S E Proximal Dol Cement

Repl Dolomite

Dykes

Centr Distal

ANNEX C -Sr isotopic values for the Alpine samples SAMPLE

1. Introduction 1.1 GENERAL REMARKS Despite many studies have been focused on magma-poor rifted margins in the last decades, some fundamental tiles in the frame of their evolution are still missing or, at least, they are incomplete. The study and the knowledge of the tectono-stratigraphic evolution of continental margins, nowadays at a very advanced stage, took advantage of different investigative methods (e.g. high resolution reflection/refraction seismic data and deep drill hole data), which allowed the definition of those steps that characterized the extensional evolution of rifted margins, their structures as well as their stratigraphic architecture (Iberia-Newfoundland, Péron-Pinvidic and Manatschal 2008;South, Central and North Atlantic, Contrucci et al. 2004[START_REF] Moulin | Geological constraints on the evolution of the Angolan margin based on reflection and refraction seismic data (ZaiAngo project)[END_REF][START_REF] Aslanian | Brazilian and African passive margins of the Central Segment of the South Atlantic Ocean: kinematic constraints[END_REF]NW and S-Australia, Karner and Driscoll 2000). These models show how a multiphase evolution of rift systems led to a complex architecture: a proximal 30 km-thick crust separated, by a necking zone, from a thinned continental crust (<10km), followed by a wide transition zone between the continental and oceanic crusts where mantle exhumation occurs. However, the thermal evolution of distal rifted margins is very poorly constrained, although the presence of hydrothermal systems seems to play a key role in determining the heat flow and thermal history. A deeper and more detailed study of such systems is thus fundamental to reconstruct the thermal and diagenetic evolution of the sedimentary successions lying above these margins. This Thesis aims to face exactly this problem highlighting the interplay between fluids and carbonate rocks involved in paleo-rifted margins development.

The evolution and formation of passive rifted margins is strictly linked to different geological processes (e.g. magmatic, tectonic and sedimentary) in which fluids play an essential role. Nonetheless, their physico-chemical properties, their pathways and source areas are still less studied and understood expecially in the sedimentary environment. Due to the oceanographic surveys (e.g. IODP/ODP) and the discoveries of hydrothermal vents at present-day ocean ridges, as well as the occurrence of widespread serpentinization processes, the relevance and spatial abundance of fluid activity in response to the late stage of continental rifting and oceanization are relatively well understood [START_REF] Pinto | Tracing mantle-reacted fluids in magma-poor rifted margin: The example of Alpine Tethyan rifted margin[END_REF][START_REF] Kelley | An off-axis hydrothermal vent field near the Mid[END_REF][START_REF] Mccaig | Oceanic detachment faults focus very large volumes of black smoker fluids[END_REF][START_REF] Kelley | Hydrothermal systems: A decade of discovery in slow spreading envirnments[END_REF][START_REF] Edmonds | Chemical signature from hydrothermal venting on slow spreading ridges[END_REF]. On the contrary, little attention has been paid to the study of such activity in the more internal part of the continental margins (proximal and distal domains) where the pre-mantle exhumation history is preserved. The difficulty in studying these sectors lies in the scarcity of available data from present-day rifted margins (most of which are proprietary) and the technical costs of drilling. Only few ODP (Ocean Drilling Program) drill holes are available, which, even if far to be considered exhaustive, shed light on the importance of fluid circulation and related mineralization (e.g. dolomitization at ODP Leg 103; [START_REF] Boillot | Les poudingues de Mendibelza: dépôs de cônes sous-marins du rift Albien des Pyrénées[END_REF]. The only way to overcome these problems and to get enough valuable data is to study those fossil rifted margins actually preserved in collisional orogens.

THE STUDY AREAS: REMNANTS OF FOSSIL RIFTED MARGINS

The findings of fossil analogues in orogens (e.g. Alps and Pyrenees) have allowed to detect directly many aspects of the evolution of passive margins and their reactivation, otherwise impossible to investigate and understand. All the processes linked to the pre-, syn-and post-rift evolution, the related structures and final architecture have been considerably improved by these discoveries.

The Alps, above all, represent probably the best natural laboratory where such studies can be addressed. This orogen clearly preserves rift-related evidence in both metamorphosed (e.g. [START_REF] Beltrando | From passive margins to orogens: The link between ocean-continent transition zonesand (ultra)high pressure metamorphism[END_REF][START_REF] Beltrando | The Valaisan controversy revisited: Multi-stage folding of a Mesozoic hyperextended margin in the Petit St. Bernard pass area (Western Alps)[END_REF] and unmetamorphosed succesions (e.g. [START_REF] Mohn | Unraveling the interaction between tectonic and sedimentary processes during lithospheric thinning in the Alpine Tethys margins[END_REF], Masini et al. 2011). To get an understanding as accurate as possible of the conditions in which the fluid circulation occurred, it is suggested to focus on those sectors of the chain that were not involved in strong orogenic events (e.g. subduction). For this reason, two areas were chosen to be studied. The first is located in the Central Alps, at the Italian-Swiss border in SE Switzerland, where wide portions of the former Adriatic paleo-rifted margin are exposed. The second area, in the western French Pyrenees, comprises well-preserved features of the former Iberian continental margin. Both sites show the relationships among basement, sediments and rift-related structures during the Jurassic and early Cretaceous continental extension. Most importantly, no strong metamorphic overprint occurred during the compressional phases.

AIMS OF THE THESIS

The focus of this work is on the diagenetic, sedimentary and tectonic processes that were active during continental extension and to which fluid activity is intimately connected. Within this context, the main goal is then to propose a model of hydrothermalism and thermal evolution controlled primarly controlled by extensional tectonics by the investigation of different types of fluid-related products such as breccias, cements, veins, replacement and newly-formed minerals that could document any fluid-rock interaction.

The present Thesis has been carried out with the aim to answer to the following main questions:

-What are the fluid-related products and their characteristics?

-What is the geological context in which these products developed?

-Which are the relationships among these products, the stratigraphy and the main rift-related structures?

-Which is the physico-chemical signal recorded by these products? And what are the processes that lead to their formation? -Where do the fluids come from and by which pathways? -How long did the fluid activity last?

-Are the fluid systems shallow or deep? Do they involve only sediments or also crustal and mantle rocks?

In order to face these key points, a multi-disciplinary approach has been adopted (for detailed descriptions of each method see "Materials and Methods"): fieldwork, microscopic analyses, cathodoluminescence, SEM-EDS, O-C, Sr and He isotopes, fluid inclusions microthermometry, geochemistry of main, trace and rare earth elements, and U-Pb dating. This well supported scientific approach can represent a good "template" for future research, not only on fossil analogues but also on present-day continental margins (e.g. Newfoundland-Iberian, Angola, Red Sea) in order to further constrain their evolution.

THESIS STRUCTURE

The Thesis is divided in two main parts discussing the Alpine and Pyrenean study areas separately. The "Alpine chapter" represents the main part of the work for two main reasons: i) the deeper overall knowledge of the geological context, and ii) the much more spectacular exposure of the outcrops compared to the Pyrenean ones. The large scale structure of the former Adriatic margin will be illustrated, which will be followed by a detailed description of the architecture of its most distal domains: the hyper-extended distal margin preserved in the Err nappe and the exhumed-mantle domain belonging to the Platta nappe (SE Switzerland). To get a much more complete knowledge of the fluid activity along the entire margin and even to highlight similarities and differences among the different domains, the proximal margin (Ortler nappe, N Italy) and the inner distal margin (Bernina nappe, SE Switzerland) have also been considered.

Concerning the study area in the Pyrenees, it is located in the most distal part of the former Iberian continental margin actually preserved in the easternmost sector of the Mauléon Basin (the so-called Chaînons Béarnais). Unfortunately, in this area, because of the very low altitude as well as the rare outcrops and low quality of the exposed sections, it has not always been possible to properly reconstruct the relationships among stratigraphy, structures and fluid-related products. Nonetheless, it is clear that fluid circulation widely affected this portion of the margin during Cretaceous rifting phases. To overcome the aforementioned problems and in order to properly interpret this area, some selected samples and key sites were chosen and compared with the Alpine ones.

Materials and methods

Fieldwork was performed in both the Alpine and Pyrenean areas. Pre, syn-and post-tectonic sedimentary sequences were sampled in the following sites:

-Il Motto (N Italy, Ortler nappe -former proximal Adriatic margin) -Chaînons Béarnais (SW France, Mauléon Basin -former hyper-extended rift system) Petrographic studies on uncovered thin sections (30 µm thick) were carried out by optical microscopy and cathodoluminescence (CL) with the aim of distinguishing different hydrothermal products that affected the sedimentary successions. CL observations were performed on polished thin sections using a CITL 8200 mk3 equipment (operating conditions of about 17 kV and 400 µA).

-
In situ quantitative microprobe analyses were performed on carbon-coated thin sections with an energy dispersive x-ray spectroscopy (EDS) Energy 200 system and a Pentafet detector (Oxford Instruments) associated with a Cambridge Stereoscan S-360 scanning electron microscope (SEM). The operating conditions were 15 kV of accelerating voltage, 1 nA of probe current and 50 seconds counting time.

Carbon and oxygen isotopic compositions of the carbonates were measured at the Stable Isotope Laboratory of the ETH Geological Institute, ETH Zurich, Switzerland using a Thermo Fisher Scientific GasBench II coupled to a Delta V mass spectrometer as described in detail in [START_REF] Breitenbach | Carbon and oxygen isotope analysis of small carbonate samples (20 to 100 µg) with a GasBench II preparation device[END_REF].

The oxygen isotope composition of dolomite was calculated using the fractionation factor of [START_REF] Rosenbaum | An isotopic study of siderites, dolomites and ankerites at high temperatures[END_REF]. The isotopic ratios for carbon and oxygen are expressed as δ 13 C and δ 18 O per mil values relative to the VPDB (Vienna Pee Dee Belemnite) standard (precision ± 0.05%). The analyses have been performed on micro-drilled powder of an as pure as possible single mineral phase.

Fluid inclusion petrography has been performed at the University of Turin on bipolished thin sections (100 µm). Micro-thermometry of primary fluid inclusions assemblages on dolomite, calcite and quartz was performed using a Linkam THMSG600 heating-freezing stage coupled with an Olympus polarizing microscope (100X objective), using the standard method described by [START_REF] Goldstein | Systematics of Fluid Inclusions in Diagenetic Minerals[END_REF]. Primary fluid inclusions of useful size for microthermometry (i.e. more than 2 μm in diameter; [START_REF] Goldstein | Systematics of Fluid Inclusions in Diagenetic Minerals[END_REF] have been considered. The distribution of these inclusions (along growth zones, as isolated inclusions, with negative crystal shape) and their constant vapor/bubble ratio have been adopted as evidence of their primary origin.

Stretched crystals or inclusions have been observed but were not considered for micro-thermometry.

Sr isotope compositions were measured with a Finnigan MAT 262V multicollector mass spectrometer at the CNR Istituto di Geoscienze e Georisorse in Pisa (Italy), running in dynamic mode. Conventional ion exchange methods were used for Sr separation from the matrix. Measured 87 Sr/ 86 Sr ratios were normalized to 86 Sr/ 88 Sr = 0.1194. During the collection of isotopic data replicate measurements of NIST SRM 987 (SrCO 3 ) standard yielded values of 0.710242 ± 17 (2s, N=19). Measurements have been also performed at the Goethe University Frankfurt (Germany) on carbonate in thick sections, using a Thermo-Finnigan Neptune multicollector inductively coupled plasma -mass spectrometer (MC-ICP-MS) attached to a RESOlution 193 nm Ar-F Excimer laser ablation system (ComPexPro 102F, Coherent), equipped with a S-155 twovolume (Laurin Technic, Australia) ablation cell. Laser spots with diameters of 120-235 µm were drilled with repetition rate of 8 Hz, and energy density of about 6-7 J/cm 2 , during 45 s of data acquisition. The depth penetration of the static spots was about 0.7 µm s -1 . Ablation and material transport occurred in a sample gas stream of Ar (0.8 l min -1 ) mixed with He (0.6 l min -1 ) and N 2 (0.005 l min -1 ), and signal homogenization directly after ablation was carried out using a "Squid" (Laurin Technic, Australia). Wash out time for all important isotopes was less than 5 seconds, which allowed a relatively high sample troughput of ca. 20-30 measurements per hour. The raw data of 86 Sr/ 87 Sr were corrected for blank (mostly 84, 86 Kr in sample gas), and isobaric interferences arising from double charged rare earth elements (Er, Yb), as well as for Ca dimers, and Rb.

Corrections for Kr, Er, Yb had only a negligible effect due to extremely low intensities for 167 Er, 173 Y ( <0.0001 Volt), and 83 Kr (<0.0007 Volt). In contrast Rb interference correction was important. At the beginning of the analytical session, soda-lime glass SRM-NIST 610 was measured 2-3times for empirical determination of 87 Rb/ 85 Rb mass bias using the Sr mass bias ( 86 Sr/ 88 Sr m relative to 86 Sr/ 88 Sr true = 0.1194) of each integration multiplied by an off-set factor. The procedure yielded after successful interference correction on 86 Sr, 88 Sr, and 85 Rb from doubly charged Yb and Er the 87 Rb/ 86 Sr ratio needed for accurate correction of the isobaric interference of 87 Rb on 87 Sr. Despite of the high 87 Rb/ 86 Sr of 2.82, with a 87 Rb 4 times the 87 Sr, we obtained a 87 Sr/ 86 Sr (0.7096 ±0.0010; n =12), which is within uncertainty of the reported value of Woodhead et al. (2001). Performance and accuracy was checked by multiple measurement of the feldspar in-house standard MIR-1, which is an isotopically homogeneous plagioclase megacryst from a lava of the Dutsin Miringa Hill volcano (Northern Cameroon Line; [START_REF] Rankenburg | Origin of megacrysts in volcanic rocks of the Cameroon volacanic chain -constraints on magma genesis and crustal contamination[END_REF]. The results of standard measurements yielded values of 87 Sr/ 86 Sr, which were in agreement (within error) to conventional TIMS data of 0.703096 ± 0.000070 (2σ, [START_REF] Rankenburg | Origin of megacrysts in volcanic rocks of the Cameroon volacanic chain -constraints on magma genesis and crustal contamination[END_REF].

The obtained values have been compared to those proposed by [START_REF] Mcarthur | Strontium Isotope Stratigraphy[END_REF] for Triassic and Jurassic seawater. U-Pb ages were acquired in situ in polished thin sections by laser ablationinductively coupled plasma-mass spectrometry (LA-ICP-MS) at the Goethe University Frankfurt (GUF), using a modified method, as previously described in [START_REF] Gerdes | Combined U-Pb and Hf isotope LA-(MC-) ICP-MS analyses of detrital zircons: Comparison with SHRIMP and new constraints for the provenance and age of an Armorican metasediment in Central Germany[END_REF], 2009). Recent studies have shown that this method yield precise and accurate ages on carbonate formed during different processes [START_REF] Li | Geochemical evidence on the source regions of Tibetan Plateau dusts during non-monsoon period in 2008/09[END_REF][START_REF] Ring | Kinematics of the Alpenrhein-Bodensee graben system in the Central Alps: Oligocene/Miocene transtension due to formation of the Western Alps arc[END_REF]. At GUF a ThermoScientific Element 2 sector field ICP-MS is coupled to a Resolution S-155 (Resonetics) 193 nm ArF Excimer laser (CompexPro 102, Coherent) equipped with a two-volume ablation cell (Laurin Technic, Australia). Samples were ablated in a helium atmosphere (0.6 l/min) and mixed in the ablation funnel with 0.7 l/min argon and 0.04 l/min nitrogen. Signal strength at the ICP-MS was tuned for maximum sensitivity while keeping oxide formation below 1% (UO/U). Static ablation used a spot size of 213µm and a fluence of < 1 J cm -2 at 6 Hz. This yielded for SRM-NIST 614 a depth penetration of about 0.5µm s -1 and an average sensitivity of 420000 cps/µg g -1 for 238 U. The detection limits for 206 Pb and 238 U were ~ 0.1 and 0.03 ppb, respectively. However, at a U signal of less 1000 cps (~ 2ppb) the data were generally discarded due to enhance scatter on the isotope ratios. Data were acquired in fully-automated mode overnight during two independent analytical sessions. Each analysis consists of 20s background acquisition followed by 20s of sample ablation and 25s washout. During 42s data acquisition, the signal of 206 Pb, 207 Pb. 208 Pb, 232 Th and 238 U were detected by peak jumping in pulse counting mode with a total integration time of 0.1s, resulting in 420 mass scans.

Prior to analysis each spot was pre-ablated for 3s to remove surface contamination. Soda-lime glass SRM-NIST 614 was used as a reference glass together with 2 carbonate standards to bracket sample analysis. Raw data were corrected offline using an in-house MS Excel © spreadsheet program [START_REF] Gerdes | Combined U-Pb and Hf isotope LA-(MC-) ICP-MS analyses of detrital zircons: Comparison with SHRIMP and new constraints for the provenance and age of an Armorican metasediment in Central Germany[END_REF], 2009). Following background correction, outliers (±2) were rejected based on the time-resolved 207 Pb/ 206 Pb and 206 Pb/ 238 U ratios. The 207 Pb/ 206 Pb ratio was corrected for mass bias (0.3%) and the 206 Pb/ 238 U ratio for inter-element fraction (ca. 5%), including drift over the 12 hours of sequence time, using SRM-NIST 614. Due to the carbonate matrix an additional correction of 9% has been applied on the 206 Pb/ 238 U, which was determined using WC-1 carbonate reference material dated by TIMS (252±2 Ma; E.T. Rasbury, pers. comm. 2014).

The WC-1 (n= 36) common Pb corrected 206 Pb/ 238 U reproduce over the three consecutive days to 251.4±6.1 Ma (2SD = 2.4%; n = 36). The not common Pb corrected data yielded a lower intercept age of 252.9±3.1 Ma. Repeated analyses (n=56) of a Zechstein dolomite (Gypsum pit, Tettenborn, Germany) used as secondary (in-house) standard yielded a lower intercept age of 255.6 ± 3.0 Ma (MSWD: 1.4), implying an accuracy and repeatability of the method of around 2% or better. The analytical results are presented in ANNEX E. Data were plotted in the Tera-Wasserburg diagram and ages calculated as lower intercepts using Isoplot 3.71 [START_REF] Ludwig | Isoplot 3.0, a geochronological toolkit for Microsoft Excel[END_REF]. All uncertainties are reported at the 2sigma level.

For noble gas measurements, few grams of mineral separates (calcite, dolomite and quartz) were selected. After loading the samples into the crusher [START_REF] Papp | Noble gas measurements from different water amounts -from microlitres to millilitres and litres[END_REF] the sample holders pumped out overnight at 50 °C. Samples were then crushed under high vacuum and measured using VG5400 noble gas mass spectrometer at Hertelendi Laboratory of Environmental Studies in Institute of Nuclear Research of the Hungarian Academy of Sciences, Hungary. The blank levels during the experiments were 1×10 -10 cm 3 STP for He, 5×10 -8 cm 3 STP for Ar. The blank correction was applied to all analyses (less than 1% for each noble gas). The sensitivity and the isotope discrimination of the mass spectrometer were calibrated by analysing known amounts of air aliquots of 2.5×10 -5 -1.0×10 -4 cm 3 for Ar and 0.12-0. 25 cm 3 for He [START_REF] Varsányi | Groundwater flow system as an archive of palaeo-temperature: Noble gas, radiocarbon, stable isotope and geochemical study in the Pannonian Basin, Hungary[END_REF][START_REF] Papp | Noble gas measurements from different water amounts -from microlitres to millilitres and litres[END_REF]. More details about the purifications and the mass spectrometer procedures can found in [START_REF] Papp | Noble gas measurements from different water amounts -from microlitres to millilitres and litres[END_REF]. The CO 2 was extracted with noble gases during vacuum crushing, and then separated by freezing using a cold finger by liquid nitrogen. The cold fingers were then filled with pure helium and closed by high vacuum valves (VAT, series 541). The amount of CO 2 was determined by a stable isotope ratio mass spectrometer (DeltaPLUS XP) in scanning mode.

Main, trace elements and REE analysis were performed by ALS Global (ALS Minerals Division-Geochemistry, Sevilla, Spain) on about 100 gr of materials for each sample. Sample preparation procedures: fine crushing (70% < 2 mm), pulverize split to 85% < 75 m, crushing QC Test, pulverizing QC Test.

Analytical procedures: up to 34 elements by ICP-MS, loss on Ignition at 1000C, total calculatin for ICP06, base metals by 4-acid dig., whole rock package (ICP-AES), total carbon and sulphur (LECO), lithium borate fusion (ICP-MS).

The Adriatic continental margin 3.1 INTRODUCTION

The Alps are an orogenic chain formed in response of two main phases of deformation: one during Late Cretaceous and the other during Cenozoic time (e.g. [START_REF] Lemoine | The continental margin of the Mesozoic Tethys in the Western Alps[END_REF][START_REF] Froitzheim | Repeated change from crustal shortening to orogenparallel extension in the Austroalpine units of Graubünden[END_REF][START_REF] Schmid | Tectonic map and overall architecture of the Alpine Orogen[END_REF]. In this mountain belt, remnants of former Adriatic and European rifted margins are widely preserved since they did not undergo most of the Alpine deformation and metamorphism [START_REF] Froitzheim | Kinematics of Jurassic rifting, mantle exhumation, and passive-margin formation in the Austroalpine and Penninic nappes (eastern Switzerland)[END_REF][START_REF] Masini | The Alpine Tethys rifted margins: Reconciling old and new ideas to understand the stratigraphic architecture of magma-poor rifted margins[END_REF]. The two paleo-rifted margins were separated one from each other by the Piemonte-Liguria domain, which represents an embryonic ocean developed during Middle to Late Jurassic time [START_REF] Lemoine | Ultramafic and gabbroic ocean floor of the Ligurian Tethys (Alps, Corsica, Apennines): in search of a genetic model[END_REF][START_REF] Manatschal | Rifting and early evolution of ancient ocean basins: the record of the Mesozoic Tethys and of the Galicia-Newfoundland margins[END_REF]. In the present-day nappe stack, the former Adriatic and European continental margins are preserved in the Southern Alps and Austroalpine units and in the Helvetic units respectively. Remnants of the Piemonte-Liguria ocean constitute the Penninic units (Fig. 3.1). Since the focus of this Thesis is on the Triassic-Jurassic evolution of the former Adriatic continental margin and its transition to the oceanic domain, a general description of their former architecture will be given in the following sections.

GEOLOGICAL SETTING

The study area is located in the southeasternmost part of Switzerland and N-Italy. This sector belongs to the Austroalpine and Upper Penninic units, which preserve one of the most outstanding sections of a magma-poor rifted margin.

Since they were not involved in the subduction during the Alpine orogeny, they reached metamorphic conditions that never exceeded prehnite-pumpellyite facies. This weak overprint led to the exceptional preservation of all the features related to the Adriatic continental margin during its Triassic-Jurassic evolution.

The nappe stack is actually subdivided into Upper, Middle and Lower Austroalpine units that overlie the Upper Penninic units that consist of ophiolitic material (Fig. 3.2). [START_REF] Froitzheim | Repeated change from crustal shortening to orogenparallel extension in the Austroalpine units of Graubünden[END_REF].

The thrust faults separating the nappes have a top-to-the-west sense of shear ("Trupchun phase or D1-phase" of [START_REF] Froitzheim | Repeated change from crustal shortening to orogenparallel extension in the Austroalpine units of Graubünden[END_REF], Mohn et al. 2010).

Since the overall orientation of the Adriatic margin was SW-NE, the late Cretaceous orogenic event resulted in the stacking of more proximal parts of the former margin onto more distal domains. The study of [START_REF] Mohn | Unraveling the interaction between tectonic and sedimentary processes during lithospheric thinning in the Alpine Tethys margins[END_REF] on the Austroalpine units enabled to understand the former architecture of the margin by the definition of different paleogeographic domains [START_REF] Mohn | Unraveling the interaction between tectonic and sedimentary processes during lithospheric thinning in the Alpine Tethys margins[END_REF] tectonically stacked in the nappe pile. In this frame, the less thinned proximal margin represents the highest structural units lying above the units derived from the former necking zone (Campo-Grosina, not studied in this Thesis), the distal margin (Bernina/Err) and the exhumed mantle domain (Platta) [START_REF] Mohn | Unraveling the interaction between tectonic and sedimentary processes during lithospheric thinning in the Alpine Tethys margins[END_REF]. Because of the altitude and the outstanding quality of the outcrops, this area became fundamental in the understanding of the architecture of hyperextended rifted margins. The so-called "Grisons transect" has been widely studied allowing the definition of the four main domains in which usually a magma-poor rifted margin is divided: the proximal margin, the necking zone, the distal margin, the ocean-continent transition (Fig. 3.3). [START_REF] Eberli | The evolution of the southern continental margin of the Jurassic Tethys Ocean as recorded in the Allgäu Formation of the Austroalpine Nappes of Graubünden (Switzerland)[END_REF]. All the reworked sediments derive exclusively from the pre-rift carbonate platform [START_REF] Froitzheim | Synsedimentary and synorogenic normal faults within a thrust sheet of the Eastern Alps (Ortler zone, Graubünden, Switzerland)[END_REF]). The syn-rift sedimentary sequence is characterized by thinning-and fining-upward cycles as well as a thinning and fining away from the fault zone. Furthermore, an inversion of the clast stratigraphy is observed in the basin due to erosion of the footwall block and redeposition derived clasts [START_REF] Eberli | The evolution of the southern continental margin of the Jurassic Tethys Ocean as recorded in the Allgäu Formation of the Austroalpine Nappes of Graubünden (Switzerland)[END_REF]. In the present-day architecture, the Ortler nappe is under-and overlain, along Alpine tectonic contacts, by other upper Austroalpine units: the Quattervals nappe above and the Campo nappe below.

The necking zone

The necking zone, exposed in the Grosina-Campo nappe (Middle Austroalpine), is the domain where major crustal thinning occurred [START_REF] Mohn | Unraveling the interaction between tectonic and sedimentary processes during lithospheric thinning in the Alpine Tethys margins[END_REF][START_REF] Mohn | Rift-related inheritance in orogens: a case study from the Austroalpine nappes in Central Alps (SE-Switzerland and N-Italy)[END_REF].

This zone juxtaposes crust that is little or not thinned (proximal margin) against strongly thinned, less than 10 km thick crust of the distal margin. Within this domain, the pre-rift sequence starts to be highly extended and can occur as extensional allochthons lying above top-basement detachment faults.

3.2.3

The distal margin (Err and Bernina nappes) The ocean-continent transition is exposed in the Platta nappe (Upper Penninic).

This domain is formed by exhumed mantle rocks intruded by gabbros and capped by detachment faults (Fig. 3.6). The Platta domain is interpreted to be associated with the same detachment system affecting also the hyper-extended domain. Such an interpretation is supported by the occurrence of extensional allochthons made of continental crust and pre-rift sediments over exhumed subcontinental mantle [START_REF] Manatschal | A continent-ocean transition recorded in the Err and Platta nappes (Eastern Switzerland)[END_REF]. Further oceanward, the exhumed mantle rocks are overlain by MORB extrusives, indicating that this domain may have developed into an embryonic oceanic domain [START_REF] Schaltegger | The transition from rifting to sea-floor spreading within a magma-poor rifted margin: field and isotopic constraints[END_REF][START_REF] Manatschal | A type sequence across an ancient magma-poor ocean-continent transition: the example of the western Alpine Tethys ophiolites[END_REF]. All three units preserve primary relationships between footwall and hangingwall rocks, including syn-tectonic sediments of the rift-related Err detachment system.

THE ADRIATIC

D2 structures reactivate, but also cut, D1 thrusts as extensional top-to-the-SE normal faults [START_REF] Froitzheim | Repeated change from crustal shortening to orogenparallel extension in the Austroalpine units of Graubünden[END_REF][START_REF] Handy | Tektonische Entwicklung Der Westlichen Zone Von Samedan (Oberhalbstein, Graubünden, Schweiz)[END_REF][START_REF] Handy | The transition from passive to active margin tectonics; a case study from the zone of Samedan (Eastern Switzerland)[END_REF].

D3 structures consist of north to northwest vergent folds and steep S-dipping thrusts showing displacements in the order of hundreds of meters.

The latest Alpine deformation consists of high-angle faults limiting the northern border of the Zone of Samedan (ZoS, already described in [START_REF] Cornelius | Geologie der Err-Julier gruppe: Das baumaterial (stratigraphie und petrographie, excl. quartär)[END_REF]. The total amount of normal displacement along this fault system can exceed half a kilometre in the center of ZoS and decreases eastwards. This phase is presumably linked to activity along the Engadine line (e.g. Schmid andFroitzheim 1993, Handy 1996).

The Jurassic architecture: the Err detachment system

The weak Alpine overprint enables to map and describe a Jurassic detachment system that is exceptionally well exposed and preserved in the Err nappe. The detachment system consists of brittle fault zones that are made of cataclastic damage zones and a peculiar core zone that separates the footwall from a hangingwall in which the pre-and syn-rift sedimentary sequences are locally preserved.

The footwall

The footwall is constituted of Paleozoic rocks inherited from the late to post-Variscan history. They are made of calcalkaline Albula granitic bodies [START_REF] Cornelius | Geologie der Err-Julier gruppe: Das baumaterial (stratigraphie und petrographie, excl. quartär)[END_REF][START_REF] Staub | Ueber den Bau der Gebirge zwischen Samedan und Julierpass und seine Beziehungen zum Falknis-un Bernina-Raum[END_REF][START_REF] Quadt | U-Pb zircon ages from igneous rocks of the Bernina nappe system (Grisons, Switzerland)[END_REF]) that intruded a Paleozoic polymetamorphic host-rock consisting of schists and gneisses. The Albula granite is by far the most common rock in the footwall. Since it preserves primary stratigraphic contacts to Permo-Triassic sediments and volcanic rocks, these basement rocks had to be in the pre-rift upper crust before onset of rifting in Jurassic time.

The detachment faults

The detachment faults correspond, at least in the areas where the footwall is formed by the Albula granite, to well characterized brittle fault zones (Fig. 3.8).

The faults are formed by tens of meter-thick damage zones constituted of characteristic green cataclasites and core zones made of black fault gouges [START_REF] Manatschal | Fluid-and reaction-assisted low-angle normal faulting; evidence from rift-related brittle fault rocks in the Alps (Err Nappe, Eastern Switzerland)[END_REF]. The green cataclasites result from the progressive cataclastic overprint of the host rock, which is related to fluid and reactionassisted breakdown processes of feldspar [START_REF] Manatschal | Fluid-and reaction-assisted low-angle normal faulting; evidence from rift-related brittle fault rocks in the Alps (Err Nappe, Eastern Switzerland)[END_REF]. The textures show a progressive change from fractured host rock, to a clast-supported cataclasite to a matrix-rich green cataclasite. In the last uppermost meters, quartz veins are common. Since these veins occur only within the damage zone crosscutting cataclastic structures and are also observed to have a cataclastic overprint, they are interpreted to be coeval with detachment faulting [START_REF] Manatschal | A continent-ocean transition recorded in the Err and Platta nappes (Eastern Switzerland)[END_REF]. This is also confirmed by geochemical studies (Manatschal et al. 2010) as well as by their occurrence as clasts in the black gouges and reworked into the Jurassic syn-rift sediments. The black gouges occur along a centimeter-to some meter-thick core zone at the top of the green cataclasite corresponding to the main zone of displacement. Where the detachment is exhumed at the seafloor it can be either eroded or directly overlain by syn-to post-rift sediments. The occurrence of clasts of black gouge in the syn-rift sediments points to the erosion of the detachment fault. In the black gouge itself, hangingwall clasts made of Triassic dolomite (Fig. 3.9) exist, but are rare compared to more abundant footwall-derived material. The discovery of clasts of the black gouge in the Jurassic sediments enabled to demonstrate that these rocks were pre-Alpine. strike [START_REF] Manatschal | Fluid-and reaction-assisted low-angle normal faulting; evidence from rift-related brittle fault rocks in the Alps (Err Nappe, Eastern Switzerland)[END_REF]. Based on the observation that the detachment faults cut Triassic dolomites and are overlain by Jurassic sediments, [START_REF] Froitzheim | Extensional detachment faulting in the evolution of a Tethys passive continental margin, Eastern Alps, Switzerland[END_REF] suggested a Jurassic age of these structures, which has been further supported by [START_REF] Manatschal | A continent-ocean transition recorded in the Err and Platta nappes (Eastern Switzerland)[END_REF]. This detachment system was active in the upper crust as documented by the break-down reactions of feldspars to phyllosilicates and by the crystal-plastic textures in quartz, suggesting that temperatures during faulting did not exceed 300 °C. Given the very characteristic nature of the fault rocks, but also their distinct chemical and mineralogical composition [START_REF] Manatschal | Fluid-and reaction-assisted low-angle normal faulting; evidence from rift-related brittle fault rocks in the Alps (Err Nappe, Eastern Switzerland)[END_REF], the green cataclasite and the black gouge can be used as marker horizons to map the Jurassic detachment faults across the whole Err nappe.

