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8. Isotopic portrayal of the Earth's upper mantle flow field

Author

Meyzen, Christine M., Blichert-Toft, Janne, Ludden, John N., Humler, Eric, Mevel, Catherine, and Albarede, Francis

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): Christine M. Meyzen (corresponding author) [1]; Janne Blichert-Toft [1]; John N. Ludden [2]; Eric Humler [3]; Catherine Mével [4]; Francis Albarède [1] Radiogenic isotope studies of Sr, Nd and [...]

Published
2007
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9. Thin crust, ultramafic exposures, and rugged faulting patterns at the Mid-Atlantic Ridge (22 degrees-24 degrees N)

Author

Cannat, Mathilde, Mevel, Catherine, Maia, Marcia, Deplus, Christine, Durand, Cecile, Gente, Pascal, Agrinier, Pierre, Belarouchi, Abdel, Dubuisson, Gilles, Humler, Eric, and Reynolds, Jennifer

Subjects
Mid-Atlantic Ridge -- Research, Rocks, Ultrabasic -- Research, Faults (Geology) -- Research, Earth sciences
Abstract

Off-axis rock sampling in the lat 22 [degrees]-24 [degrees] N region of the Mid-Atlantic Ridge shows that the emplacement of mantle-derived rocks in the sea floor has been a common process there for the past few million years. We find a good correlation between domains of positive residual gravity anomalies (inferred to have a thin crust) and the distribution of ultramafic samples. We also find that thin-crust domains have a rugged topography, thought to reflect strong tectonic disruption. We propose that these thin-crust domains are made of tectonically uplifted ultramafic rocks, with gabbroic intrusions and a thin basaltic cover. We also suggest that strong tectonic disruption may be a direct consequence of the lithological and rheological heterogeneity of these thin-crust domains.

Published
1995

10. Oceanic crust and mantle structure

Author

Mevel, Catherine and Cannat, Mathilde

Subjects
Oceanographic research -- Methods -- Research -- Usage, Underwater drilling -- Usage, Paleoceanography -- Research -- Methods -- Usage, Environmental issues, Earth sciences, Usage, Research, Methods
Abstract

The ocean drilling programs have provided us with a wealth of new information about the nature of the oceanic crust, a 5- to 10-kilometer-thick layer of rock that covers more [...]

Published
1993

12. Zircon dating of oceanic crustal accretion

Author

Lissenberg, C. Johan, Rioux, Matthew, Shimizu, Nobumichi, Bowring, Samuel A., and Mevel, Catherine

Subjects
Zircon -- Environmental aspects, Uranium-lead dating -- Usage, Earth -- Crust, Earth -- Research, Science and technology
Abstract

Most of Earth's present-day crust formed at mid-ocean ridges. High-precision uranium-lead dating of zircons in gabbros from the Vema Fracture Zone on the Mid-Atlantic Ridge reveals that the crust there grew in a highly regular pattern characterized by shallow melt delivery. Combined with results from previous dating studies, this finding suggests that two distinct modes of crustal accretion occur along slow-spreading ridges. Individual samples record a zircon date range of 90,000 to 235,000 years, which is interpreted to reflect the time scale of zircon crystallization in oceanic plutonic rocks.

Published
2009

13. Zabargad peridotite: evidence for multistage metasomatism during Red Sea rifting

Author

Dupuy, Claude, Mevel, Catherine, Bodinier, Jean-Louis, and Savoyant, Liliane

Subjects
Red Sea -- Natural history, Metasomatism (Mineralogy) -- Research, Amphiboles -- Composition, Peridotite -- Composition, Analytic geochemistry -- Research, Trace analysis -- Analysis, Earth sciences
Abstract

New analyses of rare earth elements (REEs) and abundances of K, Rb, Sr, Ba, Th, U, Ta, and Hf in peridotites from Zabargad Island, Red Sea, indicate that light REE-enriched amphibole peridotites in the northern and central bodies have undergone a complex, multistage, metasomatic history during Red Sea rifting. The metasomatism is partly attributed to the passage of alkalic basalts through the mantle lithosphere, which possibly occurred during the early, continental-rift history of the Red Sea. The metasomatism also results from the interaction of the uppermost lithosphere with hydrous crustal fluids released from thinning continental crust. The last metasomatic event is associated with the development of an oceanic hydrothermal system in the Red Sea, after the continental breakup. The available data also suggest that the Zabargad peridotites represent pieces of pan-African lithospheric mantle (the northern and central bodies) pierced by asthenospheric material (the southern body).

