianchang-Jiumen pluton in the Yanshan fold-and-thrust belt to provide regional tectonic information for Jurassic extensional episodes through an integrated multidisciplinary investigation (including structural geology, isotope chronology, Anisotropy of magnetic susceptibility (AMS), and gravity modeling).

Further, Integrating previous studies concerning other structural elements in North China during Jurassic-Early Cretaceous, an improved and more detailed structural framework of the NCB was established for understanding the Jurassic-Early Cretaceous intracontinental orogeny and associated geodynamic mechanism in East Asia.

Geological Setting

Tectonic setting

After the cratonization through Paleoproterozoic amalgamation of the Eastern, Intermediate (or Fuping), and Western blocks [START_REF] Faure | Polyorogenic evolution of the Paleoproterozoic Trans-North China Belt, new insights from the in Lüliangshan-Hengshan-Wutaishan and Fuping massifs[END_REF][START_REF] Li | Paleoproterozoic structural evolution of the southern segment of the Jiao-Liao-Ji Belt, North China Craton[END_REF][START_REF] Trap | Paleoproterozoic tectonic evolution of the Trans-North China Orogen: toward a comprehensive model[END_REF]Zhao et al., 2001), the NCB was surrounded by the Paleo-Asian Ocean in the north [START_REF] Windley | Tectonic models for accretion of the Central Asian Orogenic Belt[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 | A tale of amalgamation of three Permo-Triassic collage systems in Central Asia: oroclines, sutures, and terminal accretion[END_REF][START_REF] Xu | Middle Paleozoic convergent orogenic belts in western Inner Mongolia (China): framework, kinematics, geochronology and implications for tectonic evolution of the Central Asian Orogenic Belt[END_REF] and the eastern branches of Paleo-Tethys Ocean in the south (Hacker et al., 2000;[START_REF] Mattauer | Tectonics of the Qinling belt: build-up and evolution of eastern Asia[END_REF][START_REF] Meng | Timing of collision of the North and South China blocks: controversy and reconciliation[END_REF][START_REF] Xu | Deformation characteristics and Tectonic evolution of the eastern Qinling orogenic belt[END_REF]. In the north of the NCB, the closure of the Paleo-Asian Ocean was characterized by the amalgamation of several microcontinental blocks (e.g., the Erguna, Xing'an, Songnen, Jiamusi, and Khanka block; [START_REF] Liu | A review of the Paleozoic tectonics in the eastern part of Central Asian Orogenic Belt[END_REF]Sengör et al., 1993;[START_REF] Zhou | Nature and assembly of microcontinental blocks within the Paleo-Asian Ocean[END_REF], albeit the timing of the final closure of the Paleo-Asian Ocean remains debated, i.e., Late Devonian [START_REF] Xu | Middle Paleozoic convergent orogenic belts in western Inner Mongolia (China): framework, kinematics, geochronology and implications for tectonic evolution of the Central Asian Orogenic Belt[END_REF][START_REF] Zhao | Did the Paleo-Asian Ocean between North China Block and Mongolia Block exist during the late Paleozoic? first paleomagnetic evidence from central-eastern Inner Mongolia, China[END_REF] or Late Permian-Early Triassic [START_REF] Chen | Two contrasting Paleozoic magmatic belts in northern Inner Mongolia, China: Petrogenesis and tectonic implications[END_REF][START_REF] Chen | Evolution of the Solonker suture zone: Constraints from zircon U-Pb ages, Hf isotopic ratios and whole-rock Nd-Sr isotope compositions of subduction-and collisionrelated magmas and forearc sediments[END_REF][START_REF] Jian | Time scale of an Early to Mid-Paleozoic orogenic cycle of the long-lived Central Asian Orogenic Belt, Inner Mongolia of China: implications for continental growth[END_REF][START_REF] Jian | Evolution of a Permian intraoceanic arc-trench system in the Solonker suture zone, Central Asian Orogenic Belt, China and Mongolia[END_REF][START_REF] Li | Permian geodynamic setting of Northeast China and adjacent regions: closure of the Paleo-Asian Ocean and subduction of the Paleo-Pacific Plate[END_REF][START_REF] Lin | Permian-Triassic amalgamation of Asia: insights from Northeast China sutures and their place in the final collision of North China and Siberia[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 | A tale of amalgamation of three Permo-Triassic collage systems in Central Asia: oroclines, sutures, and terminal accretion[END_REF]. In the south, the final amalgamation between the North and South China Blocks occurred in the Triassic through multistage orogeny during the Paleozoic to the Triassic, giving rise to Late Triassic Dabie-Sulu high-pressure and ultrahigh-pressure (HP-UHP) orogenic belt (e.g., [START_REF] Mattauer | Tectonics of the Qinling belt: build-up and evolution of eastern Asia[END_REF][START_REF] Faure | Tectonics of the Dabieshan (eastern China) and possible exhumation mechanism of ultra high-pressure rocks[END_REF][START_REF] Faure | Continental subduction and exhumation of UHP rocks. Structural and geochronological insights from the Dabieshan (East China)[END_REF]Hacker et al., 2000;[START_REF] Lin | Tectonic evolution of Dabie orogen: in the view from polyphase deformation of the Beihuaiyang metamorphic zone[END_REF][START_REF] Lin | Exhumation tectonics of the HP-UHP orogenic belt in Eastern China: new structural-petrological insights from the Tongcheng massif, Eastern Dabieshan[END_REF]Li et al., 2017Li et al., , 2018;;[START_REF] Ratschbacher | Tectonics of the Qinling (Central China): tectonostratigraphy, geochronology, and deformation history[END_REF][START_REF] Ratschbacher | The Sino-Korean-Yangtze suture, the Huwan detachment, and the Paleozoic-Tertiary exhumation of (ultra) high-pressure rocks along the Tongbai-Xinxian-Dabie Mountains[END_REF]Figure 5.1).

During the Jurassic-Cretaceous, the welded East Asian continent was surrounded by the controversial, e.g., the Middle Jurassic [START_REF] Zorin | Geodynamics of the western part of the Mongolia-Okhotsk collisional belt, Trans-Baikal region (Russia) and Mongolia[END_REF][START_REF] Parfenov | Problems of tectonics of the Mongol-Okhotsk orogenic belt[END_REF][START_REF] Kravchinsky | Evolution of the Mongol-Okhotsk Ocean as constrained by new palaeomagnetic data from the Mongol-Okhotsk suture zone, Siberia[END_REF], the Late Jurassic-early Early Cretaceous [START_REF] Cogné | Late Jurassic-Early Cretaceous closure of the Mongol-Okhotsk Ocean demonstrated by new Mesozoic palaeomagnetic results from the Trans-Baikal area (SE Siberia)[END_REF][START_REF] Metelkin | Late Mesozoic tectonics of Central Asia based on paleomagnetic evidence[END_REF][START_REF] Pei | A paleomagnetic study from the Late Jurassic volcanics (155 Ma), North China: implications for the width of Mongol-Okhotsk Ocean[END_REF]Yang et al., 2015), or the Early Cretaceous [START_REF] Enkin | Paleomagnetic constraints on the geodynamic history of the major blocks of China from the Permian to the present[END_REF]. Generally, it is acknowledged that the Mongol-Okhotsk Ocean closed progressively from west to east in the north of the East Asian continent [START_REF] Zorin | Geodynamics of the western part of the Mongolia-Okhotsk collisional belt, Trans-Baikal region (Russia) and Mongolia[END_REF][START_REF] Daoudene | Timing of exhumation of the Ereendavaa metamorphic core complex (north-eastern Mongolia)-U-Pb and 40 Ar/ 39 Ar constraints[END_REF][START_REF] Kravchinsky | Evolution of the Mongol-Okhotsk Ocean as constrained by new palaeomagnetic data from the Mongol-Okhotsk suture zone, Siberia[END_REF][START_REF] Metelkin | Late Mesozoic tectonics of Central Asia based on paleomagnetic evidence[END_REF][START_REF] Dong | Late Jurassic-Early Cretaceous continental convergence and intracontinental orogenesis in East Asia: a synthesis of the Yanshan revolution[END_REF]. The onset of Paleo-Pacific Plate subduction has been considered to occur in the Late Triassic [START_REF] Sagong | Mesozoic episodic magmatism in South Korea and its tectonic implication[END_REF]Kim et al., 2015), or Early Jurassic [START_REF] Wu | The Hulan Group: its role in the evolution of the Central Asian Orogenic Belt of NE China[END_REF][START_REF] Guo | Early Jurassic subduction of the Paleo-Pacific Ocean in NE China: Petrologic and geochemical evidence from the Tumen mafic intrusive complex[END_REF][START_REF] Wang | Final closure of the Paleo-Asian Ocean and Onset of Subduction of Paleo-Pacific Ocean: Constraints from Early Mesozoic magmatism in Central southern Jilin Province, NE China[END_REF]. It is well agreed that the influence of the Paleo-Pacific tectonic regime has extended to the northern and northeastern China from the Early Jurassic (e.g., Hao et al., 2020;Li et al., 2007;[START_REF] Wang | Final closure of the Paleo-Asian Ocean and Onset of Subduction of Paleo-Pacific Ocean: Constraints from Early Mesozoic magmatism in Central southern Jilin Province, NE China[END_REF][START_REF] Wu | The Hulan Group: its role in the evolution of the Central Asian Orogenic Belt of NE China[END_REF]. 5.2; [START_REF] Darby | Paleozoic and Mesozoic tectonic evolution of central Asia: From continental assembly to intracontinental deformation[END_REF]Li et al., 2015;[START_REF] Ritts | Early Jurassic extensional basin formation in the Daqing Shan segment of the Yinshan belt, northern North China Block, Inner Mongolia[END_REF][START_REF] Zhang | Changes of Late Mesozoic tectonic regimes around the Ordos Basin (North China) and their geodynamic implications[END_REF]. In the eastern NCB, the Lower Jurassic-lower Middle Jurassic strata contain abundant basalt interlayered with andesite and pyroclastic rocks (e.g., the Nadaling or Xinglonggou Formations; Figure 5.3).

Jurassic Geological

Sedimentary studies suggest that these Lower Jurassic-lower Middle Jurassic strata were deposited in an extensional setting [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF][START_REF] Meng | Tectonic evolution of early Mesozoic sedimentary basins in the North China block[END_REF].

The late Middle Jurassic -Late Jurassic-magmatic rocks are only distributed in the eastern NCB (e.g., the Liaodong peninsula and the eastern Yanshan fold-and-thrust belt; Figure 5.2).

An Early Jurassic NE trending rift basin was recognized in the Western Hill basin in Beijing [START_REF] Xu | The characteristics of Mesozoic rift in Western Hill of Beijing [in Chinese[END_REF].

The upper Middle Jurassic strata are separated from the lower Middle Jurassic coalbearing sequences and older units by an angular unconformity (Figure 5. The volcanic and pyroclastic rocks of the Tiaojishan/Lanqi Formation cover these N-S directed thrusts. The N-S shortening was synchronous with the syntectonic Changhangou and Yungang growth strata in the western Daqingshan and Taihangshan (Li et al., 2014;[START_REF] Wang | The Jurassic structural evolution of the western Daqingshan area, eastern Yinshan belt, North China[END_REF].

The duration of this event (i.e., Event A of the Yanshanian orogeny) has been well constrained between 172 and 164 Ma [START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF].

The volcanic and pyroclastic rocks of the Tiaojishan/Lanqi Formation in lower Upper Jurassic and concomitant granite plutons (164-155 Ma) are only distributed in the eastern NCB (i.e., the Liaodong and Jiaodong peninsulas and the eastern Yanshan fold-and-thrust belt;

Figure 5.3). Coeval with this magmatic event, nearly N-S or NE trending grabens or halfgrabens were distributed in the Yanshan fold-and-thrust belt (e.g., Diaoe graben and Houcheng half-graben, [START_REF] Qi | Mesozoic tectonic setting of rift basins in eastern North China and implications for destruction of the North China Craton[END_REF]Chengde graben, Davis et al., 2001;Guojiadian half-graben, Davis et al., 2009;Figure 5.3). A detachment fault with top-to-the-NW shearing (156-150 Ma) was developed in the Kalaqin metamorphic core complex [START_REF] Lin | Structural characteristics and formation mechanism of the Kalaqin metamorphic core complex in the Yanshan area, China (in Chinese)[END_REF]Figure 5.3). In the eastern NCB, the syntectonic conglomerate and coarse sandstone in the Upper Jurassic-lowermost Cretaceous Tuchengzi/Houcheng Formation conformably overlay pyroclastic rocks of the Tiaojishan/Lanqi Formation [START_REF] Fu | Revisiting of the Yanshanian basins in western and northern Beijing, North China[END_REF][START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF]Liu et al., 2018;Figure 5.3). In the western NCB, however, Upper Jurassic-lowermost Cretaceous syntectonic conglomerate unconformably overlies upper Middle Jurassic syntectonic conglomerate (i.e., the Daqingshan, [START_REF] Wang | The Jurassic structural evolution of the western Daqingshan area, eastern Yinshan belt, North China[END_REF]the Taihangshan, Li et al., 2015; the Ordos basin and its periphery, [START_REF] Zhang | Changes of Late Mesozoic tectonic regimes around the Ordos Basin (North China) and their geodynamic implications[END_REF]Figure 5.3). A regional unconformity separates the Upper Jurassic-lowermost Cretaceous syntectonic strata from Lower Cretaceous.