The hangingwall

The hangingwall of the detachment system (Fig. 3.10) consists mainly of polymetamorphic basement that shows primary contacts to either volcanic and volcano-sedimentary sequences or siliciclastic deposits. Ladinian to Norian platform carbonates (Hauptdolomit Formation) and Rhaetian limestones and shales (Kössen Formation) constitute the youngest parts of the pre-rift sediments. The Middle-Upper Triassic succession can be up to 500 m thick; however, it is important to note that throughout the margin, the Triassic dolomites are dismembered and never preserve the original thickness. As shown in [START_REF] Mohn | Unraveling the interaction between tectonic and sedimentary processes during lithospheric thinning in the Alpine Tethys margins[END_REF] this is due to the onset of the major activity along the detachment faults. The Triassic to Lower Jurassic sedimentary units (Hauptdolomit-Kössen Fms. and Agnelli Fm. respectively) are very discontinuous in the Err nappe despite the fact that they were deposited as continuous carbonate platforms or hemipelagic sediments. In some areas, the syn-to post-rift sediments overlie directly the exhumed footwall of the detachment faults (e.g. Piz Nair, Pass Suvretta or Fuorcla Cotschna areas in [START_REF] Handy | Tektonische Entwicklung Der Westlichen Zone Von Samedan (Oberhalbstein, Graubünden, Schweiz)[END_REF][START_REF] Handy | The transition from passive to active margin tectonics; a case study from the zone of Samedan (Eastern Switzerland)[END_REF][START_REF] Manatschal | A continent-ocean transition recorded in the Err and Platta nappes (Eastern Switzerland)[END_REF] and the Triassic to Lower Jurassic cover is reworked in the syn-rift sediments. The prerift succession was disrupted as discontinuous blocks, with a very complex 3D shape over the detachment surface. These structures have been referred to as "extensional allochthon blocks" (Manatschal andNievergelt 1997, Manatschal 2004).

The syn-rift sediments consist of complex gravitational to hemipelagic sedimentary deposits that occur either unconformably over extensional allochthons (e.g. Bardella block) or directly over the tectonically exhumed basement. [START_REF] Finger | Die Zone von Samedan (unterostalpine Decken, Graubünden) und ihre jurassischen Brekzien[END_REF] (2011,2012).

TAF -Top of Agnelli Formation

The TAF is well expressed in the distal margin where it is synchronous with the first sediments sealing deep fault-bounded basins filled by calciclastic sediments in the proximal margin (top of Lower Allgäu Formation of [START_REF] Eberli | The evolution of the southern continental margin of the Jurassic Tethys Ocean as recorded in the Allgäu Formation of the Austroalpine Nappes of Graubünden (Switzerland)[END_REF][START_REF] Froitzheim | Extensional detachment faulting in the evolution of a Tethys passive continental margin, Eastern Alps, Switzerland[END_REF]. Thus, in a classical rift stratigraphic terminology, it would correspond to the post-rift sequence in the proximal margin. As shown by [START_REF] Froitzheim | Extensional detachment faulting in the evolution of a Tethys passive continental margin, Eastern Alps, Switzerland[END_REF] and [START_REF] Manatschal | A continent-ocean transition recorded in the Err and Platta nappes (Eastern Switzerland)[END_REF], in the distal margin the TAF locally corresponds to a ferromanganese hardground representing a condensed horizon dated by ammonites as late Sinemurian to early Pliensbachian [START_REF] Finger | Die Zone von Samedan (unterostalpine Decken, Graubünden) und ihre jurassischen Brekzien[END_REF][START_REF] Manatschal | A continent-ocean transition recorded in the Err and Platta nappes (Eastern Switzerland)[END_REF][START_REF] Dommergues | Early Jurassic ammonites from Bivio (Lower Austroalpine unit) and Ardez (Middle Penninic unit) areas: a biostratigraphic tool to date the rifting in the Eastern Swiss Alps[END_REF]. The occurrence of the TAF in extensional allochthons, truncated by the detachment system (e.g. Bardella allochthon) as well as the presence of hardground material as clasts in the sediments [START_REF] Finger | Die Zone von Samedan (unterostalpine Decken, Graubünden) und ihre jurassischen Brekzien[END_REF] covering the detachment clearly indicate that it predates the onset of detachment faulting. The best stratigraphic constraints are preserved in the area of Piz Bardella where the TAF caps an up to 500 m thick tilted pre-detachment succession. Elsewhere, the Agnelli Fm. can also be absent, either due to extension (tectonic omission) or erosion.

RC -Radiolarian Cherts

Radiolarian Cherts are widespread within the Alpine Tethys domain. They can be defined as the first "post-rift" sequence in the sense that they are the first sediments occurring over pillow basalts showing a MORB composition [START_REF] Weissert | A transform margin in the Mesozoic Tethys: evidence from the swiss alps[END_REF][START_REF] Wilson | Rifting along non-volcanic passive margins: stratigraphic and seismic evidence from the Mesozoic successions of the Alps and western Iberia[END_REF]Fig. 3.6). In the central Alps, the RC are dated as Bathonian to Oxfordian [START_REF] Baumgartner | Age and genesis of Tethyan Jurassic radiolarites[END_REF][START_REF] Bill | Radiolarite ages in Alpine-Mediterranean Ophiolites; constrains on the oceanic spreading and the Tethys-Atlantic connection[END_REF]. In the "Grisons transect", the RC occur in the Platta and Err nappes and can be traced from there towards proximal domains. Thus, they represent an ideal time marker horizon to determine the onset of MORB activity. That is why [START_REF] Ferreiro-Mählmann | The pattern of diagenesis and metamorphism by vitrinite reflectance and illite "crystallinity" in Mittelbünden and in the Oberhalbstein: Part 2: Correlation of coal petrographical and of mineralogical parameters[END_REF], the pre-Alpine history related to the continental break-up is well documented. In the Platta nappe, relics of the Err detachment system are found and separate extensional allochthons consisting of continental crust, Permian to Late Triassic pre-rift sediments and syn-rift sediments (Saluver Formation) in the hangingwall from the exhumed mantle rocks constituting the footwall [START_REF] Dietrich | Die ophilithe des Oberhalbsteins (Graubünden) und das Ophiolithmaterial der ostschweizrischen Molasseablagerungen, ein petrgraphisher Verleig[END_REF][START_REF] Manatschal | A continent-ocean transition recorded in the Err and Platta nappes (Eastern Switzerland)[END_REF]. The latter are composed of serpentinized peridotites derived from spinel lherzolites and harzburgites in which minor gabbroic rocks and basaltic dykes are intruded.

Palinspastic sections [START_REF] Manatschal | A continent-ocean transition recorded in the Err and Platta nappes (Eastern Switzerland)[END_REF][START_REF] Desmurs | The Steinmann Trinity revisited: mantle exhumation and magmatism along an ocean-continent transition: the Platta nappe, eatern Switzerland[END_REF] have shown that the Platta nappe consists of two units of ultramafic rocks, an upper and originally more internal (e.g. continentalward) one and a lower, external (e.g. oceanward) unit, separated by a thrust. The lower unit is covered by pillow lavas and basaltic flows and was locally intruded by Jurassic gabbros 161±1 my ago [START_REF] Schaltegger | The transition from rifting to sea-floor spreading within a magma-poor rifted margin: field and isotopic constraints[END_REF], which crystallized at shallow depths within an already serpentinized mantle [START_REF] Desmurs | The Steinmann Trinity revisited: mantle exhumation and magmatism along an ocean-continent transition: the Platta nappe, eatern Switzerland[END_REF]. Both gabbros and basalts are derived from a similar mantle source as demonstrated by [START_REF] Schaltegger | The transition from rifting to sea-floor spreading within a magma-poor rifted margin: field and isotopic constraints[END_REF]. The upper serpentinite unit is almost free of magmatic rocks, except for a few dolerite dykes and a single basaltic flow. Major changes in the mantle composition and the volume and type of magma can be observed between the two units [START_REF] Desmurs | The Steinmann Trinity revisited: mantle exhumation and magmatism along an ocean-continent transition: the Platta nappe, eatern Switzerland[END_REF][START_REF] Schaltegger | The transition from rifting to sea-floor spreading within a magma-poor rifted margin: field and isotopic constraints[END_REF][START_REF] Müntener | Refertilization of mantle peridotite in embryonic ocean basins: trace element and Nd isotopic evidence and implications for crust-mantle relationships[END_REF]. The serpentinites in the Platta nappe are overlain in some places by ophicalcites, which are in turn covered by post-rift sediments [START_REF] Dietrich | Die ophilithe des Oberhalbsteins (Graubünden) und das Ophiolithmaterial der ostschweizrischen Molasseablagerungen, ein petrgraphisher Verleig[END_REF] or by pillow lavas. These ophicalcites often show a red matrix made of carbonate containing only clasts of serpentinites [START_REF] Manatschal | A continent-ocean transition recorded in the Err and Platta nappes (Eastern Switzerland)[END_REF].

In both units forming the Platta nappe, exhumed mantle rocks, extensional allochthons and pillow basalts are stratigraphically overlain by Middle to Late Jurassic radiolarites and/or Early Cretaceous pelagic Calpionella Limestones.

Palinspastic reconstructions from the continental Err nappe to the ophiolitic Platta nappe show conspicuous analogies to present-day magma-poor continental rifted margins as the Iberian margin (W of Portugal), in terms of extensional detachment faulting, crustal thinning, sediment distribution, overall margin architecture, and tectonic evolution [START_REF] Manatschal | Rifting and early evolution of ancient ocean basins: the record of the Mesozoic Tethys and of the Galicia-Newfoundland margins[END_REF][START_REF] Whitmarsh | Evolution of magmapoor continental margins from rifting to seafloor spreading[END_REF]. Agnelli Formations [START_REF] Finger | Die Zone von Samedan (unterostalpine Decken, Graubünden) und ihre jurassischen Brekzien[END_REF][START_REF] Furrer | Stratigraphie und Fazies der Trias-Jura-Grenzschichten in den oberostalpinen Decken Graubündens[END_REF]. These breccias, by their composition and stratigraphic position, can be compared to the syn-rift Bardella Formation of [START_REF] Masini | The tectono-sedimentary evolution of a supra-detachment rift basin at a deep-water magma-poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland[END_REF][START_REF] Masini | Anatomy and tectono-sedimentary evolution of a rift-related detachment system: The example of the Err detachment (central Alps, SE Switzerland)[END_REF]Fig. 4.2 a). Among the largest clasts in the scree debris, one is particularly notable. It is more than 1 m in size and consists of grey, bedded limestones locally brecciated and is crossed by a neptunian dyke filled with yellow sediment. Grey limestones show a variety of textures, from mudstones to grainstones with crustaceans microcoprolites 0.3-1 mm in size (Favreina) and mudstones. The yellow infill ranges from mudstone to coarse packstone with bivalve shell fragments, mudstone intraclasts and angular quartz grains 50 to 100 m in size. This block shows the typical facies of the Rhaetian Kössen Formation and, as no similar beds have been found in place, it is tentatively assigned to be the basal part of the Kössen Fm, which directly overlies the Hauptdolomit Formation in the stratigraphic succession.

Actually, the Hauptdolomit Formation appears almost completely brecciated with a variable degree of disruption of the rock and style of brecciation.

At one end, the rock is only crossed by a network of veins with minor displacement of fragments; these crackle breccias (Fig, 4.2 c;[START_REF] Morrow | Descriptive field classification of sedimentary and diagenetic breccias fabrics in carbonate rocks[END_REF] pass transitionally to a breccia where clasts are significantly displaced but the 4.2 FUORCLA COTSCHNA AREA

Stratigraphy and petrography

The area of Fuorcla Cotschna, belonging to the Middle Err unit, preserves a quite complete section through a supra-detachment sedimentary basin (sensu [START_REF] Masini | The tectono-sedimentary evolution of a supra-detachment rift basin at a deep-water magma-poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland[END_REF][START_REF] Masini | Anatomy and tectono-sedimentary evolution of a rift-related detachment system: The example of the Err detachment (central Alps, SE Switzerland)[END_REF] and are generally very dull in CL. On weathered outcrop surfaces, these veins are clearly identifiable because of a yellow to orange color. Locally, up to 1 cmthick veins occur with a more complex filling made of quartz and euhedral to subhedral albite crystals some 100's micrometres large associated with dolomite.

Quartz crystals poikilotopically include carbonate grains, from minute particles less than 10 µm large to euhedral dolomite crystals 100's micrometres large.

Stratigraphically above the pre-rift sequence, even if the contact is not clearly shown, a sedimentary clast-supported breccia made up of carbonate clasts occur (Fig. 4.7 c). The clasts, mostly rounded and ranging from few centimeters to some decimeters in size, consist of Triassic carbonates belonging to the pre-rift sequence and are commonly crossed by the same kind of veins described above, which stop at the edge of the clasts. The whole rock mass is characterized by several sets of veins, up to some millimeters large, cemented by coarsely crystalline saddle dolomite, quartz and calcite. Since no basement-related clasts have been observed, this sedimentary body can be assigned to the syn-rift Bardella Formation [START_REF] Masini | The tectono-sedimentary evolution of a supra-detachment rift basin at a deep-water magma-poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland[END_REF][START_REF] Nonn | Architecture d'un système hyper-étiré: l'example des Chaînons Béarnais (bassins de Mauléon-Lourdes, Pyrénées[END_REF][START_REF] Finger | Die Zone von Samedan (unterostalpine Decken, Graubünden) und ihre jurassischen Brekzien[END_REF]Fig. 4.6;Fig. 4.7 a).

Above, a different coarse-grained sedimentary sequence occurs. It consists of clast-to matrix-supported conglomerates with angular to rounded clasts.

Carbonate clasts prevail but granitic basement-derived ones are also common.

The matrix consists of a medium to very coarse sandstone rich in quartz and feldspar grains. Due to the presence of footwall-related material and its stratigraphic position, this sequence has been interpreted as Saluver A Formation [START_REF] Masini | The tectono-sedimentary evolution of a supra-detachment rift basin at a deep-water magma-poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland[END_REF][START_REF] Nonn | Architecture d'un système hyper-étiré: l'example des Chaînons Béarnais (bassins de Mauléon-Lourdes, Pyrénées[END_REF][START_REF] Finger | Die Zone von Samedan (unterostalpine Decken, Graubünden) und ihre jurassischen Brekzien[END_REF]Fig. 4.6;4.7 d;Fig. 4.9a-f). As in the Bardella Formation, carbonate clasts are commonly crossed by veins, which stop at the edge of the clasts (Fig. 4.9 c). In some instances, these veins show a first isopachous rim of dolomite cement, 200 µm thick, with a dull brown luminescence, followed by fibrous quartz, which documents a syn-kinematic growth (Fig. 4.9 e-f). Millimeter-thick veins cemented by quartz and subordinated saddle dolomite crosscut the whole conglomerate (Fig. 4.9d).

Microprobe analyses of the dolostones occurring in the allochthon and in the clasts within the Bardella and Saluver Formations show that on the whole the replacement dolomite and the pore-filling dolomite cement are very poor in or completely free of Fe whereas vein dolomite contains up to 2.0 mole % FeCO 3 .

The Fuorcla Cotschna area clearly shows the relationships between the granitic footwall, the detachment fault and the overlying basin-filling sediments (transect B in Fig. 4.6). The footwall displays the same features already described in the Piz Val Lunga area. The detachment surface is overlain by a stratigraphic succession that starts with medium to coarse sandstone beds made up of basement-derived quartz and feldspar grains alternated with cm-thick pelitic beds. This decimeter-thick interval passes upward into a plurimetric, clastsupported and roughly graded sedimentary breccia. In its basal part, the cm-to dm-sized clasts are almost completely constituted by allochthon-derived carbonate rocks whilst the matrix is composed of a medium to coarse grained quartz and feldspar sandstone. Both the basal sandstone and the overlying breccias show mm-thick sub-vertical injections of black fine-grained material, which is derived from the gouge that caps the exhumed granite. Moreover, the breccias are crosscut by a dense network of mm-thick and some meters long veins filled with quartz and saddle dolomite (Fig. 4.9 a). The presence of basement-derived material constituting the matrix of the breccia, allows to ascribe this body to the Saluver A Formation [START_REF] Masini | The tectono-sedimentary evolution of a supra-detachment rift basin at a deep-water magma-poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland[END_REF][START_REF] Nonn | Architecture d'un système hyper-étiré: l'example des Chaînons Béarnais (bassins de Mauléon-Lourdes, Pyrénées[END_REF][START_REF] Finger | Die Zone von Samedan (unterostalpine Decken, Graubünden) und ihre jurassischen Brekzien[END_REF]Fig. 4.6). Clasts are crosscut by dolomiteand quartz-filled veins that stop at the edge of clasts showing the same features already described from Piz Val Lunga. Worth mentioning in the Saluver A unit is the presence of several meter-large blocks of Triassic dolostones in which cmto dm-large grossly tabular bodies of crackle to mosaic breccias occur with a cement of coarse dull luminescent saddle dolomite, yellowish in outcrop (Fig.

e).

Upsection, the sedimentary succession defines a thinning and fining upward trend. Conglomerates and breccias are progressively replaced by thin-to medium-bedded reddish turbidites, composed of siliciclastic sandstones and pelitic interbeds referred to the Saluver B and C units [START_REF] Masini | The tectono-sedimentary evolution of a supra-detachment rift basin at a deep-water magma-poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland[END_REF][START_REF] Masini | Anatomy and tectono-sedimentary evolution of a rift-related detachment system: The example of the Err detachment (central Alps, SE Switzerland)[END_REF][START_REF] Finger | Die Zone von Samedan (unterostalpine Decken, Graubünden) und ihre jurassischen Brekzien[END_REF]Fig. 4.6). In the uppermost part of this succession, ghosts of radiolaria have been identified within reddish siliceous mudrocks and grey cherts, interbedded with sandstone beds, which should mark the onset of Radiolarian Cherts deposition [START_REF] Masini | The tectono-sedimentary evolution of a supra-detachment rift basin at a deep-water magma-poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland[END_REF][START_REF] Masini | Anatomy and tectono-sedimentary evolution of a rift-related detachment system: The example of the Err detachment (central Alps, SE Switzerland)[END_REF][START_REF] Finger | Die Zone von Samedan (unterostalpine Decken, Graubünden) und ihre jurassischen Brekzien[END_REF]Fig. 4.6).

Nonetheless, much coarser deposits locally occur as scattered, several decimeter-

He isotopes

Analyses were carried out on saddle dolomite veins within the Hauptdolomit Fm., dedolomite and septarian-like concretion cements. All the results show a 3 He/ 4 He between 0.027 Ra and 0.100 Ra (ANNEX D).

Fluid inclusion microthermometry

More than 80 fluid inclusions from 12 doubly-polished sections have been measured to find their homogenization temperatures with a standard heating method [START_REF] Goldstein | Systematics of Fluid Inclusions in Diagenetic Minerals[END_REF]. Primary fluid inclusions of useful size for microthermometry (i.e. more than 2 μm in diameter; [START_REF] Goldstein | Systematics of Fluid Inclusions in Diagenetic Minerals[END_REF] were found in the replacement dolomite and dolomite cement of fenestral pores in the Hauptdolomit Formation, which have been gathered because of their [START_REF] Dietrich | Die ophilithe des Oberhalbsteins (Graubünden) und das Ophiolithmaterial der ostschweizrischen Molasseablagerungen, ein petrgraphisher Verleig[END_REF][START_REF] Froitzheim | Kinematics of Jurassic rifting, mantle exhumation, and passive-margin formation in the Austroalpine and Penninic nappes (eastern Switzerland)[END_REF][START_REF] Manatschal | A continent-ocean transition recorded in the Err and Platta nappes (Eastern Switzerland)[END_REF]. Differently from the present-day architecture, during the Jurassic evolution of the Adriatic margin the allochthon was floored by an extensional detachment fault whose footawall was constituted of continental crust (Albula granite). molds filled with chalcedony.

(2) Moving upsection, the sediments become coarser and dominated by many mass flow/turbidite deposits that rework either carbonate clasts (in which carbonate and quartz veins are preserved), and greyish to reddish cherts locally showing quartz-filled, septarian-like cracks (Fig. 5.6 b and d-g). On the basis of the texture and the composition of these sediments, which contain common quartz grains, they can be referred to the Saluver Formation [START_REF] Masini | The tectono-sedimentary evolution of a supra-detachment rift basin at a deep-water magma-poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland[END_REF][START_REF] Masini | Anatomy and tectono-sedimentary evolution of a rift-related detachment system: The example of the Err detachment (central Alps, SE Switzerland)[END_REF]. Meter-scale blocks of breccias composed only of carbonate lithoclasts are also present and may be referred to the Bardella Formation [START_REF] Masini | The tectono-sedimentary evolution of a supra-detachment rift basin at a deep-water magma-poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland[END_REF][START_REF] Masini | Anatomy and tectono-sedimentary evolution of a rift-related detachment system: The example of the Err detachment (central Alps, SE Switzerland)[END_REF]. Some laminated beds are widely dolomitized with dolomite rhombs up to 100µm (Fig. 5.8 a-c). ( 3) Differently from what has been observed and described at Fuorcla Cotschna, the syn-rift sediments are not crossed by fractures and/or veins.

He isotopes

Analyses were carried out on veins dolomite cement of set 1 and on both quartz and dolomite cements of veins set 2. All the 3 He/ 4 He ratios range in between 0.022 Ra and 0.039 Ra (ANNEX D).

Fluid inclusion microthermometry

About 80 primary fluid inclusions were found and measured in saddle dolomite and quartz cements of septarian-like concretions (Fig. 2) Coarsely crystalline dolomite locally occurs in the Hauptdolomit Fm. and neptunian dykes as fabric-destructive replacement, which obliterates primary textures. In the syn-rift succession it is widespread as substituting euhedral mineral phase within laminated fine-grained deposits.

3) Coarsely crystalline dolomite cement of shrinkage pores in the Hauptdolomit Fm. and of biomoldic pores in sills. The preservation of the well-defined CL zoning excludes a later recrystallization.

4) Lastly, saddle dolomite crystals occur as cement in syn-rift septarian-like concretion cracks.

Neptunian dykes and breccias

The occurrence of sills and dykes in the extensional allochthon is genetically related to tectonic events, which affected the host Hauptdolomit Formation. To be formed, they require a stage of fracturation enabling the creation of open spaces and the infiltration of the reddish pelagic sediments. Findings of sponge spicules and radiolarian ghosts in the sill-filling sediments suggest the correlation of the internal sediments with the sponge spicule-bearing Agnelli Formation. Therefore, the opening of the fissures could be dated to the early Early Jurassic when the sedimentary environment was deeper than that of in Late Triassic. Ongoing tensional stresses led to the brecciation of sills and dykes infill. was not lithified at all and thus most likely buried under a very limited thickness of younger sediments. This inference, together with fluid inclusion microthermometry performed on dolomite and quartz cements of veins and on dolomite-quartz filling cracks in syn-rift concretions, point to consider such fluids as hydrothermal. No analytical data are available for dolomite type 2 in the syn-rift sediments but, since its precipitation can be linked to the same physico-chemical conditions of dolomite type 4, hydrothermal fluids should be also responsible for the replacement process.

Veins

Septarian-like concretions and silicification

Many septarian-like concretions have been found in the basal part of syn-rift sediments right onto the top of the extensional allochthon.

The mechanisms responsible for septarian cracking are still the object of controversies. Several hypotheses have been advanced among which dehydration and shrinkage [START_REF] Raiswell | The growth of Cambrian and Liassic concretions[END_REF], excess pore pressures [START_REF] Astin | Septarian crack formation in carbonate concretions from shales and mudstones[END_REF][START_REF] Hounslow | Significance of localized pore pressures to the genesis of septarian concretions[END_REF], and synsedimentary seismic shocks [START_REF] Pratt | Septarian concretions: internal cracking caused by synsedimentary earthquakes[END_REF]. More At Mal Pass, in addition to septarian concretions, early diagenetic silicification is also documented in the matrix of ruditic beds in the syn-rift succession lying above the extensional allochthon, and especially by the occurrence of chert clasts in the ruditic beds. Since dolomite rhombs are still preserved within the quartz matrix, it can be assumed that silicification was preceded by a partial dolomitization. These processes took place at very shallow burial depths (probably decimeters to meters) so that the resulting cherts could be eroded and included in the coarsest beds of the syn-rift succession. The temperatures obtained by fluid inclusion microthermometry in quartz crystals support a hydrothermal nature also for silicifying fluids.

6. The proximal margin 6.1 IL MOTTO AREA

Stratigraphy and petrography

The study area is located in the central part of the Ortler nappe west of Livigno (Il Motto area, N Italy) and belongs to the Upper Austroalpine domain. Here, the structures of the former proximal Adriatic rifted margin are preserved in a wellexposed section in which the relationships between the sediment infill and the main high-angle normal fault bounding the basin are exposed [START_REF] Eberli | Carbonate turbidite sequences deposited in rift-basins of the Jurassic Tethys ocean (eastern Alps, Switzerland)[END_REF][START_REF] Eberli | The evolution of the southern continental margin of the Jurassic Tethys Ocean as recorded in the Allgäu Formation of the Austroalpine Nappes of Graubünden (Switzerland)[END_REF]Fig. 6.1). The syn-rift sedimentary sequence is characterized by thinningand fining-upward cycles as well as a thinning and fining away from the fault zone. Furthermore, an inversion of the clast stratigraphy is observed in the basin due to erosion and re-deposition of the footwall block during progressive exhumation along the fault [START_REF] Eberli | The evolution of the southern continental margin of the Jurassic Tethys Ocean as recorded in the Allgäu Formation of the Austroalpine Nappes of Graubünden (Switzerland)[END_REF]. In the present-day architecture, the Ortler nappe is under-and overlain along Alpine tectonic contacts by other Upper Austroalpine units, the Quattervals nappe above and the Campo nappe below. Finally, these breccias (both clasts and cement) are cut by mm-wide veins made of homogeneous dull luminescent dolomite.

The second type of breccia is constituted by polymict rubble breccia (Fig. 6.3 ad; sensu [START_REF] Morrow | Descriptive field classification of sedimentary and diagenetic breccias fabrics in carbonate rocks[END_REF], which is the result of a polyphase mechanism of disruption. Indeed, some clasts are composed of wackestone to packstone with bivalve shell fragments actually replaced by dolomite/calcite whereas others are made of a former mosaic breccia whose clasts still consist of wackestone/packstone cemented by finely to coarsely crystalline, dark orange to non-luminescent dolomite and thus different from the type 1 crackle breccia.

Some carbonate veins confined within the clasts also occur. This rubble breccia is cemented by sparry calcite showing a CL concentric zoning, from dark to very bright orange.

Fluid inclusion microthermometry

About 30 primary fluid inclusions were measured in the dolomite cement of type 1 breccias. Homogenization temperatures ranges from 86°C to 206°C (highest frequency between 130°C and 140°C; Fig. 6.5 and ANNEX B).

Breccias

The two types of breccias are matrix-free with clasts that, by their shape and spatial organization, suggest complex and repeated in situ hydro-fracturing mechanism obviously related to the pulsating activity of the Il Motto normal fault, which in the earliest Jurassic generated the well known half graben basin.

Different degrees of displacement of the clasts resulted in crackle to rubble breccias and are likely associated to the proximity with the fault damage zone and thus to more or less focused and repeated fluid fluxes.

Dolomite and calcite cements

The petrographic features of both dolomite and calcite cements enable to consider their precipitation in an open framework and in static conditions. Since their well-defined CL zoning is still preserved, it can be assumed that no subsequent recrystallization took place. The dolomite cement of type 1 breccias

shows the more depleted δ 18 O value of the dataset. Homogenization temperatures and O isotopes point to the presence of hydrothermal fluids that possibly flowed through the fault damage zone as main pathway.

Veins

Veining is not a pervasive process at Il Motto area. However, the presence of veins that stop at the edge of the clasts in type 1 breccias, and others that cut also through the dolomite cement, allows to consider the occurrence of at least two fracturing stages right before and after the emplacement of overpressured, dolomite-rich fluids to which the brecciation is related.

7. The inner distal margin

FIRST ORDER INTERPRETATION

The Piz Alv Breccia is a very complex deposit and has not been studied in detail.

However, some field and petrographic features enable to put some constraints on its genesis and age. The Piz Alv Breccia overlies the Agnelli Fm., which may be interpreted as an outer ramp deposit. Actually the Piz Alv Breccia consists of two different types of ruditic deposits: 1) the first is constituted of massively bedded megabreccias with large blocks, up to several meters in size, of Hauptdolomit and Kössen Formations that are widely dolomitized and crossed by neptunian dykes filled with dolomitized sediments; 2) the second is organized in thinner beds made of smaller clasts (up to 10 cm large) of the only Agnelli Formation, which, as well as the small neptunian dykes crosscutting the breccias, do not show dolomitization. On the basis of their paleontological content (calcisphaeres, echinoderms), albeit very scarce and poorly preserved, the neptunian dyke infillings are attributed to an open marine environment. The red and pink colour is thus not suggestive of subaerial exposure but of oxygenated conditions. The fine-grained texture moreover documents low energy levels during the deposition of internal sediments that may be defined as pelagic.

The overall evolution of Piz Alv area (Fig. 7.6) can be summarized assuming in the Early Jurassic a first stage of fragmentation of the Triassic carbonate platform and drowning of the remnants into a pelagic environment. This event was associated to fracturing, sediment infilling, and hydrothermal dolomitization and Fuorcla Cotschna (central distal margin). In Fig. 8.1 all the results are plotted in combination with the geological time scale [START_REF] Cohen | The ICS International Chronostratigraphic Chart[END_REF]updated). Measurements were performed also on quartz filling veins but the amount of U and Pb were not enough too provide reliable data. As a general consideration, the better results were obtained from the replacing minerals such as replacement dolomite and dedolomite whereas the void-filling minerals (cements of breccias and veins) do not seem to be the suitable target for this kind of analysis.

Considering the Late Triassic and Middle Jurassic times as lower-and upper ages bracketing the tectonic evolution of the Adriatic margin (e.g. deposition of the Hauptdolomit Fm. and Radiolarian Cherts respectively), it is evident that some data fall within this time lapse whereas others spread over a much wider time interval. Thus, the dataset can be subdivided in three main groups based on their significance with respect to the well-established steps that constrain the extensional evolution of the Adriatic margin (e.g. TAF, RC; [START_REF] Masini | The tectono-sedimentary evolution of a supra-detachment rift basin at a deep-water magma-poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland[END_REF]BBF, Incerpi et al., 2017).