Published
1991

15. A discontinuity in mantle composition beneath the southwest Indian ridge

Author

Meyzen, Christine M., Toplis, Michael J., Humler, Eric, Ludden, John N., and Mevel, Catherine

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): Christine M. Meyzen [1, 3]; Michael J. Toplis [1]; Eric Humler [3]; John N. Ludden [1]; Catherine Mével (corresponding author) [3] The composition of mid-ocean-ridge basalt is known to [...]

Published
2003
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16. Tectonic structure, evolution, and the nature of oceanic core complexes and their detachment fault zones (13 degrees 20 ' N and 13 degrees 30 ' N, Mid Atlantic Ridge)

Author

Escartin, Javier, Mevel, Catherine, Petersen, S., Bonnemains, Diane, Cannat, Mathilde, Andreani, Muriel, Augustin, N., Bezos, Antoine, Chavagnac, Valérie, Choi, Yujin, GODARD, Marguerite, Haaga, K., Hamelin, C., ILDEFONSE, Benoit, Jamieson, J., John, B., Leleu, Thomas, Macleod, C. j., Massot-campos, M., Nomikou, P., Olive, J. a., Paquet, Marine, Rommevaux-Jestin, Céline, Rothenbeck, M., Steinfuhrer, A., Tominaga, M., Triebe, L., Campos, R., Gracias, N., Garcia, R., Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), University of Bergen (UiB), University of Wyoming, Laramie, Cardiff University, Universitat Illes Baleares, Palma de Majorque, University of Athens, Columbia University [New York], Texas A&M University [College Station], Universitat de Girona (UdG), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), GEOMAR - Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Laboratoire de Planétologie et Géodynamique UMR6112 (LPG), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales [Toulouse] (CNES), University of Bergen (UIB), A&M University, College Station, Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), and Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, oceanic core complexes
Abstract

International audience; Microbathymetry data, in situ observations, and sampling along the 13°20′N and 13°20′N oceanic core complexes (OCCs) reveal mechanisms of detachment fault denudation at the seafloor, links between tectonic extension and mass wasting, and expose the nature of corrugations, ubiquitous at OCCs. In the initial stages of detachment faulting and high-angle fault, scarps show extensive mass wasting that reduces their slope. Flexural rotation further lowers scarp slope, hinders mass wasting, resulting in morphologically complex chaotic terrain between the breakaway and the denuded corrugated surface. Extension and drag along the fault plane uplifts a wedge of hangingwall material (apron). The detachment surface emerges along a continuous moat that sheds rocks and covers it with unconsolidated rubble, while local slumping emplaces rubble ridges overlying corrugations. The detachment fault zone is a set of anostomosed slip planes, elongated in the along-extension direction. Slip planes bind fault rock bodies defining the corrugations observed in microbathymetry and sonar. Fault planes with extension-parallel stria are exposed along corrugation flanks, where the rubble cover is shed. Detachment fault rocks are primarily basalt fault breccia at 13°20′N OCC, and gabbro and peridotite at 13°30′N, demonstrating that brittle strain localization in shallow lithosphere form corrugations, regardless of lithologies in the detachment zone. Finally, faulting and volcanism dismember the 13°30′N OCC, with widespread present and past hydrothermal activity (Semenov fields), while the Irinovskoe hydrothermal field at the 13°20′N core complex suggests a magmatic source within the footwall. These results confirm the ubiquitous relationship between hydrothermal activity and oceanic detachment formation and evolution.