The NE trending thrusts below this unconformity are widely distributed in the central YTFB (Figure 5.2; e.g., Chengde thrust, [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF]; Shanggu-Pingquan thrust, Gubeikou thrust, and Dayingzi thrust, C. [START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF] and the eastern YTFB [START_REF] Zhang | Mesozoic tectonic framework of the intraplate and evolution in the central segment Yanshan orogenic belt (in Chinese)[END_REF]. In the western YTFB, the paleostress along the dextral Shangyi-Chicheng and Pingquan-Gubeikou faults is NW-SE direction [START_REF] Zhang | Timing of deposition in the Dengzhangzi and Guojiadian Basins of the Yanshan fold-thrust belt, North China[END_REF]Figure 5.2). In the western Daqingshan, the N-S thrusts were overprinted by the NW-SE thrusts, indicated by the superimposed striations and syntectonic Daqingshan strata [START_REF] Wang | The Jurassic structural evolution of the western Daqingshan area, eastern Yinshan belt, North China[END_REF]Figure 5.2). The NW-SE thrusts are also widely developed in the Taihangshan (Zhang et al., 2020;Figure 5.2). The duration of this event (i.e., Event B of the Yanshanian orogeny) has also been well constrained around 152-135 Ma (C. [START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF]. Afterwards, the North China Craton was destroyed in the Early Cretaceous, characterized by A-type magmatism, metamorphic core complexes (MCCs), and graben or half-graben basins [START_REF] Wang | Pattern and kinematic polarity of late Mesozoic extension in continental NE Asia: Perspectives from metamorphic core complexes[END_REF][START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF], Lin et al., 2018).

Jianchang-Jiumen pluton

The granitic Jianchang-Jiumen pluton, extending ~50 km along a NE-SW long axis (Figure 5.4), is the largest one and representative for most of the Jurassic granites in North China. It consists of an early-stage medium-to fine-grained monzogranite exposed in the Jiumen pluton and a late-stage monzogranite exposed in the Jianchang pluton. Both these two plutons are metaluminous to weakly peraluminous, with geochemical features of I-type granites (Cui, 2015). According to geochemical analyses and LA-ICP-MS zircon U-Pb dating, both of them were formed by the partial melting of a lower crustal source in a subductionrelated setting during 194-176 Ma and 161-153 Ma, respectively [START_REF] Wu | Emplacement ages of the Mesozoic granites in southeastern part of the Western Liaoning Province[END_REF]Cui, 2015).

Microscopic Observations

In the Jianchang-Jiumen pluton, microstructures are investigated in 40 sampling sites to determine the relationships between the minerals and magnetic fabrics (Figure 5.6a). Two types of microstructures can be observed. At most sites (68%), magmatic fabrics are developed without any solid-state deformation ). Quartz grains are anhedral and nondeformed without signs of undulose extinction. The euhedral biotite is neither kinked nor bent with a sharp extinction. The plagioclase exhibits oscillatory zoning. Both the plagioclase and K-feldspars present euhedral crystal habits without any deformation. Besides, submagmatic fabrics can be also observed at some sites (32%). Quartz grains show an undulose extinction and weak dynamic recrystallization with some small subgrains at the border of coarse grains ). Generally, these fabrics are acquired in magmatic state without significant solid-state deformation.

Anisotropy of magnetic susceptibility (AMS)

The AMS study is an effective and practical way to reveal the structural elements of apparently isotropic to weakly deformed granitic plutons (e.g., [START_REF] Archanjo | Magnetic fabrics vs. magnetite and biotite shape fabrics of the magnetite-bearing granite pluton of Gameleiras (Northeast Brazil)[END_REF][START_REF] Bouchez | Granite is Never Isotropic: An Introduction to AMS Studies of Granitic Rocks[END_REF]. Field and microscopic observations suggest that the Jianchang-Jiumen pluton does not show any mesoscopic planar and linear fabrics. Therefore, an AMS study has been carried out on the Jianchang-Jiuemn pluton to provide quantitative structural data that cannot be gained in classical field studies. It could provide key information to depict the fabric patterns of the Jianchang-Jiuemn pluton.

Sampling and Measurements

AMS sampling was performed in 76 sites of the Jianchang-Jiumen pluton with a relatively homogeneous spatial distribution (35 sites in the Jiumen pluton and 41 ones in the Jianchang pluton). A total of 467 cores from 76 sites (more than five cores of 2.5 cm in diameter in each site) have been collected with a portable gasoline drill. In the laboratory of Paleomagnetism and Chronology of IGGCAS, each core was cut into cylindrical specimens of 2.2 cm in length.

Anisotropy of magnetic susceptibility and bulk susceptibility were measured with a KLY4

susceptometer. The ANISOFT package of programs was used for the statistical analysis of the AMS data that calculates mean orientation of three principal axes of the AMS ellipsoid (K1 ≥ K2 ≥ K3), and the parameters of the AMS ellipsoid features, i.e., anisotropy degree

(PJ = exp√{2[(η1-η) 2 + (η2-η) 2 + (η3-η) 2 ]
), and shape parameter (T =(2η2-η1-η3)/(η1-η3)), where η1 = lnK1, η2 = lnK2, η3 = lnK3, and η = (η1 + η2 + η3)/3 (Jelínek, 1978). The magnetic mineralogy was investigated to identify the magnetic carriers that contribute to the magnetic signal with the following measurements: (1) hysteresis loops; (2) Isothermal Remanent Magnetization (IRM), and ( 3) thermomagnetic (K-T) curves.

Magnetic Mineralogy

The mean magnetic susceptibility, Km = (K1 + K2 + K3)/3, of 76 sampling sites are higher than 500 μSI, ranging from 506 to 91,500 μSI (Figure 5.8 and Table S2). The high Km values in all sampling sites usually attributed to the ferromagnetic contribution (Bouchez, 2000). The hysteresis loops of six representative samples from the Jiumen and Jianchang plutons all display nonlinear variations between the applied magnetic field and the induced magnetization ). Furthermore, the narrow-waisted loops and the low-coercivity values for all these specimens indicate that the magnetite is the major magnetic susceptibility carrier. All IRM acquisition curves show a rapid increase and a sudden saturation below 200 mT (Figures 5.9d-5.9f), confirming the presence of low-coercivity minerals such as magnetite. All thermomagnetic measurements display sharp drops of magnetic susceptibility at 550-600°C, consistent with the Curie point of magnetite at 580°C ). Through the above investigations, therefore, we conclude that the magnetic fabrics of the Jianchang-Jiumen pluton are dominated by magnetite. According to the ratios of hysteresis parameters Mr/Ms and Hcr/Hc, the presence of pseudo-single domain (PSD) magnetite has been estimated [START_REF] Dunlop | Theory and application of the day plot (Mrs/Ms versus Hcr/Hc) 1. Theoretical curves and tests using titanomagnetite data[END_REF]Figure 5.10). Consequently, the principal axis of the magnetic fabrics can be correlated to the petro-fabrics of studied samples (e.g. [START_REF] Hargraves | Distribution anisotropy: the cause of AMS in igneous rocks?[END_REF][START_REF] Tarling | Magnetic Anisotropy of Rocks[END_REF].

More than 82% of sampling sites in the Jianchang-Jiumen pluton have low PJ values (< 1.2; Figure 5.8), indicating that the fabrics have been acquired in magmatic or submagmatic state rather than post-solidus one. Only a few sites (18%) have high PJ values (>1.2), coming mainly from the contact between the two sub-plutons (i.e., Jiumen and Jianchang). It is possible to create a relatively high PJ value due to strain increase near the contact zone of the two plutons.

Fifty-four percent of the sites display positive T values, and 46% of the sites show negative T values, indicating no dominant oblate or prolate shape for magnetic fabrics. There are no significant relationships among PJ, T, and Km, implying that AMS varies independently from magnetic minerals [START_REF] Borradaile | Tectonic applications of magnetic susceptibility and its anisotropy[END_REF]Figure 5.8).

Fabric Patterns of the Jianchang-Jiumen pluton

At a given site, the number of samples varies between 5 and 9. For each site, the siteaverage orientation with confidence intervals at the 95% confidence level (α95max and α95min)

was calculated for K1 and K3 axes [START_REF] Jelinek | Statistical processing of anisotropy of magnetic susceptibility measured on groups of specimens[END_REF]Figure 5.11). A confidence level lower than 25° for a magnetic axis, K1 and/or K3, is considered as well-defined, otherwise, it is poorly defined and unreliable. In the Jianchang-Jiumen pluton, at least one magnetic principal axis (K1 or K3) in more than 96% sites is well defined with low α95 values. At map scale, the fabric patterns of the Jianchang-Jiumen pluton are described in details as follows: 2. Jianchang pluton. There, the margin-parallel magnetic foliations mainly present moderately to highly outward dipping around its northwestern root (see below) and subparallel striking to the contact with the country rocks in its southeastern margin (Figure 5.12a).

The magnetic lineations display gentle to moderate NE-SW plunging throughout the pluton (Figure 5.12b).

Gravity Modeling

Gravity modeling has been proven as an efficient method to constrain the geometry and possible feeder zones of pluton (e.g., [START_REF] Améglio | Geophysical imaging of the shape of granitic intrusions at depth: a review[END_REF]Qiu et al., 2020;[START_REF] Vigneresse | Use and misuse of geophysical data to determine the shape at depth of granitic intrusions[END_REF]. To characterize the shape of the Jianchang-Jiumen pluton at depth, a gravity modeling has been performed for the Jiumen-Jianchang pluton.

Residual Bouguer anomaly map

In the Jianchang-Jiumen pluton and its adjacent area, the detailed Bouguer anomaly map (1: 200,000) was derived from the Chinese regional gravity survey, and a lower-resolution (2′×2′) Bouguer grid was acquired from the International Gravimetric Bureau database [START_REF] Bonvalot | World gravity map[END_REF]. To highlight the Jianchang-Jiumen pluton related short wavelengths anomalies in the upper crust (down to a few kilometers), the long wavelengths of the gravity anomaly from deeper structures must be subtracted from the complete Bouguer anomaly. The long wavelengths of the gravity anomaly were extracted from a lower-resolution (2′×2′)

Bouguer grid, using a 200 km low-pass Butterworth filter after several attempts. The residual Bouguer anomaly map was obtained by subtracting the filtered regional Bouguer anomaly that represents the long wavelengths of the gravity anomaly (Figure 5.13a).

In the residual Bouguer anomaly map, the Jianchang-Jiumen pluton displays a significant NE-SW trending negative anomaly that more or less correlates with the pluton boundary (Figure 5.13a). Generally, the Jianchang-Jiumen pluton shows a negative anomaly center in the northwestern part of the Jianchang pluton, corresponding to the root of the pluton. The negative anomalies decrease outwards from the root, even change into positive anomalies in its southeastern border. In its north, the negative anomaly exceeds the pluton boundary, indicating northward extension of the pluton beneath the country rocks. To the southwest, the country rocks show a high negative anomaly, indicating the possible continuity of the pluton to the west below the country rocks.

2D gravity modeling

In order to image the detailed geometry of the Jianchang-Jiumen at depth, the residual gravity anomaly has been modeled along three cross-sections, subparallel to the long or short axes of the pluton. In this modeling, several constraints have been taken into account for the final models: (1) geological contacts and structural data. These geological data are derived from the available geological map and our field observations. ( 2) Density of lithological units considered in the modeling. Densities of these units, summarized in Figure 5.13b, are derived from laboratory measurements. ( 3) Geometrical constraints of considered geological units.

During the modeling, the geometry of these geological units with fixed densities has been adjusted to match calculated gravity values with observed ones. The densities of the two plutons (2.60 g/cm 3 for the Jiumen pluton, 2.59 g/cm 3 for the Jianchang pluton) are too close to each other to produce significant gravity variations. The contact between the two plutons has no gravity reliability and only reflects our understanding of the geology with field observation and fabric measurements.

Three 2D modeling profiles image the detailed geometry of the two plutons (Figure 5.13b),

indicating (1) the Jianchang-Jiumen pluton exhibits a tabular shape with a maximal thickness of about 6 km, (2) the Jiumen pluton as one stacked sheet overlies the Jianchang pluton, (3) the highest negative anomaly, located in the northwest part of the Jianchang pluton, corresponds to the feeder zone of the Jianchang pluton, and ( 4) the Jianchang pluton, with shallow to moderately inward-dipping sidewalls, progressively thins outwards. [START_REF] Paterson | Bursting the bubble of ballooning plutons: A return to nested diapirs emplaced by multiple processes[END_REF]Paterson et al. 1998). Considering the lack of emplacement-related ductile deformation in the country rocks, these fabrics may provide a record of either chamberrelated or regional stresses dominated during the final crystallization (Paterson et al. 1998).

The Jianchang-Jiumen pluton shows margin-parallel magnetic foliations in these two subplutons (Figure 5.12). These margin-parallel magnetic foliations are usually considered as a consequence of magma expansion during the intrusion. Without any regional strain, the magmatic lineation that reflects the magma flow within the pluton would have variable orientations and plunges depending on magma convection (e.g., [START_REF] Paterson | A review of criteria for the identification of magmatic and tectonic foliations in granitoids[END_REF]). In the Jianchang-Jiumen pluton, the magnetic lineation patterns define two principle maximaoriented NW-SE (mean at 300°/29°) and NE-SW (mean at 60°/20°) for these two Jiumen-Jianchang intrusions, respectively (Figure 5.12). These two groups of magnetic lineations seem providing records of the regional stresses during their emplacement. During the Early to early Middle Jurassic, the small-scale E-W trending extensional basins or normal faults were widely distributed in the western NCB, e.g., the Ordos basin and its periphery [START_REF] Zhang | Changes of Late Mesozoic tectonic regimes around the Ordos Basin (North China) and their geodynamic implications[END_REF], the Daqingshan [START_REF] Darby | Paleozoic and Mesozoic tectonic evolution of central Asia: From continental assembly to intracontinental deformation[END_REF][START_REF] Ritts | Early Jurassic extensional basin formation in the Daqing Shan segment of the Yinshan belt, northern North China Block, Inner Mongolia[END_REF], and the Taihangshan (Li et al., 2015). These structural phenomena suggest that the Early Jurassic to early Middle Jurassic S-N extension occurred in the western NCB (Figure 5.2). In the eastern NCB, the NE trending rift basins were developed, such as the Western Hill of Beijing [START_REF] Xu | The characteristics of Mesozoic rift in Western Hill of Beijing [in Chinese[END_REF]Figure 5.2). During this stage, the eruption of basalt (the Nadaling or Xinglonggou Formations) in the eastern NCB and the development of coal-bearing basins have been considered to occur in an extensional setting [START_REF] Meng | Tectonic evolution of early Mesozoic sedimentary basins in the North China block[END_REF]Hao et al., 2020). The granitic and volcanic rocks (including the Jianchang-Jiumen pluton), only distributed in the eastern Liaoning and Yanshan, were derived from the partial melting of a lower crustal source in a subduction-related setting [START_REF] Wu | Geochronology, petrogenesis and tectonic implications of Jurassic granites in the Liaodong Peninsula, NE China[END_REF]. Considering the distribution of the Early Jurassic igneous rocks parallel to the subduction margin of the Paleo-Pacific Plate (Figure 5. concur with many studies in petrology and geochemistry (e.g., [START_REF] Wu | Geochronology, petrogenesis and tectonic implications of Jurassic granites in the Liaodong Peninsula, NE China[END_REF][START_REF] Wu | Destruction of the North China Craton in the Mesozoic[END_REF][START_REF] Wang | Final closure of the Paleo-Asian Ocean and Onset of Subduction of Paleo-Pacific Ocean: Constraints from Early Mesozoic magmatism in Central southern Jilin Province, NE China[END_REF].

