Thomas Rigaudier

@article{Tachambalath_etal2023,

title = {Data report: major and trace element composition of silicates and carbonates from Bengal Fan sediments, IODP Expedition 354},

author = {A. P. Tachambalath and C. France-Lanord and A. Galy and T. Rigaudier and J. Charreau},

doi = {10.14379/iodp.proc.354.204.2023},

year  = {2023},

date = {2023-01-01},

journal = {Proceedings of the International Ocean Discovery Program},

volume = {354},

abstract = {During International Ocean Discovery Program Expedition 354, seven sites were drilled along a 320 km east--west transect at 8textdegreeN, constituting a relic of the Neogene sediment record of Himalayan erosion. Bengal Fan is one of the largest deep-sea fans in the world where turbiditic sediments issued from the Ganga and Brahmaputra River Delta and originally supplied by the Himalayan erosion of silicate and carbonate lithologies are deposited and stored. Quantification ofthe chemical composition of silicates and carbonates is necessary to understand the tectonoclimatic history of this region. This report presents the major and trace element concentrations of silicate and carbonate fractions of selected turbiditic samples from Sites U1450 and U1451. Efficient washing followed by refined acid leaching of the sediments was performed to eliminate sea salts and carbonates from these marine sediment samples. Shipboard samples show 20%--40% excess sodium concentration associated with sea salt derived from pore water. Weak acid treatment limits the total carbonate content in the samples to less than 0.1%. Depletion of major and trace elements observed due to acid leaching is attributed to the dissolution of carbonates and cations associated with Fe-Mn oxyhydroxides.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Marrocchi_etal2023,

title = {Hydrogen isotopic evidence for nebular pre-hydration and the limited role of parent-body processes in CM chondrites},

author = {Y. Marrocchi and T. Rigaudier and M. Piralla and L. Piani},

doi = {10.1016/j.epsl.2023.118151},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

journal = {Earth and Planetary Science Letters},

volume = {611},

number = {2},

pages = {118151},

abstract = {The conditions and environments in which hydrated phases in unequilibrated meteorites formed remain debated. Among carbonaceous chondrites, Mighei-type chondrites (CMs) display a large range in the degree of aqueous alteration, and thus record different stages of hydration and alteration. Here, we report the bulk H, C, and N contents, H and C isotopic compositions, and thermogravimetric signatures of the most-and least-altered CMs known so far, Kolang and Asuka 12236, respectively. We also report in-situSIMS measurements of the hydrogen isotopic compositions of water in both chondrites. Compared to other CMs, Asuka 12236 has the lowest bulk water content (3.3 wt.% H2O) and the most D-rich water and bulk isotopic compositions ($delta$D =180 and 280 , respectively). Combined with literature data, our results show that phyllosilicate-bearing CMs altered to varying degrees accreted water-ice grains with similar isotopic compositions. These results demonstrate that the hydrogen isotopic variations in CM chondrites (i) are not controlled by secondary alteration processes and (ii) were mostly shaped by interactions between the protoplanetary disk and the molecular cloud that episodically fed the disk over several million years. The minimally altered CM chondrites Paris and Asuka 12236 display peculiar, D-rich, hydrogen isotopic compositions that imply the presence of another H-bearing component in addition to insoluble organic matter and phyllosilicates. This component is most likely the hydrated amorphous silicates that are ubiquitous in these chondrites. CM bulk H and O isotopic compositions are linearly correlated, implying that (i) amorphous silicates in CM matrices were already hydrated by disk processes before the onset of CM parent-body alteration, and (ii) the quest for a hypothetically water-free CM3 is illusory.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Blard_etal2023,

title = {Basal debris of the NEEM ice core, Greenland: a window into sub-ice-sheet geology, basal ice processes and ice-sheet oscillations},

author = {P. H. Blard and M. Protin and J. L. Tison and F. Fripiat and D. Dahl-Jensen and J. P. Steffensen and W. C. Mahaney and P. R. Bierman and A. J. Christ and L. B. Corbett and V. Debaille and T. Rigaudier and P. Claeys and ASTER Team.},

doi = {10.1017/jog.2022.122},

year  = {2023},

date = {2023-01-01},

journal = {Journal of Glaciology},

volume = {614},

pages = {1--19},

abstract = {We present new data from the debris-rich basal ice layers of the NEEM ice core (NW Greenland). Using mineralogical observations, SEM imagery, geochemical data from silicates (meteoric 10Be, $epsilon$Nd, 87Sr/86Sr) and organic material (C/N, $delta$13C), we characterize the source material, succession of previous glaciations and deglaciations and the paleoecological conditions during ice-free episodes. Meteoric 10Be data and grain features indicate that the ice sheet interacted with paleosols and eroded fresh bedrock, leading to mixing in these debris-rich ice layers. Our analysis also identifies four successive stages in NW Greenland: (1) initial preglacial conditions, (2) glacial advance 1, (3) glacial retreat and interglacial conditions and (4) glacial advance 2 (current ice-sheet development). C/N and $delta$13C data suggest that deglacial environments favored the development of tundra and taiga ecosystems. These two successive glacial fluctuations observed at NEEM are consistent with those identified from the Camp Century core basal sediments over the last 3 Ma. Further inland, GRIP and GISP2 summit sites have remained glaciated more continuously than the western margin, with less intense ice-substratum interactions than those observed at NEEM.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Bouilhol_etal2022,