To the first group (Group 1 in Fig. shows values with a "geological meaning" in the terms of processes related to Triassic-Jurassic continental extension.

Ages from Group 2 and 3 cannot be associated to the extensional evolution of the margin since they are younger than post-rift Radiolarian Chert Fm. and older than Norian Hauptdolomit Fm., respectively. [START_REF] Rasbury | Directly dating geological events: U-Pb dating of carbonates[END_REF] stated that an isotope system may be disturbed by diagenetic alteration of the original mineral (e.g. further fluid circulation). The fluids responsible for the alteration may add or remove either parent or daughter isotope or both resulting in younger or older ages of the analysed minerals. Such disturbance may not be associated to any recrystallization, as the petrography of the here analysed minerals documents. Therefore, based on strong geological constrains, also the minerals of Group 2 and 3 are surely related to the extensional evolution of the Adriatic margin even though their U-Pb ages suggest a re-opening of the radiogenic system possibly related to Alpine orogenic processes.

As previously said, Group 1 can be divided in three sub-groups. Fe-Mn oxides (Fe-Mn) and ophicalcites (OPH). As previously described, all the analysed samples have to be considered as the result of fluid-related processes that altered the former rocks or generated new forming minerals. When the same rock type comes from different paleogeographic domain it will be specified (e.g.

HD DIST = Hauptdolomit Fm. in the distal margin). Since more than one sample was analysed for each fluid-related product, they were gathered together to make the understanding and description of each set as easiest as possible.

Lastly, oxydes are expressed in wt% while trace and rare earth elements in ppm (parts per million). Elements below the detection limit were considered as absent.

Reference samples

To get a comparison with "unaltered" samples, two specimens of Hauptdolomit Fe-Mn oxides coating (Fe-Mn).

DISCUSSION AND INTERPRETATION

The rare earth elements (REE) are powerful tracers in the study of the evolution of geochemical systems and have been widely used to identify sources of oceanic REE and mixing processes within the oceans [START_REF] Elderfield | The oceanic chemistry of rare-earth elements[END_REF]. Since the first publication of REE data in hydrothermal fluids by [START_REF] Michard | Rare-earth elements and uranium in high-temperature solutions from East Pacific Rise hydrothermal vent field (13°N)[END_REF],

REE studies have been conducted on fluids from many different oceanic hydrothermal areas including the Mid-Atlantic Ridge at Lucky Strike [START_REF] Klinkhammer | Venting from the Mid-Atlantic Ridge at 37°17'N: The Lucky Strike hydrothermal site[END_REF], Broken Spur [START_REF] James | The chemistry of hydrothermal fluids from the Broken Spur site, 29°N Mid-Atlantic Ridge[END_REF], TAG [START_REF] Mitra | Rare earth element systematics of submarine hydrothermal fluids and plumes[END_REF][START_REF] Mitra | Rare earth elements in submarine hydrothermal fluids and plumes from the Mid-Atlantic Ridge[END_REF], Snakepit or MARK [START_REF] Campbell | Chemistry of hot springs on the Mid-Atlantic Ridge[END_REF][START_REF] Mitra | Rare earth element systematics of submarine hydrothermal fluids and plumes[END_REF][START_REF] Mitra | Rare earth elements in submarine hydrothermal fluids and plumes from the Mid-Atlantic Ridge[END_REF], the East Pacific Rise [START_REF] Michard | Rare-earth elements and uranium in high-temperature solutions from East Pacific Rise hydrothermal vent field (13°N)[END_REF][START_REF] Michard | The REE content of some hydrothermal fluids[END_REF], and the Lau Back-Ark Basin of the South-West Pacific [START_REF] Fouquet | Metallogenesis in Back-Arc Environments: The Lau Basin example[END_REF]. All of these investigations reported that the chondritenormalized REE (REE CN ) patterns of acidic hydrothermal fluids exhibit LREEenriched patterns with positive Eu anomalies. Furthermore, REE concentrations in hydrothermal fluids are greatly enriched compared to seawater [START_REF] Elderfield | The rare earth elements in seawater[END_REF][START_REF] De Baar | Rare earth elements in the Pacific and Atlantic Oceans[END_REF][START_REF] Piepgras | The behavior of rare earth elements in seawater: Precise determination of variations in the North Pacific water column[END_REF].

Positive Eu anomaly, which is supposed to be a clear signal of hydrothermal activity, is likely to reflect the Eu 2+ /Eu 3+ ratio in the fluid [START_REF] Zhong | Partitioning of rare earthe elements (REEs) between calcite and seawater solutions at 25°C and 1 atm, and high dissolved REE concentrations[END_REF], which is in turn strongly dependent on temperature. Eu 2+ /Eu 3+ equilibrium is established at about 250°C [START_REF] Sverjensky | Europium redox equilibria in aqueous solution[END_REF][START_REF] Bau | Rare-earth elements mobility during hydrothermal and metamorphic fluid-rock interaction and the significance of the oxidation state of europium[END_REF][START_REF] Bau | Rare earth elements fractionation in metamorphogenic hydrothermal calcite, magnesite and siderite[END_REF] has a lower affinity for sorption or incorporation into secondary minerals during water-rock interaction than Eu 3+ , and, relative to its trivalent REY neighbours, Eu 2+ preferentially partitions into the dissolved phase [START_REF] Bau | Rare-earth elements mobility during hydrothermal and metamorphic fluid-rock interaction and the significance of the oxidation state of europium[END_REF][START_REF] Bau | Rare earth elements fractionation in metamorphogenic hydrothermal calcite, magnesite and siderite[END_REF]. A positive Eu anomaly in a hydrothermal fluid is, therefore, a typical result of high-temperature water-rock interaction and cannot develop in low-temperature aqueous systems. Because of the extremely low oxygen fugacities required for significant Eu 3+ reduction at low temperature [START_REF] Bau | Rare-earth elements mobility during hydrothermal and metamorphic fluid-rock interaction and the significance of the oxidation state of europium[END_REF], carbonate-precipitating fluids with positive Eu anomalies are even very rare in extremely reducing natural systems such as methane ("cold") seeps (e.g., [START_REF] Feng | Rare earth elements in seep carbonates as tracers of variable redox conditions at ancient hydrocarbon seeps[END_REF][START_REF] Feng | Authigenic carbonates from methane seeps of the northern Congo fan: microbial formation mechanism[END_REF][START_REF] Himmler | Rare earth elements in authigenic methane-seep carbonates as tracers for fluid composition during early diagenesis[END_REF]. The HD GOUGE, on the contrary, shows positive Eu anomaly. [START_REF] Manatschal | Fluid-and reaction-assisted low-angle normal faulting; evidence from rift-related brittle fault rocks in the Alps (Err Nappe, Eastern Switzerland)[END_REF] and [START_REF] Manatschal | Channellized fluid flow and mass transfer along a rift-related detachment fault (Eastern Alps, southeast Switzerland)[END_REF] described temperatures for the detachment fault and the black gouge as high as 250°C.

Such temperature could then be responsible for the positive Eu anomaly. The hydrothermal characteristics of the studied minerals and by inference of the fluids seem to be strongly confirmed by super-chondritic Y/Ho ratio of the whole dataset (the only exception is HD CAT), which is typical of hydrothermal systems [START_REF] Bau | Comparative study of yttrium and rare-earth element behaviours in fluorite-rich hydrothermal fluids[END_REF]. The enrichment of the LREE relative to HREE observed in the whole dataset can be attributed to the greater stability of HREE complexes in hydrothermal solutions and is a common feature of hydrothermal fluids [START_REF] Douville | Yttrium and rare earth elements in fluids from various deepsea hydrothermal systems[END_REF]. Low content of REE, which is a characteristic of the presented samples, can give some indication about the residence time of fluids within the aquifer that was possibly fast recharged.

exhuming mantle. Such enrichment occurred in response to fluid migration along the Err detachment fault system, which allowed the enrichment of both cataclasites and black gouges of the detachment itself. Findings of such elements also within the analysed samples of this study could suggest that also the carbonates lying above the detachment fault recorded such serpentinizing event.

Furthermore, the staining of carbonate clasts by Fe-Mn oxides within the upper part of the syn-rift succession, point to important involvement of "mantlerelated" fluids even far from the detachment surface. Indeed, [START_REF] Pinto | Tracing mantle-reacted fluids in magma-poor rifted margin: The example of Alpine Tethyan rifted margin[END_REF] suggest the occurrence of "poisoning" of the seawater in response to venting related to serpentinization, which may confirm the "mantle overprint" recorded at the syn-to post-rift sediments transition.

The presented dataset highlights also the occurrence of crustal-related elements (e.g. Ba, Sr, Rb, Pb) that should testify and confirm a deep fluid circulation within the Albula granite (e.g. footwall of the detachment fault). In particular, the strong enrichment in Ba should confirm the occurrence of hydrothermal circulation [START_REF] Plank | The chemical composition of subducting sediment and its consequences for the crust and mantle[END_REF] Both SILIC and SEPT show strong enrichment in Sr. The explanation can be found considering those "impurities" mentioned at the beginning of this chapter.

Petrographic studies allowed to recognize a dolomitization stage that occurred Both finely and coarsely crystalline dolomites ("Replacement dolomite" in Fig. 10.1) show the least 18 O-depleted values of the whole dataset which, however, are lower than those reported in present day settings where dolomite is forming and ranges from 0 to +4 ‰ (e.g. [START_REF] Tucker | Carbonate sedimentology[END_REF][START_REF] Meister | Dolomite formation in the shallow seas of the Alpine Triassic[END_REF].

The study of fluid inclusions indeed provides temperature constraints to these dolomites, with formation temperatures averaging 120-130°C. These dolomites, fundamental time constrain and that it is recorded within dolostones presently preserved all over the Adriatic margin, the replacement event described also at Mal Pass and Il Motto areas, also characterized by negative δ 18 O values, can be assumed to be related to the same hydrothermal system described for the distal margin, in spite of the lack of homogenization temperatures of fluid inclusions.

The Hauptdolomit Formation in the proximal and distal margins, when the replacement dolomitization took place, was not deeply buried so that also in these areas the occurrence of a hydrothermal circulation can be postulated.

All the samples of the second group (dolomite and calcite veins, calcite cements and dedolomite) plot in an area of more 18 O-depleted values but the variability internal to each analyzed subgroup of samples (veins, cement etc.) is so large that it is impossible to separate it from the others on the basis of O or C isotope values alone. Homogenization temperatures of fluid inclusions confirm that also these mineral phases precipitated from high-T fluids. Crosscutting relationships inferred by field and petrographic observations, as well as U-Pb dating, clearly

show that these hydrothermal products postdate the replacement processes affecting the Hauptdolomit Fm.

Calculations of the isotope composition of fluids responsible for dolomite and calcite precipitation, made by applying the equation of [START_REF] Horita | Oxygen and carbon isotope fractionation in the system dolomite-water-CO 2 to elevated temperatures[END_REF] and [START_REF] Anderson | Stable isotopes of oxygen and carbon and their application to sedimentologic and paleoenvironmental problems[END_REF] respectively for dolomite and calcite, provide O isotope values for fluids from slightly to markedly positive (+2 to about +12 ‰ SMOW). Such positive signature may be related to different processes such as evaporative enrichment (e.g. [START_REF] Mckenzie | The dolomite problem: an outstanding controversy[END_REF], clay mineral diagenesis [START_REF] Dählmann | Fluid-sediment interactions at Eastern Mediterranean mud volcanoes: a stable isotope study from ODP Leg 160[END_REF][START_REF] Hensen | Sources of mud volcano fluids in the Gulf of Cadizindications for hydrothermal imprint[END_REF], and to the interaction with silicate minerals of siliciclastic and crystalline rocks [START_REF] Clayton | The origin of saline formation waters: Isotopic composition[END_REF][START_REF] Land | The origin and evolution of saline formation waters, Lower Cretaceous carbonates, south-central Texas and southern New Mexico[END_REF][START_REF] Hitchon | Regional subsurface hydrogeology, Peace River area, Alberta and British Columbia[END_REF][START_REF] Haeri-Ardakani | Fracture mineralization and fluid flow evolution: an example from Ordovician-Devonian carbonates, southwestern Ontario, Canada[END_REF]. In the context of an extending continental margin, meteoric waters may be ruled out and the only reasonable source of fluids feeding the complex fracturecontrolled circulation system was seawater. In particular, the stratigraphy of the studied sections, where deepwater sediments occur also directly over basement rocks topped by the detachment faults, leads to exclude the first two hypotheses.

The highly radiogenic Sr isotope values of dolomite and calcite occurring as Then, one important question arises: why apparently similar conditions produced so different mineralogies within the diagenetic products? In order to give an answer, the tectono-stratigraphic architecture of the margin at the time when the two different diagenetic stages occurred has to be taken into account.

The first carbonate-rich diagenetic stage refers to the first rifting events (SG1 and SG2), which segmented the continental margin leading to the formation of half graben basins bounded by high angle normal faults (Fig. 10.3). These main structures, that penetrated within the crust for some kilometers, are composed of different minor faults each one accommodating displacements in the order of hundreds of meters. Seawater, penetrated through these high angle faults and their damage zones. Fluids were consequently heated and chemically modified by exchanges with basement rocks, as documented by δ 18 O and Sr 87 /Sr 86 . In their way up within convective cells, seawater, which is per se a dolomitizing fluid [START_REF] Land | The origin of massive dolomite[END_REF][START_REF] Purser | Dolomites -A Volume in Honour of Dolomieu[END_REF][START_REF] Machel | Concepts and models of dolomitization: a critical reappraisal[END_REF] was hot enough to overcome the kinetic barrier to dolomitization. CO 2 degassing, promoted by pressure decrease while approaching the surface, possibly triggered this process. The second silica-rich diagenetic stage, occurring during low-angle detachment faulting (SG3), is characterized by a greater amount of tectonic displacement that is mainly horizontal and one order of magnitude higher than that of the first stage (Fig. 10.4). The volume of cataclastic belts in the crystalline basement was much greater and consequently the degree of breakdown of feldspars. Moreover, in this frame, the flux of seawater was probably shallower and much more active resulting in stronger fluid-rock interaction in turn producing a massive silica enrichment in the fluids. [START_REF] Choukroune | The ECORS Pyrenean deep seismic profile reflection data and the overall structure of an orogenic belt[END_REF][START_REF] Muñoz | Evolution of a continental collision belt: ECORS-Pyrenees crustal balanced section[END_REF]Deramond et al., 1993;[START_REF] Roure | Contribution of the ECORS seismic data to the Pyrenean geology: Crustal architecture and geodynamic evolution of the Pyrenees[END_REF][START_REF] Teixell | Crustal structure and orogenic material budget in the western central Pyrenees[END_REF]. Triassic and Jurassic aborted rift events predated the development of a major Cretaceous crustal thinning stage, which gave rise to a counter-clockwise displacement of Iberia relative to Europe [START_REF] Puigdefàbregas | Tecto-sedimentary cycles and depositional sequences of the Mesozoic and Tertiary from the Pyrenees[END_REF]Vergés and Garcia-Senz, 2001), coeval with the onset of oceanic spreading in the Bay of Biscay between approximately 125-83 Ma [START_REF] Le Pichon | Une hypothèse dévolution tectonique du Golfe de Gascogne[END_REF][START_REF] Choukroune | Tectonique des plaques et Pyrénées: Sur le fonctionnement de la faille transformante nord-pyrénéenne; comparaisons avec des modèles actuels[END_REF][START_REF] Olivet | La cinématique de la plaque Ibérique[END_REF][START_REF] Gong | The rotation of Iberia during the Aptian and the opening of the Bay of Biscay[END_REF][START_REF] Jammes | Tectono-sedimentary evolution related to extreme crustal thinning ahead of a propagating ocean; example of the western Pyrenees[END_REF].

THE BAY OF BISCAY-PYRENEAN DOMAIN

The present-day Bay of Biscay-Pyrenean domain results from the polyphasic Triassic to Early Cretaceous rift system, which led to the formation of hyperextended basins and oceanic crust in the western Bay of Biscay (Vergés and Garcia-Senz, 2001;[START_REF] Sibuet | Pyrenean orogeny and plate kinematics[END_REF][START_REF] Jammes | Tectono-sedimentary evolution related to extreme crustal thinning ahead of a propagating ocean; example of the western Pyrenees[END_REF][START_REF] Filleaudeau | Thermo-tectonic evolution of the south-central Pyrenees from rifting to orogeny: insights from detrital zircon U/Pb and (U-Th)/He thermochronometry[END_REF]Vissers and Meijer, 2012a, b;[START_REF] Clerc | Thermal control on the modes of crustal thinning leading to mantle exhumation. Insights from the Cretaceous Pyrenean hot paleomargins[END_REF][START_REF] Mouthereau | Placing limits to shortening evolution in the Pyrenees: role of margin architecture and implications for theIberia/Europe convergence[END_REF][START_REF] Tugend | Spatial and temporal evolution of hyperextended rift systems: Implication for the nature, kinematics, and timing of the Iberian-European plate boundary[END_REF][START_REF] Vacherat | Rift-tocollision transition recorded by tectonothermal evolution of the northern Pyrenees[END_REF]. This system was Lithospheric break-up and seafloor spreading in the Bay of Biscay occurred simultaneously to hyper-extension further to the east in the Pyrenean domain.

These processes are described both offshore (Parentis: [START_REF] Pinet | Crustal thinning on the Aquitaine shelf, Bay of Biscay, from deep seismic data[END_REF][START_REF] Bois | Geologic contribution of the Bay of Biscay deep seismic survey: a summary of the main scientific results, a discussion of the open questions and suggestions for further investigations[END_REF][START_REF] Brunet | Subsidence et géodynamique du basin d'Aquitaine. Relations avec l'ouverture de l'Atlantique[END_REF]Bois and Gabriel, 1994;[START_REF] Jammes | Extreme crustal thinning in the Bay of Biscay and the Western Pyrenees: from observations to modeling[END_REF][START_REF] Roca | The role of the Bay of Biscay Mesozoic extensional structure in the configuration of the Pyrenean orogen: constraints from the MARCONI deep seismic reflection survey[END_REF] and onshore (e.g. the Aulus basin: [START_REF] Lagabrielle | Submarine reworking of exhumed subcontinental mantle rocks; field evidence from the Lherz peridotites, French Pyrenees[END_REF][START_REF] Lagabrielle | Mantle exhumation, crustal denudation, and gravity tectonics during Cretaceous rifting in the Pyrenean realm (SW Europe): insights from the geological setting of the lherzolite bodies[END_REF][START_REF] Clerc | Exhumation of subcontinental mantle rocks: evidence from ultramaficbearing clastic deposits nearby the Lherz peridotite body, French Pyrenees[END_REF]; the Arzacq-Mauléon basin: Daignères et al., 1994;[START_REF] Jammes | Tectono-sedimentary evolution related to extreme crustal thinning ahead of a propagating ocean; example of the western Pyrenees[END_REF][START_REF] Jammes | Interaction between prerift salt and detachment faulting in hyperextended rift systems: the example of the Parentis and Mauléon basins (Bay of Biscay and western Pyrenees)[END_REF][START_REF] Lagabrielle | Mantle exhumation, crustal denudation, and gravity tectonics during Cretaceous rifting in the Pyrenean realm (SW Europe): insights from the geological setting of the lherzolite bodies[END_REF][START_REF] Debroas | Les brèches d'Urdach, témoins de l'exhumation du manteau pyrénéen dans un escarpement de faille vraconiencénomanien inférieur (Zone Nord Pyrénéenne, Pyrénées Atlantiques, France)[END_REF][START_REF] Masini | The tectono-sedimentary evolution of a hyper-extended rift basin: the example of the Arzacq-Mauléon rift system (Western Pyrenees, SW France)[END_REF][START_REF] Tugend | Formation and deformation of hyperextended rift systems: Insights from rift domain mapping in the Bay of Biscay-Pyrenees[END_REF]; and the Basque-Cantabrian basin; [START_REF] Pedreira | Three-dimensional gravity and magnetic modeling of crustal indentation and wedging in the western Pyrenees-Cantabrian Mountains[END_REF][START_REF] Roca | The role of the Bay of Biscay Mesozoic extensional structure in the configuration of the Pyrenean orogen: constraints from the MARCONI deep seismic reflection survey[END_REF]. [START_REF] Bois | Geologic contribution of the Bay of Biscay deep seismic survey: a summary of the main scientific results, a discussion of the open questions and suggestions for further investigations[END_REF] and East-West Expanding Spread profiles (ESPs, Marillier et al., 1988), shows that extreme crustal thinning to less than 10 km occurred. Furthermore, the interpretation of seismic profiles highlights the strong asymmetry of the basin, which is characterized by an upper and a lower plate sag basin architecture with its southern part floored by a low-angle extensional detachment fault [START_REF] Jammes | Tectono-sedimentary evolution related to extreme crustal thinning ahead of a propagating ocean; example of the western Pyrenees[END_REF][START_REF] Jammes | Extreme crustal thinning in the Bay of Biscay and the Western Pyrenees: from observations to modeling[END_REF].

The Arzacq-Mauléon rift system, located further to the SE, is a reactivated and partly exposed analogue of the Parentis Basin showing similar geophysical, tectonic and sedimentary features [START_REF] Jammes | Tectono-sedimentary evolution related to extreme crustal thinning ahead of a propagating ocean; example of the western Pyrenees[END_REF](Jammes et al., , 2010a, b;, b;Fig. 11.1). As for the Parentis Basin, the Arzacq-Mauléon rift system appears to be strongly asymmetric. Several authors suggested the occurrence of rift-related detachment faults in the Arzacq-Mauléon Basin (e.g., Ducasse and Vélasque, 1986a;Johnson and Hall, 1989a, b;Claude,1990;[START_REF] Jammes | Tectono-sedimentary evolution related to extreme crustal thinning ahead of a propagating ocean; example of the western Pyrenees[END_REF][START_REF] Lagabrielle | Mantle exhumation, crustal denudation, and gravity tectonics during Cretaceous rifting in the Pyrenean realm (SW Europe): insights from the geological setting of the lherzolite bodies[END_REF][START_REF] Masini | The tectono-sedimentary evolution of a hyper-extended rift basin: the example of the Arzacq-Mauléon rift system (Western Pyrenees, SW France)[END_REF]. Its western part was reactivated during the Pyrenean inversion in late Cretaceous to Tertiary time (Choukrune and [START_REF] Choukroune | The ECORS Pyrenean deep seismic profile reflection data and the overall structure of an orogenic belt[END_REF][START_REF] Muñoz | Evolution of a continental collision belt: ECORS-Pyrenees crustal balanced section[END_REF]Deramond et al., 1993;[START_REF] Roure | Contribution of the ECORS seismic data to the Pyrenean geology: Crustal architecture and geodynamic evolution of the Pyrenees[END_REF][START_REF] Teixell | Crustal structure and orogenic material budget in the western central Pyrenees[END_REF] as a large pop-up structure explaining the weak orogenic overprint. Here, consequently, there is a direct access to mantle, middle and upper crustal rocks as well as to the complete stratigraphic record including preto post-rift sediments.

11.2.1 Large-scale rift architecture of the Arzacq-Mauléon system [START_REF] Masini | The tectono-sedimentary evolution of a hyper-extended rift basin: the example of the Arzacq-Mauléon rift system (Western Pyrenees, SW France)[END_REF] subdivided the Arzacq-Mauléon basin in 4 main domains, which, from north to south, are (Fig. 11.2):

1. The Arzacq Basin, extending over the European continental crust, is characterized by the progressive crustal thinning from 25 km in the north to less than 20 km in the south leading to a progressive increase in the amount of Mesozoic extension moving southward [START_REF] Daignières | The Arzacq-Western Pyrenees ECORS deep seismic profile[END_REF][START_REF] Teixell | Alpine thrusts at the western termination of the Pyrenean Axial Zone[END_REF]. This is also supported by the southward thickening of the Lower and Middle Cretaceous sedimentary sequences (e.g., [START_REF] Biteau | The Aquitaine Basin[END_REF]. One of the main characteristics of this basin is that the pre-rift sequences (pre-Aptian) can be imaged and were drilled throughout the entire Arzacq Basin [START_REF] Daignières | The Arzacq-Western Pyrenees ECORS deep seismic profile[END_REF][START_REF] Esso | Géologie du bassin d'Aquitaine[END_REF]. This suggests that the upper crust was weakly stretched, which contrasts with the observed crustal thinning responsible for progressive subsidence of the basin from the Aptian onward [START_REF] Jammes | Tectono-sedimentary evolution related to extreme crustal thinning ahead of a propagating ocean; example of the western Pyrenees[END_REF].

2. The Grand Rieu High, is the boundary between the Arzacq and the hyperextended Mauléon Basin located to the south. This domain is partially lacking the pre-to syn-rift sequences and, locally, is directly sealed by post-rift sediments (e.g., Cardesse 2 drillhole in [START_REF] Esso | Géologie du bassin d'Aquitaine[END_REF][START_REF] Serrano | Le bassin d'Aquitaine: valorisation des données sismiques, cartographie structurale et potentiel pétrolier[END_REF]. It suggests that this domain acted as a topographic barrier until post-rift time.

During Pyrenean convergence, the sedimentary cover of the Grand Rieu High was decoupled and thrust northward.

3. The Mauléon Basin is part of a complex E-W directed trough system bounded by two paleohighs: the Grand Rieu High to the north and the Axial domain to the south. The Mauléon Basin corresponds to a major Cretaceous basin formed over hyper-extended Iberian crust. It differs from the Arzacq Basin by a more complex rift history, with pre-rift sediments that are discontinuous and show a strongly variable syn-rift stratigraphic architecture. [START_REF] Jammes | Tectono-sedimentary evolution related to extreme crustal thinning ahead of a propagating ocean; example of the western Pyrenees[END_REF] showed that this basin formed as a hyper-extended basin with local exhumation of middle crustal and mantle rocks in the northern part of the basin. The authors also demonstrated the occurrence of a long-offset extensional detachment fault. [START_REF] Masini | The tectono-sedimentary evolution of a hyper-extended rift basin: the example of the Arzacq-Mauléon rift system (Western Pyrenees, SW France)[END_REF] showed that a second, large-scale detachment system can be traced across the southern margin of the Mauléon Basin. In this Thesis, the investigations will focus on the easternmost part of the Mauléon Basin, the socalled Chaînons Béarnais.

.2.1 Metamorphic basement

The Paleozoic metasediments consist of thick successions of low metamorphosed siliciclastic, shaly and calcareous deposits ranging from anchizonal to lower greenschist facies [START_REF] Heddebaut | Etudes géologiques dans les massifs Paléozoïques Basques[END_REF]. These rocks are mainly exposed south of the Mauléon Basin. The post-Variscan evolution is related to the activity of strike-slip/transform faults throughout the Late Carboniferous to the Early Permian that strongly structured the lithosphere (Arthaud andMatte, 1975, 1977;Burg et al., 1994 a, b).

Pre-rift sequence (Permian to early Aptian)

This sequence shows strong thickness variations and cannot be mapped as a continuous horizon. The Triassic sediments show the classical transgression of the Muschelkalk carbonate platform over the continental deposits of the Buntsandstein made of shales, sandstones and conglomerates (e.g., Germanic

Facies: [START_REF] Curnelle | Evolution structuro-sédimentaire du Trias et de l'infra-Lias d'Aquitaine[END_REF][START_REF] Fréchengues | Stratigraphie séquentielle et micropaléontologie du Trias moyen-supérieur des Pyrénées franco-espagnoles[END_REF]. Keuper evaporites, overlying the Muschelkalk carbonate platform, represent an important weak layer acting as a decoupling horizon during the subsequent extensional (e.g., [START_REF] Canérot | Les glissements rocheux du versant sud du Layens (Vallée d'Aspe, Pyrénées occidentales)[END_REF][START_REF] Jammes | Interaction between prerift salt and detachment faulting in hyperextended rift systems: the example of the Parentis and Mauléon basins (Bay of Biscay and western Pyrenees)[END_REF] and compressional events [START_REF] Casteras | Geological map sheet of Mauléon-Licharre[END_REF]Casteras et al., 1970aCasteras et al., , b, 1971;;[START_REF] Pochat | Feuille de St Jean Pied de Port[END_REF]. Voluminous time equivalent tholeiitic magmatic activity, also known as the "ophitic" intrusions, can be found associated with the evaporites (Rossi et al., 2003 and references therein). The occurrence of the evaporitic facies is threefold: ( 1 [START_REF] Esso | Géologie du bassin d'Aquitaine[END_REF][START_REF] James | Données nouvelles sur la phase de rifting atlantique des Pyrénées occidentales au Kimméridgien[END_REF]Biteauet al., 2006;[START_REF] Jammes | Tectono-sedimentary evolution related to extreme crustal thinning ahead of a propagating ocean; example of the western Pyrenees[END_REF].

In the Arzacq-Mauléon domain, a single large-scale depocenter developed north of the future Arzacq Basin. This led to a complete Neocomian sedimentary record whereas a major regression is recorded to the south in the future Mauléon Basin. This is mostly shown by the development of a major erosional unconformity with, locally, the formation of bauxites [START_REF] Biteau | La chaîne des Pyrénées et ses avants-pays d'Aquitaine et de l'Ebre: caractéristiques structurales, evolution géodynamique et tectono-sédimentaire[END_REF][START_REF] Canérot | Les Pyrénées-Histoire Géologique[END_REF] for a review). Barremian and Lower Aptian sediments record a general south directed transgression with the development of Annelides carbonates and Sainte Suzanne marls, which have been interpreted to be deposited in a shallow marine environment [START_REF] Cassou | La formation des ''marnes de Sainte-Suzanne'' et ses faciès latéraux en Aquitaine Occidentale. Essai de zonation et de datation[END_REF]. The depocenter was still localized in the Arzacq Basin where more than 1 km of Sainte Suzanne Marls have been accommodated (e.g., Biteau et al., 2006 and references therein).

In the southern part of the domain, Barremian to Lower Aptian carbonates are either condensed within some meters or locally absent (e.g., [START_REF] Canérot | Les Pyrénées-Histoire Géologique[END_REF]. The top of the Lower Aptian carbonates represents the second important time marker that can be mapped throughout the basin. This marker corresponds to the base of the syn-rift sequence. As already shown by [START_REF] Ducasse | Géotraverse dans la partie occidentale des pyrénées de l'avant-pays aquitain au bassin de l'Ebre. Effet d'une inversion structurale sur l'édification d'une chaîne intracontinentale[END_REF], the Lower Cretaceous Fms. were already folded in the Mauléon Basin before being eroded and unconformably overlain by the Upper Aptian carbonates and marls. This is often interpreted to be linked to salt mobility (e.g., Ducasse and Vélasque, 1986a;[START_REF] Canérot | Rifting éocrétacé et halocinèse sur la marge ibérique des Pyrénées Occidentales (France). Conséquences structurales[END_REF][START_REF] James | Diapirisme et structuration post-triasique des Pyrénées occidentales et de l'Aquitaine méridionales (France)[END_REF][START_REF] Canérot | Les glissements rocheux du versant sud du Layens (Vallée d'Aspe, Pyrénées occidentales)[END_REF][START_REF] Biteau | The Aquitaine Basin[END_REF][START_REF] Teixell | The crustal evolution of the west-central Pyrenees revisited: inferences from a new kinematic scenario[END_REF] during earlier local rift events.

Syn-rift sequence (Upper Aptian to Lower Albian)

The late early Cretaceous carbonate facies record a major change in the tectonic, sedimentary and isostatic evolution of the Arzacq-Mauléon rift system. From that time onward, the Arzacq and Mauléon Basins started to be disconnected.