Jianchang pluton

In the Jianchang pluton, the current exposure is close to the roof of the pluton due to the covering of some remnants of the Jiumen pluton (Figure 5.4). The margin-parallel magnetic foliations define the dome-like roof of the Jianchang pluton (Figure 5.12a). Gravity modeling suggests that the Jianchang pluton has a tabular shape with an unflat bottom and shallow to moderately inward-dipping sidewalls (Figure 5.13). The root of the Jianchang pluton as a feeder zone is located in the northwest of its current exposure. Therefore, the Jianchang pluton with a margin-parallel fabric pattern could emplace by magma inflation from its feeder zone (Figure 5.14).

During the early Late Jurassic, the volcanic and pyroclastic rocks of the Tiaojishan/Lanqi Formation, and concomitant granite plutons (164-155 Ma) are only distributed in the eastern NCB (i.e., the Liaodong and Jiaodong peninsulas and the eastern YFTB; Figure 5.2). These magmatic rocks were also originated from the hybridization between the enriched mantlederived mafic magma and the thickened lower crust in a subduction-related setting [START_REF] Wu | Geochronology, petrogenesis and tectonic implications of Jurassic granites in the Liaodong Peninsula, NE China[END_REF]). An early Late Jurassic extension occurred in the eastern NCB, suggested by the Kalaqin metamorphic core complex with a top-to-the-NE detachment (156-150 Ma;[START_REF] Lin | Structural characteristics and formation mechanism of the Kalaqin metamorphic core complex in the Yanshan area, China (in Chinese)[END_REF], and coeval nearly N-S trending grabens or half-grabens, e.g., Diaoe graben and Houcheng halfgraben, [START_REF] Qi | Mesozoic tectonic setting of rift basins in eastern North China and implications for destruction of the North China Craton[END_REF]; Chengde graben, [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF]; Guojiadian half-graben, [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF]. Therefore, an NE-SW striking magnetic lineation could record an early Late Jurassic extensional paleostress field in the eastern NCB. Similarly, the early Late Jurassic granitoid and coeval volcanic rocks were distributed along the eastern margin of the East Asian continent (Figure 15d). It seems that early Late Jurassic NE-SW backarc extension, related to the Paleo-Pacific Plate subduction beneath the East Asian continent, occurred in the eastern NCB again (Figure 16c).

The emplacement of the Jianchang-Jiumen pluton provides new structural constraints on the Jurassic two-stage extension in the eastern NCB. Furthermore, the Jurassic two-stage extension provides new constraints on multiphase deformation sequences of the NCB during The emplacement of large-scale granitoid records tectonic information during its emplacement.

The structural studies of plutons are an effective way to reveal the coeval regional setting. In [START_REF] Wang | Cratonic reactivation and orogeny: an example from the northern margin of the North China Craton[END_REF][START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF]Figure 6.2), and the E-W trending folds and thrusts include the Unnamed fault, Malanyu anticline, and Jixian thrust fault in the south [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Ma | SHRIMP U-Pb dating of zircon from Panshan granitoid pluton in Yanshan orogenic belt and its tectonic implications (in Chinese with English abstract)[END_REF]. In the western Liaoning, the Early-Middle Triassic thrusts were covered by the volcanics in the Shuiquangou Formation in the Lingyuan area of the eastern Yanshan belt (Hu et al., 2005[START_REF] Hu | Early Mesozoic deformations of the eastern Yanshan thrust belt, northern China[END_REF]. It suggested that it was in a N-S compressional tectonic setting in the northern NCB (Figures 6.1-6.2).

Late Triassic NE-SW extension in the northern NCB

In the NCB, a Late Triassic extensional setting for the northern NCB has been proposed according to the geochemistry of the E-W trending alkaline intrusive complexes [START_REF] Yang | Petrogenesis of silica-saturated and silica-undersaturated syenites in the northern North China Craton related to post-collisional and intraplate extension[END_REF][START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF]. Fining and deepening upward depositional system and abundant volcaniclastic rocks in the remnant basins suggest a Late Triassic extensional setting in the northern NCB [START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF]Figure 6.3). In the south of Sonid Zuoqi in the vicinity of the Solonker zone, a NE-SW trending extension has been also documented in a Late Triassic metamorphic core complex [START_REF] Davis | Indosinian extension in the Solonker suture zone: the Sonid Zuoqi metamorphiccore complex, Inner Mongolia, China[END_REF]Figure 6.3). The geochemistry of the Dushan pluton and the Wangtufang pluton, similar to the Late Triassic alkaline intrusive complexes, indicates that it originated from partial melting of the lower crust with a contribution of mantle-derived materials during an extensional setting [START_REF] Ye | Petrogenesis and emplacement deformation of the Late Triassic Dushan composite pluton in the Yanshan fold and thrust belt: Implications for the tectonic settings of the northern margin of the North China Craton during the Early Mesozoic (in Chinese with English abstract)[END_REF][START_REF] Jiang | Geochronology and petrogenesis of the granites in Malanyu anticline in eastern North China Block[END_REF]. Emplacement of the Wangtufang pluton was in an extensional setting, considering:

(1) the NE-SW striking magnetic lineation, ( 2 During the Early Jurassic-early Middle Jurassic, the basin infill contains mafic volcanic rocks in the eastern NCB and widespread coal-bearing sequence in the whole NCB (Figure 6.1), which were considered to take place in an extensional setting [START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF][START_REF] Meng | Tectonic evolution of early Mesozoic sedimentary basins in the North China block[END_REF]Hao et al., 2020). The N-S extension is well recorded by E-W trending brittle normal faults in the western NCB [START_REF] Darby | Paleozoic and Mesozoic tectonic evolution of central Asia: From continental assembly to intracontinental deformation[END_REF][START_REF] Ritts | Early Jurassic extensional basin formation in the Daqing Shan segment of the Yinshan belt, northern North China Block, Inner Mongolia[END_REF][START_REF] Zhang | Changes of Late Mesozoic tectonic regimes around the Ordos Basin (North China) and their geodynamic implications[END_REF]Li et al., 2015;Figure 6.4). The NNE-SSW and nearly N-S extensional normal faults were identified in the Upper Triassic-Lower Jurassic strata in the central and northeastern Ordos Basin [START_REF] Zhang | Changes of Late Mesozoic tectonic regimes around the Ordos Basin (North China) and their geodynamic implications[END_REF]Figure 6.4). In the Yungang and Guangling Basins, the normal faults cut the conglomerates in the lower Lower Jurassic, covered by the upper Lower Jurassic strata (Li et al., 2015;Figure 6.4). The sedimentary studies showed a fining and deepening upward depositional system from the Upper Triassic to Lower Jurassic strata, suggesting a Late Triassic extensional tectonic setting in the Lingwu-Jingle Basin [START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF]Li et al., 2015). In the southwestern Daqingshan, the E-W trending normal faults cut the unconformity between the Lower Jurassic and Archeozoic [START_REF] Darby | Paleozoic and Mesozoic tectonic evolution of central Asia: From continental assembly to intracontinental deformation[END_REF]Figure 6.4). The small-sized grabens were developed, dominated by the growth normal faults. In the eastern NCB, the structural and sedimentary studies suggested that the North China Craton was in an extensional setting during the Early-early Middle Jurassic [START_REF] Meng | Tectonic evolution of early Mesozoic sedimentary basins in the North China block[END_REF]. Early Jurassic granitoid and coeval volcanic rocks only occurred in the eastern MCB. The Jiumen pluton, together with NE trending rift basin in the Western Hill of Beijing, records a NW-SE extension in the eastern NCB (Figure 6.4).

Late Middle Jurassic N-S compression

The early Middle Jurassic N-S compressional event (i.e., Event A of Yanshanian Orogeny) is well recorded by the unconformity above the coal-bearing strata and the syntectonic conglomerate and sandstone (Figure 6.1). The Event A was presented as the unconformity between the volcanics in the Tiaojishan Formation and the different underlying strata [START_REF] Faure | Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the NCC?[END_REF]. The extensive deformations related to Event A have been overlaid by the volcanics in the Tiaojishan Formation. E-W trending thrusts and fault-related folds mainly localized in the northern NCB (Figure 6.5), e.g., the N-S thrusts covered by the Changhangou and Yungang growth strata in the western Daqingshan and Taihangshan (Li et al., 2014;[START_REF] Wang | The Jurassic structural evolution of the western Daqingshan area, eastern Yinshan belt, North China[END_REF]), E-W trending Miyun-Xifengkou fault and secondary faults in the middle YFTB [START_REF] Chen | Geometric and kinematic evolution of basement-cored structures: intraplate orogenesis within the Yanshan Orogen, northern China[END_REF][START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF]), E-W trending Sandaogou fault in the eastern YFTB (Zhao, 2016). In the Yanshan belt, the fold and thrust belt in the Proterozoic-Paleozoic strata were covered by the he volcanics in the Tiaojishan Formation, e.g., Mengjiazhuang anticline and Duanshuao-Jianbaoshan thrust fault ( Li et al., 2016), Miyun-Xifengkou fault, Zhujiagou fault, Qingshuihu fault, Xinglong fault, Gaobanhe fault, Sanpo fault, Banbishan fault, and Lengkou fault [START_REF] Chen | Geometric and kinematic evolution of basement-cored structures: intraplate orogenesis within the Yanshan Orogen, northern China[END_REF], Davis et al., 2001;[START_REF] Zhang | Mesozoic tectonic framework of the intraplate and evolution in the central segment Yanshan orogenic belt (in Chinese)[END_REF]. The duration of this event has been well constrained between 172 and 164 Ma [START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF]). [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Qi | Mesozoic tectonic setting of rift basins in eastern North China and implications for destruction of the North China Craton[END_REF], and the top-to-the-NE shearing detachment fault in the Kalaqin metamorphic core complex [START_REF] Lin | Structural characteristics and formation mechanism of the Kalaqin metamorphic core complex in the Yanshan area, China (in Chinese)[END_REF]Figure 6.6). Nevertheless, it is characterized by two sequences of overlapping synorogenic conglomerates in the western NCB (Figure 6.1). Therefore, the early Late Jurassic NE-SW extension only occurred in the eastern NCB (Figures 6.1 and 6.6). sequence thrusting [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF]. In the mid-western YFTB, map-scale NE trending thrusts overprint the late Middle Jurassic E-W trending thrusts, accommodated by the dextral strike-slip shear zones [START_REF] Faure | Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the NCC?[END_REF][START_REF] Lin | From dextral contraction to sinistral extension of intracontinental transform structures in the Yanshan and northern Taihang Mountain belts during Early Cretaceous: Implications to the destruction of the North China Craton[END_REF]. The paleostress along the dextral strike-slip faults is NW-SE direction [START_REF] Lin | From dextral contraction to sinistral extension of intracontinental transform structures in the Yanshan and northern Taihang Mountain belts during Early Cretaceous: Implications to the destruction of the North China Craton[END_REF]. The NE trending thrusts and the strike-slip structures are considered to be kinematically coupled, with the E-W trending strike-slip structures as transcurrent fault zones linking the NE trending thrusts along two sides of the dextral strike-slip zones [START_REF] Faure | Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the NCC?[END_REF][START_REF] Lin | From dextral contraction to sinistral extension of intracontinental transform structures in the Yanshan and northern Taihang Mountain belts during Early Cretaceous: Implications to the destruction of the North China Craton[END_REF]. In the Yinshan belt, late Middle Jurassic N-S thrusting was overprinted by the younger Late Jurassic NW-SE thrusting in the western Daqingshan, indicated by the superimposed striations [START_REF] Wang | The Jurassic structural evolution of the western Daqingshan area, eastern Yinshan belt, North China[END_REF], whereas large scale low-angle thin-skinned thrusts recorded a NW-SE compression in the eastern Daqingshan [START_REF] Gong | Late Mesozoic tectonic evolution and kinematic mechanisms in the Daqing shan at the northern margin of the North China Craton[END_REF]. The NW-SE thrusts are also widely developed in the Taihangshan (Li et al., 2015;Zhang et al., 2020). The NW-SE thrusting dominated multidirectional compression resulted in the shortening deformation during the Late Jurassic along the marginal zones of the Ordos basin [START_REF] Zhang | Changes of Late Mesozoic tectonic regimes around the Ordos Basin (North China) and their geodynamic implications[END_REF]. The duration of this event (i.e., event B of Yanshanian movement) has also been well constrained around 152-135 Ma (C. Li et al, 2016).