Published
2017

17. First direct observation of coseismic slip and seafloor rupture along a submarine normal fault and implications for fault slip history

Author

Escartín, Javier, Leclerc, Frédérique, Olive, Jean-Arthur, Mevel, Catherine, Cannat, Mathilde, Petersen, Sven, Augustin, Nico, Feuillet, Nathalie, Deplus, Christine, Bezos, Antoine, Bonnemains, Diane, Chavagnac, Valérie, Choi, Yujin, Godard, Marguerite, Haaga, Kristian A., Hamelin, Cédric, Ildefonse, Benoit, Jamieson, John W., John, Barbara E., Leleu, Thomas, MacLeod, Christopher J., Massot-Campos, Miquel, Nomikou, Paraskevi, Paquet, Marine, Rommevaux-Jestin, Céline, Rothenbeck, Marcel, Steinführer, Anja, Tominaga, Masako, Triebe, Lars, Campos, Ricard, Gracias, Nuno, Garcia, Rafael, Andreani, Muriel, and Vilaseca, Géraud

Published
2016
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18. The Kallisti Limnes, carbon dioxide-accumulating subsea pools

Author

Camilli, Richard, Nomikou, Paraskevi, Escartin, Javier E., Ridao, Pere, Mallios, Angelos, Kilias, Stephanos P., Argyraki, Ariadne, Andreani, Muriel, Ballu, Valerie, Campos, Ricard, Deplus, Christine, Gabsi, Taoufic, Garcia, Rafael, Gracias, Nuno, Hurtos, Natalia, Magi, Lluis, Mevel, Catherine, Moreira, Manuel, Palomeras, Narcis, Pot, Olivier, Ribas, David, Ruzie, Lorraine, Sakellariou, Dimitris, Camilli, Richard, Nomikou, Paraskevi, Escartin, Javier E., Ridao, Pere, Mallios, Angelos, Kilias, Stephanos P., Argyraki, Ariadne, Andreani, Muriel, Ballu, Valerie, Campos, Ricard, Deplus, Christine, Gabsi, Taoufic, Garcia, Rafael, Gracias, Nuno, Hurtos, Natalia, Magi, Lluis, Mevel, Catherine, Moreira, Manuel, Palomeras, Narcis, Pot, Olivier, Ribas, David, Ruzie, Lorraine, and Sakellariou, Dimitris

Abstract

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 5 (2015): 12152, doi:10.1038/srep12152., Natural CO2 releases from shallow marine hydrothermal vents are assumed to mix into the water column, and not accumulate into stratified seafloor pools. We present newly discovered shallow subsea pools located within the Santorini volcanic caldera of the Southern Aegean Sea, Greece, that accumulate CO2 emissions from geologic reservoirs. This type of hydrothermal seafloor pool, containing highly concentrated CO2, provides direct evidence of shallow benthic CO2 accumulations originating from sub-seafloor releases. Samples taken from within these acidic pools are devoid of calcifying organisms, and channel structures among the pools indicate gravity driven flow, suggesting that seafloor release of CO2 at this site may preferentially impact benthic ecosystems. These naturally occurring seafloor pools may provide a diagnostic indicator of incipient volcanic activity and can serve as an analog for studying CO2 leakage and benthic accumulations from subsea carbon capture and storage sites., This research was supported by the Eurofleets Caldera 2012 Project (EU), a NASA Astrobiology Science & Technology for Exploring Planets grant #NNX09AB76G (USA), a CAREER Award grant #OCE-0955674 to R. Camilli from the National Science Foundation (USA), and IPGP (France).

Published
2015

21. The deep sea and sub-seafloor frontier

Author

Kopf, Achim, Camerlenghi, Angelo, Canals, Miquel, Ferdelman, Timothy, Mevel, Catherine, Pälike, Heiko, Roest, Walter, Ask, Maria, Jørgensen, Bo Barker, Boetius, Antje, De Santis, Angelo, Früh-Green, Gretchen, Lykousis, Vasilis, McKenzie, Judith, Meinert, Jürgen, Parkes, John, Schneider, Rasph, and Weaver, Philipp

Published
2012

23. Multiscale chemical heterogeneities beneath the eastern Southwest Indian Ridge (52°E–68°E): Trace element compositions of along-axis dredged peridotites