The Arzacq Basin, located north of the Grand Rieu High, records an increased subsidence [START_REF] Brunet | Subsidence history of the Aquitaine basin determined from subsidence curves[END_REF]; carbonate platforms developed on highs surrounded by more subsiding basins were filled by marls and formation of salt diapirs (e.g., [START_REF] Biteau | The Aquitaine Basin[END_REF]. In the Mauléon Basin, the Upper Aptian carbonates and marls (Urgonian facies) record a crustal extension phase associated with the formation of tilted blocks and extensional fault-bounded basins. Their base corresponds to an important unconformity that can be observed throughout the Mauléon Basin. The Albian carbonate system consists of carbonate platform and marl deposits [START_REF] Esquevin | Les séries de l'Aptien et de l'Albien des régions nord-pyrénéennes et sud-aquitaines (France Sud)[END_REF][START_REF] Canérot | Sequence stratigraphy and sedimentary unconformities: western Pyrenees (field data) and southern Aquitanian basin (subsurface data): examples[END_REF]Claude, 1990 and references therein). Upsection and to the south, the marls are progressively replaced by siliciclastic turbiditic beds, known in the literature as Flysch Noir, which are in turn replaced by more proximal conglomeratic facies (up to 900m of conglomerates mainly formed by Paleozoic metasediments derived from the uplift and erosion of the Axial Zone; Boirie and Souquet, 1982). The transition from the Albian-Cenomanian conglomerate fan deposits in the south to shales and turbidites in the north suggests the existence of a complete depositional sedimentary system ranging from the platform across the slope into a deep marine fan. However, the existence of blocks composed of Jurassic to Aptian limestone (the Chaînons Béarnais ridges), interpreted by [START_REF] Jammes | Tectono-sedimentary evolution related to extreme crustal thinning ahead of a propagating ocean; example of the western Pyrenees[END_REF] as extensional allochthons, seems to control the distribution of the conglomerate fan deposits and its transition with the deep marine facies. Although Flysch Noir deposits occur throughout the Mauléon Basin, they were not found further north across the Grand Rieu High [START_REF] Serrano | Le bassin d'Aquitaine: valorisation des données sismiques, cartographie structurale et potentiel pétrolier[END_REF]. The intrusive and extrusive alkaline rocks are time equivalent to the Flysch Noir and mainly occur in the northern part of the Mauléon Basin and above the Grand Rieu high [START_REF] Serrano | Le bassin d'Aquitaine: valorisation des données sismiques, cartographie structurale et potentiel pétrolier[END_REF]Montignyet al., 1986).

Post-rift sequence (Cenomanian onward)

A new transgression over the Axial domain resulted in a progressive cessation of the siliciclastic input that was replaced by thick carbonate platform deposits.

This event is recorded in the Mauléon Basin by a platform-driven sedimentation and the development of calciturbiditic and hemipelagic systems. The occurrence of these sediments over the Grand Rieu High (e.g., [START_REF] Razin | Evolution tecto-sédimentaire alpine des Pyrénées basques à l'Ouest de la transformante de Pampelona[END_REF][START_REF] Claude | Etude stratigraphique, sédimentologique et structural des dépôts mésozoïques au Nord du massif du Labourd. Rôle de la faille de Pamplona (Pays Basque[END_REF]Mulderet al., 2009) suggests that in Cenomanian time, the Grand Rieu High was not acting anymore as a high separating the Mauléon and the Arzacq Basins. A significant amount of post-rift subsidence over the Grand Rieu high is also

shown by the thick Turonian succession in this domain (e.g., [START_REF] Serrano | Le bassin d'Aquitaine: valorisation des données sismiques, cartographie structurale et potentiel pétrolier[END_REF]. In the Arzacq Basin, no major changes were recorded with the continuation of the carbonate-dominated sedimentation [START_REF] Biteau | The Aquitaine Basin[END_REF].

Mantle-derived rock occurrences in the Mauléon Basin

In the Mauléon Basin a number of outcrops showing mantle-derived serpentinized peridotites can be found. In contrast to the mantle rocks exposed in the eastern Pyrenees (e.g. Lherz), the mantle rocks in the western Pyrenees are not associated with North Pyrenean Variscan Massifs (Saint Barthelemy, Trois Seigneurs, Milhas;[START_REF] Fabriès | Petrogenetic evolution of orogenic lherzolite massifs in the central and western Pyrenees[END_REF], nor with the Pyrenean fault zone. These bodies are commoly found at the base of east-west trending ridges composed of Upper Triassic to Lower Cretaceous sediments (Chaînons Béarnais ridges) and only locally register the HT-LP metamorphism conversely widely diffused in the eastern part of the chain [START_REF] Fortane | Lherzolites and the western ''chaînons Béarnais'' (French Pyrenees): Structural and paleogeographical pattern[END_REF]Thiebaut et al., 1992;[START_REF] Lagabrielle | Mantle exhumation, crustal denudation, and gravity tectonics during Cretaceous rifting in the Pyrenean realm (SW Europe): insights from the geological setting of the lherzolite bodies[END_REF]. Such metamorphic event was characterized by a temperature peak barely exceeding 400°C [START_REF] Clerc | Exhumation of subcontinental mantle rocks: evidence from ultramaficbearing clastic deposits nearby the Lherz peridotite body, French Pyrenees[END_REF]. Petrological and geothermobarometric studies of these ultramafic bodies show that they underwent a two-step exhumation with a first rise from 60 to 25 km depth, probably during late Hercinian times, followed by a further step from 25 km to shallower and cooler levels [START_REF] Fabriès | Petrogenetic evolution of orogenic lherzolite massifs in the central and western Pyrenees[END_REF] from 117 to 109 Ma (Visers et al., 1997;[START_REF] Fabriès | Petrogenetic evolution of orogenic lherzolite massifs in the central and western Pyrenees[END_REF]. In the past, various scenarios have been proposed for their emplacement: from purely tectonic mechanisms, such as solid intrusion of mantle rocks into sediments during strike-slips events [START_REF] Vielzeuf | Crustal splitting and the emplacement of Pyrenean lherzolites and granulites[END_REF], to tectonosedimentary processes in which mantle rocks were exhumed during Variscan time (Mattauer andChoukroume, 1974, Fontane et al., 1986) and reworked in a middle Cretaceous flysch (Fontane et al., 1986). More recently, [START_REF] Lagabrielle | Submarine reworking of exhumed subcontinental mantle rocks; field evidence from the Lherz peridotites, French Pyrenees[END_REF] and [START_REF] Jammes | Tectono-sedimentary evolution related to extreme crustal thinning ahead of a propagating ocean; example of the western Pyrenees[END_REF]Jammes et al. ( , 2010) ) proposed that these rocks were exhumed during Albian time to the seafloor before they were reworked and deposited in the overlying younger sediments.

3 THE CHAÎNONS BÉARNAIS

The Chaînons Béarnais form a series of E-W trending fold-thrust structures made of continuous late Triassic-to Lower Cretaceous sediments (Fig. 11.3).

These ridges are floored by a south-verging Pyrenean faults tipically occurring within the Triassic evaporites [START_REF] Teixell | The crustal evolution of the west-central Pyrenees revisited: inferences from a new kinematic scenario[END_REF]. The three ridges comprise from north to south: the Mail Arrouy, the Sarrance and the Layens. The base of the Mesozoic sequence is represented by the Triassic Keuper facies with shales, evaporites, breccias and ophites, followed by Jurassic to Aptian platform limestones and dolomites. These sediments represent the original pre-rift cover of the northern Iberian margin (Canerot andDelavaux, 1986, Canerot et al., 1978), now entirely detached from the Palaeozoic basement [START_REF] Lagabrielle | Mantle exhumation, crustal denudation, and gravity tectonics during Cretaceous rifting in the Pyrenean realm (SW Europe): insights from the geological setting of the lherzolite bodies[END_REF][START_REF] Teixell | The crustal evolution of the west-central Pyrenees revisited: inferences from a new kinematic scenario[END_REF]. This sedimentary succession is intimately associated with peridotite (lherzolite) bodies and scarse Palaeozoic basement rocks, most of them located at the base of the Mesozoic sequence. As a whole, the Chaînons Béarnais represent remnants of the most distal part of the Iberian continental margin. Within this context, the three ridges are considered as extensional allochthons [START_REF] Jammes | Tectono-sedimentary evolution related to extreme crustal thinning ahead of a propagating ocean; example of the western Pyrenees[END_REF][START_REF] Lagabrielle | Mantle exhumation, crustal denudation, and gravity tectonics during Cretaceous rifting in the Pyrenean realm (SW Europe): insights from the geological setting of the lherzolite bodies[END_REF][START_REF] Masini | The tectono-sedimentary evolution of a hyper-extended rift basin: the example of the Arzacq-Mauléon rift system (Western Pyrenees, SW France)[END_REF][START_REF] Teixell | The crustal evolution of the west-central Pyrenees revisited: inferences from a new kinematic scenario[END_REF] over hyper-thinned continental crust as well as exhumed mantle. ascribed to be part of the Paleozoic basement [START_REF] Casteras | Carte géologique de la France 1/50,000[END_REF]Fig. 11.4).

Because of the very scarse outcrop conditions and the lack of a detailed geological map (mapping was beyond the purpose of the Thesis), in the following the focus will be on the main features clearly related to fluid circulation that affected the study area. For a more detailed description of the stratigraphic succession, the reader can refer to Notices Explicative de la Carte Géologique au 1/50.000 Feuille Lourdes [START_REF] Casteras | Carte géologique de la France 1/50,000[END_REF]. In this section, some interesting "windows" where fluid-related, post-depositional modifications affected the host rocks are well recognizable will be described. In particular, the most interesting fluid-related products were found associated to the lithostratigraphic units: Ophites, I 1 , I 2-3 , J 7-3 and J 8 [START_REF] Casteras | Carte géologique de la France 1/50,000[END_REF]) that, from now on, will be defined as Sedimentary Breccia Unit (Ophites, I 1 and I 3-2 ), Black Dolomites Unit (J 7-3 ) and Black Limestones Unit (J 8 ). Within the latter, [START_REF] Casteras | Carte géologique de la France 1/50,000[END_REF] distinguished one sub-unit (J 8m ), which refers to not better defined "metamorphic limestones" possibly making part of the Hercynian basement.

For each Unit, a stratigraphic and petrographic description will be given as well as a first order interpretation based also on analytical data (stable isotopes and fluid inclusions), when available. To conclude, an overall summary of the evolution of the area will be proposed. 12. Black Dolomites Unit (Callovian-Oxfordian)

STRATIGRAPHY AND PETROGRAPHY

This lithostratigraphic unit is composed of coarse to very coarse crystalline, pyrite-rich, black dolostones that never show a well-defined bedding and can reach, in the Feuille Lourdes (Castéras et al., 1970), a maximun thickness of 400m. On the weathered surface they show a karstic appearance and locally alternate with dolomitic limestones. These dolomites were not dated by their fossil content but only relatively to the over-and underlying sediments. So that, they were assigned to the Callovian-Oxfordian (Castéras et al., 1970).

In the study area, the Black Dolomites Unit is characterized by a coarsely Where the deformation is stronger, mosaic to rubble breccias (sensu [START_REF] Morrow | Descriptive field classification of sedimentary and diagenetic breccias fabrics in carbonate rocks[END_REF] affect the Black Dolomites Unit. These breccias were never observed in place but only as clasts within the Genie Longue torrent. Nonetheless, they are clearly constituted by the previously described black dolostones. Indeed, they are made of millimeter-to some centimeter-large, coarsely crystalline dolomite clasts, angular in shape and dull in CL. Within some clasts, ooids are still recognizable (Fig. 12.2). The clasts themselves show different degree of internal deformation: from almost preserved dolostones to strongly fractured and brecciated clasts cemented by bright orange luminescing dolomite. The mosaic to rubble breccias (Fig. 12.3) are cemented by two generations of saddle dolomite. The first, almost isopachous and up to 500 µm thick, shows CL zoning from bright to dark orange. Commonly, in between the clasts and the first dolomite cement, a geopetally filling, dolomitized fine-grained sediment occurs.

The second cement, finally, is still dolomite and is characterized by a bright, poorly zoned, orange luminescence (Fig. 12.3 b-f).

In few cases, a third cement made of dark orange/brown luminescing calcite occurs (Fig. 12.3 g-h). It is not always easy to define the timing of precipitation of this calcite cement since it occurs both between the two dolomite cements or before the first one. In any case, it occurs as calcite spar with crystals size ranging between tens to hundreds of microns. Locally, some fractures are filled with the first dolomite cement fringing the cavitiy walls followed by a yellow to dark brown zoned calcite cement.

The whole breccias (e.g. clasts and cements) are then crosscut by several randomly oriented dolomite veins that are recognizable only by CL observation.

They occur as tens to hundreds microns wide fractures filled with an almost homogeneous orange dolomite cement. Lastly, tens of microns wide calcite veins, with a dark brown to dull luminescence in CL, are present. One main style of dolomitization was detected within the Black Dolomites Unit.

The rock mass was widely dolomitized leading to the present-day coarse crystalline texture (Fig. 12.1). Such recrystallization, and the related increase of crystal size, asks for the presence of (high-T?) fluids as driving process. This hypothesis may also be supported by the negative O isotopes values (Fig. 12.5). As shown in the Feuille Lourdes [START_REF] Casteras | Carte géologique de la France 1/50,000[END_REF], the Black Limestones Unit in the study area is supposed to be deformed by a main syncline structure.

Breccias

In its inner part (Fig. 11.4), "metamorphosed limestones" were reported by [START_REF] Casteras | Carte géologique de la France 1/50,000[END_REF], which represent the main focus of the following description. Indeed, for about 2 km from the dam of Peyras towards the top of the Genie Longue torrent, the Black Limestones Unit has been described as recrystallized white, scapolite-rich marbles that were also the target of exploitation (two abandoned quarries are present in the area). With the present work, it will be clarified that the white marbles represent only one of the many different post-depositional modifications experienced by the Black Limestones Unit. Two are the main sites where it was possible to investigate the post-depositional modification affecting the Black Limestones Unit within the "metamorphosed area". The first, in its northern part, comprises two quarries located along the Genie Longue river (Quarries area). The second, south of the quarries and developing only for some tens of meters along the riverbed, is characterized by new and different types of rocks (Riverbed area). Locally, a dolomite rim, zoned in CL, fringes the clasts and is always coupled with a hundreds m thick rim of dolomitized fine-grained sediment. Both the clasts and the calcite cement show a homogeneous orange CL luminescence. The former is characterized by a poorly zoned orange luminescence whereas the latter shows well defined, yellow to brownish, concentric zoning (Fig. 13.5 e-f). 3) The third type is a polimict breccia made of larger clasts, cm to dm in size, bluish on the weathered surface composed of micro-crystalline limestones, and smaller, mm to cm in size, ones made of fine grained dolostones (Fig. 13.6 a-b).

The clasts are within a complex cement composed of i) coarse grained dolomite crystals (up to 500 µm) with dark orange, poorly zoned, luminescence, and ii) yellowish to dark orange luminescing sparry calcite (300 µm; Fig. 13.6 c-d). About ten meters from the three types of hydrofracturing breccias, the second main type of breccia crops out. It is a carbonate sedimentary breccia presently slightly to strongly deformed by compaction and shearing (Fig. 13.7 a-b). The mm-large clasts, made of crystalline dolomite (with veins that stop at the edge of the clasts) within a micritic matrix, show stylolitic contacts due to compaction and/or tectonic deformation (Fig. 13.7 c-d-e-f). Pyrite, often oxidized, is also quite abundant. Both the clasts and matrix are orange in CL with the clasts slightly brighter than the matrix. In the latter, some detrital dolomite crystals occur surrounded by an overgrowth marked by CL orange luminescence. Lastly, cm-large calcite and dolomite veins cut through the whole rock mass.

Fluid inclusion microthermometry

More than 40 primary fluid inclusions were measured on calcite and dolomite cements of the hydrofracturing breccias type 1 and 3, respectively (Fig. 13.8 and ANNEX H). As shown in Fig. 13.9, homogenization temperatures of dolomite cement range from 152°C to 203°C with the highest frequency between 180°C and 190°C. The calcite cement shows higher values from 227°C to 249°C with the highest frequency between 240°C and 250°C. Nonetheless, the forming process seems to be the same. Indeed, the shape of the clasts and their spatial organization within the cements ask for overpressured fluids disrupting the former host rocks. The fact that the clasts are not made of the only Black Limestones Unit but also of the stratigraphically underlying Black Dolomites Unit, suggests that a conspicuous vertical displacement through the sedimentary column took place.

The contact between the hydraulic and sedimentary breccias was never observed. The sedimentary breccias (Fig. 13.6), nonetheless, on the basis of their deformed texture could represent a shear zone/tectonic contact.

In any case, the two main types of breccias found in the Quarries area are younger in age than both the encasing Black Limestones and Black Dolomites Units as demonstrated by the composition of the clasts of breccia type 2 and 3.

Hence, a post-Kimmeridgian age is suggested.

Calcite and dolomite cements

The

Veins

Veins are not widespread in the Quarries area and mainly affect the sedimentary breccias. The definition of the exact timing of their formation is so far not clear.

13.5 THE RIVERBED SITE

Stratigraphy and petrography

In the northern part of the study area within the talweg of the Genie Longue torrent and only for some tens of meters, strongly recrystallized carbonate rocks crop out. In the Feuille Lourdes (Castéras et al., 1970), they were included within the sub-unit "metamorphosed limestones". In the few spots where they were observed, they look discordant, by variable angles, with respect the surrounding lithotypes (Black Limestones Unit and their modifications). The stratigraphic or tectonic contact with these sediments has never been observed.

These rocks show a regular and planar foliation where dm-to m-large whitish and bluish layers alternate each other (Fig. 13.10 a). Whitish layers are composed of finely crystalline dolomite with some scattered authigenic quartz crystals (up to 400 m large) that poikilotopikally includes the carbonate matrix.

Sulphide and opaque minerals also occur (from few m to tens of m). Fine grained quartz (detrital?) is also present between the dolomite crystals. Under cathodoluminescence and excluding the non-luminescent quartz, the rock appears with a homogeneous orange colour. The bluish layers are still made of fine grained dolomite in which coarser stretched and parallel to the bedding, policrystalline porphyroclasts made of dolomite crystals, up to 500 m large, exist (Fig. 13.10 b-c-d). Quartz is still present both in the porphyroclasts and in the matrix (Fig. 13.10 g-h). Some relicts of possible former scapolite [START_REF] Casteras | Carte géologique de la France 1/50,000[END_REF], 500 m large and presently completely replaced by fine grained aggregates of K-rich alumo-silicates, occur (Fig. 13.10 e-f). Such porphyroblasts include poikilotopically the carbonate matrix. The regular and planar foliation, the fine-grained matrix with coarser grained porphyroclasts (percentage of matrix compared to porphyroclasts of 50-90%)

and the monomineralic composition of the layered rocks found within the Genie Longue torrent, allow to define these rocks as carbonate mylonites [START_REF] Burlini | Fabric and seismic properties of Carrara marble mylonite[END_REF][START_REF] Sibson | Fault rocks and fault mechanisms[END_REF][START_REF] Scholz | The brittle-plastic transition and the depth of seismic faulting[END_REF][START_REF] Schmid | Towards a genetic classification of fault rocks: geological usage and tectonophysical implications[END_REF]Fig. 13.9).

The present-day, fine-grained texture is suggested to derive from a more coarsegrained parent rock in response to intra-crystalline deformation and recrystallization. Finding of marbles (Fig. 13.11) in the close vicinity of the mylonites may support such hypothesis. The porphyroclasts could then represent resistant relics of a more coarse-grained original fabric of former rock. The presence of quartz and former scapolite (Fig. 13.10 e-f-g-h) that poikilotopikally grew over the carbonate matrix suggests the involvement of fluids after the "mylonitization" process that affected the precursor rock.

14. Sedimentary Breccias Unit

STRATIGRAPHY AND PETROGRAPHY

Based on the Feuille Lourdes [START_REF] Casteras | Carte géologique de la France 1/50,000[END_REF], along the southern ridge of the study area as well as its northeastern part, evaporites, ophites and sedimentary breccias widely crop out. The ophites and the evaporites are assigned to the Keuper, whereas the breccias are described by the authors as Rhaetian to Sinemurian in age.

In this area three types of sedimentary breccias have benn distinguished: ophitic monomictic, polimictic and carbonate monomictic. The Ophite unit, conversely to what has been proposed in the Feuille Lourdes [START_REF] Casteras | Carte géologique de la France 1/50,000[END_REF], occurs as monomict clast-supported sedimentary breccia, with an overall thickness of about 20 meters. It is constituted exclusively of almost rounded ophitic clasts ranging in size from some centimeters to around a meter (Fig. 14.1 a). Laterally, the ophitic breccia passes to clast-to matrix-supported, polimict sedimentary breccias mainly composed of carbonate clasts, and subordinately ophitic clasts.

On average, the clasts are mm-to cm-large, even if some larger, mainly ophitic clasts can be up to some decimeter (Fig.

Fluid-related products

In terms of fluid circulation, the features described for the three types of breccias allow to distinguish at least three main stages in the fluid history of the studied area.

1) A first fluid flow event took place within the sedimentary column before its erosion and re-deposition as documented by the dolomite veins preserved within the clasts (Fig. 14.2 a-d). Apparently, such fluid flow did not lead to recrystallization of the host rocks but occurred only through discrete fractures in the rock mass. Nonetheless, some portions of the sedimentary sequence underwent pervasive recrystallization as the occurrence of coarse-grained Black Dolomites Unit clasts records (Fig. 14.2 e-f).

2) The second stage occurred after the deposition of the breccias. It is documented by the formation of authigenic minerals (quartz, albite and sulphides) that grew over both the matrix and the clasts of the breccias (Fig. 14.2 g-h and Fig. 14.3 d-f). Such mechanism suggests that the breccias were not completely lithified insofar allowing a diffuse circulation of fluids.

3) The elongated calcite crystals within the pressure shadows (Fig. where dolomite is forming (0 to +4‰; [START_REF] Tucker | Carbonate sedimentology[END_REF][START_REF] Meister | Dolomite formation in the shallow seas of the Alpine Triassic[END_REF]. Comparing this dataset with the one described in the Alpine areas (Fig. 10.2), it looks evident that the overall trend is completely similar. The replacement minerals, which inherited the former δ 18 O signature of the precursor rock, are always less depleted than the void filling ones cementing veins and breccias, which, on the contrary, are pure new forming phases.

Calculations of the isotopic composition of fluids (for the only Black Limestones Unit) responsible for dolomite and calcite precipitation, made by applying the equation of [START_REF] Horita | Oxygen and carbon isotope fractionation in the system dolomite-water-CO 2 to elevated temperatures[END_REF] and [START_REF] Anderson | Stable isotopes of oxygen and carbon and their application to sedimentologic and paleoenvironmental problems[END_REF] respectively, provide O isotope values for fluids markedly positive (+9 ‰ SMOW for dolomite to about +12 ‰ SMOW for calcite). Such positive signature may be related to different processes such as evaporative enrichment (e.g. McKenzie, 1981), clay mineral diagenesis [START_REF] Dählmann | Fluid-sediment interactions at Eastern Mediterranean mud volcanoes: a stable isotope study from ODP Leg 160[END_REF][START_REF] Hensen | Sources of mud volcano fluids in the Gulf of Cadizindications for hydrothermal imprint[END_REF], and to the interaction with silicate minerals of siliciclastic and crystalline rocks [START_REF] Clayton | The origin of saline formation waters: Isotopic composition[END_REF][START_REF] Land | The origin and evolution of saline formation waters, Lower Cretaceous carbonates, south-central Texas and southern New Mexico[END_REF][START_REF] Hitchon | Regional subsurface hydrogeology, Peace River area, Alberta and British Columbia[END_REF][START_REF] Haeri-Ardakani | Fracture mineralization and fluid flow evolution: an example from Ordovician-Devonian carbonates, southwestern Ontario, Canada[END_REF]. Taking into account the model of [START_REF] Jammes | Tectono-sedimentary evolution related to extreme crustal thinning ahead of a propagating ocean; example of the western Pyrenees[END_REF] where the Chaînons Béarnais were considered to be extensional allochthons in a hyper-extended domain, the only reasonable source of fluid feeding the hydrothermal system is seawater. As for the Alpine areas, also in this case an interaction with basement rocks could be addressed as the main reason to explain such positive signature. In this case, moreover, the occurrence of Keuper evaporites at the base of the Mesozoic sedimentary column likely provided a contribution in determining the positive isotopic signature.

The mylonites and marbles

The

Sedimentary Breccias Formation

No geochemical data are available for the Sedimentary Breccias Unit. However, petrography and cathodoluminescence investigations shed light on some important aspects related to fluids circulation. Apart from authigenic quartz and sulphides, the widespread occurrence of authigenic albite is noteworthy. Albite is quite common in high-grade diagenetic to low-grade metamorphic carbonate rocks [START_REF] Spötl | Authigenic albite in carbonate rocks -a tracer fro deep-burial brine migration?[END_REF]. Euhedral habit, chemical composition and crystallographic properties are the major lines of evidence that allow to distinguish detrital albite from the authigenic one. Indeed, the latter is almost compositionally pure [START_REF] Kastner | Authigenic feldspars in carbonate rocks[END_REF][START_REF] Spötl | Authigenic albite in carbonate rocks -a tracer fro deep-burial brine migration?[END_REF] and commonly shows the peculiar Roc-Tourné twinning, which is not present in magmatic or metamorphic albites [START_REF] Kastner | Authigenic feldspars in carbonate rocks[END_REF]. Furthermore, it is characterized by the absence of CL luminescence due to its chemical purity [START_REF] Richter | Cathodoluminescence of authigenic albite[END_REF].

The carbonate grains poikilotopikally included within the authigenic albites, represent remnants of the host rock and provide one more distinctive feature with respect to the magmatic ones [START_REF] Kastner | Authigenic feldspars in carbonate rocks[END_REF]. Albite crystals are present both in the carbonate clasts and in the carbonate matrix, and in some cases they grow across the clast-matrix boundary. This provides a further evidence of a post-depositional growth of albite crystals. Concerning the mechanism of authigenesis in carbonate rocks, two different models have been proposed: the first is based on isochemical transformation of the host rock [START_REF] Kastner | Low temperature feldspars in sedimentary rocks[END_REF], whereas the second takes into account metasomatic transformation due to migration of brines [START_REF] Kastner | Low temperature feldspars in sedimentary rocks[END_REF][START_REF] Spötl | Authigenic albite in carbonate rocks -a tracer fro deep-burial brine migration?[END_REF]. In the eastern Pyrenees, albitites are known as a product of fluid/rock interactions occurring during a syn-extensional metasomatic event dated at about 100 Ma [START_REF] Boulvais | Cretaceous albitization and dequartzification of Hercynian peraluminous granite in the Salvezines Massif (French Pyrenees)[END_REF][START_REF] Fallourd | In situ LA-ICP-MS U-Pb titanite dating of Na-Ca metasomatism in orogenic belts: the North Pyrenean example[END_REF][START_REF] Poujol | In-situ LA-ICP-MS U-Th-Pb dating of metasomatic fluid circulation: Evidence of regional-scale albitization in the Pyrenees[END_REF]. The geographical distribution of albitites closely matches that of talc/chlorite mineralizations related to a hydrothermal event of regional extent during mid-Cretaceous time [START_REF] Schärer | Formation of the Trimouns talc-chlorite deposit (Pyrenees) from persistent hydrothermal activity between 112 and 97 Ma[END_REF]. Interestingly, also in the study area albite occurrences are stratigraphically close to the Mg-rich alumo-silicates ("sandwiches") affecting the Black Limestones Unit, which are likely to be talc and chlorite. Such ore deposits have been attributed by [START_REF] Boulvais | Carbonate alteration associated with talc-chlorite mineralization in the eastern Pyrenees, with emphasis on the St. Barthelemy Massif[END_REF] as due to seawater modified by chemical exchange with crustal rocks. The albitizing fluids are considered to be related to hot (200-300 °C) Na-and Si-rich fluids with high salinity [START_REF] Spötl | Authigenic albite in carbonate rocks -a tracer fro deep-burial brine migration?[END_REF][START_REF] Rais | distribution of authigenic albites in a limestone succession of the Helvetic Domain, eastern Switzerland[END_REF]. This high salinity is supposed to be referable to a primary magmatic feature [START_REF] Hall | Hydrothermal alteration associated with the Iron Hat iron skarn deposit, eastern Mojave Desert, San Bernardino, California[END_REF][START_REF] Aslund | Metasomatism of the Revenue Granite and aureole rocks, Mt Isa Inlier, Queensland: syndeformational fluid flow and fluid-rock interaction[END_REF], to an interaction of aqueous metamorphic/magmatic fluids with evaporite levels [START_REF] Oliver | Hydrothermal history of the Mary Kathleen Fold Belt, Mt Isa Block, Queensland[END_REF][START_REF] Barton | Evaporitic-source model for igneousrelated Fe oxide-(REE-Cu-Au-U) mineralization[END_REF], or should represent a primary characteristic of surface-derived brines [START_REF] Mclelland | Hydrothermal alteration of late-to post-tectonic Lyon Mountain Granitic Gneiss, AdirondackMountains, New York: Origin of quartz-sillimanite segregations, quartz-albite lithologies, and associated Kiruna-type low-Ti Feoxide deposits[END_REF]. The evolution of the Pyrenean hyper-extended rift system is characterized by different aborted rifting events in the Triassic and Upper Jurassic time before the major Cretaceous crustal thinning stage [START_REF] Puigdefàbregas | Tecto-sedimentary cycles and depositional sequences of the Mesozoic and Tertiary from the Pyrenees[END_REF]Vergés and Garcia-Senz, 2001). Such rifting events were obviously associated with tectonic activity, which exposed different rocks to erosional processes at different times. The Sedimentary Breccias Unit could therefore be interpreted as the sedimentary product of erosion and re-sedimentation of the Triassic-Jurassic sedimentary sequence tectonically involved in the ongoing extensional events.

As already demonstrated in the Alps [START_REF] Pinto | Tracing mantle-reacted fluids in magma-poor rifted margin: The example of Alpine Tethyan rifted margin[END_REF][START_REF] Incerpi | Evidence of hydrothermal fluid flow in a hyperextended rifted margin: the case study of the Err nappe (SE Switzerland)[END_REF]this Thesis) and in the Basque Cantabrian Basin and Pyrenees (e.g., [START_REF] Lopez-Horgue | Structurally controlled hydrothermal dolomites in Albian carbonates of the Ason valley, Basque Cantabrian Basin, Northern Spain[END_REF][START_REF] Salardon | Interactions between tectonics and fluid circulations in an inverted hyper-extended basin: Example of mesozoic carbonate rocks of the western North Pyrenean Zone (Chaînons Béarnais, France)[END_REF], every tectonic stage that characterizes the extensional evolution of hyper-extended domains is related to strong fluid circulation. Such circulation took place over a long time and a large area and affected the whole sedimentary column (e.g. pre-, syn-and post-rift sediments).

In this frame, the fluid-related products described in the Sedimentary Breccias

Unit can be the proof for a long-lasting fluid activity that took place in the sedimentary column before and after its erosion. For such reason, the breccias cannot be considered as part of the pre-rift sequence. Based on the presented observations, this Unit is most likely related to erosional episodes connected with the mid-Cretaceous extensional tectonic. Such hypothesis is also supported by the post-depositional albitization affecting the breccias, which was dated as mid-Cretaceous [START_REF] Boulvais | Cretaceous albitization and dequartzification of Hercynian peraluminous granite in the Salvezines Massif (French Pyrenees)[END_REF][START_REF] Fallourd | In situ LA-ICP-MS U-Pb titanite dating of Na-Ca metasomatism in orogenic belts: the North Pyrenean example[END_REF][START_REF] Poujol | In-situ LA-ICP-MS U-Th-Pb dating of metasomatic fluid circulation: Evidence of regional-scale albitization in the Pyrenees[END_REF].