Discussion of geodynamic mechanism

In the northern NCB, the closure of the Paleo-Asian Ocean is variously interpreted.

According to some authors, it occurred in the Late Devonian [START_REF] Xu | Middle Paleozoic convergent orogenic belts in western Inner Mongolia (China): framework, kinematics, geochronology and implications for tectonic evolution of the Central Asian Orogenic Belt[END_REF][START_REF] Xu | Framework and evolution of the middle Paleozoic orogenic belt between Siberian and North China Plates in northern Inner Mongolia[END_REF][START_REF] Zhao | Did the Paleo-Asian Ocean between North China Block and Mongolia Block exist during the late Paleozoic? first paleomagnetic evidence from central-eastern Inner Mongolia, China[END_REF], afterward, the Central Asian Orogenic Belt experienced an intracontinental rifting, and the formation of small-sized oceanic basins during the Late Carboniferous-Early Permian period. The final event formed the Solonker tectonic zone, partly also accommodated by strike-slip faulting during the Late Permian to Early Triassic (Xu et al., 2014;[START_REF] Li | Triassic southeastward subduction of North China Block to South China Block: insights from new geological, geophysical and geochemical data[END_REF]. Alternatively, it has been argued that the final closure of the Paleo-Asian Ocean along the Solonker suture zone occurred during the Late Permian to the Early Triassic [START_REF] Chen | Two contrasting Paleozoic magmatic belts in northern Inner Mongolia, China: Petrogenesis and tectonic implications[END_REF][START_REF] Chen | Evolution of the Solonker suture zone: Constraints from zircon U-Pb ages, Hf isotopic ratios and whole-rock Nd-Sr isotope compositions of subduction-and collisionrelated magmas and forearc sediments[END_REF][START_REF] Eizenhöfer | Final closure of the Paleo-Asian Ocean along the Solonker Suture Zone: Constraints from geochronological and geochemical data of Permian volcanic and sedimentary rocks[END_REF][START_REF] Jian | Time scale of an Early to Mid-Paleozoic orogenic cycle of the long-lived Central Asian Orogenic Belt, Inner Mongolia of China: implications for continental growth[END_REF][START_REF] Jian | Evolution of a Permian intraoceanic arc-trench system in the Solonker suture zone, Central Asian Orogenic Belt, China and Mongolia[END_REF][START_REF] Li | Permian geodynamic setting of Northeast China and adjacent regions: closure of the Paleo-Asian Ocean and subduction of the Paleo-Pacific Plate[END_REF]Li et al., 2014;[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 | A tale of amalgamation of three Permo-Triassic collage systems in Central Asia: oroclines, sutures, and terminal accretion[END_REF]. Whatever the model, during the Late Permian to Early Triassic, the northern part of the NCB was characterized by N-S compression (Figure 6.8a). This deformation featured by E-W trending ductile shear zone and thick-and thin-skinned folds and faults, occurred progressively from the northern margin toward the interior (Wan, 2012, [START_REF] Wang | Cratonic reactivation and orogeny: an example from the northern margin of the North China Craton[END_REF].

An E-W trending Late Triassic alkaline intrusive complexes and the associated mafic rocks occurred at around 231-215 Ma in the northern NCB (Yang, 2012, Zhang et al., 2012, 2014). They were derived from partial melting of lower crust and metasomatized enriched lithospheric mantle with some materials from the depleted asthenospheric mantle [START_REF] Yang | Petrogenesis of silica-saturated and silica-undersaturated syenites in the northern North China Craton related to post-collisional and intraplate extension[END_REF][START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF][START_REF] Zhang | Temporal and spatial variations of Mesozoic magmatism and deformation in the North China Craton: implications for lithospheric thinning and decratonization[END_REF][START_REF] Zhu | Timing of destruction of the North China craton[END_REF], indicating the upwelling of the asthenospheric mantle and the asthenosphere-lithospheric mantle interaction during the early lithospheric thinning or modification of the North China Craton (e.g., Han et al., 2004). 134 [START_REF] Davis | Indosinian extension in the Solonker suture zone: the Sonid Zuoqi metamorphiccore complex, Inner Mongolia, China[END_REF]. It was generally acknowledged that it was related to the deep process after the final amalgamation of the NCB and the Mongolian arc terranes (Figure 6.8b), despite the trigger mechanism remains debated, e.g., intraplate extension [START_REF] Yang | Petrogenesis of silica-saturated and silica-undersaturated syenites in the northern North China Craton related to post-collisional and intraplate extension[END_REF], postcollisional or post-orogenic lithospheric delamination [START_REF] Zhang | Early Mesozoic alkaline complexes in the northern North China Craton: implications for cratonic lithospheric destruction[END_REF], and mantle upwelling in front of the subducting slab of Mongol-Okhotsk plate [START_REF] Meng | Late Triassic uplift, magmatism and extension of the northern North China block: Mantle signatures in the surface[END_REF].

During the Early Jurassic-early Middle Jurassic, N-S extension occurred in the western NCB, whereas NW-SE trending extension occurred in the eastern NCB. Considering Late Triassic NE-SW extensional setting in the northern NCB (Qiu et al., 2020), the N-S extension in the western NCB should be a result of post-collision following the Triassic collision between the North and South China blocks [START_REF] Zhang | Changes of Late Mesozoic tectonic regimes around the Ordos Basin (North China) and their geodynamic implications[END_REF]. The Jiumen pluton, together with NE trending rift basin in the Western Hill of Beijing, records a NW-SE extension in the eastern NCB (Figure 6.4). Early Jurassic granitoid and coeval volcanic rocks (including these of the eastern NCB) constitute a NE-SW-trending magmatic belt along the eastern margin of the East Asian continent (Figure 6.4). Accordingly, the NW-SE extension in the eastern NCB could be in a backarc setting in response to the onset of the Paleo-Pacific Plate subduction beneath the NCB (Figure 6.8c), concur with many studies in petrology and geochemistry (e.g., [START_REF] Wu | Geochronology, petrogenesis and tectonic implications of Jurassic granites in the Liaodong Peninsula, NE China[END_REF][START_REF] Wu | Destruction of the North China Craton in the Mesozoic[END_REF][START_REF] Wang | Final closure of the Paleo-Asian Ocean and Onset of Subduction of Paleo-Pacific Ocean: Constraints from Early Mesozoic magmatism in Central southern Jilin Province, NE China[END_REF].

The early Middle Jurassic N-S compression (i.e., Event A of Yanshanian Orogeny) occurred in the northern NCB (Figure 6.5). The extensive E-W trending thrusts and faultrelated folds, related to Event A, mainly localized in the northern NCB (Figure 6.5). In the north of the East Asian continent, it is generally believed that the Mongol-Okhotsk Ocean closed progressively from west to east during the Jurassic-Early Cretaceous [START_REF] Zorin | Geodynamics of the western part of the Mongolia-Okhotsk collisional belt, Trans-Baikal region (Russia) and Mongolia[END_REF][START_REF] Kravchinsky | Evolution of the Mongol-Okhotsk Ocean as constrained by new palaeomagnetic data from the Mongol-Okhotsk suture zone, Siberia[END_REF][START_REF] Metelkin | Late Mesozoic tectonics of Central Asia based on paleomagnetic evidence[END_REF]. The far-field compression, related to the closure of Mongol-Okhotsk Ocean between amalgamated North China-Mongolian terrane and the Siberian Craton, is considered the best explanation for this N-S intraplate compressional event in the northern NCB (Figure 6.8d).

Similar to the Early Jurassic-early Middle Jurassic time, the early Late Jurassic granitoid and coeval volcanic rocks were distributed along the eastern margin of the East Asian continent (Figure 6.8d). The early Late Jurassic NE-SW extension only occurred in the eastern NCB. It is recorded by the emplacement of the Jianchang pluton, brittle normal faults in the grabens or half-grabens [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Qi | Mesozoic tectonic setting of rift basins in eastern North China and implications for destruction of the North China Craton[END_REF], and the top-to-the-NE shearing detachment fault in the Kalaqin metamorphic core complex [START_REF] Lin | Structural characteristics and formation mechanism of the Kalaqin metamorphic core complex in the Yanshan area, China (in Chinese)[END_REF]Figure 6.6). It Considering that Late Jurassic NW-SE compression characterized by the NE trending thrusts and fault-related folds occurred in South China (J. [START_REF] Li | Out-of-sequence thrusting in polycyclic thrust belts: an example from the Mesozoic Yanshan belt, North China Craton[END_REF], this large-scale NW-SE compression in the NCB could be a consequence of the Paleo-Pacific plate subduction beneath the East Asian continent (Figure 6.8f). However, the coeval top-to-the-SSW ductile Sihetang thrusting shear zone formed in the middle YFTB [START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF]Zhu et al., 2015;Figure 6.8f). It seems that the far-field compression related to the closure of Mongol-Okhotsk Ocean might have also influenced deep structure in the northern NCB again. During the Early Cretaceous, large-scale NW-SE extension in the East Asian continent is expressed by metamorphic core complexes, graben or half-graben basins, and A-type magmatism (Wang et al., 2011;[START_REF] Lin | Late Mesozoic extensional tectonics in the North China Craton and its adjacent regions: a review and synthesis[END_REF][START_REF] Wu | Destruction of the North China Craton in the Mesozoic[END_REF]. The thick (∼200 km) Archean lithosphere mantle beneath the eastern NCB was replaced by a thin (<80 km) juvenile one [START_REF] Fan | Destruction of aged lower lithosphere and accretion of asthenosphere mantle beneath eastern China[END_REF][START_REF] Griffin | Composition and thermal structure of the lithosphere beneath South Africa, Siberia and China: porton microprobe studies[END_REF][START_REF] Menzies | Palaeozoic and Cenozoic lithoprobe and the loss of >120km of Archean lithosphere, Sino-Korean craton, China. In Magmatic Processes and Plate Tectonic[END_REF]. It was related to the subduction and rollback of the Paleo-Pacific Plate [START_REF] Wu | Destruction of the North China Craton in the Mesozoic[END_REF].

Chapter 7. Conclusions and Perspectives

Conclusions

The stable North China Craton began to transform in the Mesozoic, and decratonization, cratonic destruction, or lithospheric thinning occurred during Early Cretaceous. Although the destruction of the North China Craton occurred in the Cretaceous, this is controversial with various estimates as to the onset of destruction, i.e., Late Triassic (Han et al., 2004;[START_REF] Yang | Tracing magma mixing in granite genesis: in situ U-Pb dating and Hf-isotope analysis of zircons[END_REF]Yang et al., , 2010b[START_REF] Yang | Petrogenesis of silica-saturated and silica-undersaturated syenites in the northern North China Craton related to post-collisional and intraplate extension[END_REF], or Late Jurassic [START_REF] Gao | Recycling lower continental crust in the North China Craton[END_REF] by sporadic small grabens or normal faults [START_REF] Darby | Paleozoic and Mesozoic tectonic evolution of central Asia: From continental assembly to intracontinental deformation[END_REF][START_REF] Davis | Mesozoic tectonic evolution of the Yanshan fold and thrust belt, with emphasis on Hebei and Liaoning provinces, northern China[END_REF][START_REF] Davis | Triassic and Jurassic tectonics in the eastern Yanshan belt, North China: insights from the controversial Dengzhangzi Formation and its neighboring units[END_REF][START_REF] Ritts | Early Jurassic extensional basin formation in the Daqing Shan segment of the Yinshan belt, northern North China Block, Inner Mongolia[END_REF][START_REF] Zhang | Changes of Late Mesozoic tectonic regimes around the Ordos Basin (North China) and their geodynamic implications[END_REF][START_REF] Meng | Early Mesozoic tectonic settings of the northern North China craton[END_REF][START_REF] Meng | Tectonic evolution of early Mesozoic sedimentary basins in the North China block[END_REF]Li et al., 2015;[START_REF] Qi | Mesozoic tectonic setting of rift basins in eastern North China and implications for destruction of the North China Craton[END_REF]. As such, the extensional tectonics and associated geodynamic mechanism remains poorly constrained due to rare geological records. In this thesis, through the multidisciplinary studies of three plutons, it provides new insights into the emplacement mechanism of the Early Mesozoic granitic pluton and associated extensional tectonic setting, from which we draw four main conclusions.

1. The multidisciplinary study comprising field and microstructural observations, isotope chronology, AMS measurements, and gravity modeling enables us to better understand the emplacement process of the Late Triassic Dushan pluton. The Dushan pluton consists of monzogranite and biotite-rich marginal facies with a progressive petrographic fabric change between them. The arc-shaped gneissosity with locally mylonitic foliations in the southwestern margin is compatible with the magnetic foliation across the pluton, defining an elliptic domelike fabric pattern with a NE-SW striking long axis. The NE-SW trending stretching lineations in the mylonitic zones are also concordant with the magnetic lineations measured in the pluton.

It presents a continuum of fabric variation from magmatic to solid-state conditions within pluton. The tabular or tongue-like Dushan pluton was probably built through the feeder zone in its northeast, with a first biotite-rich sill-shape intrusion then the inflation of conduit-fed monzogranite magma batches. The progressive and southward magma intrusions might make inflations not only upwards, downwards, but also laterally. The inflation of the successive magma might deform and even recrystallize the former cool-down magma, and form an arcshaped, gneissic to mylonitic foliation in the southwestern margin of the pluton. Considering that the similar ductile deformation observed in the southern margin of the pluton is absent in the country rocks, the pluton structure recorded rather its emplacement process than the Late Triassic regional tectonics.