title = {Decoupling of inorganic and organic carbon during slab mantle devolatilisation},

author = {P. Bouilhol and B. Debret and E. Inglis and M. Warembourg and T. Grocolas and T. Rigaudier and J. Villeneuve and K. W. Burton},

doi = {10.1038/s41467-022-27970-0},

year  = {2022},

date = {2022-01-01},

journal = {Nature Communications},

volume = {13},

number = {308},

abstract = {Serpentinites are an important sink for both inorganic and organic carbon, and their behavior during subduction is thought to play a fundamental role in the global cycling of carbon. Here we show that fluid-derived veins are preserved within the Zermatt-Saas ultra-high pressure serpentinites providing key evidence for carbonate mobility during serpentinite devolatilisation. We show through the O, C, and Sr isotope analyses of vein minerals and the host serpentinites that about 90% of the meta-serpentinite inorganic carbon is remobilized during slab devolatilisation. In contrast, graphite-like carbonaceous compounds remain trapped within the host rock as inclusions within metamorphic olivine while the bulk elemental and isotope composition of organic carbon remains relatively unchanged during the subduction process. This shows a decoupling behavior of carbon during serpentinite dehydration in subduction zones. This process will therefore facilitate the transfer of inorganic carbon to the mantle wedge and the preferential slab sequestration of organic carbon en route to the deep mantle.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Debret_etal2022,

title = {High-pressure synthesis and storage of solid organic compounds in active subduction zones},

author = {B. Debret and B. M\'{e}nez and H. Bouquerel and P. Bouilhol and N. Mattielli and C. Pisapia and T. Rigaudier and H. M. Williams},

doi = {10.1126/sciadv.abo2397},

year  = {2022},

date = {2022-01-01},

journal = {Science Advances},

volume = {8},

pages = {eabo2397},

abstract = {Recent thermodynamic and experimental studies have suggested that volatile organic compounds (e.g., methane, formate, and acetate) can be produced and stabilized in subduction zones, potentially playing an important role in the deep carbon cycle. However, field evidence for the high-pressure production and storage of solid organic compounds is missing. Here, we examine forearc serpentinite clasts recovered by drilling mud volcanoes above the Mariana subduction zone. Notable correlations between carbon and iron stable-isotope signatures and fluid-mobile element (B, As and Sb) concentrations provide evidence for the percolation of slab-derived CO2-rich aqueous fluids through the forearc mantle. The presence of carbonaceous matter rich in aliphatic moieties within high-temperature clasts (\>350textdegreeC) demonstrates that molecular hydrogen production associated with forearc serpentinization is an efficient mechanism for the reduction and conversion of slab-derived CO2-rich fluids into solid organic compounds. These findings emphasize the need to consider the forearc mantle as an important reservoir of organic carbon on Earth.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Quesnel_etal2022,

title = {Significance of H2 and CO release during thermal treatment of natural phyllosilicate-rich rocks},

author = {B. Quesnel and L. Truche and M. Cathelineau and M. C. Boiron and M. Lempart-Drozd and T. Rigaudier and A. Derkowski and E. C. Gaucher},

doi = {10.1016/j.chemgeo.2021.120647},

year  = {2022},

date = {2022-01-01},

journal = {Chemical Geology},

volume = {588},

pages = {120647},

abstract = {Phyllosilicates may trap hydrogen (H2) in the crust, but they may also produce it through various processes, including oxidative dehydrogenation. The dehydrogenation temperature depends on the type and composition of the phyllosilicates considered, but it may be as low as 300 textdegreeC. Here, we document the release of H2 and CO during thermal treatment of chloritite (300 textdegreeC) and talc (500 textdegreeC) from the Trimouns deposits (Eastern Pyrenees, France). Thermal release of gases coupled to stable isotope analysis has been used to recover and characterize H2 and CO, the two detected gases. Hydrogen content may be as high as 7 ppm with $delta$DH2 values ranging from −258texttenthousand to -- 224texttenthousand for sub-pure chloritite and − 140texttenthousand for pure talc. CO content ranges between 3 ppm and 35.3 ppm with very homogeneous $delta$13CCO values between −27.6texttenthousand and − 25.7texttenthousand. This study supports the idea that H2 was produced during experiments by dehydrogenation. The origin of CO remains enigmatic, but its carbon isotope composition suggests a link to the few amounts of graphite documented in chloritite and talc from the deposit. This work also reports extensive hydrogen isotope fractionation between H2 produced by dehydrogenation and both talc and chloritite. Dehydrogenation of phyllosilicates is a potential source term of H2 in numerous magmatic-hydrothermal settings and must thus be accounted for in the budget of the H2 geochemical cycle.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Laurent_etal2021,