EVOLUTIONARY MODEL

Based on the observations and related interpretations exposed in the previous sections, the following evolutionary model for the study area can be proposed (Fig. 15.1).

1) Carbonate-rich stage:

-First event of circulation of (hot) fluids to which the pervasive and fabric-destructive dolomitization of the Black Dolomites Unit is related.

-Second event of circulation of dolomite-rich fluids and formation of crackle, mosaic and rubble breccias within the Black Dolomites Unit.

These fluids, strongly overpressured, could also be possibly responsible 2015) and the occurrence of serpentinized lherzolites in the Chaînons Béarnais [START_REF] Lagabrielle | Mantle exhumation, crustal denudation, and gravity tectonics during Cretaceous rifting in the Pyrenean realm (SW Europe): insights from the geological setting of the lherzolite bodies[END_REF], the source of Mg enabling such dolomitization could then be related to serpentinizing processes that took place in mid-Cretaceous time during mantle exhumation [START_REF] Masini | The tectono-sedimentary evolution of a hyper-extended rift basin: the example of the Arzacq-Mauléon rift system (Western Pyrenees, SW France)[END_REF]. The tectonic activity, to which the fluid circulation is strictly connected, was also the trigger responsible for the erosion of the sedimentary column and the subsequent deposition of the Sedimentary Breccias Unit.

2) Na-and SiO 2 -rich stage:

-First event of circulation of Na-and Si-rich fluids as poikilotopic growth of quartz and albite over the matrix and clasts of the Sedimentary Breccias Unit attest. The occurrence of authigenic sulphides demonstrates that the chemistry of the circulating fluids was even more complex.

In the Fuorcla Cotschna area (Adriatic distal margin), rare authigenic albite has been found within veins cutting through the extensional allochthon. It was not possible to date precisely that stage of fracturation so the authigenesis could have occurred both prior or after the BBF (i.e. affecting only the pre-rift rocks of the allochthon or also the syn-rift sequence). Since the Sedimentary Breccias Unit that can be tentatively defined as syn-rift sediments, is affected by diffuse albitization and knowing that such process in the eastern Pyrenees has been described in relation to mid-Cretaceous metasomatic event, it can be assumed that also in the Chaînons Béarnais domain it took place during the hyper-extension phases.

One more important stage characterized the evolution of the study area even if it is very difficult to place in the frame proposed so far: the marble and mylonite To answer all these questions and to better constrain the evolution of the whole area more analyses are required as well as more fieldwork. Field activity should allow to better understand the tectono-stratigraphic architecture of the area by the re-definition of the lithostratigraphy and highlighting the reciprocal relationships among all the different "new and old" units. U-Pb dating will be fundamental in order to constrain chronologically all the described evolutionary steps as well as Sr isotopes in order to define the amount of interaction with crustal basement rocks and/or evaporites. Because of the abundance of mantlerelated rocks in close vicinity to the study area and the Chaînons Béarnais in general, He isotopes will eventually permit to comprehend if mantle-derived fluids played a role within the here presented hydrothermal system as suggested by [START_REF] Salardon | Interactions between tectonics and fluid circulations in an inverted hyper-extended basin: Example of mesozoic carbonate rocks of the western North Pyrenean Zone (Chaînons Béarnais, France)[END_REF]. 16.2 THE RESULTS

The Adriatic rifted margin

The main focus of the Thesis is the Adriatic distal margin in its central and outer parts. To get a more complete understanding of the system, observations and analyses were also performed in the proximal margin and the inner distal margin.

The distal margin

Four sites were chosen within the distal margin. -Fracturation events and formation of quartz veins throughout the whole syn-rift sedimentary sequence and within the extensional allochthons.

-Formation of silica-rich septarian-like concretions and Fe-Mn oxides coating of clasts of calciruditic beds in the uppermost part of the syn-rift sequence.

-Deposition of post-rift Radiolarian Cherts.

-Persistence of fluid activity and subsequent formation of syndepositional chert nodules.

-Further silicification and dolomitization processes within the matrix of calciruditic beds in the basal part of the Radiolarian Cherts. for calcite cement of breccia type 1 suggest a hydrothermal fluid circulation.

The Riverbed area

In close proximity to the breccias, strongly recrystallized carbonate rocks occur.

Because of their strongly foliated texture these rocks are considered as mylonites. Some relicts of possible former scapolite are presently replaced by fine-grained aggregates of K-rich alumo-silicates. Authigenic quartz is also present. The rock is completely dolomitized. In close vicinity with the mylonites, coarse crystaline dolomite marbles were found. These marbles could represent the protolith of the mylonites as demonstrated by the porphyroclast within the mylonites as well as the nearly identical O and C isotopic signature (δ 13 C between 1 and 3‰ VPDB; δ 18 O about -7‰ VPDB).

The Sedimentary Breccias Unit

Within this Unit two different lithostratigraphic units that in the literature were assigned to the Rhaetian-Sinemurian, were gathered together. By the present work, it has been possible to propose a re-interpretation of the age of the unit. It is made of three types of sedimentary breccias that are: 1) monomict ophitic breccia, 2) polimict carbonate-ophitic breccia, and 3) polimict carbonate breccia. 2) Na-and SiO 2 -rich stage is documented by diffuse authigenesis of quartz and albite in the Sedimentary Breccias Unit. Moreover, the occurrence of sulphides makes the chemistry of the fluid even more complex.

In summary, the main result of this thesis is to confirm the fundamental role of faults, and the associated fracture zones, as plumbing structures of the hydrothermal system. However, the style of faulting seems to importantly control the chemistry of fluids and therefore the composition of the diagenetic products that the circulation of fluids generates within the highest part of the hydrothermal system, i.e. the pre-tectonic sedimentary rocks and the syntectonic sediments. In the early rifting stage, tectonically dominated by normal faults, fluids are seawaters that penetrate at some kilometer depths within basement rocks where they are heated, insofar acquiring a dolomitization potential over carbonate sediments that are met along the upward flowing part of the hydrothermal cell. In the second stage of the rifting process, when faults merge at depth into detachment faults, the volume of cataclastic crustal rocks is much greater and consequently much more massive is the fluid-rock interaction with basement rocks which mainly involves feldspar alteration and delivers silica to the fluids. In the absence of solid evidence about the direct involvement of mantle rocks and/or fluids in the hydrothermal circulation system, this mechanism appears as the more likely to explain the marked change in space and time of the diagenetic products from carbonate-rich to quartz-rich along extensional continental margin transects.

OPEN QUESTIONS AND FUTURE PERSPECTIVE

The multidisciplinary approach adopted in this project allowed to understand how the fluid circulation during continental extension is strong and pervasive.

Many lines of evidence point to the same conclusion: hydrothermal fluids played a key role in the syn-to post-depositional modification of the pre-to post-rift sedimentary rocks constituting the margins. Even if a quite detailed evolutionary model has been proposed, some open questions still remain unsolved for both the Adriatic and Iberian margin.

Adriatic proximal margin:

-How far from the fault surface is the fluid flow developed?

-Is the fluid circulation affecting only the footwall or also the Lower Jurassic turbiditic deposits of the hanging wall?

-Is the second diagenetic stage really not recorded?

Adriatic distal margin:

-Is the entire supra-detachment basin affected by the same processes described in this Thesis?

-Do they depend on the thickness of the sedimentary succession?

-Are the post-tectonic sediments really post-tectonic?

Pyrenean hyper-extended rift system:

-What is the absolute age (U-Pb dating) of the hydrothermal minerals affecting the pre-and syn-rift sediments?

-Did the fluids interact with the continental basement (Sr isotopes)?

-Are mantle-related fluids involved in the hydrothermal system (He isotopes)

-What is the geochemical signal recorded within the sediments (main, trace and rare earth elements)?

-What is the relation between the marbles-mylonites and the other Units?

As a future perspective, it would be very interesting to compare the here presented dataset to the present-day hyper-extended margins. One of the targets could be the present-day Iberia continental margin since it shows similar tectono-stratigraphic features to those of the Adriatic margin. Furthermore, not only the overall architecture makes the comparison of great interest. Indeed, in the ODP Leg 103 [START_REF] Boillot | Les poudingues de Mendibelza: dépôs de cônes sous-marins du rift Albien des Pyrénées[END_REF]

  Piz Alv (SE Switzerland, Err nappe -former inner distal Adriatic margin) -Piz Val Lunga and Fuorcla Cotschna (SE Switzerland, Err nappeformer central distal Adriatic margin) -Mal Pass (SE Switzerland, Err nappe -former outer Adriatic distal margin)

Fig

  Fig. 3.1 -Tectonic map of the Alps modified after Schmid et al. (2004) and Mohn et al. (2010) with the location of study area (red square).

Fig

  Fig. 3.2 -3D block diagram of the present-day Alpine architecture of SE-Switzerland and N-Italy showing the Austroalpine and Penninic nappe stack (modified after Mohn et al., 2010;

Fig. 3

 3 Fig. 3.3 -Cartoon schematically showing the evolution of the Adriatic continental margin from the first rifting stages in Late Triassic-early Lower Jurassic to the exhumation of mantle-related rocks in Middle Jurassic time. The main stratigraphic record here represented varies in facies and thickness from the proximal margin to the distal margin and mantle exhumed areas. Location of key cross-sections from these areas, shown in figures 3.4, 3.5 and 3.6, are here highlighted as well as 10.3 and 10.4 which refer to fluid pathways within the proximal and distal margin. The section (d)shows also the distribution of the main paleogeographic domains of the margin (red terms) and refers to the major Alpine units (black terms). OCT: Ocean-Continent Transition; Err det.: Err detachment system; Bernina det.: Bernina detachment system. Modified after[START_REF] Mohn | Necking of continental crust in magma-poor rifted margins: Evidence from the fossil Alpine Tethys margins[END_REF].

Fig. 3

 3 Fig. 3.5 -Schematic representation of the architecture of the distal margin preserved in the Austroalpine nappes (modified after Mohn et al. 2011).

  DISTAL MARGIN: THE ERR NAPPE3.3.1 The present-day Alpine architectureLike in the reminder of the Austroalpine units, the Err domain was overprinted by deformation phases, which are classically referred to as D1 to D5 phases (e.g.[START_REF] Froitzheim | Repeated change from crustal shortening to orogenparallel extension in the Austroalpine units of Graubünden[END_REF] Fig. 3.7). The major D1 structure in the study area is the thrust separating the Julier half-klippe, belonging to the Bernina nappe, from the underlying Err nappe. Second order D1 thrusts can also be found in the Err nappe subdividing it into an Upper, Middle and Lower Err unit. The Upper Err unit is only discontinuously preserved as klippen in post-thrust (D3) synclines (e.g. Padella-Schlattain and Piz Bleis Marscha;Manatschal and Nieverglet 1997). The middle Err unit represents the main body of the Err nappe. The Lower Err unit can be observed in the so-called Jenatsch tectonic window and also along the frontal contact of the Err nappe with the Platta nappe to the west.

Fig. 3

 3 Fig. 3.7 -Geological map of the Err nappe (from Masini et al. 2012).

Fig

  Fig. 3.8 -Schematic profile across a Jurassic detachment fault in the Err nappe showing the main lithologies accompanying the extensional detachment fault. The thickness of the lithologies in the profile are average values, since the real thickness changes considerably along

Fig. 3

 3 Fig. 3.9 -Cm-to dm-large dolomite clasts within the black gouge, which marks the top of the detachment fault system at (a) Piz Val Lunga and (b) Fuorcla Cotschna areas (Err nappe).

  distinguished these syn-rift sediments in two formations, the Bardella and Saluver Fms. The subdivision was mainly based on their composition: the Bardella Fm. is made of reworked Triassic to Early Jurassic carbonates (pre-rift rocks > 185 Ma) whereas the Saluver Fm. includes mainly basement-derived material. The observation that the Bardella Fm. is interleaved with the Saluver Fm. shows that the two sedimentary systems coexisted. It implies that during the evolution of the basin, at least two clastic sedimentary sources where available, one resedimenting the pre-rift Mesozoic platform carbonates and the other reworking detachment fault rocks and tectonized basement (Fig. 3.10). Finger (1978) further subdivided the Saluver Fm. into a coarse-grained Saluver A sub-formation at the base, an intermediate Saluver B and a fine-grained Saluver C at the top. The author defined three different facies tracts, namely the basal, the intermediate and the top tracts corresponding approximately to the Bardella and Saluver A Fm. (basal), Saluver B (intermediate) and Saluver C and post-rift deposits (top).3.3.3 The major time lines in the Adriatic distal marginBecause of the poly-phase nature of rifting along the whole margin, a new subdivision of the sediments filling the supra-detachment basins (sensu[START_REF] Masini | The tectono-sedimentary evolution of a supra-detachment rift basin at a deep-water magma-poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland[END_REF]) is required in order to avoid misunderstanding about the interpretation of the concept of pre-, syn-and post-rift sediments.[START_REF] Masini | The tectono-sedimentary evolution of a supra-detachment rift basin at a deep-water magma-poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland[END_REF], therefore, tried to link sedimentation to tectonic activity of the detachment system. In this context, they highlighted the importance to define two major time horizons (Fig.3.10): the Top of Agnelli Formation (TAF) and the base of the Radiolarian Cherts (RC) to better constraints the timing of the tectono-sedimentary history of the distal margin.

Fig. 3 .

 3 Fig. 3.10 -(a) Stratigraphic log through a supra-detachment basin in the Adriatic distal margin showing the general architecture of the pre-, syn-and post-rift sediments. (b) Evolution of the Samedan supra-detachment basin from the onset to the cessation of the tectonic activity within the Adriatic distal margin. Within this domain, the Agnelli Fm. is represented by a condensed horizon. (a) and (b) modified after Masini et al.

  [START_REF] Masini | The tectono-sedimentary evolution of a supra-detachment rift basin at a deep-water magma-poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland[END_REF] used the RC as a time marker indicating the age of breakup within the continent, which then separates syn-rift from post-rift sequences. The definition of these two time lines enabled the authors to define the sedimentary sequence from the onset of detachment faulting until the emplacement of MORB over exhumed mantle. This depositional interval corresponds to a time range between Pliensbachian (about 185 Ma) and Bathonian (about 165 Ma), giving the maximum duration during which detachment systems may have been active in the distal margin and adjacent OCT. 3.4 THE ADRIATIC OCEAN-CONTINENT TRANSITION: THE PLATTA NAPPE Together with the lower Austroalpine Err nappe, the Platta nappe preserves remnants of a segment of the southeastern margin of the Jurassic Piemonte-Liguria ocean. The Platta nappe, originally situated oceanwards of the Err nappe, represents the ocean-continent transition of the former Adriatic continental rifted margin (Fig. 3.11). Because of the lack of an Alpine-related high-pressure and temperature metamorphic overprint (T max never exceeded approximately 250°C,

Fig. 3 . 11 -

 311 Fig.3.11 -Section across the Platta-Err, Tasna and Chenaillet ophiolite units. The maps show the present-day position of these units in the Alps as well as their paleogeographic position in the northern Alpine Tethys basin. The Platta-Err section is modified after[START_REF] Manatschal | An ancient ocean-continent transition in the Alps: the Totalp, Err-Platta, and Malenco units in the eastern Central Alps (Graubünden and northern Italy). Eclogae Geologicae[END_REF] and the Tasna section after[START_REF] Manatschal | What is the tectono-metamorphic evolution of continental break-up: The example of the Tasna Ocean-Continent Transition[END_REF].

Fig

  Fig. 4.1 -Panoramic view of Piz Val Lunga area. The dashed line marks the extensional detachment fault separating the extensional allochthon (hangingwall) and the Albula granite (footwall).

Fig. 4

 4 Fig. 4.2 -(a) Schematic sketch, not to scale, representing the main features observed in Piz Val Lunga area. The present-day stratigraphy is upside down due to Alpine tectonics. The extensional allochthon, made up of carbonates from the Hauptdolomit Fm., actually show different textures: monomict mosaic (b) and crackle (c) breccias, which are locally crossed by polymict rubble breccias (d). (e) The base of the allochthon is characterized by clast-supported, monomict, poorly sorted breccias with subangular to subrounded clasts. Note the fracture geopetally filled with red sediment and white quartz cement. (f) Irregular dedolomitization (bluish color) affects the greiysh dolomite breccias at the base of the allochthon. (g) Partial silicification (whitish color) of the matrix of the Bardella Fm. breccias. Scales: lens cap (about 6 cm in diameter).

  fragments still fit one to another (mosaic breccias, Fig.4.2 b). Bedding and/or lamination can still be recognized, although slightly offset. These rocks are locally crossed at high angles by irregular bodies of polymict rubble breccias i.e. breccias with lithologically different clasts, which do not match(Fig. 4.2 d, Fig. 4.3 a-b;[START_REF] Morrow | Descriptive field classification of sedimentary and diagenetic breccias fabrics in carbonate rocks[END_REF]. In addition to the fenestral laminated finely-crystalline dolomites, coarsely crystalline lithotypes also occur as clasts. All these breccias are matrix-free, clast-supported and the voids among clasts are filled with a coarse, equant calcite spar that in cathodoluminescence (CL) is characterized by a clear oscillatory zoning (Fig.4.3 c). Cathodoluminescence and SEM-BSE images moreover show that the coarsely crystalline litho-types in the breccia mainly consist of sparry calcite, with a moderate to bright yellow luminescence, which selectively replaces discrete concentric zones within non-luminescent dolomite crystals (Fig.4.3 d-e). The whole rock body is crosscut by a system of calcite-filled veins mainly perpendicular to the bedding. Another type of breccia occurs as dm-thick bodies close to and parallel to the detachment fault. It is a clast-supported, monomict, poorly sorted breccia with sub-angular to subrounded clasts, which do not exceed 5-10 cm and a yellowish to reddish matrix.Clasts are composed of dolostones with variable crystal sizes (Fig.4.2 e). CL allows to distinguish clasts with very dull luminescence, from the brightly luminescing finely crystalline calcite matrix and thus to observe that clasts may be as small as a few tens of microns (Fig.4.4 a-b). The breccias are crosscut by mm-wide fissures with complex fills that include fine-grained sediment, locally laminated, and quartz cement (Fig.4.2 e; Fig.4.4 c-d). The latter forms a thin rim of crystals on the edges of the fissure subsequently filled with sediment, and plugs the remaining voids with larger crystals. In larger veins, sediment and quartz cement rims alternate with sediment geopetally lying on quartz crystal terminations (Fig.4.4 e-f). Locally all these breccias show irregular, dm-sized portions where the brecciated structure is almost completely obliterated and the rock is fully made of calcite (Fig.4.2 f). The latter, lastly, is affected by a patchy silicification, which gives rise to irregular, dm-large portions where the carbonate rock is replaced by a mosaic of fine-grained quartz. In some instances, the breccias are affected by a selective replacement of dolomite by calcite as described above, although on a lesser extent. Silicification also affects the breccias composed of clasts of the Upper Triassic Kössen and Lower Jurassic Agnelli Formations. The degree of silicification is variable on short distances (Fig.4.2 g; Fig.4.5 a-d), from nearly complete, to restricted to the matrix among clasts, or to mm-to cm-wide, irregular bands consisting of fine-grained quartz crystals or chalcedony.

Fig. 4

 4 Fig. 4.3 -(a) Hand specimen of Hauptdolomit Fm. characterized by brecciated texture. (b) Transmitted light and (c) CL images of polymict rubble breccias cemented by coarse equant calcite spar, which shows oscillatory zoning. (d) TL, (e) CL and (f) SEM-BSE images of the former coarsely, crystalline, dull luminescent dolomite, dark grey in SEM-BSE, largely replaced by sparry calcite, which shows a moderate to bright yellow CL and is light grey in SEM-BSE.

Fig. 4

 4 Fig. 4.4 -Hauptdolomit Fm. textures at the base of the allochthon: (a) TL and (b) CL images of clast-supported, monomict poorly sorted breccias with dull luminescent dolomite clasts in a finely crystalline calcite matrix. (c) TL and (d) crossed polarizers images of mm-large fissures within the clast-supported, monomict breccias with a complex fill including fine-grained sediment, locally laminated, and quartz cement. (e) TL and (f) crossed polarizer images of larger veins filled with quartz. Note thin sediment drapes geopetally overlying euhedral terminations of quartz crystals.

Fig. 4

 4 Fig. 4.5 -(a) Hand specimen and (b) outcrop scale images of partially to fully silicified syn-rift Bardella Fm. overlying the extensional allochthon. (c) TL and (d) crossed polarizer images highlighting the fine-grained silicification affecting the matrix of the Bardella Fm.

  filled with syn-to early post-rift sediments. The Fuorcla Cotschna section is under-and overlain by minor, Alpine shear zones, which may have overprinted some of the Jurassic structures. However, the observed field relations clearly indicate a pre-Alpine age for most of the structures both in the basement and in the sediments. Similar to the Piz Val Lunga area, a Jurassic detachment fault separates a granitic footwall, constituted by the Albula granite and poly-metamorphic basement rocks, from the hanging wall represented by the Bardella pre-rift extensional allochthon and syn-rift sediments onlapping the detachment with a very gentle angle (Fig. 4.6).

Fig. 4

 4 Fig. 4.6 -Schematic sketch, not to scale, of the Fuorcla Cotschna area and localization of the two transects (A and B) to which the stratigraphic description refers.

Fig. 4

 4 Fig. 4.7 -(a) Stratigraphic log, not to scale, of the Fuorcla Cotschna area based on transects A and B described in the text and shown in Fig. 4.6. (b) Massive dolostones belonging to the Hauptdolomit Fm. crossed by randomly oriented fractures filled with orange-yellow saddle dolomite. (c) Bardella Fm.: sedimentary clast-supported breccias made up of Triassic carbonate clasts. (d) Saluver A Fm.: clasts-to matrixsupported conglomerates with carbonate and basement-derived clasts in a coarse sandy matrix. Note veins within clasts stopping at clast edges. (e) Decimeter-sized block of Bardella Fm. reworked in the red sandstones of the Saluver Fm. (f) Thickbedded conglomerates constituted of carbonate and basement-derived clasts showing

Fig. 4

 4 Fig. 4.8 -(a) Massive dolostones belonging to the Hauptdolomit Fm. crossed by randomly oriented fractures filled with orange-yellow saddle dolomite. (b) TL image of finely crystalline dolostone with shrinkage pores filled with dolomite cement. (c) CL detail of a shrinkage pore filled with concentrically zoned dolomite cement showing alternaces of bright to dull reddish orange zones. (d) TL image of a sucrosic dolostone of the Hauptdolomit Fm. crossed by a coarsly crystalline saddle dolomite vein.

Fig. 4 .

 4 Fig. 4.10 -(a) Hand specimen and (b) field occurrence of septarian-like concretions in the uppermost part of Saluver Fm. (c) TL and (d) crossed polarizers images of the septarian-like fracture fill. Isopachous, botroidal chalcedony rims the cavity and is followed by a coarse mosaic of quartz crystals in the inner part of the cavities.

Fig. 4 .

 4 Fig. 4.11 -(a) Hand specimen and (b) field occurrence of polymict brownish calciruditic bed in the uppermost part of Saluver Fm. and in basal part of the Radiolarian Chert Fm. (c) TL and (d) crossed polarizers images highlighting the polymict origin of the clasts and their Fe-Mn oxide coating, and the finely silicified matrix.

Fig. 4 .

 4 Fig. 4.12 -Stable isotope data: δ 18 O versus δ 13 C cross plot for dolomite and calcite minerals from Piz Val Lunga (PVL) and Fuorcla Cotschna (FCT) areas. Values relative to VPDB standard.

  genetic relationships and represent set 1, in the calcite cement of breccias representing set 2, and in the calcite due to dedolomitization corresponding to set 3. The very small size of inclusions hindered low-temperature runs aimed at determining the fluid composition. As shown in Fig. 4.13 and ANNEX B, set 1 homogenization temperatures ranges from 88°C to 152°C with the highest frequency between 120°C and 130°C. The calcite cement (set 2) shows values from 77°C to 203°C with the highest frequency between 130°C and 140°C whereas dedolomite calcite (set 3) ranges from 96°C to 114°C.

Fig. 4 .

 4 Fig. 4.13 -Histogram of the homogenization temperatures for replacement dolomite and dolomite cement, calcite cement and de-dolomite.

Fig. 4 .

 4 Fig. 4.14 -Stratigraphic evolution of the Adriatic central distal margin as recorded at Piz Val Lunga and Fuorcla Cotschna areas. TAF: Tof of Agnelli Fm.; BBF: Base of Bardella Fm.; RC: Radiolarina Chert Fm.

Fig. 5

 5 Fig. 5.1 -(a) Photograph of Mal Pass area where the stratigraphic contact between the extensional allochthon, made of Hauptdolomit Fm., and the syn-rift sediments is preserved. The present-day overturned position is due to the Alpine deformation. (b) Schematic sketch, not to scale, representing the main features observed at Mal Pass area.

Fig. 5

 5 Fig. 5.3 -(a) Neptunian dykes and sills in the Hauptdolomit Fm. filled by brecciated, reddish dolomitized wackestones (b). (c) Hand specimen and (d) field photograph of quartz-dolomite vein cutting through the brecciated Hauptdolomit Fm.

Fig. 5

 5 Fig. 5.4 -Dolomite veins within the Hauptdolomit Fm. in the extensional allochthon. (a) Hand specimen, (b-c) field photograph, and CL images (d) of polyphae saddle dolomite filling.

Fig. 5

 5 Fig. 5.6 -(a) Stratigraphic log, not to scale, of the Mal Pass area. (b) Clast of brecciated chert nodule within the rudite beds . (c) Septarian-like concretions occurring in the marly sediments right onto the extensional allochthon. (d) Chert clast in the rudite beds. (e) Meter-scale block of Bardella Fm. embedded in turbidite deposits. (f) Stratigraphic contact between greenish mudrocks and coarse-grained sediments. (g) Detail of coarse-grained sediments.

Fig. 5

 5 Fig. 5.8 -(a) Hand specimen of laminated syn-rift sediments. (b) TL and (c) CL images highlighting the pervasive dolomitization affecting the syn-rift sediments

Fig. 5

 5 Fig. 5.9 -Stable isotope data: δ 18 O versus δ 13 C cross plot for dolomite and calcite minerals from Mal Pass (MP) area. Values relative to VPDB standard.

  5.10) and veins (Fig. 5.11; ANNEX B). Quartz cement of septarian-like concretions shows values ranging from 112°C to 190°C with highest frequency between 140°C and 150°C and in the range 150-160°C for dolomite. Veins homogenization temperatures ranges from 119°C to 205°C for the quartz cement (highest frequency between 130°C and 140°C) and from 138°C to 159°C for the saddle dolomite (highest frequency between 140°C and 150°C).

Fig. 5 .

 5 Fig. 5.10 -Histogram of the homogenization temperatures obtained by standard heating method[START_REF] Goldstein | Systematics of Fluid Inclusions in Diagenetic Minerals[END_REF] for quartz cement in septarian-like concretions in syn-tectonic sediments.

  Veins represent the most widespread feature in Mal Pass area even if they only occur within the extensional allochthon. Indeed, it is affected by a huge amount of both saddle dolomite and dolomite-quartz veins that, due to the style of vein filling (mosaic of mainly unoriented crystals), point to a precipitation in static conditions and in open fissures. Taking the neptunian dykes as a relative time marker, the occurrence of two main phases of veining, which are themselves polyphase, can be established. A first stage (set 1), preceding the formation of the dykes, is characterized by saddle dolomite cements and affects pervasively the Hauptdolomit Fm. in the extensional allochthon. The second stage (set 2), which crosscuts both the Hauptdolomit Fm. and the neptunian dykes, postdate the formation, sediment filling and brecciation of fissures. It also marks a change in the chemistry of the fluids, as the presence of quartz cements in this second generation of veins documents. The relationships between quartz and dolomite cements are not always unambiguous, implying that the two mineral phases could be co-genetic in origin. Conversely, from time to time, because of the presence of corrosion gulfs, well-defined growth zones and CL zoning it is possible to suggest that dolomite predates the precipitation of quartz. To this second stage, finally, can be related the formation of the quartz-rich septarianlike concretions and the dolomitization of the syn-rift sediments.Type 4 dolomite, as discussed above, is suggested to be related to fracturation and development of vein set 2 in the allochthon. The strong difference in behavior of the allochthon and the overlying syn-rift sediment (Saluver Fm.) to the passage of fluids, which resulted in veins in the former and in formation of concretions and a diffuse dolomitization in the latter, shows that the Saluver Fm.

recently

  [START_REF] Hendry | Jurassic septarian concretions from NW Scotland record interdependent bacterial, physical and chemical processes of marine mudrock diagenesis[END_REF] proposed that volume contraction and resulting crack formation is due, at very shallow burial depths, to syneresis of claybearing sediments enhanced by the decay of bacterial EPS. The septarian concretions of Mal Pass largely consist of silicified sediments with cracks filled with quartz and dolomite and as such differ from most of those described in literature, which are cemented by calcite. However, the geometry of the cracks is definitely the same and the bacterially-aided syneresis hypothesis by[START_REF] Hendry | Jurassic septarian concretions from NW Scotland record interdependent bacterial, physical and chemical processes of marine mudrock diagenesis[END_REF] seems to fit the features of the Mal Pass concretions.The presence of both quartz and dolomite in septarian cracks allows to interpret their formation as related to the second stage of veining (set 2). Keeping in mind that the veins stop sharply at the top of the allochthon, it can be suggested that overpressured fluids opened their way through the allochthon, made of fully lithified rocks, flowing within discrete fractures. This channelized, focused, flow abruptly changed at the boundary with the fine-grained syn-rift succession where it became diffuse and found open spaces where quartz and dolomite could precipitate in the pores of the not fully cemented concretion bodies and especially in the cracks.

Fig. 6

 6 Fig. 6.1 -(a) Panoramic picture and interpreted drawing of Il Motto area in order to show the averall architecture of the area characterized by a high-angle normal fault bounding a half-graben basin. Modified after Mohn et al. (2010).

Fig. 6

 6 Fig. 6.2 -Field photograph of (a) crackle and (b) mosaic breccias. (c) TL and (d) CL images of the dolomite cement of the breccia.

Fig. 6

 6 Fig. 6.3 -. (a) Hand specimen and (b) field photograph of rubble breccia. (c) TL and (d) CL images highlighting the polyphase cementation (dolomite and calcite) of the breccia.

Fig

  Fig. 6.4 -Stable isotope data: δ 18 O versus δ 13 C cross plot for dolomite minerals from Il Motto (MO) area. Values relative to VPDB standard.

Fig. 6

 6 Fig.6.5 -Histogram of the homogenization temperatures obtained by standard heating method[START_REF] Goldstein | Systematics of Fluid Inclusions in Diagenetic Minerals[END_REF] for dolomite cements of breccias in the Hauptdolomit Fm.

7. 1

 1 PIZ ALV AREA7.1.1 Stratigraphy and petrographyThe Piz Alv area belongs to the Bernina unit that is made of Carboniferous to Early Permian igneous rocks intrusive into polymetamorphic Variscan basement[START_REF] Spillmann | The Pre-Alpine Basement of the Lower Austroalpine Nappes in the Bernina Massif (Grisons, Switzerland; Valtellina, Italy)[END_REF][START_REF] Quadt | U-Pb zircon ages from igneous rocks of the Bernina nappe system (Grisons, Switzerland)[END_REF]. Mesozoic sediments occur only locally as slices at the Piz Alv area, where a complete pre-rift succession is preserved (Fig. 7.1) including: Permian rhyolites, massive shallow marine Triassic dolomites and Upper Triassic lagoonal sediments, overlain by Lower Jurassic limestones (Agnelli Formation).