2. To better understand Late Triassic tectonic setting in the northern NCB, the emplacement mechanism of the Wangtufang pluton, which recorded the synmagmatic regional tectonic signature, has been investigated. Zircon U-Pb ages, and Hf isotopic data, and wholerock geochemical analyses suggest that the Late Triassic Wangtufang pluton composed of syenogranite and diorite is derived from partial melting of lower crust with some depleted mantle components. Both the syenogranite and diorite appear isotropic. Anisotropy of magnetic susceptibility and gravity studies have been carried out to characterize internal fabrics and shape of the pluton. The diorite forms just thin remnants above the syenogranite. The syenogranite with a series of NW-SE trending dykes intruded into the diorite and its country rocks. In the syenogranite, the gently dipping magnetic foliations strike nearly parallel to the pluton border. The shallow plunging magnetic lineations mainly strike NE-SW. Combining NE-SW trending elongated subsurface shape with central root, unflat bottom, and moderate-to high-inward dipping sidewalls, the syenogranite could be considered as a lopolith-like intrusion. The syenogranite was likely emplaced by inflation of magma pulses from its central Indeed, due to rare geological records, it is difficult to recognize the regional tectonic framework from few small remnant basins. In this thesis, through the multidisciplinary studies of three plutons, the author provides some arguments for the Early Mesozoic extensional episodes. The structural study of plutons is an effective and practical way to unravel regional tectonic setting coeval with the emplacement process (e.g., Bouchez & Gleizes, 1995;[START_REF] Bouchez | Granite is Never Isotropic: An Introduction to AMS Studies of Granitic Rocks[END_REF][START_REF] Sant'ovaia | Composite-laccolith emplacement of the post-tectonic Vila Pouca de Aguiar granite pluton (northern Portugal): a combined AMS and gravity study[END_REF][START_REF] De Saint Blanquat | Multiscale magmatic cyclicity, duration of pluton construction, and the paradoxical relationship between tectonism and plutonism in continental arcs[END_REF][START_REF] Lin | Late Mesozoic compressional to extensional tectonics in theYiwulüshan massif, NE China and its bearing on the evolution of the Yinshan-Yanshan orogenic belt part II: Anisotropy of magnetic susceptibility and gravity modeling[END_REF]. However, there is not necessary and unique correlation between emplacement mechanism with tectonic setting (i.e. compressive, extensive, strike-slip). Moreover, the link with geodynamic context (i.e. plate convergence, plate divergence, intraplate) is not directly corresponding. Thus, to provide reliable arguments for the Early Mesozoic extensional tectonics, more multidisciplinary studies are needed, such as structural reconstruction of basins and investigations on the magmatic plutons and their adjacent areas.

Huabiao

Figure 1 . 1

 11 Figure 1.1 Simplified geological sketch map of the East Asian continent (Modified from Lin & Wei, 2018).

Figure 1 . 2

 12 Figure 1.2 Regional structural framework of the Yanshan fold and thrust belt (Zeng, Unpublished)

Figure 1 .

 1 Figure 1.3 (a) Distribution of Mesozoic intrusive rocks in the NCB. (b) Histogram of zircon U-Pb ages of Mesozoic igneous rocks in the NCB. (c) Projection of zircon U-Pb ages along the AB line perpendicular to the Mesozoic structural strike of the NCB in panel a, showing a younging trend from east to west for the Jurassic igneous rocks, but a reverse trend for the Cretaceous rocks. (Inset) Graphical representation of a function controlling distance from trench to magma arc with subduction zone dip angles (from Wu et al., 2019).

4 .

 4 Photos piece 1250Thin section piece 320 Oriented thin section piece 68 Major elements sample 9 Trace elements sample 11 Cathodoluminescence grain 8 Zircon U-Pb SIMS dating sample 8 In-situ zircon Hf isotopes sample 2 AMS samples site 167 AMS measurment core 943 Magnetic mineralogical analysis sample 39 Gravity modeling profile 12

  Mesozoic, it transited to the Pacific tectonic regime from the Paleo-Tethys tectonic regime in eastern China, corresponding to the evolution of the Paleo-Pacific Plate (Izanagi Plate). However, timing and process of the subduction beneath the East Asian continent remain controversial. The borehole encountered the early Early Jurassic volcanics on the continental shelf of the East China Sea. Due to the nature of continental margin arc, the volcanics were considered to be related to the onset of the Paleo-Pacific Plate subduction beneath the South China Block

Figure 2 . 1

 21 Figure 2.1 Triassic tectonic framework of the North China Craton

Figure 2 . 2

 22 Figure 2.2 Stratigraphic correlation of the Triassic strata (Data from: Meng et al., 2019;

Figure 2 . 3 Figure 1

 231 Figure 2.3 Jurassic-earliest Cretaceous tectonic framework of the North China Craton

Figure 2 . 4

 24 Figure 2.4 Stratigraphic correlation of the Jurassic-lowest Cretaceous strata (Modified from

Figure 3 . 1

 31 Figure 3.1 Simplified geological map of the Yanshan fold and thrust belt. CFSZ: Chicheng-Fengning ductile shear zone, FLSZ: Fengning-Longhua, ductile shear zone, DNSZ: Damiao-Niangniangmiao ductile shear zone, UF: Unamed fault, JXT: Jixian thrust, MLYA: Malanyu anticline, XBCB: Xiabancheng basin, YZB: Yingzi basin, NDB: Niuying-Dengzhangzi basin, DS: Dushan pluton.

  .1). During the Early Cretaceous, extensional tectonics became prevalent in the NCB and superimposed on the YFTB. Early Cretaceous magmatism, rift basins, and metamorphic core complexes are widely developed in the NCB and its adjacent regions (Lin & Wei, 2018; Figure 3.1c). 3.3. Field Observations in the Dushan pluton 3.3.1. Lithological Units and Bulk Architecture The Dushan pluton intrudes into the northeast part of the E-W trending Malanyu anticline (Figure 3.1). To the northeast of the Dushan pluton, the Dashizhu pluton consists mainly of granite and granodiorite (Ye et al. 2014; Xiong et al., 2017; Figure 3.2). The country rocks, composed of Archaean gneiss (Qianxi Group) and Proterozoic unmetamorphosed carbonates (Changcheng group and Jixian group), are deformed by NE-SW striking fold-and-thrust belts (Figure 3.2). Around the Dushan pluton, the contact with the country rocks is sharp with a regular elliptical shape (Figures 3.2 and 3.3a). The foliation in the gneiss dips mainly at moderate to high angles to the NNW or SSE (Figure 3.3b). Some post-folial folds can be observed (Figure 3.3c). Close to the contact, the foliation of the gneiss is roughly parallel to the border of the Dushan pluton (Figure 3.2). The arc-shaped fold-and-thrust belt appears on the northwestern side of the Dushan pluton (Figure 3.3d). The planar structures of the country rocks unwrap along the elliptical contact of the pluton. It seems that country-rock structures were deflected by the Dushan pluton.3.3.2. Fabric and Structure of the Dushan Pluton The Dushan pluton, which extends ~30 km along a NE-SW long axis, consists of monzogranite with a biotite-rich marginal facies (Figure 3.2; Ye et al. 2014; Jiang et al., 2018).

Figure 3 . 2

 32 Figure 3.2 Structural geological map of the Dushan pluton and adjacent area. U-Pb zircon data from: Jiang et al. (2018); Luo et al. (2003); Xu et al. (2016); Ye et al. (2014); Xiong et al. (2017). (a) Stereonet for foliations in the Dushan pluton; (b) Stereonet for foliations in the country rocks.

Figure 3 . 3 Figure 3 . 4

 3334 Figure 3.3 Field photographs of the country rocks. (a) Western contact between the Dushan pluton and its country rocks. (b) Country rocks in the southeast of the Dushan pluton. (c) Folded gneiss to the south of the Dushan pluton. (d) Country rocks in the north of the Dushan pluton. part of the Dushan pluton, whereas its central and northeastern parts display only weak planar

  .4f). The mylonite exhibits a margin-parallel foliation with NE-SW trending lineation outlined by plagioclase and K-feldspar crystals that consistently plunge 30°-40° to the southwest. Along the SW-plunging (N210°E) lineation (Figure 3.4e), Sigmoidal shaped K-feldspars indicated a top-to-the-SW shearing (Figure 3.4f). Note that similar mylonitic fabrics are not present in the country rocks close to the pluton.

( 2 )( 3 )

 23 ) Magmatic fabrics and weak solid-state fabrics. The magmatic fabrics concern the northeastern Dushan pluton(Figures 3.5a and 3.5g). Quartz crystals are anhedral, nondeformed, and do not exhibit obvious shape preferred orientation. Joints in quartz grains are planar or weakly lobate (Figure3.5a). However, a weak solid-state overprint is also commonly present in the Dushan pluton(Figures 3.5b and 3.5g). Millimeter-sized quartz grains show a weak undulose extinction. Sometimes, small well-individualized quartz grains occur at the border of the coarse grains (Figure 3.5b) suggesting that they underwent slight dynamic recrystallization. The euhedral biotite flakes have a sharp extinction and are neither kinked nor bent. Significant solid-state deformation has not been observed. Hence, these weak solid-state fabrics are probably acquired mainly under hightemperature subsolidus conditions, indicative of submagmatic to solid-state flow. Moderate solid-state fabrics. Many samples from the southwestern part and local areas of the northeastern part of the Dushan pluton exhibit moderate solid-state fabrics. Quartz grains display intensive dynamic recrystallization and are replaced by aggregates of newly formed grains (Figures 3.5c-3.5d and 3.5g). Numerous subgrains with serrated boundaries display a conspicuous undulose extinction. The biotite grains are kinked and bent. The quartz grains are organized into ribbons and form a gneissosity. At this stage, the plagioclase and K-feldspars do not display any recrystallization or deformation suggesting low-grade temperature conditions during deformation (300-400°C; Passchier & Trouw, 2005). Strong solid-state microstructures. Approaching the southern border of the Dushan pluton, the monzogranite is locally mylonitized (Figures 3.5e-3.5g). Quartz aggregates with irregular grain boundaries record widespread recrystallization by subgrain rotation. The biotite flakes are commonly elongate, kinked and bent but plagioclase grains and Kfeldspars are devoid of ductile deformation. Extremely fine-grained quartz and feldspar sigma-type tails occur on K-feldspar and plagioclase residual phenoclasts, suggesting temperature conditions between 300 and 400°C (Passchier & Trouw, 2005) and pointing to a top-to-the-SW sense of ductile shearing in the locally mylonitic structures (Figure 3.5f). In short, an increase intensity of solid-state fabrics is observed in the Dushan pluton from the northeast to the southwest (Figure 3.5g), without sharp boundaries between fabric types. Mylonitic fabrics develop in the southernmost part of the pluton, close to the

Figure 3 . 5

 35 Figure 3.5 Microstructures of typical investigated samples in the Dushan pluton. (a) Magmatic microstructures in the northeastern part of the Dushan pluton. (b) Submagmatic or high temperature solid-state microstructures in the northern Dushan pluton. (c) Moderate solid-state microstructures in the central Dushan pluton. (c) Moderate solid-state microstructures in the southern Dushan pluton. (e) Strong solid-state microstructures in the southern Dushan pluton. (f) Strong solid-state microstructures in mylonitic monzogranite of the Dushan pluton. (g) Distribution map of the different types of microstructures. Bi = biotite, Kfs = K-feldspar, Pl = Plagioclase, Qz = quartz.

  Samples 17DS39 and DS44 are collected from the monzogranite in the western Dushan pluton and the granodiorite in the southern Dashizhu pluton, respectively (Figure3.2).The zircon grains from these two samples are subhedral, transparent, and 50-150 μm in length with aspect ratios between 1:1 and 3:1. CL images show clear oscillatory zoning (Figure 3.6a). Th/U ratios of Sample 17DS39 vary from 0.14 to 1.21. Twenty-one analyses of the 206 Pb/ 238 U and 207 Pb/ 235 U results plotted on a Concordia diagram are relatively consistent, yielding a Concordia age of 217.6±1.5 Ma, interpreted as the Late Triassic crystallization age of the Dushan pluton (Figure 3.6b, Table3.1). Th/U ratios of Sample DS44 range from 0.71 to 1.66. Twenty-one analyses of the 206 Pb/ 238 U and 207 Pb/ 235 U results, excluding one inherited grain at 2437 Ma, show a Concordia age of 225.6±1.5 Ma (Figure 3.6b, Table 3.1). It corresponds to the Late Triassic emplacement age of the Dashizhu pluton.3.6. Measurement of Anisotropy of Magnetic SusceptibilityPlanar fabrics are hardly observable in the northeastern and central parts of the Dushan pluton, and when a planar fabric can be observed, the mineral lineation never shows up, except within the mylonites. It is well-established that magnetic fabrics record the fabric elements of

Figure 3 . 6

 36 Figure 3.6 Cathodoluminescence (CL) images and U-Pb diagrams of Concordia age of representative zircons from collected samples. White elliptical circles are Secondary Ion Mass Spectrometer (SIMS) analysis locations; the numbers are ages. MSWD: mean square of weighted deviates.

Figure 3 . 7

 37 Figure 3.7 AMS scalar parameters of the Dushan pluton. (a) Histogram of site mean magnetic susceptibility (Km). (b) Day plot of hysteresis parameters. Mrs: saturation of magnetic remanence, Ms: saturation of induced magnetization, Hcr: coercivity of magnetic remanence, Hr: coercivity of the measured sample. SD: single domain, PSD: pseudo-singledomain, MD: multidomain. (c) Shape parameter T versus anisotropy degree PJ value. (d) Bulk magnetic susceptibility Km versus shape parameter T. (e) Anisotropy degree PJ value versus Km.

  3.8): (1) Isothermal Remanent Magnetization (IRM); (2) thermomagnetic (K-T) curves, and (3) hysteresis loops. The measurements are performed in the Laboratory of Paleomagnetism and Chronology of IGGCAS, Beijing.

  Figure 3.8 Magnetic mineralogy investigations of representative specimens from the Dushan pluton. (a-c) hysteresis loops, (d-f) acquisition of isothermal remanent magnetization (IRM), and (g-i) thermomagnetic curves (K (T) curves).