title = {Epigenic vs. hypogenic speleogenesis governed by H2S/CO2 hydrothermal input and Quaternary icefield dynamics (NE French Pyrenees)},

author = {D. Laurent and C. Durlet and G. Barr\'{e} and P. Sorriaux and P. Audra and P. Cartigny and C. Carpentier and G. Paris and P. Collon and T. Rigaudier and J. Pironon and E. C. Gaucher},

doi = {10.1016/j.geomorph.2021.107769},

year  = {2021},

date = {2021-01-01},

journal = {Geomorphology},

volume = {387},

pages = {107769},

abstract = {Hypogenic caves, linked to carbonate rock dissolution due to CO2- and H2S-rich ascending deep waters, represent more than 10% of karstic networks worldwide; a proportion that increases as these systems are better constrained. However, interaction between hypogenic and epigenic processes is still poorly understood, especially since the subsequent invasion of surface water often obliterates the morphological and mineral markers of hypogenic activities. The Ari`ege Valley (French Pyrenean foothills) hosts significant karstic networks epigenically reworked by several episodes of glacier meltwater penetration during the successive coverage of Quaternary icefields. Among these karstic systems, the Vapeur and Ermite caves were probably initiated by a hypogenic component during the Miocene. In particular, multiple-S, Sr, H, C, and O isotopes of thermo-mineral waters and calcite-sulfate speleothems confirm that hydrothermal fluids reached the caves, and subsequently interacted with Quaternary glacial epigenic phases. Deep fluids conveyed CO2 and H2S, both produced from the thermochemical reduction of Triassic evaporites at depth. H2S oxidation and CO2 hydration in the cave atmosphere, above the water table, created sulfuric and carbonic acids responsible for an intense karstification. Interpretation of isotopic data, together with a geomorphological, mineralogical and textural study of cave minerals, allow us to propose a speleogenetic model in which the respective impact of epigenic and hypogenic processes was driven by base-level changes during successive Quaternary glacial/interglacial epochs: (i) during glacial periods, invasion of glacier meltwater within the karst led to the dilution of the hydrothermal water, and was responsible for an textquotelefttextquoteleftepigenic mechanical-dominanttextquoterighttextquoteright speleogenesis through water-related abrasion; (ii) interglacial epochs were marked by base-level drops and the establishment of a vadose domain in caves, favoring the widening of karstic conduits through carbonic and sulfuric acid condensation-corrosion during thermal water degassing. This textquotelefttextquotelefthypogenic chemical-dominanttextquoterighttextquoteright speleogenesis was active until a new advance of glaciers, and this cycle occurred several times.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Piani_etal2020,

title = {Earthtextquoterights water may have been inherited from material similar to enstatite chondrite meteorites},

author = {L. Piani and Y. Marrocchi and T. Rigaudier and L. G. Vacher and D. Thomassin and B. Marty},

doi = {10.1126/science.aba1948},

year  = {2020},

date = {2020-01-01},

journal = {Science},

volume = {369},

number = {6507},

pages = {1110--1113},

abstract = {The origin of Earthtextquoterights water remains unknown. Enstatite chondrite (EC) meteorites have similar isotopic composition to terrestrial rocks and thus may be representative of the material that formed Earth. ECs are presumed to be devoid of water because they formed in the inner Solar System. Earthtextquoterights water is therefore generally attributed to the late addition of a small fraction of hydrated materials, such as carbonaceous chondrite meteorites, which originated in the outer Solar System where water was more abundant. We show that EC meteorites contain sufficient hydrogen to have delivered to Earth at least three times the mass of water in its oceans. EC hydrogen and nitrogen isotopic compositions match those of Earthtextquoterights mantle, so EC-like asteroids might have contributed these volatile elements to Earthtextquoterights crust and mantle.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Vacher_etal2020,

title = {Hydrogen in chondrites: Influence of parent body alteration and atmospheric contamination on primordial components},

author = {L. Vacher and L. Piani and T. Rigaudier and D. Thomassin and G. Florin and M. Piralla and Y. Marrocchi},