Fig. 7. 1 -

 1 Fig. 7.1 -Photograph and drawing of Piz Alv area showing the large-scale structure viewed from the SW in order to highlight the relationships between the pre-and syn-rift sediments. Modified after Mohn et al. 2012.

Fig. 7

 7 Fig. 7.2 -(a) TL and (b) CL images of saddle dolomite vein within a clast of the Piz Alv breccia. The vein dolomite shows a well-defined CL zoning similar to that of dolomite cements of type 1 breccias at Il Motto (proximal margin). (c) TL and (d) CL images of bivalve preserved within a clast made of dolomitized wakestone (Kössen Fm.). (e) TL detail of a clast of Agnelli Fm. Within the pore, echinoderm fragments are recognizable. (f) Hand specimen of breccia made of rounded dark grey clasts of Agnelli Fm. that show a brighter, few millimeter thick, halo in their outer part.

Fig. 7

 7 Fig. 7.3 -(a) Field occurrence and (b) hand specimen of non-dolomitized breccias. Recrystallization occurs only within the matrix. (c) TL and (d) CL photomicrographs of rounded cavities, corresponding to unrecognizable former bioclasts, in the clasts. They are cemented by a calcite spar showing a well defined CL zoning from nonluminescent to bright yellow and dull orange.

Fig. 7

 7 Fig. 7.4 -(a) Field photograph and (b) hand specimen of neptunian dyke cutting through both the large blocks and breccia beds. (c) The red sediment also occurs as matrix of the brecciated host rocks close to the dykes (d) The laminated infill of the neptunian dykes commonly shows convolution. (e) TL and (f) CL images of dolomitized reddish sediment cut by dolomite vein. The dolomite cement shows CL zoning from non luminescent to bright orange.

Fig. 7

 7 Fig. 7.5 -Stable isotope data: δ 18 O versus δ 13 C cross plot for dolomite and calcite minerals from Piz Alv area. The orange dot corresponds to the dolomite replacing the host Hauptdolomit Fm. The blue squares refer to dolomite sills and dikes cutting through the Alv Breccia. The yellow squares represent the recrystallized matrix of the Alv breccia.

Fig. 7

 7 Fig. 7.6 -Schematic interpretation, not to scale and based on field observations and petrographic study, of Piz Alv area at the time of deposition of the Alv Breccia. The Alv Breccia is mainly composed of two types of sedimentary breccias: a) megabreccias with large blocks, up to several meters, made of Hauptdolomit and Kössen Fms. crossed by dolomitized neptunian dykes; b) thinner bedded breccias whose clasts, up to a decimeter in size, are made of the only Agnelli Fm. These breccias are then crosscut by a new generation of dykes which are not dolomitized.

  8.1) belong those data, between the middle Late Triassic to Middle Jurassic time, obtained from replacement dolomite of host Hauptdolomit Fm. and saddle dolomite cement of veins. Using the major time lines described in[START_REF] Masini | The tectono-sedimentary evolution of a supra-detachment rift basin at a deep-water magma-poor rifted margin: the example of the Samedan Basin preserved in the Err nappe in SE Switzerland[END_REF] TAF and RC) and[START_REF] Incerpi | Evidence of hydrothermal fluid flow in a hyperextended rifted margin: the case study of the Err nappe (SE Switzerland)[END_REF] BBF), it is possible to establish the occurrence of three sub-groups (SG): SG 1 , pre-TAF and ranging from Rhaetian to middle Pliensbachian, includes ages of the replacement dolomite from each paleogeographic domain (proximal margin, inner, central and outer distal margin); SG 2 , post-TAF and pre-BBF ranging from middle Pliensbachian to late Toarcian, is composed of coarsegrained replacement dolomite samples from the extensional allochthon at Piz Val Lunga and Fuorcla Cotschna (central distal margin); SG 3 , post-BBF to RC, has only one data which is referred to the vein-cementing saddle dolomite within the extensional allochthon at Fuorcla Cotschna (central distal margin).Group 2 (post-RC) gathers all the samples, from the only distal margin, with ages younger than Middle Jurassic, but mainly Cretaceous and younger. They consist of replacement dolomite, most of the calcite cement of breccia and dedolomite, and saddle dolomite cement of veins.Group 3 is composed of those samples with ages older than middle Late Triassic which refer to calcite cement of breccia (Piz Val Lunga) and saddle dolomite of veins (Fuorcla Cotschna).8.2 DISCUSSION AND INTERPRETATIONTaking the middle Late Triassic to Middle Jurassic as the time range in which the extensional phases took place in the Adriatic rifted margin, only Group 1

  SG 1 shows the most homogeneous ages and, furthermore, some of the lowest standard deviation. Most of the data plot around the Triassic-Jurassic boundary with ages of about 200 Ma. As demonstrated and described in previous chapters, the replacement dolomitization of the host Hauptdolomit Formation is supposed to be related to hydrothermal fluids (based on fluid inclusions microthermometry, O and Sr isotopes). U-Pb datings allow to document that deep fluid circulation cells started to be active right after the deposition of the Hauptdolomit Fm. (and syn-deposition of the Kössen Formation) and affected the whole margin. The fluid flow and dolomitization processes continued even after the deposition of the Agnelli Formation, in a time when water depth increased but before the onset of detachment faulting as the predominant tectonic style dissecting the continental margin. SG 2 ages, middle Pliensbachian to Toarcian in age (TAF-BBF range), from the extensional allochthon in the distal margin, can be explained as a dolomitization event that in the distal margin is strictly related with the emplacement of the extensional allochthons onto the detachment fault and is characterised by nearly the same physico-chemical conditions of the older dolomitizing event as demonstrated by petrography, CL, fluid inclusion and stable isotopes. SG 3 , spanning from Aalenian to Callovian, can be related to the products of fluid flow, which affected the syn-rift sediments in the distal margin. The only sample belonging to this subgroup refers, interestingly, to saddle dolomite cement of vein crosscutting the extensional allochthon at Fuorcla Cotschna. It can therefore confirm the fact that the fracturing and veining, easily identifiable in the syn-rift sedimentary succession, were also recorded within the extensional allochthon. Beltrando et al. (2015) described for the Southern Alps several stages of extensional faulting from Middle Triassic to the Sinemurian in the Adriatic plate, followed by a more focused deformation in the Late Pliensbachian-Toarcian. The authors established the occurrence of various heating-cooling cycles among which one is dated at 215-200 Ma (ZHe data). Such a thermal perturbation was coeval with the onset of rift-related deformation at lower crustal levels, which predated normal faulting at upper crustal levels by about 10-15 Ma. Extensional deformation at all crustal levels started from about 185 to 180 Ma leading to complete crustal excision at about 165 Ma. These thermal events reported by the authors match quite precisely with our U-Pb ages. Indeed, SG 1 can further support the occurrence of the Late Triassic-Early Jurassic thermal stage whereas SG 2 refers to processes that occurred when the deformation localized in the distal part of the Adriatic margin.

Fig. 8

 8 Fig. 8.1 -U-Pb dating results have been gathered in three main groups as discussed in the text. On the basis of the major time lines TAF-BBF-RC (Fig. 4.14), the Group 1 is furthermore divided into three subgrups (SG1-2-3). The data are plotted in combinationwith the geological time scale[START_REF] Cohen | The ICS International Chronostratigraphic Chart[END_REF] updated). TAF: Top of Agnelli Fm.; BBF: Base of Bardella Fm.; RC: Radiolarian Chert Fm.

  Fm. (REF HD) sampled far from Triassic-Jurassic faults (Lombardian basin and Quattervals nappe, courtesy of Prof. Fabrizio Berra), and hence from active fluid activity, have been analysed in order to have a signal as undisturbed as possible. Furthermore, data from Pinto et al. (2015) are here considered for black gouge of detachment fault (REF GOUGE) and cataclasite (REF CAT) affecting the Albula granite in the distal margin domain and for post-rift Radiolarian Chert Fm. (REF RAD). The two REF HD samples are characterized by the lowest amount of trace elements with appreciable concentration only in Ba, Sr, V, Pb and Zn. As to REE, these samples show the lesser total amount of rare earth elements (ƩREE = 2.35 ppm) also considering that Eu, Tb, Y and Ho are below the detection limit. For such reason it has not been possible to calculate the Y/Ho ratio nor consider the Eu anomaly. A slightly negative Ce anomaly occurs (Ce/Ce* = 0.763). REF CAT and GOUGE show trace elements patterns strongly enriched compared to the analysed samples (e.g. Ba, Rb, Zr) with smaller maxima in Ga, Sr, V, Cu, Ni. Pb, Zn. Total REE contents are 199 and 213 ppm for REF CAT and GOUGE, respectively. Y/Ho ratio is slightly super-chondritic (> 26-28). LREE are slightly fractionated relative to HREE (La/Yb = 7 to 10), no Ce anomaly (Ce/Ce* = 0.99) occurs whereas negative Eu anomaly is present (Eu/Eu* = 0.59 to 0.62). REF RAD are strongly enriched in Ba, Rb, Zr and Ni. Other relevant trace elements are V, Co, Cu and Zn. Generally, REF RAD shows higher concentrations than the samples analysed in this Thesis. ƩREE is almost 100 ppm, Y/Ho is lower than that of chondrite (Y/Ho = 25), no Ce anomaly occurs (Ce/Ce* = 1.01) whereas negative Eu anomaly is present (Eu/Eu* = 0.66), La/Yb ratio is 10 (LREE/HREE). 9.3 THE HAUPTDOLOMIT FM. ALONG THE ADRIATIC CONTINENTAL MARGIN Analyses were performed on the Hauptdolomit Fm. all over the Adriatic margin (proximal domain, central and outer distal domain) where it occurs in the footwall of the main fault at the Il Motto area and as extensional allochthons at Piz Val Lunga, Fuorcla Cotschna and Mal Pass areas. All the samples show trace elements concentrations higher than that of REF HD (Fig. 9.1 a). Some elements, such as Ba, Cr, Rb, Sr, Zr, Cu, Pb and Zn show about the same values all over the margin even if a slight increase occurs moving from the proximal part towards the outer domains. Conversely, V, As and Mo have higher amount in the samples of the proximal margin. Concerning the REE (Fig. 9.1 b), all the HD samples amount of rare elements (ƩREE < 20 ppm) compar samples with the only exception of the REF HD ( the trace elements, an increase in the total amount of REE from the proximal domain to the distal one occurs. All the samples do not show Ce anomaly (no negative or positive) whereas negative Eu anomalies occur (Eu/Eu* = 0.63 to 0.85) as well as super-chondritic Y/Ho ratio (> 26 light rare earth elements compared to heavy rare earth elements (La/Yb = 10 to 15).

Fig. 9 . 1 -

 91 Fig. 9.1 -Trace elements content (in ppm) and chondrite

Fig. 9

 9 Fig. 9.2 -Trace elements content (in ppm) and chondrite Hauptdolomit Fm. in the Adriatic distal margin. REF GOUGE and CAT: reference samples of black gouge and cataclasite from Pinto et al. (2015); REF HD: reference samples of Hauptdolomit Fm. (courtesy of Prof. Hauptdolomit Fm. in the distal margin; HD GOUGE: clasts of Hauptdolomit FM. within the black gouge; HD CAT: cataclasite made of Hauptdolomit Fm.; DEDOL: dedolomite.

Fig. 9

 9 Fig. 9.4 -Trace elements content (in ppm) and chondrite 101

Furthermore, positive

 positive Eu anomaly has been related to fluid-rock interactions such as breakdown of plagioclase[START_REF] Mclennan | Rare earth elements in sedimentary rocks: influence of provenance and sedimentary processes[END_REF]. Alteration of plagioclase widely occurred within the Albula granite in the Err Nappe in response to the detachment fault activity. Negative Eu anomaly of the analysed samples from the Adriatic margin can be also explained, even if in contrast to what has just been mentioned, based on[START_REF] Lüders | REE fractionation in carbonates and fluorites[END_REF] who stated that carbonates formed from fluids which interacted with granites may show a negative Eu anomaly.

  prior to the fine grained silicification (as demonstrated by the occurrence of dolomite rhombs within the silicified matrix of calciruditic beds and chert nodules). Carbonates generally contain high amount of Sr, which could have been inherited, giving that high Sr content even after the almost complete silicification of the rocks. SEPT samples contain both sparse dolomite rhombs and saddle dolomite cementing fractures in septarian-like concretions. Such carbonate content can be responsible for high Sr values. Further in situ measurements are required to better characterize and constrain the geochemical history of fluids involved in the extensional phases affected the Adriatic continental margin. depositional processes such as dolomitization, veining, and silicification are observed in different paleo-geographic domains of the Adriatic continental margin, others are exclusive of only one site. The cataclastic breccias, calcite cementation, dedolomitization are observed only at Piz Val Lunga area and Fe-Mn oxide coating only at Fuorcla Cotschna area. Other individual features are the absence of veining in syn-rift sediments at Mal Pass area, and the lack of quartz at Il Motto area. Each of these aspects sheds light on the mechanical and chemical processes that acted in an articulated rifting history that, depending on sites, is recorded by different tectono-stratigraphic settings. Each outcrop is a window over different segments of such a complex system and enables to observe what happened at the base and within the allochthon, in the lower part of the syn-tectonic sedimentary succession or in its upper, younger part. Everywhere, however, circulating fluids clearly appears to have been of primary importance in determining the final aspects of the rocks. Isotope geochemistry and fluid inclusion microthermometry, trace elements and REE enable to constrain some characteristics of these fluids, their circulation patterns and also the timing. 10.2 CONSTRAINTS ON THE HYDROTHERMAL FEATURES OF THE FLUIDS δ 13 C values of all the analyzed samples from the different paleogeographic domains fall in the range of 0 to +4 ‰ which is characteristic of normal marine sedimentary carbonates and show no significant contribution of organic matter decomposition. δ 18 O values, conversely, are all negative showing a quite wide range from 0 to -16 ‰. Nonetheless, a common trend can be observed (Fig. 10.1) throughout the entire Adriatic margin based on δ 18 O. The less depleted values are always those related to the replacement dolomite whereas the more depleted ones refer to the new forming minerals (e.g. calcite and dolomite cements of breccias and veins). Looking at Fig. 10.1 it is evident that from the proximal towards the outer distal margin, a constant decrease in δ 18 O values in replacement and authigenic minerals occurs even if the distinction between the two is always well recognizable.

Fig. 10. 1 -

 1 Fig. 10.1 -Stable isotope data: δ 18 O versus δ 13 C cross plot for dolomite and calcite minerals from the whole Adriatic continental margin. Values relative to the VPDB standard. A detailed description of each group of data is given in previous chapters.

  in the distal domain(Piz Val Lunga, Fuorcla Cotschna, Piz Alv) already occur as clasts in the Bardella Fm. and thus they could not have been buried more than the cumulative thickness of the Kössen and Agnelli Formations, which does not exceed a few 100's meters. Burial temperatures reached by Upper Triassic dolostones before middle Early Jurassic were thus surely significantly lower than those documented by fluid inclusion microthermometry and a dolomitization event related to the upward advection of hydrothermal fluids is thus supported (e.g. Lopez-Horgue et al., 2010). The hydrothermal characteristics of the fluids are also confirmed by REE systematics (e.g. Y/Ho, LREE/HREE, weak Eu anomaly). Furthermore, such an event is strongly constrained by U-Pb ages, which point to a dolomitizing stage, widely affecting the Hauptdolomit Formation, at about 200 Ma which interestingly corresponds to a thermal event documented by Beltrando et al. (2015) on the basis of ZHe data in the western part of the Southalpine domain. Keeping in mind this

  replacing and authigenic minerals, conversely, demonstrate a fundamental contribution by feldspars and thus support a circulation of fluids within the quartzo-feldspatic basement rocks of the Albula granite and/or Permian siliciclastics. Trace elements analyses show enrichments in some elements (e.g. Ba, Sr, Pb) which inevitably ask for an important interaction between fluids and crustal rocks.On the whole, the quite wide range of variability of δ 18 O values is suggested to depend on the characteristics of the flow paths. Many variables are to be taken into account such as depth and rate of circulation of fluids in the basement in addition to mixing with seawater. All these factors, which govern the degree of fluid-rock interaction and hence temperature and enrichment in 18 O, interact in such a complex way that is probably impossible to model in detail.10.3 EVOLUTIONARY MODELOn the basis of the considerations exposed above, the following scenario for the Triassic-Jurassic evolution of the Adriatic continental margin preserved in the Err nappe may be suggested. Two main stages in the post-depositional evolution can be distinguished (Fig.10.2) according to the extensional deformation phases ature of fluids. 1) The first affects the pre-rift successions (Hauptdolomit, Kössen, Agnelli Formations) before their reworking and resedimentation as clasts within the syn-rift sequences (Bardella and Saluver Formations). This stage (pre-BBF; Rhaetian to late Early Jurassic) mainly involves fluids rich in carbonate and includes several processes such as dolomitization of calcareous sediments, dolomite cementation of pores, veining (formation of fractures and filling with saddle dolomite), formation and cementation of breccias with dolomite and calcite, and minor quartz precipitation in veins. It may be related to the early phases of rifting (SG 1 U-Pb ages) recorded in the proximal margin and to the phase of localization of the deformation in the distal domain (SG 2 U-Pb ages). 2) The second stage (post-BBF; Middle to early Late Jurassic) affects the whole succession (pre-, syn-and post-rift) although it is best recognized in synto post-rift sediments. It took place during and after the deposition of Bardella, Saluver and Radiolarian Cherts Formations, documenting an involvement of large amounts of SiO 2 into the system with resulting precipitation of quartz (veins, septarian-like concretions, diffuse silicification). To this stage is also related the income of mantle-related elements (e.g. Fe-Mn oxides).

Fig. 10

 10 Fig. 10.2 -Paragenetic sequence showing the relative timing of post-depositional processes and related products affecting the pre-to post-tectonic sediments of the Adriatic continental margin. This interpretation is based on the data of the different analysed paleogegraphic domain. The width of the lines is qualitatively proportional to the magnitude of each process (modified after Incerpi et al., 2017). TAF = Top of Agnelli Fm.; BBF = Base of Bardella Fm.; RC = Radiolarian Cherts.

Fig. 10

 10 Fig. 10.3 -Schematic representation of the Adriatic continental margin architecture and fluid flow circulation during the first diagenetic stage.

Fig. 10

 10 Fig. 10.4 -Schematic representation of the Adriatic distal margin architecture and fluid flow circulation duringthe second diagenetic stage.

Fig. 10

 10 Fig. 10.5 -Reconstructed paleogeographic section across the Adriatic continental margin (modified after Mohn et al. 2010). The black analysed in this Thesis. The red arrows highlight, schematically, the chemistry of the fluids as depicted by the multi-disciplinary approach adopted in this work. The main changes occurred simoultaneously to the exhumation of continental crust and mantle related rocks in response to detachment fault activity.

  reactivated during latest Cretaceous to Oligocene time by N-S directed compression due to the convergence of the European and Iberian plates. Although the Pyrenean compressional overprint resulted in the inversion of the Lower Cretaceous basins and reactivated most of the rift-related structures, it has the advantage that it uplifted and exposed the basal parts of a former hyperextended rift basin. Similar to the Alps, the Bay of Biscay-Pyrenean domain can be considered to represent a natural laboratory to investigate hyper-extended rift systems (Fig. 11.1).

Fig. 11 . 1 -

 111 Fig. 11.1 -Map of the rift domains preserved in the Bay of Biscay and their fossil analogues from the Pyrenean domain. Extensional rift structures and thrust faults from the Armorican and Western Approach margins are based on the work of Thinon (1999). Modified after Tugend et al. (2014).

4.

  The Axial domain, further to the south, corresponds to the western equivalent of the Axial Zone of the Central and Eastern Pyrenees. It corresponds to the southern border of the former hyper-extended basin. One of the key characteristics is the occurrence of a major hiatus and the unconformable deposition of the Upper Cretaceous (Cenomanian and younger) post-rift carbonate platform over Paleozoic basement.

Fig. 11 .

 11 Fig. 11.2 -(a) Simplified geological map of the Arzacq-Mauleon rift system preserved in the western Pyrenees (modified after Jammes et al., 2010b). (b) Schematic restoration of the Mauléon Basin prior the onset of pyrenean compression. Only the pre-rift basement and sedimentary rocks are represented (modified after Jammes et al., 2009).

  ) above upper crustal rocks and Lower Triassic sediments within a stratigraphic context (e.g., the Axial Zone), (2) in diapiric structures inside Cretaceous sediments, or (3) at the base of a massive Rhaetian to lower Aptian sequence (e.g., Chaînons Béarnais) separated tectonically from mantle derived rocks or Cretaceous sediments. Most of the contacts between the Keuper sediments and the underlying and overlying units are tectonized. A Late Triassic transgression resulted in the development of a second carbonate platform (up to 1500 m thick and composed of alternations of dolomites, limestones and marls) starting from Raethian time. Regionally, E-W trending subsiding basins started to develop from Tithonian onward (e.g.,

Fig. 11 .

 11 Fig. 11.3 -Simplified geological map of the Chaînons Béarnais cropping out in the easternmost part of the Mauléon basin (map modified after the BRGM 1/50,000

Fig

  Fig. 11.4 -Detail of the geological map of the Feuille Lourdes BRGM 1/50.000 showing the study area which is geographically part of the Foret des Tres Crouts.

  crystalline, subhedral to euhedral, replacement dolomite whose crystals can reach 300µm in size. Under CL it is not luminescent. These dolostones show different degrees of disruption of the rock. Where it is less deformed, the Black Dolomites Unit is affected by randomly oriented, few µm wide, fracture sets (only visible by CL investigation) filled by dolomite cement, bright orange under cathodoluminescence (Fig.12.1). These micro-fissures usually occur along the crystal contacts even if they also cut through them. Locally, some open spaces occur. They are cemented by dolomite whose crystals, 100-200 µm large, show a bright orange, very poorly zoned CL luminescence (Fig.12.1). By their features, these portions of the rock mass can be considered as incipient crackle breccias (sensu[START_REF] Morrow | Descriptive field classification of sedimentary and diagenetic breccias fabrics in carbonate rocks[END_REF].

Fig. 12. 1 -

 1 Fig. 12.1 -Crackle breccias: (a) TL and (b) CL images highlighting the diffuse fissure sets developed along crystal contacts and within them, cemented by orange luminescing dolomite. The host rock (Black Dolomites Unit) is dull in CL. (c) TL and (d) CL images showing cavities within the host rock filled with orange, poorly zoned, dolomite cement.

Fig. 12

 12 Fig. 12.2 -Locally, within the clasts of the mosaic-rubble breccias, ooids are still recognizable despite the diffuse replacement dolomitization.

Fig. 12

 12 Fig. 12.3 -Mosaic to rubble breccias. (a) Hand specimens. (b) TL and (c) CL images showing the two generations of dolomite cements of the breccias. The clasts are dull

Fig. 12

 12 Fig. 12.4 -Stable isotope data: δ 18 O versus δ 13 C cross plot for dolomite minerals of Black Dolomites Unit. Values relative to VPDB standard.

  After the almost complete recrystallization, the Black Dolomites Unit underwent modifications related to the emplacement of overpressured carbonate-rich fluids, which gave rise to different textures. Where the circulation was less intense it generated µm large, randomly oriented fractures along the dolomite crystals contacts and/or within the crystals themselves (crackle breccias; Fig.12.1). Such a pervasive infiltration could have been facilitated by inter-crystalline porosity related to the previous pervasive dolomitizing event. Conversely, where the flow was more concentrated and/or overpressured, a higher degree of disruption occurred by hydraulic deformation that resulted in the formation of mosaic and rubble breccias (Fig.12.3). The occurrence of sediment geopetally filling the cavities (Fig.12.3 d-f) of the breccias suggests the hydrofracturation took place close to the seafloor. Overpressured fluids generated the open framework texture of the breccias, which was in close vicinity and connected to the water-sediment interface that allowed the infiltration of sediment. The fact that the internal sediment is dolomitized suggests the infiltration occurred concomitantly with the circulation of fluids (e.g.,[START_REF] Barale | Very hot, very shallow hydrothermal dolomitization: An example from the Maritime Alps (north-west Italy-south-east France)[END_REF].12.3.3 Dolomite and calcite cementsSince the dolomite cements within the inter-and intra-crystalline fissures of the host rock and the first cement of the mosaic-rubble breccias show similar CL features (Fig. 12.1 a-d and Fig. 12.3 b-c), it allows to consider the two cements as related to the same fluid flow event. The petrographic features and the quite well defined zoning of the first dolomite cement (type 1) suggest that the precipitation occurred in open spaces and in static conditions. New fluid pulsations generated the second dolomite cement (type 2) as well as the calcite one (Fig. 12.3 g-h). Even if the timing of precipitation is not obvious, it documents a change in the chemistry of the fluids. Possibly, as the calcite cement has been found both before and after the first dolomite cement, it may be assumed a multi-stage occurrence for the CaCO 3 -rich fluid circulation.12.3.4 VeinsVeins are not abundant within the Black Dolomites Unit and seem to be confined to those portions of the host rock that experienced the more intense fluid circulation. Both dolomite and calcite veins were found cutting through the breccias implying the fracturing stage and subsequent circulation of fluids took place after the formation of the breccias themselves. Unit crops out in the central part of the study area and shows an overall thickness of 200-300 meters[START_REF] Casteras | Carte géologique de la France 1/50,000[END_REF]. It is made of fine-grained, well-bedded limestones alternated with black to reddish marly limestones. Locally it is also dolomitized. The fossil content includes: serpulides, Exogyra virgule, Pseudocyclammina virgulina, Haplophragmium, Pseudocyclammina gr. jaccardi-personata. Valvulinella jurassica is common throughout the Unit and allowed[START_REF] Casteras | Carte géologique de la France 1/50,000[END_REF] to date this lithostratigraphic unit to the Kimmeridgian. These limestones, on the whole, are microsparitic, dark orange in CL and cut by dolomite and calcite veins hundreds of m large (Fig.13.1 a-b). Bivalve shells, echinoderm and gastropod fragments, oncoids and cortoids are preserved even if recrystallized. Some bioclasts are coated by pyrite. Locally, the Black Limestones Unit is characterized by the occurrence of several, up to 300 m long, "sandwiches" made of fibrous calcite growing perpendicularly to and encasing fibrous aggregates of Mg-rich aluminosilicates (Fig.13.1 c-d). The first results of Raman spectroscopy investigations revealed that such silicates are hydrated and characterized by spectra similar to that of talc and chlorite.

Fig. 13. 1 -

 1 Fig. 13.1 -Black Limestones Unit: (a) Field occurrence and (b) hand specimen. (c) TL and (d) crossed polarizers images of the "sandwiches" within the limestones. The inner part, made of Mg-rich alumo-silicates, is encased within perpendicularly growing, fibrous calcite.

Fig. 13 Fig

 13 Fig. 13.2 -Localization of the investigated sites in the Black Limestones Unit: the Quarries site and the Riverbed site. The geological map and its legend are the same of Fig. 11.5.

Fig. 13

 13 Fig. 13.3 -Breccia type 1. (a) Field occurrence and (b) hand specimen. The clasts are made of limestone whereas the cement is made of sparry calcite. (c) TL and (d) crossed polarizers images of the clasts and the calcite cement.

Fig. 13

 13 Fig. 13.5 -Detail breccia type 2. (a-c) TL and (b-d) CL images of poorly sorted breccias crosscut by fractures filled with dolomite and calcite cements. (e) TL and (f) CL details of the orange to brown zoning of the calcite cement.

Fig. 13

 13 Fig. 13.6 -Breccia type 3. (a) Field image. (b), (c) TL and (d) CL images of the polimict clasts (limestones and dolostones) of the breccia cemented by dolomite and calcite.

Fig. 13

 13 Fig. 13.7 -Deformed sedimentary breccia. (a) Field image and (b) hand specimen. In (b) is evident that carbonate veins crosscut the whole breccia. (c) TL and (d) CL images showing that deformation (compaction and shearing) affected the sedimentary breccia. The clasts are brighter in CL. (e) TL and (f) crossed polarizers images showing stylolites at the clasts boundaries and within the matrix.

Fig. 13

 13 Fig. 13.8 -Stable isotope data: δ 18 O versus δ 13 C cross plot for calcite clasts and cements from the Quarry sites. Values relative to VPDB standard.

Fig. 13

 13 Fig. 13.9 -Histogram of the homogenization temperatures for calcite and dolomite cements of breccia types 1 and 3 respectively.

  different cements of the hydrofracturing breccias were precipitated in open spaces and in static conditions. Finding of breccias cemented by chemically different mineral phases, in close vicinity one to the others, imply a change in the physico-chemical properties of the fluids even if always in a carbonatedominated system. The dolomite cement of breccia type 3 (Fig.13.6) as well as the calcite cement of breccia type 1, shows homogenization temperature anomalously high also considering that the overall thickness of the post-Kimmeridgian succession cannot supply for such values only by sedimentary overburden. Furthermore, the negative O isotopic values (Fig. 13.8) support the idea that the cements precipitated from hydrothermal fluids.

Fig. 13

 13 Fig. 13.10 -(a) Field image and (b) hand specimen of carbonate mylonites. In the bluish layers porphyroclasts of the former coarse-grained rock are preserved. (c) TL and (d) CL details of the porphyroclasts. (e) TL and (f) crossed polarizers images of

Fig. 13 .

 13 Fig. 13.11 -(a) TL and (b) CL images of dolomite marbles. Note the coarse grained textures and the sutured contact among the crystals.

Fig. 13

 13 Fig. 13.12 -Stable isotope data: δ 18 O versus δ 13 C cross plot for dolomite marbles and mylonites. Values relative to VPDB standard.

  14.1 b and Fig. 14.2 c-d). Compositionally, the carbonate clasts are mainly made of micritic to microsparitic limestones, oolitic limestones showing different degrees of dolomitization, and finely to coarsely crystalline dolostones (Fig. 14.2 a-f). Locally gastropods and bivalve shells are still recognizable, even if recrystallized. Dolomite veins, confined within the clasts, are common and characterized by orange luminescencing crystals, up to few hundreds of m in size (Fig. 14.2 a-d). Among the siliciclastic material, clasts made of polycrystalline quartz occur (Fig. 14.3 a-b). The crystals, up to 10 µm large, subhedral to euhedral, show a particular grain organization: the larger crystals are in the center of the clasts whereas, moving towards the edge, the grain size decreases progressively. Around some carbonate and ophitic clasts, pressure shadows filled with mm-long, elongated crystals of calcite are present (Fig. 14.3 c). The matrix of this mixed breccia is a grainstone made of the same material of the clasts and detrital quartz. It is important to note the occurrence of authigenic quartz (30-40 µm large) and albite that poikilotopically grow over the matrix, including carbonate crystals (Fig. 14.2 g-h and Fig. 14.3 d-e-f). The albite, chemically almost pure, is euhedral and randomly oriented, up to 2 mm long, showing the characteristic Roc Tourné twinning and dull luminescence under CL. It occurs within the clasts, the matrix and across the contact of the two. Also authigenic opaque minerals (sulphides up to 500 µm large) are widely distributed. Lastly, some dolomite veins crosscut the entire breccia body (e.g. both clasts and matrix). A third sedimentary breccia type (Fig. 14.1 c), stratigraphically above the previously described ophitic and polimict breccias, occurs in the study area. It is clast-supported and composed solely of carbonate clasts within a matrix that shows the same features of the polimict breccias (e.g. authigenic quartz, albite and opaque minerals). The clasts, which generally range in size from few mm to cm, are made of micrities, microsparitic limestones and fine grained laminated dolostones preserving the pristine features of the rock (e.g. shrinkage pores, fossils). Some clasts show borings possibly referable to Lithophaga at the edge. Within some clasts, dolomite veins occur. Other clasts, conversely, are strongly recrystallized and the recognition of pristine features is no longer possible. It is the case of coarse grained, sucrosic dolostones that under CL are almost nonluminescent and preserve some cavities filled with orange luminescing dolomite cement. By their petrographic and CL features, such clasts are clearly referable to the Black Dolomites Unit. Few dolomite veins, characterized by a concentric CL zoning alternating dull and bright orange CL zones, cut through the whole rock mass.