Author

Seyler, Monique, Brunelli, Daniele, Toplis, Michael, Mevel, Catherine, Université de Lille, Sciences et Technologies, Dipartimento di Scienze della Terra [Modena], Università degli Studi di Modena e Reggio Emilia = University of Modena and Reggio Emilia (UNIMORE), Istituto di Scienze Marine [Bologna] (ISMAR), Istituto di Science Marine (ISMAR ), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR)-National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Modena e Reggio Emilia (UNIMORE), Consiglio Nazionale delle Ricerche (CNR)-Consiglio Nazionale delle Ricerche (CNR), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Indian Ocean, abyssal peridotite, mantle heterogeneities, trace elements, ultraslow spreading ridge, abyssal peridotite, ultraslow spreading ridge, trace elements, mantle heterogeneities, Indian Ocean, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography
Abstract

International audience; [1] The Southwest Indian Ridge is characterized by frequent outcrops of mantle rocks in a very slow spreading context. In situ measurements of trace element concentrations in pyroxenes of these rocks, and associated petrogenetic modeling, are reported. Overall, the measured compositions cover the whole range typically observed for abyssal peridotites. The greatest subkilometer-scale compositional variability is observed in the region east of the Melville fracture zone. The best explanation for the observed variability is given by concurrent melting and migration of melts strongly enriched in the most incompatible rare earth elements, such as those produced by a garnet-bearing source, or by refertilization with mixed garnet-and spinel-derived partially aggregated melts. Because the regionally associated basalts bear no "garnet signature" in their chemical compositions, we conclude that the residual mantle preserves the signature of a mantle source component that does not appear in the erupted magmas. Comparison between along-axis variations of basalt isotopic compositions and peridotite chemical compositions suggests that local isotopic enrichments displayed by some basalts can be associated with the "garnet signature" in the peridotite and that our sampling represents only a fraction of the global variability of the subaxial mantle. To the west of the Melville fracture zone, samples are more depleted and homogeneous at dredge scale. In addition to containing enriched components, petrologic modeling indicates that the peridotitic mantle beneath the entire section underwent (previous?) partial melting in the garnet stability field before melting at lower pressures.

Published
2011

24. Multiscale chemical heterogeneities beneath the eastern Southwest Indian Ridge (52 degrees E-68 degrees E): Trace element compositions of along-axis dredged peridotites

Author

Seyler, Monique[ 1 ], Brunelli, Daniele[ 2,3,4 ], Toplis, Michael J.[ 5 ], and Mevel, Catherine[ 6 ]

Abstract

The Southwest Indian Ridge is characterized by frequent outcrops of mantle rocks in a very slow spreading context. In situ measurements of trace element concentrations in pyroxenes of these rocks, and associated petrogenetic modeling, are reported. Overall, the measured compositions cover the whole range typically observed for abyssal peridotites. The greatest subkilometer-scale compositional variability is observed in the region east of the Melville fracture zone. The best explanation for the observed variability is given by concurrent melting and migration of melts strongly enriched in the most incompatible rare earth elements, such as those produced by a garnet-bearing source, or by refertilization with mixed garnet-and spinel-derived partially aggregated melts. Because the regionally associated basalts bear no "garnet signature" in their chemical compositions, we conclude that the residual mantle preserves the signature of a mantle source component that does not appear in the erupted magmas. Comparison between along-axis variations of basalt isotopic compositions and peridotite chemical compositions suggests that local isotopic enrichments displayed by some basalts can be associated with the "garnet signature" in the peridotite and that our sampling represents only a fraction of the global variability of the subaxial mantle. To the west of the Melville fracture zone, samples are more depleted and homogeneous at dredge scale. In addition to containing enriched components, petrologic modeling indicates that the peridotitic mantle beneath the entire section underwent (previous?) partial melting in the garnet stability field before melting at lower pressures.

Published
2011

25. Faire société. La politique de la ville aux États-Unis et en France

Author

Donzelot, Jacques, Mevel, Catherine, Wyvekens, Anne, Institut de Physique du Globe de Paris (IPGP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences sociales du Politique (ISP), École normale supérieure - Cachan (ENS Cachan)-Université Paris Nanterre (UPN)-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SHS.SOCIO]Humanities and Social Sciences/Sociology, Société, Etats-Unis, France, Politique, ComputingMilieux_MISCELLANEOUS, [SHS.SCIPO]Humanities and Social Sciences/Political science
Abstract