doi = {10.1016/j.gca.2020.05.007},

year  = {2020},

date = {2020-01-01},

urldate = {2020-01-01},

journal = {Geochimica et Cosmochimica Acta},

volume = {281},

pages = {53--66},

abstract = {Hydrogen occurs at the near percent level in the most hydrated chondrites (CI and CM) attesting to the presence of waterin the asteroid-forming regions. Their H abundances and isotopic signatures are powerful proxies for deciphering the distri-bution of H in the protoplanetary disk and the origin of Earthtextquoterights water. Here, we report H contents and isotopic compositionsfor a set of carbonaceous and ordinary chondrites, including previously analyzed and new samples analyzed after the pow-dered samples were degassed under vacuum at 120textdegreeC for 48 hours to remove adsorbed atmospheric water. By comparing ourresults to literature data, we reveal that the H budgets of both H-poor and H-rich carbonaceous chondrites are largely affectedby atmospheric moisture, and that their precise quantification requires a specific pre-degassing procedure to correct for ter-restrial contamination. Our results show that indigenous H contents of CI carbonaceous chondrites usually considered themost hydrated meteorites might be almost a factor of two lower than those previously reported, with uncontaminated D/H ratios differing significantly from that of Earthtextquoterights oceans. Without pre-degassing, the H concentrations of H-poor samples(e.g., CVs chondrites) are also affected by terrestrial contamination. After correction for contamination, it appears that theamount of water in chondrites is not controlled by the matrix modal abundance, suggesting that the different chondritic par-ent bodies accreted variable amounts of water-ice grains. Our results also imply that (i) thermal metamorphism play an impor-tant role in determining the H content of both CV and ordinary chondrites but without affecting drastically their H isotopiccomposition since no clear D enrichment is observed with the increase of petrographic type and (ii) the D enrichment of ordi-nary chondrite organics does not result from the loss of isotopically light H2induced by metal oxidation but is rather linked tothe persistence of a thermally resistant D-rich component},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fallick_etal2019,

title = {Remarkably uniform oxygen isotope systematics for co-existing pairs of gem-spinel and calcite in marble, with special reference to Vietnamese deposits},

author = {A. E. Fallick and G. Giuliani and T. Rigaudier and A. J. Boyce and V. L. Pham and V. Pardieu},

doi = {10.1016/j.crte.2018.11.008},

year  = {2019},

date = {2019-01-01},

journal = {Comptes Rendus. G\'{e}oscience},

volume = {351},

pages = {27--36},

abstract = {Oxygen isotope systematics for co-existing pairs of gem-spinel and calcite in marble from Vietnam and other worldwide deposits have been determined in order to characterize the O-isotope fractionation between calcite and spinel. In Vietnam, the $Delta$18Occ--sp (= 3.7 textpm 0.1texttenthousand for six samples from the An Phu and Cong Troi deposits) is remarkably constant. The combination of these data with those obtained on calcite--spinel pairs of Paigutan (Nepa},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Quesnel_etal2019,

title = {Nature and origin of mineralizing fluids in hyperextensional systems : The case of cretaceous Mg metasomatism in the Pyrenees},

author = {B. Quesnel and M. C. Boiron and M. Cathelineau and L. Truche and T. Rigaudier and G. Bardoux and P. Agrinier and M. Saint Blanquat and E. Masini and E. C. Gaucher},

doi = {10.1155/2019/7213050},

year  = {2019},

date = {2019-01-01},

journal = {Geofluids},

abstract = {During the Albian, the hyperextension of the Pyrenean passive margin led to a hyperthinning of the continental crust and the subsequent subcontinental mantle exhumation. The giant Trimouns talc-chlorite deposit represents the most prominent occurrence of Albian metasomatism in the Pyrenees, with the occurrence of the largest talc deposit worldwide. Consequently, this deposit, which is located on a fault zone and a lithological contact, represents one of the major drains at the scale of the Pyrenees and one of the best geological targets in order to determine the origin(s) of the fluid(s) that circulated during this period. Talc-chlorite ore is characterized by the presence of brines trapped in dolomite, quartz, and calcite fluid inclusions in the vicinity of the talc-rich zone. Considered as being responsible for the formation of talc, these fluids may be interpreted in several ways: (i) primary brines expelled from Triassic evaporites, (ii) secondary brines produced through halite leaching by diagenetic/metamorphic fluids, and (iii) brines derived from seawater serpentinization of mantle rocks. Stable isotope analyses ($delta$13C, $delta$18O, $delta$D, and $delta$37Cl) and Cl/Br ratio measurements in fluid inclusions and their host minerals were carried out in order to determine the origin of the fluid(s) involved in the formation of the ore deposit. The data are consistent with a primary brine origin for the mineralizing fluid, which could have been expelled from the Triassic levels. Other hypotheses have been tested, for example, the production of brines via the seawater concentration during serpentinization. The geochemical proxies used in this study provide equivocal results. The first hypothesis is by far the most realistic one considering the numerous occurrences of Trias formations nearby, their deformation during the extension, and the drainage of the expulsed brines as evidenced by the high-salinity fluid inclusions found all around the deposit. Alternatively, the exhumation of the mantle is considered as a major source of heat and stress that favored brine migration along the major shear zones. Our results fit well with brine circulation in a hyperextensional geodynamic context, which is related to the formation of the talc-chlorite ore, the thinning of the continental crust, and the exhumation of the subcontinental mantle, in accordance with recent works.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Scheffer_etal2019,