Fig. 14. 1 -

 1 Fig. 14.1 -(a) Field photograph of monomict ophitic breccias. (b) Hand specimen of polimict breccias. The green clast is made of ophite, which is encased within the matrix that is mainly made of carbonate. (c) Field picture of monomict carbonate breccias.

Fig. 14

 14 Fig. 14.3 -(a) TL and (b) crossed polarizers images of a clast made of polycrystalline quartz. Note the decreasing grain size towards the edge of the clast. Within the matrix, euhedral opaque minerals are easily recognizable. (c) Crossed polarizers image of

  14.3 c)suggest its precipitation in a time of ongoing tectonic activity. It could be related to later stages connected to the compressional pyrenean evolution. This stage is possibly related also to the formation of those carbonate veins that cut through the whole rock package. 15. Discussion: Stratigraphy and Fluid flow evolution 15.1 INTRODUCTION Despite the very poor outcrop conditions, many lines of evidence point to the occurrence of a strong fluid activity within the study area (Forêt de Tre Crouts). Such circulation led to significant post-depositional modifications of the host rocks: pervasive and almost complete replacement dolomitization, micro-to mesoscale fracturation and veining, strong hydrofracturation, recrystallization and variable degrees of ductile deformation. Each process reflects different physico-chemical conditions as demonstrated by the several different resulting textures and fluid-related mineral phases. Unfortunately, it was not possible to truly understand the geometric relationships among the different rock types so that only general considerations can be proposed. Nonetheless, the results of the present work provide undisputable proofs for a strong fluid-related history in the rocks that derive from the former hyper-extended domain. The provided interpretations, albeit not fully constrained by a complete analytical dataset (e.g. lack of fluid inclusion microthermometry and U-Pb dating), will take advantage and based on those proposed for the better studied Alpine counterpart presented in this Thesis and on the recent study of Salardon et al. (2017) on the Pyrenees. As already discussed in the introductory part (cfr. 11.3), the Chaînons Béarnais ridges have been interpreted to represent extensional allochthons lying over detachment faults in the most distal part of the Iberian continental margin (Jammes et al. 2009). For such reason, it is possible to compare the tectonostratigraphic architecture of the study area, as well as the fluid-related products, with that of the distal domain of the Adriatic rifted margin preserved in the Alps. 15.2 CONSTRAINTS ON THE HYDROTHERMAL FEATURES OF THE FLUIDS 15.2.1 Black Dolomites and Black Limestones Units δ 13 C values of all the analyzed samples from the Black Dolomites and Black Limestones Units show values between 0 and +3,5 ‰, which is characteristic of normal marine sedimentary carbonates with no significant contribution of organic matter decomposition. Only one sample of calcite cement of breccia type 1 (Black Limestones Unit) has a slightly negative δ 13 C value (about -2 ‰). On the contrary, δ 18 O isotopic values are always negative within a wide range from 0 to -14 ‰. Excluding for a while the mylonites and marbles, and based only on δ 18 O values, two main groups of data can be distinguished: the less depleted values belonging to the host rocks (limestones and replacement dolomite) and the more depleted ones referring to new forming minerals, such as calcite and dolomite, which precipitated in open fractures of the hydraulic breccias. The two groups are slightly overlapping, expecially for the Black Dolomite Unit. As previously stated and even if not constrained by fluid inclusion microthermometry, the replacement dolomitization affecting the dolostones could be related to hot fluid circulation to which the observed depletion of oxygen isotopes may be related. Indeed, the replacement dolomite shows δ 18 O values that are lower than those documented in present day settings

  carbonate mylonites and their precursors (marbles) show the same O and C isotopic pattern. The same negative O isotopic values shown by both rock types suggest that the mylonites derived from the deformation of an already recrystallized rock. Interestingly, the pale bands of the carbonate mylonites are less depleted than both the dark ones and marbles. In any case, two different steps characterized the evolution of these rocks. The first led to the complete recrystallization of the former protolith giving rise to dolomite marbles and their negative δ 18 O values. The second stage involved the already recrystallized rock mass and was related to a strong ductile deformation event resulting in the development of mylonitic texture. The very coarse crystal size of the marbles and the subsequent mylonitization are both processes that need a "hot environment" to occur as well as involment of fluids. The occurrence of quartz and former scapolite (?) poikilotopikally grown over the carbonate foliation point to consider a silica-rich fluid flow event after or at least simultaneously to the mylonitization. Former scapolite (?), presently replaced by microcrystalline assemblages of K-rich alumo-silicates highlight that new fluid-rock interaction took place within these rocks in a later stage of their evolution.

  15.3 NEW INTERPRETATION OF THE STRATIGRAPHIC SETTING OF THE STUDY AREAFinding of clasts made of unaltered limestones and dolostones, strongly dolomitized rocks, dolomite and calcite cements identical to those which have been described for Black Limestones and Black Dolostones Unit within the Sedimentary Breccias Unit has strong implications in terms of stratigraphic architecture of the area. Indeed,[START_REF] Casteras | Carte géologique de la France 1/50,000[END_REF] assigned a Rhaetian-Sinemurian age to these sedimentary breccias only on the base of the stratigraphic relationships with the over-and underlying rocks (Aalenian-Toarcian limestones and Keuper evaporites and ophites, respectively). As demonstrated by field observations and petrographic studies carried out in the present Thesis, these breccias cannot be older than the younger rocks that compose the clasts and the matrix, i.e. at least the Callovian-Oxfordian Black Dolomites unit.

  for the formation of hydrofracturing breccias type 3 within the overlying Black Limestones Unit. Indeed, such breccias are the only one cemented by dolomite. The clasts of these breccias are polimict including not only the Black Dolomites Unit but also the Black Limestones Unit.Therefore, a flow of overpressured fluids thorough the two lithostratigraphic units can be inferred which led to a conspicuous amount of disruption and vertical displacement in post-Kimmeridgian time.-First phase of circulation of calcite-rich fluids as documented by the cement within mosaic to rubble breccias of the Black Dolomites Unit and that of breccia types 1, 2 and 3 within the Black Limestones Unit.Hydrofracture breccias have been widely documented in the pre-rift sedimentary sequence preserved at Il Motto area and within the extensional allochthon at Piz Val Lunga area of the Adriatic continental margin. Also in those cases, overpressured fluids generated crackle, mosaic and rubble breccias to which a vertical displacement of the clasts was associated. The study area, as well as the whole Chaînons Béarnais[START_REF] Salardon | Interactions between tectonics and fluid circulations in an inverted hyper-extended basin: Example of mesozoic carbonate rocks of the western North Pyrenean Zone (Chaînons Béarnais, France)[END_REF], interestingly recorded the same processes even on a larger scale. Indeed, both clasts and cement crystals are larger in size possibly implying higher amount of fluids and/or overpressure. In the Adriatic distal margin, hydraulic fracturing has been genetically related to the activity of the Err detachment fault. Also for the Pyrenean study area the same scenario could be envisaged (e.g. circulation of fluids related to mid-Cretaceous hyperextension). Indeed, in the Chaînons Béarnais[START_REF] Salardon | Interactions between tectonics and fluid circulations in an inverted hyper-extended basin: Example of mesozoic carbonate rocks of the western North Pyrenean Zone (Chaînons Béarnais, France)[END_REF], after a first fracturing event which is the result of the first rifting phases affecting the rift system, described a second major fracturing event that affected the Liassic to Albian sediments to which an increase in temperature of the fluids and depletion of δ 18 O are associated. The authors attribute a diffuse replacement dolomitization as well as the dolomite-calcite cementation of hydraulic breccias and veins to this stage. On the basis of chemical exchanges due to serpentinization presented byPinto et al. (

  formation. Despite still being related to hydrothermal fluids, these rocks underwent a completely different mechanism of deformation. Indeed, all the other described rocks are the result of brittle hydrofracturation whereas the marbles were affected by a completely ductile deformation leading to mylonitization. Such ductile deformation characterized, to a lesser extent, also the sedimentary breccias found in the Quarries site.Many questions remain open, based on the available data and field observations:What is the relation between the marbles-mylonites and the surrounding Black Limestones Unit? Is there any link between the mylonites and the deformed sedimentary breccias of the Quarries site? Do they represent a shear gradient within the same fault zone? Are they really part of the same lithostratigraphic unit? If not, what is the real architecture of the study area? Are the mylonites and marbles part of a tectonic slice of pre-Keuper succession?

Fig. 15. 1 -

 1 Fig. 15.1 -Paragenetic sequence showing the relative timing of post-depositional processes and related products affecting the pre-to syn-tectonic sediments of the Pyrenean hyper-extended rift system. The width of the lines is qualitatively proportional to the magnitude of each process.

  From the inner part and moving oceanwards they are: Piz Alv, Piz Val Lunga, Fuorcla Cotschna and Mal Pass. Apart from the Piz Alv area, where only syn-rift sediments were studied (Piz Alv breccia), in the other sites the investigations focused on extensional allochthons mainly made of peritidal dolomites of the Norian Hauptdolomit Fm. and on the Lower to Middle Jurassic syn-to post-rift sediments filling supradetachment basins (Bardella and Saluver Fms., Radiolarian Cherts). Both the extensional allochthons and the syn-rift sediments directly overlie low-angle detachment faults. The Bardella and Saluver Fms. consist of gravitational deposits related to the erosion of the extensional allochthon and basementderived material from the footwall of the detachment, respectively. The tectonostratigraphic evolution of a supra-detachment basin is confined within two major time lines: TAF -Top of Agnelli Fm. (e.g. the last pre-rift sediments in the distal margin, ~185 Ma) and the RC -Radiolarian Cherts (e.g. the first post-rift sediments, ~165 Ma). The study of the fluid activity in the distal margin allowed to depict a complex fluid-related history that led to different processes to which the precipitation of different mineral phases is due. Some of these fluid-related products were found only within the extensional allochthons whereas others affected also the syn-to post-rift sedimentary sequence. For such reason, a new fundamental time line, that corresponds to a hiatus in the sedimentation, has been introduced in order to truly understand the polyphase evolution of the system: the BBF -Base of Bardella Formation (e.g., the base of the first syn-rift sediments in the distal margin). Based on this, two main stages in evolution of the Adriatic distal margin were recognized: 1) First, carbonate-rich, stage Pre-TAF: -Deposition of the Hauptdolomit Fm. -Rhaetian-Hettangian tectonic activity leading to the formation of neptunian dykes and sills in the Hauptdolomit Fm. as recorded at Piz Alv and Mal Pass areas. -Diffuse replacement dolomitization and dolomite cementation of pores of the Hauptdolomit Fm. and neptunian dykes. Post-TAF and pre-BBF: -Onset low-angle detachment faults activity to which cataclastic deformation at the base of those pre-rift volumes of rocks, which will become extensional allochthons, and abrupt release of overpressured fluids (e.g. fault-valve mechanism) are related. The latter is documented by hydraulic brecciation with development of calcite cement, partial dedolomitization of the Hauptdolomit Fm. and cataclasite, fracturation and vein filling with saddle dolomite cements. 2) Second, silica-rich, stage (syn-to post-BBF) -Ongoing tectonic activity generated topography and following erosion of the extensional allochthons resulting in the deposition of the syn-rift Bardella and Saluver Fms.

The

  BBF does not mark only a temporal constrain in the evolution of the distal margin but also an important change in the chemistry of the fluid system through time. In fact, the pre-to syn-BBF stages are characterized by carbonatedominated fluids with only minor occurrence of silica. On the contrary, the post-BBF diagenetic stage is strongly silica-rich and lasted, at least, until the deposition of the first post-rift sediments.Geochemical analyses and fluid inclusion microthermometry were performed on different fluid-related products, belonging to the pre-and post-BBF stages, in order to characterize the physico-chemical properties of the fluids.-O and C isotopes analyses performed on replacement dolomite and new forming minerals (dolomite and calcite cements of breccias and veins) show a common trend all over the distal margin. Slightly positive δ 13 C is in the range of normal marine carbonates; δ 18 O, on the contrary, is slightly to strongly negative. The replacement dolomite shows always the less depleted δ 18 O values (up to -6‰ VPDB), whereas the more depleted ones refer to dolomite and calcite cements of breccias and veins (up to -16‰ VPDB).-Homogenization temperatures of fluid inclusions measured on the replacement dolomite, calcite cement and dedolomite, dolomite and quartz of veins as well as septarian-like concretions show values in the range of 100°C to 150°C. Such values cannot be explained only by the sedimentary overburden that was few 100's of meters at the time of the fluid circulation. Therefore, the occurrence of hydrothermal fluids is strongly suggested. This hypothesis is also confirmed by REE systematics (Y/Ho, LREE/HREE, weak Eu anomaly).-Calculation of the isotopic composition of the fluids responsible for dolomite and calcite precipitation provides slightly to strongly positive O isotope values (+2 to +12‰ SMOW). These results, supported by the highly radiogenic Sr isotope values of the same mineral phases, point to an intense interaction between the fluids and the granitic footwall of the detachment faults. Such interpretation is further constrained by the "crustal" values of the He isotopes.-Geochemical analyses on trace elements seem to confirm this hypothesis as demonstrated by enrichment in some elements (e.g. Ba, Sr, Pb) typical of crustal rocks. Moreover, elements like Cr, V, Ni seem to shed light on a possible interaction of fluids with mantle-related rocks. The occurrence of Fe-Mn oxides found in the upper part of the syn-rift sedimentary succession may have the same origin.-Finally, U-Pb dating on replacement dolomite gave constrains about the timing of emplacement of dolomitizing fluids. Most of the analyses on samples belonging to the Hauptdolomit Fm. from different paleogeographic domains indicate that the replacement process took place at about 200 Ma. Thus, this event may coincide with the onset of rifting, which is well preserved in the proximal margin, and lasted until the late Early Jurassic when deformation localized in the future distal margin.On the basis of the described observations and data, it is important to underline how the Adriatic distal margin records a long-lasting and multi-stage fluidrelated history. These characteristics refer to different stages in the margin evolution, from the very first phases in the proximal margin to the last extensional events in the distal margin, simultaneous with the exhumation of mantle rocks. The evolution of the fluids, and hence their chemistry, is directly connected with the tectono-stratigraphic evolution of the margin.16.2.1.2 The proximal marginThe proximal margin, preserved at the Il Motto area, is characterized by a halfgraben basin bounded by a high-angle normal fault that was active during the Hettangian, representing the onset of rifting along the Adriatic margin. Samples of Hauptdolomit Fm. from the footwall of the main fault highlight the occurrence of two main fluid-related processes: i) pervasive and fabricdestructive replacement dolomitization followed by ii) hydraulic brecciation of the host rock, which gave rise to breccias cemented by dolomite and calcite. The petrographic features of the replaced Hauptdolomit Fm., similar to those of the others domains of the Adriatic margin, allow to ascribe the replacement dolomitization to the pre-BBF stage. U-Pb ages (~200 Ma) support this hypothesis. The textures of the breccias related to hydrofracturing, the negative δ 18 O isotopic values (about -6‰ VPDB) and the microthermometric results (T h in the range 130-140°C) of the dolomite cement require the occurrence of overpressured hydrothermal fluid circulation. As for the distal margin, the sedimentary column was not sufficiently thick to justify the obtained temperatures by burial only. Fluid flow may have been triggered by the activity of the main faults bounding the half-graben basins, which rooted down in the basement, allowing the fluids to get highly radiogenic Sr isotope values. At the Il Motto area, finally, the post-BBF silica-rich diagenetic stage has not been observed. 16.2.2 The Pyrenean hyper-extended rift system The study area (Chaînons Béarnais) is localized in the eastern termination of the Mauléon Basin, which is a hyper-extended supra-detachment basin formed in response to the mid-Cretaceous aborted rifting predating Pyrenean collision. The focus of the study is the pre-rift, Upper Triassic to Lower Cretaceous, sedimentary sequence preserved as extensional allochthons. As for the Alpine area, the target is the post-depositional modification of the sediments due to fluid circulation. Because of the poor outcrop conditions, only discontinuous observations were possible. Three lithostratigraphic units, in particular, were affected by diffuse fluid circulation: the Black Dolomites Unit (Callovian-Oxfordian), the Black Limestones Unit (Kimmeridgian) and the Sedimentary Breccias Unit (post-Kimmeridgian?). 16.2.2.1 The Black Dolomites Unit The Black Dolomites Unit is made of coarse crystalline dolostones, which are the result of an almost complete replacement dolomitization of the former host rocks. Such replacement represents the first fluid-related event recorded in the area. Even if homogenization temperatures of fluid inclusions are missing, the increase of crystal size may be explained by the occurrence of hot fluids. After the dolomitization, the Unit underwent strong brecciation. The breccias are genetically related to the circulation of overpressured carbonate-rich fluids as the polyphase dolomite and calcite cements document. The occurrence of sediment geopetally filling the cavities of the breccias allow to consider that the hydrofracturation took place at shallow levels in the sedimentary column and in connection with the seafloor. Since the internal sediment is dolomitized, its deposition should have occurred concomitantly with the circulation of dolomitizing fluids. O-C isotopic values of replacement dolomite and dolomite cement of breccias show the same trend already described for the Adriatic margin. δ 13 C values are slightly positive whereas δ 18 O values are slightly (replacement dolomite up to -8‰ VPDB) to strongly negative (dolomite cement up to -13‰ VPDB). Despite the absence of homogenization temperatures of fluid inclusions, stable isotope geochemistry may support a hydrothermal character for the fluids responsible of replacement and brecciation. 16.2.2.2 The Black Limestones Unit The Black Limestones Unit is stratigraphically above the Black Dolomites Unit and consists of fine-grained well-bedded limestones, locally containing fibrous aggregates of Mg-rich alumo-silicates (talc and chlorite). The Unit shows the most abundant diversity in terms of rock types and fluid-related processes of the whole study area. For such reason, two different sites have been distinguished: the Quarries area and the Riverbed area. The Quarries area The Quarries area is mainly constituted of hydrofracturing and sedimentary breccias. The first type is further composed of three different types of breccias depending on the mineralogy of the clasts and the cements. Type 1 is made of clasts of limestones within a coarse calcite cement, type 2 is made of already dolomitized clasts of the Black Dolomite Unit encased in a fine-grained calcite cement, type 3 is a polimict breccias whose clasts are made of limestones and dolostones within a complex cement made of dolomite and calcite. All the three types of breccias, because of their textures, had to be formed by circulation of overpressured carbonate-rich fluids. The second rock type is a deformed carbonate sedimentary breccia made of sheared dolomite clasts within a micritic matrix and is closely associated to the first one. O and C isotope analyses were performed on the host limestone and the calcite cement of type 1 hydraulic breccia. The slightly positive δ 13 C and the negative δ 18 O (up to -14‰ VPDB) combined with homogenization temperatures in the range of 180-190°C for dolomite cement of breccia type 3 and 240-250°C

Findings

  of clasts made of Black Dolomites and Limestones Units within breccias type 2 and 3 allowed to assign a younger age to this Unit (e.g. at least Kimmeridgian). In terms of fluid circulation, this Unit records different interesting stages:-A first fluid flow event affected the sedimentary column before its erosion and re-deposition as the dolomite veins within the clasts of the breccias document. Some portions of the sedimentary sequence underwent pervasive dolomitization as the coarse-grained clasts made of Black Dolomites Unit records.-The second stage occurred after the deposition of the breccias. It is documented by authigenic minerals (quartz, albite and sulphides) that grew over the matrix and clasts. Diffuse albitization has been described in the eastern Pyrenees connected to a mid-Cretaceous HT-LP metamorphic event.-Elongated calcite crystals within pressure shadows around some carbonate and ophitic clasts suggest its precipitation in a time of ongoing tectonic activity. This could be considered as a later stage connected to the compressional Pyrenean evolution. The formation of the carbonate veins cutting through the whole rock package may be possibly related to this stage.On the whole, the Pyrenean study area registered two main polyphase stages related to fluid circulation: 1) Carbonate-rich stage led to the fabric-destructive replacement dolomitization of the Black Dolomites Unit. New pulsations generated the hydraulic breccias within the same Unit. This stage could also be responsible of the formation of breccia type 3 in the Black Limestones Unit. Calcite cements in the breccias of Black Dolomites Unit and Black Limestones Unit document that the physicochemical features of fluids changed to calcite-prone.

  The prevailing lithotype of the allochthon is represented by grey dolostones characterized by an alternation of homogeneous, finely crystalline and thinly laminated beds showing shrinkage pores filled with dolomite and calcite cement.

	These distinctive features allow to assign these rocks to the Upper Triassic
	peritidal dolomites of the Hauptdolomit Formation. Locally the allochthon is
	overlain by clast-supported breccias with angular to sub-rounded clasts of cm-to
	m-size. Clasts include: mudstones, grainstones with ooids whose cortices are
	partially dissolved and replaced by calcite spar; wackestones to packstones with
	peloids and benthic foraminifers (Glomospira, Triasina); wackestones with
	sponge spicules replaced by calcite spar; coarse crinoidal grainstones;
	packstones with peloids, crinoid and bivalve shell fragments, and sparse benthic
	foraminifers (Involutina). Clasts of cherts containing crinoids, ghosts of silicified
	peloids and patches of quartz and chalcedony, which represent void-filling silica
	cements, also occur. The matrix of the breccias consists of a packstone with
	peloids and bioclasts and sand-sized lithoclasts with the same composition and
	texture of the coarser clasts, and shows compactional features. The texture,
	composition and presence of biostratigraphically significant foraminifera allow
	to assign these clasts to the Upper Triassic Kössen and to the Lower Jurassic

  , which drilled the distal part of the Iberia margin, a diffuse hydrothermal dolomitization is described. Petrographic characteristics as well as stable isotope geochemistry are completely similar to those presented in this work. The analytical dataset, on the contrary, is much less developed; it would thus be useful to apply the here presented methodologies. Annex A -O and C isotopic values of the Alpine samples. MO = Il Motto area; PA = Piz Alv area; PVL = Piz Val Lunga area; FCT = Fuorcla Cotschna area; MP = Mal Pass area. ANNEX B -Homogenization temperature of fluid inclusions. MO = Il Motto area; PVL = Piz Val Lunga area; FCT = Fuorcla Cotschna area; MP = Mal Pass. ANNEX D -He isotopic values. PVL = Piz Val Lunga area; FCT = Fuorcla Cotcschna area; MP = Mal Pass area.ANNEX F -Main and trace elements geochemistry of the Alpine samples. Rare earth elements analyses performed on the Alpine samples. ANNEX H -O and C isotopic values of Pyrenean samples and homogenization temperatures (T h ) of fluid inclusions.