International audience

Published
2003

26. Behavior of Li and its isotopes during serpentinization of oceanic peridotites

Author

Decitre, Sylvie, Deloule, Etienne, Reisberg, Laurie, James, Rachael, Agrinier, Pierre, Mevel, Catherine, Centre de Recherches Pétrographiques et Géochimiques (CRPG), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), The Open University [Milton Keynes] (OU), Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, lithium, oceanic crust, serpentinization, Lithium, geochemical cycle, isotopes
Abstract

[1] Analyses of Li and Li isotopes in serpentinized peridotites have been performed using Thermo-Ionisation Mass Spectrometry (TIMS) and Secondary Ion Mass Spectrometry (SIMS) techniques on samples collected from the southwest Indian Ridge (SWIR). In the bulk samples, Li concentrations range from 0.6 to 8.2 ppm, while whole rock delta(6)Li values range from -2.9 to -14parts per thousand. In situ analyses display a greater range in both Li concentration (0.1-19.5 ppm) and Li isotopic composition ( -27 to +19parts per thousand), with the serpentinized portions having higher Li concentrations than the associated relict phases. These variations may reflect changes in Li partitioning and isotopic fractionation between serpentine and fluid with temperature and water/rock ratio. They may also be explained by changes in the composition of the serpentinizing fluid over the course of serpentinization. As the serpentine forms by interaction with a circulating fluid, it preferentially removes (6)Li, causing the Li in the fluid to become isotopically heavier. The isotopic composition of the initial hydrothermal fluid is dominated by basalt-derived Li, which easily overwhelms the very low Li content originally present in seawater. As this fluid circulates through ultramafic rocks, it induces the formation of serpentine that incorporates this mantle-derived Li. Hence, Li in serpentine is mainly derived from oceanic crust rather than from seawater and serpentinization involves Li recycling within this crust. Consequently, Li isotopes are good tracers of the hydrothermal contribution in serpentinizing fluid. These results imply that serpentinized peridotites are probably only a minor sink of oceanic Li.

Published
2002

34. Les ' pillow-lavas' spilitiques des massifs ophiolitiques du Chenaillet et des Gets ( Alpes françaises) . Structures et minéraux magmatiques reliques, étude chimique et zonations Comparaison avec les ' pillow-lavas' métamorphisés du Queyras et de Hte Ubaye

Author

Mevel, Catherine, Laboratoire de pétrographie, Université Pierre et Marie Curie - Paris 6 (UPMC), Université Pierre et Marie Curie - Paris VI, J.R. Kienast, and Talour, Pascale

Subjects
pilow lavas, laves en coussin, mineralogie, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, [SDU.STU.PE] Sciences of the Universe [physics]/Earth Sciences/Petrography, métamorphisme, Chenaillet, Les Gets
Abstract

Caractérisation des zonations existant à l'intérieur des coussins spilitiques tant du point de vue structural que chimique. Processus a l'origine de la différenciation chimique que l'on y observe. Nature originelle des laves dont dérivent ces spilites. Éventuelles modifications chimiques subies par les coussins sous l'influence du métamorphisme., pas de résumé

Published
1975

35. Observations par submersible de croûte océanique affleurant sur le banc de Gorring (SW Portugal) : évidences de processus de démantèlement des gabbros en milieu sous-marin

Author

Lagabrielle, Yves, Auzende, Jean-marie, Cornen, Geoffrey, Juteau, Thierry, Lensch, G, Mevel, Catherine, Nicolas, Adolphe, Prichard, H, Ribeiro, A, and Vanney, Jr

Abstract

0bservations made from the submersible SP 3000 Cyana on the southern flank of mount Ormonde (Gorringe Bank) have shown that in oceanic depths, processes of alteration and disintegration of gabbros and dolerites occurred. These processes give us a better understanding of source zones of Alps, Apennines and Corsica where sands, breccias and olistoliths ofgabbros outcrop. [NOT CONTROLLED OCR], Les observations faites à partir de l'engin submersible SP 3000 Cyana sur le flanc sud du mont Ormonde (banc de Gorringe) mettent en évidence, en milieu sous-marin profond, d'importants processus d'altération et de désintégration des gabbros et des dolérites. Ces processus nous permettent de mieux comprendre artains gisements des Alpes, des Apennins et de Corse ou affleurent sables, brêches et olistolithes de gabbros. [OCR NON CONTRÔLE]

Published
1981

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