title = {The Lavrion Pb-Zn-Ag--Rich vein and breccia detachment-related deposits (Greece): Involvement of evaporated seawater and meteoric fluids during postorogenic exhumation},

author = {C. Scheffer and A. Tarantola and O. Vanderhaeghe and P. Voudouris and P. G. Spry and T. Rigaudier and A. Photiades},

doi = {10.5382/econgeo.4670},

year  = {2019},

date = {2019-01-01},

journal = {Economic Geology},

volume = {114},

number = {7},

pages = {1415--1442},

abstract = {The formation of ore deposits in the Lavrion Pb-Zn-Ag district was associated with Miocene detachment that accommodated orogenic collapse and exhumation of high-grade nappes across the ductile-brittle transition. This district consists of (1) low-grade porphyry Mo style, (2) Cu-Fe skarn, (3) high-temperature carbonate replacement Pb-Zn-Ag, and (4) vein and breccia Pb-Zn-Ag mineralization. The vein and breccia mineralization locally contains high-grade silver in base metal sulfides that are cemented by fluorite and carbonate gangue. The rare earth element contents of these gangue minerals, chondrite-normalized patterns, and fluid inclusion studies suggest that they precipitated from a low-temperature hydrothermal fluid. Primary and pseudosecondary fluid inclusions in fluorite and calcite are characterized by a wide range of homogenization temperatures (92textdegree--207textdegreeC) and salinities of up to 17.1 wt % NaCl equiv. Secondary fluid inclusions only represent \<5 vol % of the total fluid trapped. Fluids extracted from inclusions in fluorite have values of $delta$D = --82.1 to --47.7texttenthousand (Vienna-standard mean ocean water [V-SMOW]) and $delta$18O = --10.4 to --5.1texttenthousand (V-SMOW). These data and low ratios of Cl/Br measured by crush-leach analyses for fluids in fluorite (102--315) and calcite (162--188) are compatible with the ore fluid being the result of mixing of meteoric water with evaporated seawater. These data suggest that fluids leading to the deposition of late Pb-Zn-Ag--rich vein- and breccia-style mineralization in Lavrion were related to circulation of mixed evaporated seawater and meteoric fluids that was enhanced by brittle deformation. This contrasts with the fluids of magmatic origin related to the formation of low-grade porphyry Mo, Cu-Fe skarn, and high-temperature carbonate replacement deposits spatially related to the Plaka granodiorite.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Morin_etal2018,

title = {Annual sediment transport dynamics in the Narayani basin, Central Nepal : Assessing the impacts of erosion processes in the annual sediment budget},

author = {G. P. Morin and J. Lav\'{e} and C. France-Lanord and T. Rigaudier and A. P. Gajurel and R. Sinha},

doi = {10.1029/2017JF004460},

year  = {2018},

date = {2018-01-01},

journal = {Journal of Geophysical Research ?\u{I} Earth Surface},

volume = {123},

abstract = {Identifying the roles of erosional processes in the denudation of mountain ranges requires a better understanding of erosional sensitivity to climatic, topographic, or lithologic controls. We analyzed erosion in the Narayani River basin (draining central Nepal and presenting contrasted lithologic and geochemical signatures in its outcropping rocks and a wide variety of erosional processes and climaticconditions) to assess the relative contributions of erosion processes to the annual sediment export. By combining acoustic Doppler current profiler measurements with depth profiles and daily surface samplings of the suspended load, we propose a simplified model to precisely calculate sediment fluxes at the basin outlet. We estimate an equivalent erosion rate of 1:8+0:35-0:2 mm/year for the year 2010, similar to the average value of 1:6+0:35-0:2 mm/year estimated from 15 years of records and long-term (textasciitildeky) denudation rates of 1.7 mm/year derived from cosmogenic nuclides. The stability of erosion is attributed to efficient bufferingbehavior and spatial integration in the drainage system. Strong relations between rainfall events and the sediment export suggest that the system is mainly supply limited. Combining physical calculation of sediment fluxes with grain size analyses and geochemical tracers (hydroxyl isotopic compositions, carbonate contents, and total organic carbon content), we estimate that glacial and soil erosion do not contribute more than 10% and a few percentage, respectively, to the total budget and are only detectable during premonsoon and early monsoon periods. During the monsoon, erosion by landslides and mass wasting events overwhelms the sediment budget, confirming the dominant role of these erosional processes in activemountain chains.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Truche_etal2018,

title = {Clay minerals trap hydrogen in the Earthtextquoterights crust: Evidence from the Cigar Lake uranium deposit, Athabasca},

author = {L. Truche and G. Joubert and M. Dargent and P. Martz and M. Cathelineau and T. Rigaudier and D. Quirt},