	Unit Repl. Dol. M02 M02 PA 1 PVL PVL PVL PVL PVL PVL PVL 10 PVL 11 PVL 12 PVL 12 PVL 12 PVL 17 PVL 17 PVL 26 FCT FCT FCT 3L FCT FCT FCT Unit Cem Cc + Dedol PA 8 PA 10 PA 10 PVL 8 PVL 9 PVL 3 PVL 3 PVL 4 PVL PVL PVL PVL PVL PVL MP 24 Calcite veins PVL 3 PVL 4 PVL PVL PVL PVL FCT 4 FCT 5 Sample Proximal -Cem Dol δ 13 C % VPDB 2,04 1,66 1,72 1,27 1,88 1,60 1,38 1,05 0,76 2,90 3,07 1,48 1,43 1,52 2,46 1,21 2,71 1,20 0,98 0,73 2,24 2,42 2,35 δ 13 C % VPDB 2,41 2,65 2,76 0,14 -0,23 0,51 0,23 0,30 1,88 1,91 0,88 1,94 0,88 2,71 0,88 0,24 0,22 1,42 2,79 2,80 2,79 1,69 1,74 T h °C (±0,1) δ 18 O % VPDB -0,76 0,05 -0,57 -4,60 -4,79 -5,62 -3,72 -2,81 -2,31 -3,60 -1,47 -2,33 -4,10 -3,73 -2,71 -1,01 -3,45 -2,15 -3,68 -3,14 -3,99 -3,13 -1,97 δ 18 O % VPDB -1,66 -1,78 -1,91 -6,07 -8,90 -7,41 -7,90 -7,25 -7,97 -12,05 -6,85 -11,80 -12,72 -5,19 -15,02 -9,81 -6,33 -7,08 -6,78 -6,98 -7,74 -9,16 M02 86 141,3 86,2 144,3 116,3 145,8 120,8 146,2 125,2 153,1 127,8 155,5 128,3 157,9 135 158,8 135,7 161,6 137,6 170,2 137,8 174,7 138,8 186,9 139 191 139,2 205,9 139,6 Central dist-Repl Dol PVL 5-9-12 87,9 125,8 FCT 8 91 125,9 93,2 126 T h °C (±0,1) Outer Dist -Qtz sept MP 11 112,1 151,6 126,8 153,8 129,2 153,8 130,1 154 133,9 154 135,8 154,7 140,2 156,4 140,5 158,8 141,1 158,9 141,2 160 141,7 170,2 141,9 175,4 144 175,6 144,1 175,8 145,5 176 145,8 187,2 148,1 189,2 148,2 Outer Dist -Dol sept MP 11 155,1 156,8 158,2 Sample He R/Ra Ar ccSTP/g ccSTP/g Central Distal -Vein Dolomite Sample Unit Cem Dol. VPDB δ 13 C % M02 2,84 PA 1 2,97 PA 1 2,11 PA 5 3,43 PVL 26 2,88 PVL 26 2,84 Cem Dol. PVL 26 2,79 PVL 26 1,50 PVL 26 2,62 PVL 26 2,66 PVL 26 2,62 FCT 1 1,35 FCT 3 1,03 FCT 3 1,04 FCT 3 1,02 FCT 75 0,77 MP 8 1,08 MP 18 1,33 MP 19 1,15 MP 20 1,41 MP 21 1,19 MP 22 1,35 Sample °C (±0,1) δ 18 O % VPDB -5,55 -2,52 -4,90 -3,00 -8,92 -10,36 -7,46 -8,62 -8,18 -9,51 -5,99 -6,33 -5,74 -6,56 -6,78 -13,84 -14,30 -8,74 -14,24 -14,00 -14,41 T h Central dist-Repl Dol 121 145,2 121,2 145,5 121,2 146 121,4 146,7 121,6 146,8 121,8 147,3 123,2 147,6 124,8 147,7 124,9 152,5 Central Dist -Cem CC + Dedol PVL 5-9-15 77,4 118,2 78,3 118,5 88,7 118,9 91,5 122,5 92,7 123 95,5 125,5 96,1 129,5 97 131,5 97,6 134,3 T h °C (±0,1) Outer Dist -Vein Qtz MP 17 119,8 137,4 120,8 138,8 121 139 121,6 139,3 122,2 141,7 125,3 141,7 129,9 143,3 130 145 130,7 146,8 135,1 149 135,8 162,1 137,1 204,5 Outer Dist -Vein Dol MP 17 138,2 146,1 143,9 146,2 144,6 147,8 144,9 153,3 145,2 157,5 146 158,3 40 Ar/ 36 Ar CO 2 ccSTP/g PVL 26 3,11E-06 0,044 0,00070 798,6 8,70E-04 FCT_1 3,96E-07 0,038 0,00048 434,6 2,88E-03 FCT_3 5,34E-08 0,047 0,00021 296,3 6,02E-05 FCT_8 1,46E-07 0,028 0,00015 368,9 1,17E-03 FCT_71 6,74E-09 0,100 4,86E-04 FCT_75 2,56E-07 0,027 0,00074 297,5 Outer Distal -Vein Dolomite MP 8 3,77E-06 0,039 0,00099 296,6 4,90E-03 MP 18 1,14E-06 0,028 0,00043 379,9 8,25E-04 MP_23 2,44E-06 0,022 0,00034 296,3 7,94E-04 MP_19 1,19E-06 0,034 0,00027 295,5 1,04E-03 Central Distal -Dedolomite PVL_15 4,81E-07 0,034 4,09E-03 Outer Distal -Vein Quartz MP 18 1,26E-06 0,026 0,00152 334,5 7,45E-04 Sample age (Ma) Sample age (Ma) Replac. Dolomite Cem Calcite -Dedolomite MO 198,9 ± 3,3 PVL 118 ± 29 PA 206 ± 20 231 ± 18 PVL 176,7 ± 4,7 198 ± 3,5 179 ± 11 Dolomite vein 144 ± 24 PVL 45 ± 36 145 ± 12 FCT 169 ± 11 200,4 ± 6,4 228 ± 64 FCT 176 ± 17 113 ± 36 192,5 ± 9 202 ± 4,8 MP 202 ± 10 207,8 ± 2,7 202,9 ± 4 SAMPLE SiO2 Al2O3 Fe2O3 CaO MgO Na2O % % % % % % REF HD RE 13 0,05 0,02 0,06 31 21,5 0,01 RE 30 0,34 0,18 0,07 30,6 21,2 0,01 HD MO 1 1,12 0,49 0,37 31 20,8 0,03 MO 2 0,39 0,19 0,18 30,6 20,7 0,02 PA 1 14,4 6,96 3,39 22,9 14,8 0,05 PA 1 1,83 0,7 0,35 31,2 20,5 0,05 PVL 8 1,73 0,69 0,3 34,2 17,8 0,01 PVL 22 4,88 0,45 0,17 51,5 1,03 0,01 FCT 1 1,62 0,68 0,39 30,6 20,7 0,01 FCT 3 18,25 0,34 0,66 25 16,65 0,03 FCT 8 1,67 0,49 0,4 31,1 20,9 0,01 FCT 65 39 0,19 0,35 19,05 13,3 0,01 MP 21 1,39 0,24 0,31 31,1 21,4 0,03 MP 23 5,43 1,07 0,61 28,9 19,7 0,03 HD GOUGE PVL 1 14,95 1,49 1,52 31,9 10,8 0,01 PVL 2 9,4 1,25 1,46 34,4 12,6 0,01 FCT 7 4,25 0,41 0,86 30,4 19,75 0,01 HD CAT PVL 12 2,58 1,27 0,38 37,1 13,95 0,01 PVL 54 25,4 0,03 1,18 23,4 15,65 0,03 DEDOL PA 10 1,76 0,58 0,28 51,3 2,3 0,02 PVL 15 1,77 0,58 0,35 52 1,45 0,02 PVL 59 1,83 0,22 0,23 51,1 1,58 0 PVL 60 2,75 0,92 0,45 49,5 2,84 0,01 K2O Cr2O3 TiO2 MnO P2O5 SrO BaO LOI C % % % % % % % % % <0.01 <0.01 <0.01 0,01 <0.01 <0.01 <0.01 45,8 12,95 0,02 <0.01 0,01 0,01 0,02 <0.01 <0.01 45,6 12,75 0,17 <0.01 0,02 0,01 0,02 <0.01 <0.01 46,3 12,1 0,07 <0.01 0,01 0,01 0,01 <0.01 <0.01 45,9 12,7 2,58 0,01 0,33 0,04 0,27 <0.01 0,01 34,3 8,85 0,18 <0.01 0,03 0,02 0,02 <0.01 <0.01 44,8 12,5 0,23 <0.01 0,04 0,03 <0.01 0,01 <0.01 46,3 12,4 0,14 <0.01 0,02 0,02 0,03 0,03 <0.01 43,1 11,35 0,22 <0.01 0,03 0,01 0,02 0,01 <0.01 47 12,5 0,08 <0.01 0,01 0,01 <0.01 0,01 <0.01 39 10,6 0,18 <0.01 0,03 0,03 0,01 0,01 <0.01 46,6 12,5 0,08 <0.01 0,01 0,01 <0.01 <0.01 <0.01 28,9 7,91 0,1 <0.01 0,01 0,07 0,01 <0.01 <0.01 45,1 12,65 0,34 <0.01 0,03 0,04 0,01 0,01 <0.01 43,7 11,65 0,28 <0.01 0,06 0,48 0,03 0,02 0,03 38,4 10,25 0,2 <0.01 0,05 0,38 0,02 0,02 0,01 41,3 11,05 0,11 <0.01 0,01 0,15 0,01 0,01 <0.01 45,6 12,4 0,37 <0.01 0,07 0,05 0,02 <0.01 <0.01 45,1 12 <0.01 <0.01 <0.01 0,02 0,01 <0.01 <0.01 34,9 9,46 0,18 <0.01 0,03 0,02 0,03 0,01 <0.01 43 11,4 0,19 <0.01 0,03 0,18 <0.01 0,01 0,03 43,7 11,75 0,05 <0.01 0,01 0,13 0,01 <0.01 0,05 43,1 11,6 0,33 <0.01 0,03 0,2 0,01 <0.01 0,03 42,1 11,3 0,04 <0.01 <0.01 0,07 0,01 <0.01 0,07 43,7 12 0,11 0,01 0,03 0,02 0,62 <0.01 <0.01 8,69 2,3 S Ba Cr Cs Ga Ge Hf Nb Rb % ppm ppm ppm ppm ppm ppm ppm ppm <0.01 1,8 <10 <0.01 <0.1 <5 <0.2 <0.2 0,3 <0.01 4,9 <10 0,21 0,3 <5 <0.2 0,2 2 0,01 10,6 10 0,66 0,7 <5 <0.2 0,5 6,3 <0.01 5 10 0,14 0,3 <5 <0.2 0,2 2,8 0,01 113,5 50 5,11 9 <5 1,8 7,8 90,2 0,01 13 <10 0,34 0,9 <5 <0.2 0,7 7,3 0,01 19,4 10 0,62 1 <5 0,2 0,9 10,7 0,01 13,1 20 0,43 0,6 <5 <0.2 0,4 6,1 <0.01 8,2 10 0,46 0,9 <5 0,2 0,4 8,3 <0.01 5,7 <10 0,31 0,2 <5 <0.2 <0.2 3,5 <0.01 10,1 10 0,35 0,4 <5 0,2 0,4 8,9 0,1 7 10 0,09 0,5 <5 <0.2 0,2 2,5 <0.01 6,4 10 0,06 0,5 <5 <0.2 0,2 2,9 <0.01 21,9 10 0,35 1,5 <5 0,2 0,7 12 0,06 293 20 0,95 2,4 <5 0,5 2,4 13,1 0,03 93,7 20 0,79 2,2 <5 0,3 1,6 9,9 <0.01 16,7 <10 0,21 0,3 <5 <0.2 <0.2 6 0,01 27,9 20 2,02 1,9 <5 0,6 1,4 18,6 0,01 4 10 <0.01 0,1 <5 <0.2 <0.2 0,3 0,01 12,5 10 0,47 0,8 <5 0,2 0,7 7,7 0,05 240 10 0,85 0,8 <5 <0.2 0,6 8,9 0,02 473 10 0,16 0,5 <5 <0.2 0,3 2,9 0,06 226 10 1,37 1,3 <5 0,2 0,8 15,7 0,01 538 10 0,04 0,4 <5 <0.2 0,2 2 0,01 15,7 50 0,34 0,7 <5 0,2 1,2 5,7 Sn Sr Ta Th U V W Zr As ppm ppm ppm ppm ppm ppm ppm ppm ppm 1 85,7 0,1 <0.05 7,49 57 <1 2 0,4 <1 97,3 0,1 0,16 4,56 21 <1 3 0,8 1 108 0,1 0,42 5,92 140 <1 5 53,6 <1 108,5 0,1 0,23 5,87 63 1 3 11,8 2 89,8 0,5 5,72 1,93 54 1 67 4,9 1 93,9 0,1 0,55 0,56 10 <1 7 3,4 2 107,5 <0.1 0,51 2,42 23 <1 8 1,1 <1 320 <0.1 0,32 1,73 18 1 5 0,7 1 106,5 <0.1 0,39 0,59 24 <1 9 1,3 1 99,7 <0.1 0,18 0,39 14 <1 4 0,4 <1 89,7 <0.1 0,42 1,48 29 <1 8 1,6 1 54,2 0,1 0,13 2,38 9 <1 2 14 1 56,5 0,2 0,13 0,48 19 <1 3 0,4 1 235 0,2 1,01 1,12 13 <1 9 2,9 3 284 0,1 1,12 3,06 36 1 20 4,4 1 251 <0.1 0,83 1,79 16 1 11 50,3 1 125,5 <0.1 0,12 1,1 7 <1 2 1,1 1 104 0,1 1,02 2,85 72 1 20 1,6 1 57 0,1 <0.05 3,28 19 <1 0 4,5 1 273 0,1 0,53 1,03 13 <1 8 1,3 <1 129 <0.1 0,5 3,59 22 1 7 6,6 1 113 0,1 0,3 1,6 14 <1 2 4,1 1 133 0,2 0,83 2,98 13 <1 7 7,3 1 145 0,1 0,11 2,29 14 <1 2 3,6 1 53,1 0,2 1,83 1,35 18 <1 9 4,8 Bi Hg In Re Sb Se Te Tl Ag ppm ppm ppm ppm ppm ppm ppm ppm ppm 0,02 0,008 <0.005 0,001 0,16 0,2 <0.01 <0.02 <0.5 0,02 0,009 <0.005 0,001 0,17 <0.2 0,01 0,03 <0.5 0,1 0,02 0,006 0,013 1,64 0,3 0,01 0,14 <0.5 0,06 0,02 <0.005 0,008 0,85 0,3 <0.01 0,08 <0.5 0,15 0,019 0,02 <0.001 0,35 0,8 0,57 0,05 <0.5 0,12 0,036 0,009 <0.001 0,42 0,4 0,08 0,03 <0.5 0,03 0,013 <0.005 0,003 0,13 0,4 0,01 0,02 <0.5 0,01 0,019 <0.005 0,001 0,06 0,2 0,01 0,02 <0.5 0,01 0,044 <0.005 <0.001 0,18 0,2 <0.01 0,02 <0.5 <0.01 0,026 <0.005 <0.001 0,08 0,2 <0.01 <0.02 <0.5 0,01 0,011 <0.005 0,001 0,06 0,2 0,01 0,02 <0.5 0,62 0,205 0,022 0,001 2,04 0,3 0,01 0,17 <0.5 0,02 0,012 <0.005 <0.001 0,19 0,2 <0.01 <0.02 <0.5 0,07 0,023 0,007 <0.001 0,24 0,4 0,01 0,03 <0.5 0,07 0,029 0,011 0,002 0,12 0,8 <0.01 0,12 <0.5 0,05 0,016 0,008 0,001 0,14 0,7 <0.01 0,03 <0.5 <0.01 0,014 <0.005 0,001 0,1 0,3 <0.01 0,02 <0.5 0,02 0,035 0,006 0,001 0,19 0,4 <0.01 0,04 <0.5 0,12 0,034 0,005 0,002 0,55 0,2 0,01 0,03 <0.5 0,06 0,008 <0.005 <0.001 0,23 0,3 0,02 <0.02 <0.5 0,01 0,027 <0.005 0,06 0,46 0,8 <0.01 0,18 <0.5 0,02 0,016 <0.005 0,015 0,3 0,4 0,01 0,1 <0.5 0,05 0,023 0,005 0,003 0,51 0,7 <0.01 0,12 <0.5 0,03 0,03 <0.005 0,01 0,26 0,2 0,01 0,03 <0.5 0,1 0,029 0,01 <0.001 0,39 1 0,01 0,04 <0.5 SAMPLE SiO2 Al2O3 Fe2O3 CaO MgO Na2O % % % % % % DOL VEINS PVL 26 8,22 1,19 1,19 33,2 14,1 0,03 FCT 8 1,59 0,4 0,5 30,8 21,5 0,01 MP 10 0,76 1,05 29,4 18 0,01 MP 38 0,12 0,27 19,45 13,45 0,01 MP 0,69 0,22 0,5 30,7 21 0,03 MP 0,24 0,06 0,18 32 22,1 0,04 MP 20,4 0,09 0,38 25,9 17,45 0,02 Fe-Mn PVL 11 9,77 1,6 1,9 29,7 16,5 0,04 FCT 12 24,2 0,56 1,7 22,5 14,15 0,05 OPH MP 9,41 0,7 1,91 44,8 7,71 0,01 K2O Cr2O3 TiO2 MnO P2O5 SrO BaO LOI C % % % % % % % % % 0,38 0,01 0,07 0,05 0,02 0,01 <0.01 42,5 11,45 0,14 <0.01 0,02 0,06 0,01 0,01 <0.01 46,4 12,5 0,27 <0.01 0,03 0,15 0,01 0,01 <0.01 41,7 11,2 0,05 <0.01 <0.01 0,04 <0.01 <0.01 0,01 28,7 8,04 0,08 <0.01 0,01 0,05 <0.01 <0.01 <0.01 45,1 12,6 0,04 <0.01 <0.01 0,05 <0.01 <0.01 <0.01 45,3 12,8 0,05 <0.01 <0.01 0,05 <0.01 <0.01 <0.01 36,4 8,41 S Ba Cr Cs Ga Ge Hf Nb Rb % ppm ppm ppm ppm ppm ppm ppm ppm 0,05 21 60 1,32 1,4 <5 0,6 1,3 16,4 <0.01 13,1 10 0,31 0,5 <5 <0.2 0,2 7,4 <0.01 13,8 10 0,38 1,2 <5 <0.2 0,5 10,6 0,01 81,2 10 0,16 0,1 <5 <0.2 <0.2 1,9 <0.01 5,6 10 0,13 0,4 <5 <0.2 0,2 2,4 <0.01 4,2 10 0,08 0,1 <5 <0.2 <0.2 0,7 <0.01 5,5 10 0,03 0,2 <5 <0.2 <0.2 1,2 0,02 32,6 20 1,4 2,5 <5 0,5 1,9 18,3 0,01 12,1 10 0,18 2,5 <5 0,2 0,2 3,9 <0.01 8,9 470 0,16 0,9 <5 <0.2 <0.2 0,5 Sn Sr Ta Th U V W Zr As ppm ppm ppm ppm ppm ppm ppm ppm ppm 2 172,5 <0.1 1,11 2,16 19 1 2,6 <1 130,5 <0.1 0,22 1,32 26 <1 0,6 1 173,5 0,1 0,56 0,65 15 <1 0,8 1 114 0,1 0,29 0,33 8 <1 10,5 1 177 0,1 0,13 0,19 14 <1 1,8 1 160,5 0,1 0,05 0,06 18 2 0,6 1 124 0,1 0,08 0,09 14 <1 <2 <0.1 Bi Hg In Re Sb Se Te Tl Ag ppm ppm ppm ppm ppm ppm ppm ppm ppm 0,03 0,036 0,006 0,014 0,26 0,7 <0.01 0,07 <0.5 0,01 0,015 <0.005 0,001 0,06 0,2 0,01 <0.02 <0.5 0,03 0,036 0,008 <0.001 0,14 0,4 <0.01 0,02 <0.5 0,28 0,033 0,011 <0.001 1,16 0,5 0,01 0,03 <0.5 0,04 0,023 0,014 <0.001 0,27 0,5 <0.01 <0.02 <0.5 0,02 0,01 0,008 <0.001 0,1 0,2 <0.01 <0.02 <0.5 0,02 0,012 0,011 <0.001 0,17 0,3 <0.01 <0.02 <0.5 0,05 0,156 0,009 <0.001 0,33 0,6 0,1 0,05 <0.5 0,02 0,016 <0.005 0,003 0,12 0,3 0,01 0,02 <0.5 0,02 0,011 <0.005 <0.001 0,12 0,2 0,01 <0.02 <0.5 Cd Co Cu Li Mo Ni Pb Sc Zn ppm ppm ppm ppm ppm ppm ppm ppm ppm 0,8 5 3 <10 1 1 3 1 11 0,5 2 <1 <10 <1 <1 <2 <1 10 <0.5 2 5 <10 1 6 4 1 17 <0.5 1 2 <10 1 1 379 <1 52 <0.5 1 4 <10 1 5 4 2 16 <0.5 <1 2 <10 1 2 4 1 14 <0.5 2 3 <10 1 <1 <2 1 11 ANNEX G -SAMPLE La Ce Pr Nd Sm Eu ppm ppm ppm ppm ppm ppm REF HD RE 13 0,6 0,5 0,05 0,2 0,03 <0.03 RE 30 1 1,3 0,15 0,5 0,12 <0.03 cond 3,4086 1,492 1,1223 0,7737 0,5099 0 HD MO 1 1,8 3,1 0,37 1,3 0,29 0,06 MO 2 1,5 1,9 0,22 0,8 0,2 0,03 cond 7,0303 4,1446 3,3109 2,321 1,6655 0,8036 PA 1 3 5,8 0,61 2,4 0,41 0,11 cond 12,782 9,6154 6,8462 5,305 2,7872 1,9643 PA 1 18,2 50,9 4,21 15,8 2,88 0,62 cond 77,546 84,383 47,25 34,925 19,579 11,071 PVL 8 1,8 3 0,35 1,4 0,24 0,06 PVL 22 2 3,1 0,33 1,3 0,29 0,05 FCT 1 2,7 4,8 0,58 2,5 0,57 0,1 FCT 3 2,6 5,3 0,59 2,3 0,4 0,11 FCT 8 2,5 4,2 0,43 1,8 0,39 0,1 FCT 65 1,1 1,4 0,17 0,5 0,06 <0.03 cond 9,0186 6,0234 4,5829 3,6104 2,2094 1,25 MP 21 1,8 2,8 0,38 1,4 0,28 0,06 MP 23 5,3 10,2 1,16 4,3 0,83 0,26 cond 15,126 10,776 8,642 6,2997 3,7729 2,8571 HD GOUGE PVL 1 8,8 13,9 1,85 7,9 2,39 0,9 PVL 2 10,2 17,3 2,11 8,4 2,63 1,36 FCT 7 2,1 3,6 0,42 1,7 0,31 0,43 Gd Tb Dy Y Ho Er Tm Yb Lu ppm ppm ppm ppm ppm ppm ppm ppm ppm <0.05 <0.01 <0.05 <0.5 <0.01 <0.03 0,01 <0.03 <0.01 0,11 <0.01 0,06 <0.5 <0.01 0,03 0 0,03 0,01 0,2798 0 0,1236 0 0 0,0944 0,2066 0,0923 0,2058 0,24 0,03 0,22 1,1 0,04 0,08 0,01 0,12 0,02 0,14 0,02 0,1 0,7 0,01 0,08 0,01 0,04 0,01 0,9664 0,6887 0,6593 0,5769 0,4496 0,5035 0,4132 0,4923 0,6173 0,48 0,08 0,4 3,1 0,08 0,26 0,03 0,23 0,03 2,4415 2,2039 1,6481 1,9872 1,4388 1,6362 1,2397 1,4154 1,2346 2,98 0,41 2,23 14,6 0,51 1,36 0,17 1,13 0,18 15,158 11,295 9,1883 9,359 9,1727 8,5588 7,0248 6,9538 7,4074 0,26 0,05 0,35 1,5 0,06 0,18 0,01 0,19 0,02 0,23 0,04 0,24 1,3 0,04 0,12 <0.01 0,12 0,01 0,5 0,07 0,35 2,1 0,07 0,18 0,02 0,16 0,02 0,48 0,06 0,34 2,1 0,07 0,14 0,01 0,14 0,02 0,36 0,05 0,26 1,6 0,05 0,15 0,01 0,15 0,02 0,08 0,01 0,05 <0.5 <0.01 0,04 0,01 <0.03 <0.01 1,6192 1,2856 1,0919 0,9188 0,8693 0,8496 0,4132 0,7795 0,6173 0,3 0,05 0,24 1,9 0,03 0,16 0,02 0,11 0,02 0,89 0,14 0,75 4,9 0,15 0,43 0,05 0,36 0,04 3,0264 2,6171 2,0396 2,1795 1,6187 1,8565 1,4463 1,4462 1,2346 2,96 0,53 3,17 19,7 0,6 1,81 0,23 1,47 0,2 3,28 0,5 3,31 19,4 0,55 1,57 0,19 1,13 0,14 0,41 0,04 0,28 1,9 0,04 0,16 <0.01 0,1 0,01 11,275 9,8255 9,2844 8,7607 7,1343 7,4261 5,7851 5,5385 4,8011 0,45 0,07 0,31 2,2 0,1 0,26 0,03 0,29 0,03 ƩREE Y/Ho La/Yb Ce/Ce* Eu/Eu* ppm 1,39 3,31 0 36,927 0 0,7628 8,78 5,76 36 14,28 0,6334 0,8591 17,02 38,75 9,031 0,753 1,0279 116,18 28,627 11,151 0,6427 1,394 9,47 9,17 14,72 14,66 12,07 3,42 29,655 11,57 0,6609 0,9369 9,55 29,76 37,778 10,459 0,8455 0,9425 66,41 72,07 11,5 34,454 5,4108 1,3721 0,8678 15,69 La Ce Pr Nd Sm Eu Gd Tb Dy Y Ho Er Tm Yb Lu ƩREE Y/Ho La/Yb Ce/Ce* Eu/Eu* SAMPLE ppm ppm ppm ppm ppm ppm SILIC PVL 58 28,1 16,9 6,39 26 4,66 0,99 FCT 12 2,5 4,5 0,47 1,9 0,41 0,11 cond 65,19 17,739 38,496 30,836 17,233 9,8214 SEPT MP 10 5,3 10,6 1,17 4,1 0,81 0,17 FCT 11 1,4 12 0,25 0,9 0,32 0,03 FCT 71 0,7 0,7 0,06 0,3 0,05 <0.03 MP 4 5,8 15,2 1,71 5,8 1,15 0,24 cond 14,061 15,957 8,9506 6,134 3,9599 1,9643 DOL VEINS PVL 26 4,9 8,3 0,96 4,2 0,63 0,18 FCT 8 2,7 4,5 0,5 2,1 0,37 0,08 cond 16,191 10,61 8,193 6,9629 3,399 2,3214 MP 8 7,2 14,4 1,83 6,9 1,33 0,35 MP 18 2,2 4,2 0,54 1,8 0,49 0,06 MP 19 2,9 6,3 0,82 3 0,56 0,12 MP 20 2,7 5,6 0,75 2,7 0,54 0,11 MP 21 2,6 5,3 0,71 2,9 0,65 0,1 cond 14,998 11,87 10,438 7,6481 4,8538 2,6429 Fe-Mn PVL 11 6,2 10,9 1,33 5,4 1,23 0,3 FCT 12 2,2 3,6 0,4 1,6 0,39 0,07 cond 17,895 12,019 9,7082 7,7365 5,5065 3,3036 OPH MP 24 1,2 0,5 0,13 0,7 0,18 0,09 cond 5,1129 0,8289 1,459 1,5473 1,2237 1,6071 ppm ppm ppm ppm ppm ppm ppm ppm ppm 5,15 0,66 3,74 31,6 0,81 2,14 0,25 1,25 0,18 0,45 0,08 0,47 3 0,1 0,29 0,05 0,31 0,05 14,242 10,193 8,6733 11,09 8,1835 7,6463 6,1983 4,8 4,7325 0,83 0,11 0,72 4,9 0,16 0,38 0,07 0,34 0,06 0,25 0,05 0,24 1,2 0,04 0,13 <0.01 0,17 0,02 <0.05 <0.01 <0.05 <0.5 <0.01 <0.03 <0.01 <0.03 <0.01 1,08 0,17 0,99 6,6 0,18 0,53 0,07 0,46 0,05 2,7467 2,2727 2,0087 2,0353 1,7086 1,6362 1,4463 1,4923 1,3374 0,73 0,09 0,63 3,4 0,11 0,38 0,04 0,24 0,03 0,32 0,05 0,31 2,2 0,07 0,18 0,01 0,15 0,01 2,6704 1,9284 1,9365 1,7949 1,6187 1,7621 1,0331 1,2 0,823 1,39 0,19 0,96 6,7 0,17 0,48 0,06 0,31 0,04 0,34 0,05 0,21 1,3 0,03 0,14 0,02 0,11 0,02 0,51 0,1 0,49 3 0,09 0,27 0,02 0,31 0,04 0,6 0,08 0,47 2,4 0,08 0,27 0,03 0,2 0,04 0,48 0,06 0,37 2,7 0,07 0,26 0,04 0,25 0,04 3,3774 2,6446 2,0602 2,0641 1,5827 1,7873 1,405 1,4523 1,4815 1,14 0,17 1,14 6 0,22 0,67 0,07 0,5 0,07 0,35 0,05 0,35 2,2 0,07 0,24 0,02 0,21 0,03 3,7894 3,0303 3,0696 2,6282 2,6079 2,8634 1,8595 2,1846 2,0576 0,21 0,04 0,24 2,2 0,04 0,13 0,02 0,16 0,03 1,0682 1,1019 0,9889 1,4103 0,7194 0,8181 0,8264 0,9846 1,2346 ppm 128,82 14,69 38,022 13,581 0,6269 0,3541 29,72 17 1,81 40,03 33,421 9,422 0,5956 1,4224 24,82 13,55 31,111 13,492 0,7705 0,9212 42,31 11,51 18,53 16,57 16,53 36,591 10,327 0,6527 0,9487 35,34 11,78 28,276 8,1915 0,7232 0,9119 5,87 55 5,1928 1,4057 0,3035 Unit δ 13 C δ 18 O Unit T h BDU -Host % VPDB % VPDB BLU -Cement °C (±0,1) MAR 3,29 -6,77 Cc breccia type 1 MAR 8 2,62 -4,52 227,9 MAR 2,27 -3,84 240,7 MAR 2,61 -7,79 240,2 MAR 2,67 -10,78 249,2 RI 9 3,05 -6,51 249,3 MB 2 2,95 -3,37 228,9 BDU -Cement 232,8 MAR 8 1,61 -9,25 244,7 MAR 1,38 -8,60 Dol breccia type 3 MAR 2,16 -9,32 156,6 162,7 MB 2 1,81 -12,10 157,7 177,3 BLU -Host 152,2 173 RI 1 1,19 -1,26 158,9 185,8 RI 1 1,17 -1,79 155 180,2 RI 5 0,82 -1,09 163,3 175,7 MAR 2,58 -7,37 181,3 190,2 MAR 2 2,39 -5,29 184,6 191,4 MAR 2,57 -7,37 187,4 179,4 BLU -Cement 203,1 186 97,8 Sample PVL 61 5,83 0,12 0,38 34,1 16,8 0,03 0,08 <0.01 0,03 2,74 0,01 0,01 <0.01 33,9 9,22 0,02 12,5 20 0,23 2,2 <5 0,4 0,4 4,6 <1 193 <0.1 0,63 2,72 20 1 12 2,6 0,02 0,025 <0.005 0,001 0,07 0,4 <0.01 <0.02 <0.5 0,4 <0.01 0,07 0,05 0,03 <0.01 <0.01 41,4 10,95 1 96,9 0,1 1,32 1,98 32 1 2,3 0,6 4 17 10 2 4 8 2 36 cond 29,967 19,231 16,386 13,263 12,078 16,012 0,05 0,01 <0.05 <0.5 0,01 <0.03 <0.01 0,03 <0.01 2,01 MAR 0,97 -7,66 163,3 189,9 -8,01 FCT 5 1,80 -8,44 PVL 58 78,7 0,44 0,56 10,45 0,52 0,02 0,79 0,01 0,08 0,03 0,01 <0.01 <0.01 8,02 2,11 0,02 38,5 30 1,22 3,1 <5 0,4 1,6 31 1 41 0,3 1,35 1,43 27 1 16 1,4 0,26 0,023 0,011 <0.001 0,41 0,2 0,03 0,04 <0.5 0,07 <0.01 0,03 2,42 <0.01 0,02 <0.01 34,7 9,37 <1 190,5 <0.1 0,43 2,39 17 <1 3,8 <0.5 5 2 <10 2 1 11 1 7 PVL 12 3 5,4 0,65 2,4 0,41 0,09 1,2716 1,1019 0,6386 0,7051 0,9892 0,8181 0,6198 0,9846 0,6173 20 8,0056 0,5762 0,9107 RI 11 1,61 -6,54 164 195,9 SILIC FCT 12 25,4 0,58 1,97 21,4 12,9 0,05 0,12 0,01 0,01 0,11 <0.01 <0.01 0,01 3,43 0,6 <0.01 45,7 30 0,24 0,7 <5 <0.2 <0.2 4,5 <1 23,2 <0.1 0,11 0,37 75 6 2 2,4 0,06 <0.005 <0.005 <0.001 0,68 <0.2 0,14 <0.02 0,5 <0.01 0,07 0,03 0,15 0,03 0,01 <0.01 36,6 8,93 1 149 0,1 <0.05 0,08 10 <1 2,4 <0.5 30 11 <10 1 382 2 3 13 HD CAT PVL 54 0,7 0,8 0,07 0,3 0,04 <0.03 0,63 0,1 0,48 4,3 0,12 0,28 0,04 0,27 0,05 19,77 MB 2 -1,97 -13,62 166,1 194,8 -13,91 FCT 75 1,34 -1,54 MP 23 2,12 MP 10 80 2,49 0,94 5,46 3,31 0,16 <0.01 <0.01 <0.01 0,01 <0.01 <0.01 <0.01 0,52 0,09 0,02 4,6 30 0,03 0,3 <5 <0.2 <0.2 0,2 1 3,8 0,1 <0.05 0,11 7 2 <2 3,8 0,17 0,043 <0.005 <0.001 0,51 0,2 0,01 0,03 <0.5 cond 7,8824 5,1393 4,0404 2,9841 1,5296 0,8036 3,2045 2,7548 1,9778 2,7564 2,1583 1,7621 1,6529 1,6615 2,0576 35,833 10,257 0,6858 0,6782 Mylon-Marb 172,8 181,2 -13,59 MP 8 -0,14 -4,40 MP 11 0,35 -9,57 MP 16 1,78 -4,05 FCT 11 88,1 0,28 4,17 1,53 0,87 <0.01 0,64 0,01 0,07 0,04 0,02 <0.01 <0.01 8,89 2,37 0,01 46,6 30 1,26 2,8 <5 0,5 1,7 30,8 1 86,6 0,2 1,34 0,42 20 1 19 1,9 0,2 0,035 0,01 <0.001 0,44 0,4 0,05 0,04 <0.5 PA 10 4 4,9 0,75 3,1 0,61 0,14 2,29 0,34 2,51 15,7 0,53 1,67 0,18 1,45 0,19 58,43 MAR 2,06 -6,87 172,9 185,3 SEPT FCT 71 97,9 0,09 1,32 0,34 0,12 0,14 cond 17,043 8,1233 8,4175 6,8523 4,1468 2,5 0,26 0,04 0,29 2,7 0,05 0,19 0,03 0,13 0,02 10,87 MAR 1,67 -1,11 171,2 181,8
	MP 18 2,54 0,41 MP 4 62,13 MAR 5	1,92 78,3 PVL 15 2,36 15,3 -5,30 2,04 9,1 0,43 13,8 1,15 1,26 1,55 7,9 0,17 3,09 -6,71	2,22 6,8 0,81 1,69 0,08 0,13 0,63 179,9 182
	MP 20 DEDOL 0,14 0,02 5,4 MAR 3	0,84 PVL 59 0,09 1,11	-3,47 2,3 0,6 0,01 -7,86	3	0,33 0,07	0,01	1,3	0,18 0,03 <0.01 184,7	0,05
	MP 21 6,6506 5,5785 5,4079 5,4968 4,5863 5,0189 4,0289 3,7231 3,4979 1,50 -6,04 PVL 60 9,2 16,8 2,13 8 2,11 0,48 33,627 6,2943 0,7747 0,8797
	MP 22	1,02 PVL 61	-4,43 1,4	1,8	0,22		0,8	0,18	0,03
	MP 23	2,51 cond	-7,79 23,434 14,672 11,869 9,3391	7,07 5,3125
			230 232	219 221 227 229 233

99,6134,5 107,6

127,6 100,1 135,2 108,4 129,9 100,3 137,5 113,7 131,4 101,3 137,7 114,8 134,8 104,2 139,5 116,8 135,2 104,7 141,4 117,7 136 105,7 171,7 118,2 136,8 107,7 198 118,2 141,3 113,6 202,8 120 142,2 117,2 120,4 143

Due to oxidizing conditions in seawater, Ce 2+ is oxidized in Ce 3+ , which is less mobile resulting in Ce depletion of the seawater itself. Therefore, marine water commonly possesses a negative Ce anomaly [START_REF] Elderfield | The rare earth elements in seawater[END_REF][START_REF] De Baar | Rare earth elements in the Pacific and Atlantic Oceans[END_REF][START_REF] Hu | Geochemistry of sediments on the Rio Grande Rise and the redox evolution of the South Atlantic Ocean[END_REF], which is then inherited by carbonates formed in a marine environment. Converserly, positive Ce anomalies mainly occur due to detrital input [START_REF] Nath | Trace and rare earth elemental variation in Araban Sea sediments through a transect across the oxygen minimum zone[END_REF][START_REF] Madhavaraju | Rare earth elements in limestones of Kallankurichchi Formation of Ariyalur Group, Tiruchirapalli Cretaceous, Tamil Nadu[END_REF][START_REF] Madhavaraju | Geochemistry of the Dalmiapuram Formation of the Uttatur Group (Early Cretaceous), Cauvery basin, southeastern India: implications on provenance and paleo-redox conditions[END_REF]Madharavarju et al. 2010), diagenesis (Armstrong-Altrin et al., 2003) and scaveging processes [START_REF] Masuzawa | Settling particles with positive Ce anomalies from the Japan Sea[END_REF], and paleo-redox conditions [START_REF] Liu | Cerium, a chemical tracer for paleo-oceanic redox conditions[END_REF]. Only two sets of samples show evident Ce anomalies within the whole dataset: SILIC and SEPT with negative and positive anomalies respectively. All the other samples show very weak to no anomalies.

The clear difference in total amount of REE (ƩREE) of HD REF relative to the other samples as well as the absence of Y and Ho (below the detection limit) suggest that the so far described fluid-related processes (e.g. replacement dolomitization, dedolomitization) which affected the Hauptdolomit Fm. were key processes leading to the enrichment of REE as well as trace elements.

The distal margin

With a more detailed look at the distal margin preserved at Piz Val Lunga, Fuorcla Cotschna and Mal Pass areas, it becomes evident how the portions of HD more involved in the activity of the detachment fault recorded higher concentration of both trace and rare earth elements. Indeed, both HD GOUGE and DEDOL are strongly enriched. In the first case the enrichment can be related to fluids circulated along the detachment and/or interaction with the black gouge. In the second case, fluids responsible of dedolomitization of both HD and HD CAT may be ascribed for the enrichment too.

The proximal margin

The medium to coarsely crystalline dolostones replacing the former Hauptdolomit Fm. at Il Motto area, by similarities with those observed in others domains of the Adriatic margin and by U-Pb ages, are referred to the first carbonate-rich stage (pre-BBF).

The textures of the described breccias and the mineralogy of the cements point to the presence of hydrofracturing processes related to the upflow of overpressured carbonate-rich fluids. Microthermometry and negative O isotopic values of breccia dolomite cement (type 1) document the involvement of hydrothermal fluids. Even if there are not unequivocal proofs about the ages of the breccias and related cements, their strict association with the master fault bounding the half-graben seems to constrain their formation to the Hettangian tectonic activity occurring at Il Motto. By that moment, the thickness of the Hauptdolomit Formation of which the footwall consisted was not more than