3. 2 ;

 2 Bouchez, 2000). Only 2 AMS sites (DS17 and DS20) display the Km values less than 500×10 -6 SI, usually attributed to an exclusively paramagnetic contribution. A broad correlation between petrographic facies type and Km variations can be observed, with lower Km values for the biotite monzogranite marginal facies and higher ones for other facies (Figure3.9a).The hysteresis loops of six representative samples display nonlinear variations of hysteresis curves, indicating a dominance of the ferromagnetic minerals). All IRM acquisition curves show a sudden saturation below 300 mT). All thermomagnetic measurements display sharp drops of magnetic susceptibility at 550-600°C, suggesting the presence of magnetite as the principal susceptibility carrier).

  Figure 3.9 AMS maps of the Dushan pluton (a) Mean magnetic susceptibility map, (b) Anisotropy degree map, and (c) Shape parameter map in the Dushan pluton.

Figure 3 .

 3 Figure 3.10 Equal-area projections (lower hemisphere) of AMS results for each sampling site. Confidence ellipses at 95% level are drawn around each average orientation direction. (a) K1, long axis or magnetic lineation; K3, short axis or pole to magnetic foliation.

Figure 3 .

 3 Figure 3.11 Mesoscopic and magnetic fabric patterns and orientation diagrams of K3 and K1. (a) Foliations. (b) Lineations.

Figure 3 .

 3 Figure 3.12 Gravity modeling. (a) Residual Bouguer gravity anomaly of the Dushan pluton and adjacent areas after subtraction of a 380 km wavelength regional trend from the complete Bouguer anomaly. Symbols and captions are the same as in Figure 2. (b) 2-D gravity modeling across the Dushan pluton. Note that the arrows show the possible feeder zones for the pluton.

  1. A continuum of fabric variation from magmatic to solid-state conditions in the Dushan plutonThe central and northeastern parts of the Dushan pluton display weak or invisible mineral preferred orientation, and in the southwestern part of the pluton a gneissosity, even with locally developed mylonitic structures, defines the pluton margin). However, no sharp boundaries between these magmatic and solidstate fabrics can be observed across the pluton (Figure3.5). The strong solid-state fabrics are only developed in the mylonitic zones in the southernmost part of the pluton (Figure3.5g). The pervasive gneissosity develops southwards, and the mylonitic fabric is only exposed when approaching the margin. However, the country rocks never present such a similar penetrative fabric that appears to be restricted in the granite. Strongly flattened xenoliths without any stretching lineation are distributed in the gneissic monzogranite(Figure 3.4d). In locally the mylonitic zones, the fabrics are associated with a top-to-the-SW ductile shearing(Figures 3.5f

and 3 .

 3 11b). These structural data suggest that the Dushan pluton underwent a southwestward increasing strain gradient of solid-state deformation. Magmatic fabrics extensively remain preserved in the northeast part of the Dushan pluton (Figure3.5g). Moreover, the mesoscopic planar fabrics (i.e. gneissic and mylonitic foliations) are geometrically compatible with the magnetic foliations that strike parallel to the pluton contact (Figure3.11a). The cartographic elliptic dome-like pattern with a NE-SW striking long axis is in good agreement with both mesoscopic and magnetic foliations, despite the fabrics dip inwards close to the southeastern border of the pluton. The stretching lineations observed in the mylonitic zones strike NE-SW, and are also concordant with the magnetic lineations measured in the pluton (Figure3.11b).

  and 3.13). The funnel-shaped Dashizhu pluton sharply thins away from the feeder zone, implying that the current exposure may be also close to the root of the Dashizhu pluton. According to the geochronological results from both plutons, the Dashizhu pluton firstly intruded into Malanyu anticline at ca. 225 Ma, then the Dushan pluton intruded against the southwestern sidewall of the Dashizhu pluton at ca. 220 Ma.

  2) an unflat floor and inward dipping sidewalls; (3) the strongly flattened xenoliths without stretching lineations in the gneissic monzogranite; (4) the deflection of country-rock structures; and (5) the arc-shaped fold-and-thrust belt unwrapping along the Dushan pluton in the northwest. The dominant NE-SW lineations may reflect main southwestward intrusion, due possibly to the blocking of the Dashizhu pluton to the northeast (Figure 3.11b). The latter arrivals of magma might inflate, deform and even recrystallize the former cooled-down magma.

Figure 3 .

 3 Figure 3.13 Scenarios for multiple emplacement of the Dushan pluton and ductile shear zone nucleation. (a) 3-D schematic sketch summarizing emplacement of the Dushan pluton. (b) Cross sections of the Dushan pluton showing its emplacement. The overlying rocks above the current exposure are not considered, and the shape of the plutons at depth is inferred from gravity data.

Chapter 4 .

 4 Emplacement of the Late Triassic granitic Wangtufang pluton 4.1. Introduction

Figure. 4 . 1

 41 Figure. 4.1 Simplified geological map of the Yanshan fold and thrust belt and location of the Wangtufang pluton. CFSZ: Chicheng-Fengning ductile shear zone, FLSZ: Fengning-Longhua, ductile shear zone, DNSZ: Damiao-Niangniangmiao ductile shear zone, UF: Unnamed fault, JXT: Jixian thrust, MLYA: Malanyu anticline, XBCB: Xiabancheng basin, NDB: Niuying-Dengzhangzi basin, WTF: Wangtufang pluton.

  The Wangtufang pluton has a subcircular surface exposure with a radius of about 12 km. It mainly consists of syenogranite in the southwest and diorite in the northeast (Figure4.2).Macroscopically, these two types of rocks (i.e., pale red syenogranite and dark gray diorite) appear totally isotropic, lacking of any planar and linear structures at outcrops(Figures 4.3a

and 4 .

 4 Figure. 4.2 Geological map and cross-sections in the Wangtufang pluton and its adjacent area. Numbers in circles and stereonet show the locations and attitudes of the measured dykes, respectively. U-Pb zircon data from Liu et al. (2012). See Figure 4.1 for location.

Figure 4 . 3

 43 Figure 4.3 Field photographs of the Wangtufang pluton and its country rocks. (a) Syenogranite in the south of the Wangtufang pluton. (b) Diorite in the north of the Wangtufang pluton. (c) Archaean gneiss in the south of the Wangtufang pluton. (d) NW-SE trending lineation in Archaean gneiss. (e) Sigmoidal K-feldspar porphyroclast in Archaean gneiss, indicating a top-to-the-SE sense of shearing. (f) Migmatitic granite in the north of the Wangtufang pluton. northwest, steep and weak foliations are developed in the migmatitic granite near the contact

Figure 4 . 4

 44 Figure 4.4 Field photographs of the dykes and xenoliths in the Wangtufang pluton. (a) Syenogranitic dykes near the contact between the syenogranite and the diorite. (b) Dioritic xenoliths in the syenogranitic dykes. (c) Syenogranitic dykes near the northeastern border of the Wangtufang pluton. (d) Dioritic xenolith in the syenogranite.

Figure 4 . 5

 45 Figure 4.5 Microstructures of typical investigated samples in the Wangtufang pluton. (a) Distribution map of the different types of microstructures. (b) and (c) Magmatic microstructures in the syenogranite and the diorite, respectively. (d) and (e) Submagmatic microstructures in the syenogranite and the diorite, respectively.

( 7 .

 7 77-9.14 wt %) and low MgO(2.52-3.63 wt %) contents, with Mg # of 30.67-51.97. The samples plot in the monzodiorite and monzonite fields in the total alkali versus silica diagram (Figure 4.7a). Both the syenogranite and the diorite are peraluminous (Figure 4.7b) and can be categorized as high-K calc-alkaline series rocks (Figure 4.7c). 4.4.3. In-situ zircon Hf isotopes Previously analyzed zircon grains for U-Pb isotopes were chosen for In-situ zircon Hf isotopic analyses. It was carried out in situ on a Neptune multi-collector ICP-MS equipped with a Geolas-193 laser ablation system at IGGCAS. Results for in situ Hf isotope analyses of zircons are shown in Figure 4.9 and

Figure 4 . 7

 47 Figure 4.7 Chemical analyses diagrams of major elements for the Wangtufang pluton. (a) SiO2 vs. Na2O+K2O diagram. (b) SiO2 vs. K2O diagram. (c) Plot of A/CNK vs. ANK.

Figure 4

 4 Figure 4.8 Trace elements diagrams for the Wangtufang pluton. (a) Chondrite-normalized REE patterns. (b) Primitive mantle normalized element spider patterns.

Figure 4 . 9

 49 Figure 4.9 Diagram of εHf(t) vs. U-Pb ages Plot of all previously analyzed zircons for U-Pb isotopes in the Wangtufang pluton. Hf isotopic compositions of zircons from the contemporaneous plutons are from: Yang et al. (2012); Ye et al. (2014) and Xiong et al. (2017).

  been sampled for AMS measurements in the Wangtufang pluton, 20 in the syenogranite and 16 in the diorite. The measurements are realized in the Laboratory of Paleomagnetism and Chronology of IGGCAS. A total of 204 cores from 36 sampling sites were cut into cylindrical Table 3. LA-ICP-MS in-situ Hf isotopic analyses of zircons for the Wangtufang pluton.specimens of 2.2 cm in length and 2.5 cm in diameter. The anisotropy magnetic susceptibility and the bulk susceptibility were measured with a KLY4 susceptometer. The mean orientation of three principal axes of the AMS ellipsoid (K1 ≥ K2 ≥ K3), the shape parameter (T), and

Figure 4 .

 4 Figure 4.10 AMS scalar parameters of the Wangtufang pluton. (a) Histogram of site mean magnetic susceptibility (Km). (b) Anisotropy degree PJ value vs. Bulk magnetic susceptibility Km. (c) Shape parameter T vs. Bulk magnetic susceptibility Km. (d) Shape parameter T vs. anisotropy degree PJ value.

Figure 4 .

 4 Figure 4.11 Magnetic mineralogy investigations of representative specimens from the Wangtufang pluton. (a-c) hysteresis loops, (d-e) acquisition of isothermal remanent magnetization (IRM), and (gi) thermomagnetic curves (K (T) curves).

Figure 4 . 2 (

 42 Figure 4.12 Day plot of hysteresis parameters. Mrs: saturation of magnetic remanence, Ms: saturation of induced magnetization, Hcr: coercivity of magnetic remanence, Hr: coercivity of the measured sample. SD: single domain, PSD: pseudo-singledomain, MD: multidomain.More than 92% of the sampled sites display an anisotropy degree (PJ) lower than 1.2

Figure 4 .

 4 Figure 4.13 Equal-area projections (lower hemisphere) of AMS results for each sampling site. Confidence ellipses at 95% level are drawn around each average orientation direction.defined, whereas it is considered as well-defined or reliable when lower than 25°. More than

Figure 4 .

 4 Figure 4.14 Mesoscopic and magnetic fabric patterns and orientation diagrams of K3 and K1. (a) Foliations. (b) Lineations.

Figure 4 .

 4 Figure 4.15 Gravity modeling. (a) Residual Bouguer gravity anomaly of the Wangtufang pluton and adjacent areas after subtraction of a 200 km wavelength regional trend from the complete Bouguer anomaly. Symbols and captions are the same as in Fig. 2. (b) 2D gravity modeling across the Wangtufang pluton. Note that the arrows show the possible feeder zones for the pluton.

Figure 4 . 6 )

 46 . Concerning the fabric pattern of the diorite, magnetic foliations show variable dip angles and scattered magnetic lineations, and this may be due to the later intrusion of the syenogranite(Figure 4.14). The border-parallel magnetic foliations are usually considered as a consequence of magma inflation during the intrusion.Gravity modeling reveals thin remnants of diorite, which are close to the roof of the syenogranite (Figure4.15). Furthermore, field observations indicate that numerous syenogranite dykes intruded into the diorite with sharp contact and dismembered the diorite after its fully crystallization(Figure 4.4). As the fabric pattern seems to be modified, it is difficult to retrace the emplacement process of the diorite, therefore, we shall focus on the emplacement of the syenogranite.In the syenogranite, the current exposure is close to the roof of the pluton due to the covering of the diorite remnants (Figure4.15). The mostly subhorizontal magnetic foliations, roughly parallel to the contact, develop near the roof (Figure4.14a). Bouguer gravity anomaly reveals a NE-SW trending elongated subsurface shape with an overall funnel-shaped geometry, an unflat bottom, and moderate-to highinward dipping sidewalls(Figure 4.15). The root of the syenogranite as a feeder zone is located in its center. Thus, it might be estimated as a lopolith-like intrusion(Figure 4.16). Considering the lack of significant emplacement-related ductile deformation in the country rocks, the syenogranite with a concentric fabric pattern could emplace by the inflation of the magma from its central feeder zone and the pluton is built up by floor depression (Figure 4.16). The subhorizontal magnetic fabrics could have developed by magmatic flow subparallel to a roof, represented by the floor of the diorite (e.g., McNulty

Figure 4 .

 4 Figure 4.16 Block diagrams of emplacement mode of the Wangtufang pluton.

Figure 4 .

 4 Figure 4.17 Triassic tectonic framework of the NCB showing Late Triassic tectonic setting of the northern NCB. XBCB: Xiabancheng basin, NDB: Niuying-Dengzhangzi basin, WTF: Wangtufang pluton.