doi = {10.1016/j.epsl.2018.04.038},

year  = {2018},

date = {2018-01-01},

journal = {Earth and Planetary Science Letters},

volume = {493},

pages = {186--197},

abstract = {Hydrogen (H2)-rich fluids are observed in a wide variety of geologic settings including gas seeps in serpentinized ultramafic rocks, sub-seafloor hydrothermal vents, fracture networks in crystalline rocks from continental and oceanic crust, and volcanic gases. Natural hydrogen sources can sustain deep microbial ecosystems, induce abiotic hydrocarbons synthesis and trigger the formation of prebiotic organic compounds. However, due to its extreme mobility and small size, hydrogen is not easily trapped in the crust. If not rapidly consumed by redox reactions mediated by bacteria or suitable mineral catalysts it diffuses through the rocks and migrates toward the surface. Therefore, H2 is not supposed to accumulate in the crust. We challenge this view by demonstrating that significant amount of H2 may be adsorbed by clay minerals and remain trapped beneath the surface. Here, we report for the first time H2 content in clay-rich rocks, mainly composed of illite, chlorite, and kaolinite from the Cigar Lake uranium ore deposit (northern Saskatchewan, Canada). Thermal desorption measurements reveal that H2 is enriched up to 500 ppm (i.e. 0.25 molthinspacekg−1 of rock) in these water-saturated rocks having a very low total organic content (\<0.5 wt%). Such hydrogen uptake is comparable and even exceeds adsorbed methane capacities reported elsewhere for pure clay minerals or shales. Sudoite (Al--Mg di-trioctahedral chlorite) is probably the main mineral responsible for H2 adsorption in the present case. The presence of multiple binding sites in interlinked nanopores between crystal layers of illite-chlorite particles offers the ideal conditions for hydrogen sorption. We demonstrate that 4 to 17% of H2 produced by water radiolysis over the 1.4-Ga-lifetime of the Cigar Lake uranium ore deposit has been trapped in the surrounding clay alteration haloes. As a result, sorption processes on layered silicates must not be overlooked as they may exert an important control on the fate and mobility of H2 in the crust. Furthermore, the high capacity of clay minerals to sorb molecular hydrogen may also open up new opportunities for exploration of unexpected energy resources and for H2 storage based on geo-inspired materials.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Scheffer_etal2017,

title = {CO2 flow during orogenic gravitational collapse : Syntectonic decarbonation and fluid mixing at the ductile-brittle transition (Lavrion, Greece)},

author = {C. Scheffer and A. Tarantola and O. Vanderhaeghe and T. Rigaudier and A. Photiades},

doi = {10.1016/j.chemgeo.2016.12.005},

year  = {2017},

date = {2017-01-01},

journal = {Chemical Geology},

volume = {450},

pages = {248--263},

abstract = {The knowledge of CO2 transfer between carbonate reservoirs is a key issue to understanding climate evolution through geologic times. Convergent plate boundaries representmajor zones for carbon recycling via burial of carbonates. In this paper, we document syntectonic decarbonation of marble at the ductile-brittle transition during the emplacement of the low-angle mylonitic to cataclastic detachment exposed in the Lavrion peninsula along the western border of the Attico-Cycladic Metamorphic Complex. This process is evidenced by the presence, in a quartz vein boudinaged and transposed in the mylonitic marble, of CO2-rich fluid inclusions (i) dismembered and deformed along quartz subgrain boundaries, (ii)within deformation lamellae and (iii) in planes crosscutting subgrains. Microstructural analysis, stable isotope equilibrium and VX properties show that CO2 results from syntectonic decarbonation under a 70--115 textdegreeCtextperiodcenteredkm−1 thermal gradient during exhumation accommodated by regional NNE-SSWextension. We propose that decarbonation and CO2 release under HT/LP conditions were triggered by the increase in temperature caused by thermal relaxation of the thickened crust further enhanced by the intrusion of a granodiorite pluton duringMiocene gravitational collapse of the Hellenic orogenic belt. Subsequent circulation of surface-derived fluid equilibrated with carbonaceous material of organic origin above the ductile-brittle transition led to precipitation of low 13C carbonates. This study points that the production of CO2 by syntectonic decarbonation of marble layers, representing tectonically accreted carbonates along convergent plate boundaries, should be considered in the carbon cycle and might thus impact the climate.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Scheffer_etal2017_2,

title = {The Lavrion Pb-Zn-Fe-Cu-Ag detachment-related district (Attica, Greece) : Structural control on hydrotermal flow and element transfer-deposition},

author = {C. Scheffer and A. Tarantola and O. Vanderhaeghe and P. Voudouris and T. Rigaudier},