Figure 5 . 1

 51 Figure 5.1 Simplified geological sketch map of the East Asian continent (Modified from Lin & Wei, 2018).

  Cretaceous intracontinental orogeny is a key element of the East Asian tectonics. After Paleozoic-Triassic amalgamation, the welded East Asian continent was bounded by the Mongol-Okhotsk Ocean in the north, Bangong-Nujiang Ocean in the southwest, and the Paleo-Pacific Ocean in the southeast. Jurassic-Early Cretaceous deformations are widespread through East Asia (Figure 5.1; Dong et al., 2015). As such, any proper understanding of the Mesozoic East Asian tectonics requires a clear vision on the Jurassic-

  Mongol-Okhotsk Ocean, the Paleo-Pacific Ocean, and the Bangong-Nujiang Ocean. The Mesozoic tectonics of the NCB is mainly related to the spatial-temporal influence of the Paleo-Pacific and Mongol-Okhotsk tectonic regimes (Figure 5.1). The closure time of the Mongol-Okhotsk Ocean between the Siberian Craton and the North China-Mongolian terrane remains

  Overview of the NCB Due to the intense deformation during the Yanshanian orogeny, Jurassic strata mainly remain in the Ordos basin, the Yinshan-Yanshan fold and thrust belt, as well as Taihangshan, and Bohai Bay-Hefei basins (Figure 5.2). The Lower Jurassic-lower Middle Jurassic strata in the NCB consist of conglomerate, sandstone, and mudstone intercalated with thick coal beds (Figure 5.3). In these strata of the western NCB, the E-W trending normal faults are widely recognized in the Ordos basin and its periphery, such as Daqingshan, and Taihangshan (Figure

Figure 5 . 2

 52 Figure 5.2 Simplified geological map showing the Jurassic structures and magmatic rocks in the NCB (Modified from Zhang et al., 2007). SGB: Shiguai basin; YGB: Yungang basin; NJB: Ningwu-Jingle basin; XHB: Xuanhua basin; WHB: Western Hill basin; DEB: Diaoe basin; HCB: Houcheng basin; CDB: Chengde basin; NDB: Niuyingzi-Dengzhangzi basin; KLQ: Kalaqin metamorphic core complex. See Figure 5.1 for locations.

  3). The syntectonic conglomerate and sandstone (i.e., Longmen (J2l) and Jiulongshan (J2j) Formations,Li et al., 2014; Xiahuayuan Formation (J2x),Liu et al., 2018; Changhangou Formation (J2c),Wang et al., 2017; Yungang Formation (J2y),Li et al., 2014) overlay this unconformity. The nearly N-S directed thrusts related to this event widely occurred within the Yanshan fold and thrust belt (Figure 5.3; e.g., the Duanshuwa-Jianbaoshan thrust, C. Li et al., 2016; Miyun-Xifengkou fault and secondary faults, Zhujiakou fault, Xinglong fault, Gaobanhe fault, Sanpo fault, and Banbishan fault,[START_REF] Chen | Geometric and kinematic evolution of basement-cored structures: intraplate orogenesis within the Yanshan Orogen, northern China[END_REF] Lengkou fault, Zhang et al., 2004; Sandaogou fault, Zhao, 2016).

Figure 5 . 3

 53 Figure 5.3 Stratigraphic correlation of the Jurassic-lowest Cretaceous strata (Modified from Darby et al., 2001). See Figure 5.2 for locations of the basins.

Figure 5 . 4 .

 54 Figure 5.4. Structural geological map of the Jianchang-Jiumen pluton and adjacent areas. U-Pb zircon data are from Wu et al. (2006) and Cui (2015). See Figure 5.2 for locations.The Jianchang-Jiumen pluton intrudes into Archaean migmatite and Neoproterozoic-

Figure 5 . 5 .

 55 Figure 5.5. Field photographs of the Jianchang-Jiumen pluton and its country rocks. (a) Fine-and medium-grained monzogranite in the Jiumen pluton. (b) Monzogranite in the Jianchang pluton. (c) Hornstone in the northeast of the Jiumen pluton. (d) Marble in the northwest of the Jiumen pluton. (e) Marble in the west of the Jiumen pluton. (f) Migmatite in the south of the Jianchang pluton. pluton (Figure 5.4).

Figure 5 . 6 .

 56 Figure 5.6. Microstructures of typical investigated samples in the Jianchang-Jiumen pluton. (a) Distribution map of the different types of microstructures. (b) and (d) Magmatic fabrics in the Jiumen and Jianchang plutons, respectively. (d) and (e) Submagmatic microstructures in the Jiumen and Jianchang plutons, respectively.

Figure 5 . 7 .

 57 Figure 5.7. Cathodoluminescence (CL) images and U-Pb diagrams of Concordia age of representative zircons from collected samples. White solid ellipses are Secondary Ion Mass Spectrometer (SIMS) U-Pb analysis locations. MSWD: mean square of weighted deviates.

Figure 5 .

 5 Figure 5.8. AMS scalar parameters of the Jianchang-Jiumen pluton. (a) Histogram of site mean magnetic susceptibility (Km). (b) Anisotropy degree PJ value vs. Bulk magnetic susceptibility Km. (c) Shape parameter T vs. Bulk magnetic susceptibility Km. (d) Shape parameter T vs. anisotropy degree PJ value.

Figure 5 . 9 .

 59 Figure 5.9. Magnetic mineralogy investigations of representative specimens from the Jianchang-Jiumen pluton. (a-c) hysteresis loops, (d-e) acquisition of isothermal remanent magnetization (IRM), and (g-i) thermomagnetic curves (K (T) curves).

Figure 5 .

 5 Figure 5.10. Day plot of hysteresis parameters. Mrs: saturation of magnetic remanence, Ms: saturation of induced magnetization, Hcr: magnetic coercivity of magnetic remanence, Hr: magnetic coercivity of the measured sample. SD: single domain, PSD: pseudo-single domain, MD: multidomain.1. Jiumen pluton. The magnetic foliations throughout the Jiumen pluton generally dip outwards

Figure 5 .

 5 Figure 5.11. Equal-area projections (lower hemisphere) of AMS results for each sampling site.Confidence ellipses at 95% level are drawn around each average orientation direction.

Figure 5 .

 5 Figure 5.12. Magnetic fabric patterns and orientation diagrams of K3 and K1. (a) Foliations. (b) Lineations.

Figure 5 .

 5 Figure 5.13. Gravity modeling. (a) Residual Bouguer gravity anomaly of the Jianchang-Jiumen pluton and adjacent areas after subtraction of a 200 km wavelength regional trend from the complete Bouguer anomaly. Symbols and captions are the same as in Figure 5.4. (b) 2D gravity modeling across the Jianchang-Jiumen pluton.

1 .

 1 Significance of Magnetic FabricsThe Jianchang-Jiumen pluton appears isotropic without obvious mineral preferred orientation in the field). Microstructural observations reveal that the fabrics recorded in the Jianchang-Jiumen pluton are mainly magmatic and submagmatic (Figure5.6), indicating these fabrics were acquired developed during, or just after, the crystallization of the magma. The magnetic fabrics of the Jianchang-Jiumen pluton are dominated by the pseudosingle domain (PSD) magnetite, presenting relatively low PJ value (Figure5.8), suggesting also a magmatic origin of fabrics in the Jianchang-Jiumen pluton. The preserved magmatic fabrics in the pluton usually represent only the last increment of strain during crystallization, since the fabrics in earlier stages are easily reset by the flowing magma[START_REF] Yuan | Evaluating flow from structures in plutons[END_REF]

5. 7 . 2 .

 72 Emplacement Modes and Their Bearings on the Regional Tectonics 5.7.2.1. Jiumen pluton Geochronological data suggest that the Jiumen pluton and the Jianchang pluton were emplaced during the Early Jurassic (~190 Ma) and the early Late Jurassic (~158 Ma), respectively(Figure 5.4). Gravity modeling reveals the Jianchang-Jiumen pluton corresponds to two partly overlapping intrusions (Figure5.13). The Jiumen pluton, as one stacked sheet close to its bottom, overlies the northwestern part of the Jianchang pluton. In the northeast, the pre-existing Yangjiazhangzi syncline were developed before the emplacement of the Jiumen pluton, suggested by the Late Triassic granitic stock intruded into its core (Figure5.4).Although the Jiumen pluton and its country rocks were cut by the nearly E-W and NE-SW trending fold and thrust belts, all the bedding in the contact metamorphic aureole strikes subparallel to the pluton boundary and dip outwards. It seems that the Jiumen pluton intruded into the core of the anticline adjacent to the Yangjiazhangzi syncline. Considering the steeply outward dipping and margin-parallel foliations and absence of the syn-magmatic ductile shearing in the country rocks, the Jiumen pluton could emplace as a phacolith-like intrusion by the inflation of the magma in the anticlinal core(Figure 5.14).

  2), therefore, we argue that the Jiumen pluton, presenting a NE-SW magnetic lineation, have recorded a NW-SE trending back arc extensional paleostress field related to the subduction of the Paleo-Pacific Plate. Accordingly, the NW-SE extension in the eastern NCB could be in a backarc setting in response to the onset of the Paleo-Pacific Plate subduction beneath the NCB,

Figure 5 .Chapter 6 .

 56 Figure 5.14. Emplacement mode of the Jianchang-Jiumen pluton.

  this paper, to better understand tectonic setting and dynamic mechanism during Triassic to earliest Cretaceous in the northern NCB, an integrated multidisciplinary investigation, including structural geology, geochronology, geochemistry, AMS, and gravity modeling, has been conducted in Late Triassic Dushan pluton in Eastern Hebei, Late Triassic Wangtufang pluton in northern Hebei and Jurassic Jianchang-Jiumen pluton in western Liaoning. Through the emplacement of three plutons, three extensional stages, including Late Triassic, Early Jurassic-early Middle Jurassic, and early Late Jurassic occurred in the North China Craton. It further constrains regional tectonic framework of the North China Craton during Triassicearliest Cretaceous and related geodynamic mechanism. 6.1. Early Mesozoic tectonic framework of the northern NCB Three extensional stages, including Late Triassic, Early Jurassic-early Middle Jurassic, and early Late Jurassic, provide new constraints on multiphase deformation sequences of the NCB during Triassic-Early Cretaceous. Integrating previous studies concerning other structural elements and associated kinematics in different stages of Jurassic-Early Cretaceous, an improved and more detailed structural framework of the NCB was established for understanding of Jurassic-Early Cretaceous intracontinental orogeny and associated geodynamic mechanism (Figure 6.1). 6.1.1. Early-Middle Triassic N-S compression in the northern NCB In the NCB, the Triassic strata overlie conformably the Permian strata, while the Upper Triassic strata overlie unconformably the underlying strata (Figure 6.1; Meng et al., 2019). In the northern NCB, the ductile shear zone concerns the E-W trending Chicheng-Fengning, Fengning-Longhua, and Damiao-Niangniangmiao ductile shear zones in the north (Wan, 2012;

Figure 6 . 1

 61 Figure 6.1 Early Mesozoic tectono-stratigraphic summary diagram in the NCB.

Figure 6 . 2

 62 Figure 6.2 Early-Middle Triassic tectonic outline of the NCB. CFSZ: Chicheng-Fengning ductile shear zone, FLSZ: Fengning-Longhua, ductile shear zone, DNSZ: Damiao-Niangniangmiao ductile shear zone, UF: Unnamed fault, JXT: Jixian thrust, MLYA: Malanyu anticline, XBCB: Xiabancheng basin, NDB: Niuying-Dengzhangzi basin.

  ) the NE-SW trending elongated subsurface pluton shape, and (3) the orthogonal NW-SE striking syenogranitic dykes considered as tension gashes during the NE-SW trending extension. Therefore, the Wangtufang pluton provides reliable arguments to the Late Triassic intracontinental extensional setting already suggested in the northern NCB (Figure 6.3). 6.1.3. Early Jurassic-early Middle Jurassic N-S extension in the western NCB and NW-SE extension in the eastern NCB

Figure 6 . 3

 63 Figure 6.3 Late Triassic tectonic outline of the NCB. MLYA: Malanyu anticline, XBCB: Xiabancheng basin, NDB: Niuying-Dengzhangzi basin.

Figure 6 . 4

 64 Figure 6.4 Early Jurassic-early Middle Jurassic tectonic outline of the NCB. SGB: Shiguai basin; YGB: Yungang basin; WHB: Western Hill basin.

Figure 6 .

 6 Figure 6.5 late Middle Jurassic tectonic outline of the NCB. SGB: Shiguai basin; YGB: Yungang basin; MXF: Miyun-Xifengkou fault; NEF: Nangou-Erdaogou fault.

6. 1 . 6 .

 16 Late Late Jurassic-Early Cretaceous NW-SE large-scale compression and extension The late Late Jurassic-Earliest Cretaceous mainly NW-SW compressional event (i.e., Event B of Yanshanian Orogeny) is well recorded by the syntectonic conglomerates and the unconformity above them (Figure 6.1). The NE trending thrusts and fault-related folds are well developed throughout the NCB (Figure 6.7). In the mid-eastern YFTB, NE-NNE trending thinand thick-skinned thrust sheets have accommodated a NW-SE shortening via in-and out-of-

Figure 6 . 6 early

 66 Figure 6.6 early Late Jurassic tectonic outline of the NCB. DEB: Diaoe basin; HCB: Houcheng basin; CDB: Chengde basin; NDB: Niuyingzi-Dengzhangzi basin; KLQ: Kalaqin metamorphic core complex.

Figure 6 . 7 late

 67 Figure 6.7 late Late Jurassic tectonic outline of the NCB. SGB: Shiguai basin; YGB: Yungang basin; NJB: Ningwu-Jingle basin; MXF: Miyun-Xifengkou fault; SHTT: Sihetang thrust.

  Contemporaneous surface uplift and supracrustal stretching occurred in the northern NCB (Figure 6.1). The Wangtufang pluton recorded the Late Triassic NE-SW intracontinental extension already suggested in the northern NCB. Besides, a Late Triassic metamorphic core complex was developed in the south of Sonid Zuoqi in the vicinity of the Solonker suture zone Dec. 2020 Chapter 6

Figure 6 . 8

 68 Figure 6.8 Simplified geological maps showing Triassic-Early Cretaceous structures and magmatic rocks in North China, and geodynamic setting. (a) Early-Middle Triassic. (b) Late Triassic. (c) Early Jurassic-early Middle Jurassic. (d) late Middle Jurassic. (e) early Late Jurassic. (f) late Late Jurassic.

  seems that early Late Jurassic NE-SW backarc extension, related to the Paleo-Pacific Plate subduction beneath the East Asian continent, occurred in the eastern NCB again (Figure 6.8e). Therefore, Jurassic Paleo-Pacific Plate subduction-related two-stage backarc extension, interrupted by the far-field N-S compression related to the closure of Mongol-Okhotsk Ocean, occurred in the eastern NCB (Figure 6.8).