doi = {10.1016/j.tecto.2017.06.029},

year  = {2017},

date = {2017-01-01},

journal = {Tectonophysics},

volume = {717},

pages = {607--627},

abstract = {The impact of lithological heterogeneities on deformation, fluid flow and ore deposition is discussed based on the example of the Lavrion low-angle detachment partly accommodating gravitational collapse of the Hellenides orogenic belt in Greece. The Lavrion peninsula is characterised by a multiphase Pb-Zn-Fe-Cu-Ag ore system with a probable pre-concentration before subduction followed by progressive remobilisation and deposition coeval with the development of a low-angle ductile to brittle shear zone. The mylonitic marble below the detachment shear zone is composed of white layers of pure marble alternating with blue layers containing impurities (SiO2, Al2O3, carbonaceous material). Ductile mylonitic deformation is more pervasive in the less competent impure blue marble. We propose that localised deformation in the impure marble is associated with fluid circulation and dolomitisation, which in turn causes an increase in competence of these layers. Mineralised cataclastic zones, crosscutting the mylonitic fabric, are preferentially localised in the more competent dolomitic layers. Oxygen and carbon isotopic signatures of marble invaded by carbonate replacement deposits during ductile to ductile-brittle deformation are consistent with decarbonation coeval with the invasion of magmatic fluids. Mineralised cataclastic zones reflecting brittle deformation evolve from low 13C to low 18O signatures, interpreted as local interaction with carbonaceous material that trends toward the contribution of a surface-derived fluid. These features indicate that the Lavrion area records a complex deposition history influenced by the evolution of fluid reservoirs induced by the thermal and mechanical evolution of the marble nappe stack. Ore remobilisation and deposition associated with the activity of the low-angle detachment is (i) firstly related to the intrusion of the Plaka granodiorite leading to porphyry-type and carbonate replacement mineralisation during ductile-brittle deformation and (ii) then marked by progressive penetration of surface-derived fluids guided by strain localisation in the more competent levels leading to epithermal mineralisation associated with brittle deformation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Rey_etal2016,

title = {Global climate perturbations during the Permo-Triassic mass extinctions recorded by continental tetrapods from South Africa},

author = {K. Rey and R. Amiot and F. Fourel and T. Rigaudier and F. Abdala and M. O. Day and V. Fernandez and F. Fluteau and C. France-Lanord},

doi = {10.1016/j.gr.2015.09.008},

year  = {2016},

date = {2016-01-01},

urldate = {2016-01-01},

journal = {Gondwana Research},

volume = {37},

pages = {384--396},

abstract = {Several studies of the marine sedimentary record have documented the evolution of global climate during the Permo-Triassic mass extinction. By contrast, the continental records have been less exploited due to the scarcity of continuous sections from the latest Permian into the Early Triassic. The South African Karoo Basin exposes one of the most continuous geological successions of this time interval, thus offering the possibility to reconstruct climate variations in southern Laurasia from the Middle Permian to Middle Triassic interval. Both air temperature and humidity variations were estimated using stable oxygen ($delta$18Op) and carbon ($delta$13Cc) isotope compositions of vertebrate apatite. Significant fluctuations in both $delta$18Op and $delta$13Cc values mimic those of marine records and suggest that stable isotope compositions recorded in vertebrate apatite reflect global climate evolution. In terms of air temperature, oxygen isotopes show an abrupt increase of about + 8 textdegreeC toward the end of the Wuchiapingian. This occurred during a slight cooling trend from the Capitanian to the Permo-Triassic boundary (PTB). At the end of the Permian, an intense and fast warming of + 16 textdegreeC occurred and kept increasing during the Olenekian. These thermal fluctuations may be related to the Emeishan (South China) and Siberian volcanic paroxysms that took place at the end of the Capitanian and at the end of the Permian, respectively. Vertebrate apatite $delta$13Cc partly reflects the important fluctuations of the atmospheric $delta$13C values, the differences with marine curves being likely due to the evolution of local humidity. Both the oxygen and carbon isotope compositions indicate that the PTB was followed by a warm and arid phase that lasted 6 Ma before temperatures decreased, during the Late Anisian, toward that of the end-Permian. Environmental fluctuations occurring around the PTB that affected both continental and marine realms with similar magnitude likely originated from volcanism and methane release.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gaudin_etal2015,

title = {Mineralogical and $delta$18O--$delta$D isotopic study of kaolinized micaschists at Penestin, Armorican Massif, France: New constraint in the kaolinization process},