  . Before the Cretaceous destruction of the North China Craton, the North China Craton has undergone two orogenic cycles, including Paleozoic continental collisions with Mongolian arc terranes and South China Block at block boundaries, and Jurassic-Early Cretaceous intracontinental orogeny (also called Yanshanian Orogeny). It gave rise to a complicated assemblage of folds, thrust and reverse faults, normal faults, and intrusive rocks in the NCB during multiphase deformations. Due to modification of multiphase deformations, only some clues of extensional episodes, coeval with the igneous rocks possibly implying onset of the destruction of the North China Craton, have been found

4 .

 4 conduit and built up by floor depression. Emplacement of the syenogranite was in an extensional setting, considering: (1) the NE-SW striking magnetic lineation, (2) the NE-SW trending elongated subsurface pluton shape, and (3) the orthogonal NW-SE striking syenogranitic dykes considered as tension gashes during the NE-SW trending extension. The Wangtufang pluton provides reliable arguments to the Late Triassic intracontinental extensional setting already suggested in the northern NCB. 3. The Jurassic-Early Cretaceous intracontinental orogeny in East Asia is expressed by a complicated structural feature in the NCB with multiphase deformations that timing and kinematics are crucial to decipher the geodynamics of the NCB. Particularly, Jurassic extensional tectonics in North China remains ambiguous due to sporadic geological records. A multidisciplinary investigation on the Jurassic Jianchang-Jiumen pluton has been performed to provide tectonic information for Jurassic extensional episodes. The phacolith-like Jiumen pluton (~190 Ma) reveals margin-parallel foliations produced by magma inflation in the anticlinal core, while the tabular-like Jianchang pluton (~158 Ma) with margin-parallel foliations, intruded by magma inflation, underlay the Jiumen pluton. Two patterns of magnetic lineations recorded Early Jurassic NW-SE extension and early Late Jurassic NE-SW extension in the eastern NCB, respectively. Through the emplacement of three plutons, three extensional stages, including Late Triassic, Early Jurassic-early Middle Jurassic, and early Late Jurassic occurred in the North China Craton. It further constrains regional tectonic framework of the North China Craton during Triassic-earliest Cretaceous. The North China Craton experienced Late Triassic intracontinental NE-SW extension related to deep-seated tectonic process, following the closure of Paleo-Asian Ocean or subsequent intracontinental compression. Large-scale Late Triassic extensional structures in the northern North China Craton influenced one-third of the craton, indicating the beginning of craton destruction. During the Jurassic, the Early Jurassicearly Middle Jurassic N-S post-collisional extension occurred in the western North China Craton after the amalgamation between North China and South China, whereas Early Jurassicearly Middle Jurassic NW-SE trending and early Late Jurassic ENE-WSW extension and associated magmatism occurred in the eastern North China Craton. The subduction of the Paleo-Pacific plate had an impact on lithosphere of the eastern North China Craton until the cratonic destruction during Early Cretaceous (126 Ma). The two-stage extension was interrupted by late Middle Jurassic N-S compression related to the closure of Mongol-Okhotsk Ocean, followed by large-scale late Late Jurassic-Early Cretaceous NW-SE compression and extension related to the subduction and rollback of the Paleo-Pacific Plate, respectively. 7.2. Perspectives The Phanerozoic tectonic evolution of the NCB is related to two orogenic cycles, including Paleozoic continental collisions with Mongolian arc terranes and South China Block at block boundaries, and Jurassic-Early Cretaceous intracontinental orogeny (Yanshanian Orogeny). The Early Mesozoic tectonic evolution of the NCB is expressed by a complicated structural feature in the NCB with multiphase deformations that timing and kinematics are crucial to decipher the geodynamics of the NCB. Particularly, Early Mesozoic extensional tectonics in North China remains ambiguous due to sporadic geological records. To understand multiphase evolution of the NCB, it is crucial to clarify Early Mesozoic extensional tectonics and its relationship to the dynamics of plate subduction/collision along active boundaries.

  QIU Tectonique extensive du Mésozoïque inférieur dans le nord du Craton de Chine du Nord et ses implications géodynamiques Le craton de Chine du Nord est resté stable du Mésoprotérozoïque au Paléozoïque, après sa formation au Paléoprotérozoïque. Le craton stable de Chine du Nord a commencé à se transformer au Mésozoïque, et la destruction du craton ou l'amincissement lithosphérique ont eu lieu au cours du Crétacé inférieur. Avant la destruction du Crétacé, le craton de Chine du Nord a subi deux cycles orogéniques, y compris les collisions continentales d'âge Paléozoïque avec les arcs magmatiques mongols et le bloc de Chine du Sud, et l'orogenèse intracontinentale d'âge Jurassique-Crétacé précoce (également appelée orogenèse Yanshanienne). Certains indices d'épisodes d'extension au début du Mésozoïque ont été identifiés dans les petites reliques des bassins sédimentaires ou des failles normales. En tant que telle, la tectonique extensive pendant la déformation polyphasée et le mécanisme géodynamique associé restent mal contraint en raison de rares enregistrements géologiques. Pour mieux comprendre le contexte tectonique et le mécanisme géodynamique du Mésozoïque dans le bloc de Chine du Nord, une étude pluridisciplinaire, comprenant la géologie structurale, la géochronologie, la géochimie, l'AMS et la modélisation gravimétrique, a été menée dans les plutons de Dushan du Trias supérieur dans l'est de Hebei, de Wangtufang du Trias supérieur au nord de Hebei et de Jianchang-Jiumen du Jurassique à l'ouest du Liaoning. Notre étude montre que: (i) les structures mésoscopiques et magnétiques du pluton de Dushan étaient plutôt liées à sa construction et non à la tectonique régionale du Trias supérieur; (ii) Le pluton de Wangtufang était mis en place au cours d'une extension intracontinentale orientée NE-SW au Trias supérieur; (iii) Le pluton jurassique de Jianchang-Jiumen a enregistré une extension au Jurassique inférieur orientée NW-SE et une extension d'âge Jurassique supérieur orientée NE-SW dans l'est du bloc de Chine du Nord; (iv) Trois stades d'extension contraignent davantage le cadre tectonique régional du craton de Chine du Nord et le mécanisme géodynamique associé au cours du Mésozoïque inférieur. Le Trias tardif était une période d'extension intracontinentale après la formation finale de la Ceinture de l'Asie Centrale Orogénique (CAOB) ou la compression intracontinentale ultérieure. L'extension avait lieu en deux étapes au cours du Jurassique inférieur-Jurassique moyen et du Jurassique supérieur, et la compression et l'extension NW-SE au Jurassique tardif--Crétacé inférieur étaient probablement liées à la subduction de la plaque Paléo-Pacifique. L'extension a été interrompue par la compression N-S à la fin du Jurassique moyen probablement due à la fermeture de l'océan Mongol-Okhotsk. Mots clés: Craton de Chine du Nord, Pluton granitique, Mésozoïque inférieur, Tectonique extensive, Mécanisme géodynamique Early Mesozoic extensional tectonics in the northern North China Craton and its geodynamic implications The North China Craton formed a stable craton from Mesoproterozoic to Paleozoic, after its assembly during the Paleoproterozoic. The stable North China Craton began to transform in the Mesozoic, and decratonization, cratonic destruction, or lithospheric thinning occurred during the Early Cretaceous. Before the Cretaceous destruction, the North China Craton has undergone two orogenic cycles, including Paleozoic-Triassic continental collisions with Mongolian arc terranes and South China Block at block boundaries, and the Jurassic-Early Cretaceous intracontinental orogeny (also called Yanshanian Orogeny). Some clues of extensional episodes during the Early Mesozoic have been found in sporadic small grabens or normal faults. As such, the extensional tectonics during the multiphase deformation and associated geodynamic mechanism remains poorly constrained due to rare geological records. To better understand the Mesozoic tectonic setting and dynamic mechanism in the North China Craton, an integrated multidisciplinary investigation, including structural geology, geochronology, geochemistry, AMS, and gravity modeling, has been conducted in the Late Triassic Dushan pluton in Eastern Hebei, Late Triassic Wangtufang pluton in northern Hebei and Jurassic Jianchang-Jiumen pluton in western Liaoning. Our study shows that: (i) Both mesoscopic and magnetic fabrics in the Late Triassic Dushan pluton were rather related to its building than to the Late Triassic regional tectonics; (ii) The Wangtufang pluton emplaced during a Late Triassic NE-SW trending intracontinental extensional setting; (iii) The Jurassic Jianchang-Jiumen pluton recorded Early Jurassic NW-SE extension and early Late Jurassic NE-SW extension in the eastern NCB; (iv) Three extensional stages further constrain the regional tectonic framework of the NCB and associated geodynamic mechanism during the Early Mesozoic. The Late Triassic was an intracontinental extensional setting after the final formation of the Central Asian Orogenic Belt (CAOB) or subsequent intracontinental compression. Two-stage extension during the Early Jurassic-early Middle Jurassic and early Late Jurassic, and the late Late Jurassic-Early Cretaceous NW-SE compression and extension were probably related to the subduction of the Paleo-Pacific Plate. It was interrupted by the late Middle Jurassic N-S compression probably related to the closure of Mongol-Okhotsk Ocean. Keywords: North China Block, Granitic pluton, Early Mesozoic, Extensional tectonics, Dynamic mechanism Institut des Sciences de la Terre d'Orléans 1A, rue de la Férollerie -45071 Orléans Cedex 2, France Institute of Geology and Geophysics, Chinese Academy of Sciences No. 19, Beitucheng Western Road, Chaoyang District, 100029, Beijing, P.R.China

Table 1 .1 Physical workload of the thesis

 1

Table 3 .1 SIMS zircon U-Pb data of the collected samples in the Dushan pluton.

 3

Table 4

 4 In the total alkali versus silica diagram (Figure4.7a), all samples plot in granite field.The diorite displays a SiO2 abundance of 51.88-56.31 wt %. It is characterized by a high Al2O3

	.2. The

content

(15.78-19

.66 wt %), a wide K2O range of 1.46-3.50 wt % and total alkalis (K2O+ Na2O, 6.68-8.16 wt %), with Na2O/K2O ratios of 1.33-2.97. They have relatively high Fe2O3 T

Table 4

 4

	.3. Zircons from the syenogranite (WTF5) have

Table 5 .1 Continued.Table 5 .1 Continued.

 55

Table 5 .2 Continued.Table 5 .2 Continued.

 55

  6.1.5. Early Late Jurassic NE-SW extension in the eastern NCB In the eastern NCB, the early Late Jurassic volcanic and pyroclastic rocks (Tiaojishan/Lanqi Formation) and coeval granite plutons are distributed in the eastern YFTB and the Liaodong and Jiaodong peninsulas (Figures 2.4 and 6.1). The early Late Jurassic NE-SW extension is recorded by the emplacement of the Jianchang pluton, brittle normal faults in the grabens or half-grabens

consistent, yielding a Concordia age of 209.0 ± 1. 4 Ma, interpreted as the Late Triassic crystallization age of the syenogranite (Figure 4.6,Table 4.1). This age is in agreement with previous age at 207 ± 1 Ma [START_REF] Liu | Rapid exhumation of basement rocks along the northern margin of the North China craton in the early Jurassic: Evidence from the Xiabancheng Basin, Yanshan Tectonic Belt[END_REF]Figure 4.2). Th/U ratios of Sample WTF13 range from 0.38 to 1.50. Nineteen analyses of 206 Pb/ 238 U and 207 Pb/ 235 U results show a Concordia age of 208.8 ± 1.8 Ma (Figure 4.6,Table 4.1). It corresponds to the Late Triassic emplacement age of the diorite, older than a previous age at 191 ± 1 Ma [START_REF] Liu | Rapid exhumation of basement rocks along the northern margin of the North China craton in the early Jurassic: Evidence from the Xiabancheng Basin, Yanshan Tectonic Belt[END_REF]Figure 4.2). The ages of the syenogranite and diorite are the same within errors. Hacker, B. R., Wang, X., Eide, E. A., & Ratschbacher, L. (1996). "Qinling-Dabie ultrahigh-pressure collisional orogen". In The tectonic evolution of Asia, Edited by: Yin, A. and Harrison, T. M. 345-370.

Cambridge, UK: Cambridge University Press.

Han, B. F., Kagami, H., & Li, H. M. (2004). Age and Nd-Sr isotopic geochemistry of the Guangtoushan alkaline granite, Hebei Province, China: implications for early Mesozoic crust-mantle interaction in North China Block (in Chinese with English abstract). Acta Petrologica Sinica, 20, 1375-1388. Han, G.Q., Liu, Y.J., Neubauer, F., Genser, J., Zhao, Y.L., Wen, Q.B., Li, W.M., Wu, L.N., Jiang, X., & Zhao, L.M. (2012). Provenance analysis of Permian sandstones in the central and southern Da Xing'an Mountains, China: Constraints on the evolution of the eastern segment of the Central Asian Orogenic Hao, W., Zhu, G., & Zhu, R. (2019). Timing of the Yanshan Movement: evidence from the Jingxi Basin in the Yanshan fold-and-thrust belt, eastern China. International Journal of Earth Sciences, 108 (6), 1961[START_REF] Jelinek | Statistical processing of anisotropy of magnetic susceptibility measured on groups of specimens[END_REF]. Hao, W., Zhu, R., & Zhu, G. (2020). Jurassic tectonics of the eastern North China Craton: Response to initial