author = {A. Gaudin and V. Ansan and T. Rigaudier},

doi = {10.1016/j.catena.2015.05.006},

year  = {2015},

date = {2015-01-01},

journal = {Catena},

volume = {133},

pages = {97--106},

abstract = {Many kaolinite occurrences developed from Paleozoic rocks forming the basement of the Armorican Massif in western France. Their origin, hydrothermal alteration and/or weathering, is still discussed. In order to provide new constraints to this debate, we studied the kaolinite occurrence at Penestin in the southern part of the Armorican Massif using several approaches, including field and petrological observations, mineralogical analyses (XRD) and stable oxygen--hydrogen isotope analyses. An alteration profile was developed from faulted micaschists showing, from the bottom to the top of the profile, a reddish saprolite zone with pure white kaolinite fissures cutting across the schistosity and a white kaolinite zone, 5--10 m thick. The detailed study by XRD of the layer silicates enabled us to characterize a mineralogical sequence with increasing alteration intensity, which is coherent with a weathering evolution: mica, chloritetextrightarrowillite/vermiculite (chlorite) mixed-layer mineraltextrightarrowvermiculitetextrightarrowvermiculite/kaolinite mixed-layermineraltextrightarrowkaolinite.Moreover,an intense iron leaching process occurs within the kaolinitezone,which is characterized by a bleaching of this zone combined with iron oxyhydroxide precipitation along/within fractures and cracks. The isotopic analyses of kaolinite from the zone and fissures gave $delta$18O values ranging from19.64 to21.21texttenthousand, and$delta$D values ranging from−69.4 to−65.8texttenthousand. This confirms that kaolinite was formed by low-temperature water--rock interactions in contact with meteoric fluids during weathering processes. Isotopic and stratigraphic data suggest that this weathering occurred before the Messinian (textasciitilde7 Ma) and probably dates back to the Eocene, during which the climate was sub-tropical at this location.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kuga_etal2014,

title = {Nitrogen isotopic fractionation during abiotic synthesis of organic solid particles},

author = {M. Kuga and N. Carrasco and B. Marty and Y. Marrocchi and S. Bernard and T. Rigaudier and B. Fleury and L. Tissandier},

doi = {10.1016/j.epsl.2014.02.037},

year  = {2014},

date = {2014-01-01},

journal = {Earth and Planetary Science Letters},

volume = {393},

pages = {2--13},

abstract = {The formation of organic compounds is generally assumed to result from abiotic processes in the Solar System, with the exception of biogenic organics on Earth. Nitrogen-bearing organics are of particular interest, notably for prebiotic perspectives but also for over all comprehension of organic formation in the young Solar System and in planetary atmospheres. We have investigated abiotic synthesis of organics upon plasma discharge, with special attention to N isotope fractionation. Organic aerosols were synthesized from N2--CH4 and N2--CO gaseous mixtures using low-pressure plasma discharge experiments, aimed at simulating chemistry occurring in Titantextquoteright atmosphere and in the protosolar nebula, respectively. The nitrogen content, the N speciation and the N isotopic composition were analyzed in the resulting organic aerosols. Nitrogen is efficiently incorporated in to the synthesized solids, independently of the oxidation degree, of the N2 content of the starting gas mixture, and of the nitrogen speciation in the aerosols.The aerosols are depleted in 15N by15--25- relative to the initial N2 gas, whatever the experimental setup is. Such an isotopic fractionation is attributed to mass-dependent kinetic effect(s). Nitrogen isotope fractionation upon electric discharge cannot account for the large N isotope variations observed among Solar System objects and reservoirs. Extreme N isotope signatures in the Solar System are more likely the result of self-shielding during N2 photodissociation, exotic effect during photodissociation of N2 and/or low temperature ion-molecule isotope exchange. Kinetic N isotope fractionation may play a significant role in the Titantextquoterights atmosphere. On the Titantextquoterights night side, 15N depletion resulting from electron driven reactions may counterbalance photo-induced 15N enrichments occurring on the daytextquoterights side.We also suggest that the low $delta$15N values of Archaean organic matter (Beaumont and Robert,1999) are partly the result of abiotic synthesis of organics that occurred at that time, and that the subsequent development of the biosphere resulted in shifts of $delta$15N towards higher values.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Licht_etal2014_2,

title = {Asian monsoons in a late Eocene greenhouse world},

author = {A. Licht and M. Cappelle and H. A. Abels and J. B. Ladant and J. Trabucho-Alexandre and C. France-Lanord and Y. Donnadieu and J. Vanderberghe and T. Rigaudier and C. L\'{e}cuyer and D. Terry Jr and R. Adriaens and A. Boura and Z. Guo and Aung Naing Soe and J. Quade and G. Dupont-Nivet and J. J. Jaeger},

doi = {10.1038/nature13704},

year  = {2014},

date = {2014-01-01},

journal = {Nature},

volume = {513},

pages = {501--506},

abstract = {The strong present-day Asian monsoons are thought to have originated between 25 and 22 million years (Myr) ago, driven by Tibetan--Himalayan uplift. However, the existence of older Asian monsoons and their response to enhanced greenhouse conditions such as those in theEocene period (55--34Myrago) are unknownbecause of the paucity of well-dated records. Here we show late Eocene climate records revealing marked monsoon-like patterns in rainfall and wind south and north of the Tibetan--Himalayan orogen. This is indicated by low oxygen isotope values with strong seasonality in gastropod shells and mammal teeth from Myanmar, and by aeolian dust deposition in northwest China. Our climate simulations support modern-like Eocene monsoonal rainfall and show that a reinforced hydrological cycle responding to enhancedgreenhouse conditions counterbalanced the negative effect of lowerTibetanrelief onprecipitation. These strong monsoons later weakened with the global shift to icehouse conditions 34Myr ago.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}