107 results on '"Angiboust, Samuel"'
Search Results
2. Multiple sulfur isotopes evidence deep intra-slab transport of sulfate-rich fluids
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Genot, Isabelle, Angiboust, Samuel, and Cartigny, Pierre
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- 2024
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3. The B isotopic signature of serpentine from obducted ophiolites: Mixing of fluids and tectonic implications
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Martin, Celine, Flores, Kennet E., Harlow, George E., Angiboust, Samuel, Hodel, Florent, and Guice, George L.
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- 2023
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4. Cretaceous thermal evolution of the closing Neo-Tethyan realm revealed by multi-method petrochronology
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Holtmann, Regina, Muñoz-Montecinos, Jesús, Angiboust, Samuel, Cambeses, Aitor, Bonnet, Guillaume, Brown, Allison, Dragovic, Besim, Gharamohammadi, Zeynab, Rodriguez, Mathieu, Glodny, Johannes, Kananian, Ali, and Agard, Philippe
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- 2022
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5. Jolts in the Jade factory: A route for subduction fluids and their implications for mantle wedge seismicity
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Angiboust, Samuel, Muñoz-Montecinos, Jesus, Cambeses, Aitor, Raimondo, Tom, Deldicque, Damien, and Garcia-Casco, Antonio
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- 2021
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6. Episodic hydrofracturing and large-scale flushing along deep subduction interfaces: Implications for fluid transfer and carbon recycling (Zagros Orogen, southeastern Iran)
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Muñoz-Montecinos, Jesús, Angiboust, Samuel, Garcia-Casco, Antonio, Glodny, Johannes, and Bebout, Gray
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- 2021
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7. Fluid and mass transfer along transient subduction interfaces in a deep paleo-accretionary wedge (Western Alps)
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Epstein, Gabe S., Bebout, Gray E., and Angiboust, Samuel
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- 2021
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8. Deep mantle serpentinization in subduction zones: Insight from in situ B isotopes in slab and mantle wedge serpentinites
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Martin, Céline, Flores, Kennet E., Vitale-Brovarone, Alberto, Angiboust, Samuel, and Harlow, George E.
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- 2020
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9. Exhumation of eclogitic ophiolitic nappes in the W. Alps: New age data and implications for crustal wedge dynamics
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Angiboust, Samuel and Glodny, Johannes
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- 2020
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10. Scales of fluid-rock interaction and carbon mobility in the deeply underplated and HP-Metamorphosed Schistes Lustrés, Western Alps
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Epstein, Gabe S., Bebout, Gray E., Angiboust, Samuel, and Agard, Philippe
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- 2020
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11. Fingerprinting and relocating tectonic slices along the plate interface: Evidence from the Lago Superiore unit at Monviso (Western Alps)
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Gilio, Mattia, Scambelluri, Marco, Agostini, Samuele, Godard, Marguerite, Pettke, Thomas, Agard, Philippe, Locatelli, Michele, and Angiboust, Samuel
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- 2020
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12. Garnet fracturing reveals ancient unstable slip events hosted in plate interface metasediments
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Angiboust, Samuel, Ioannidi, Paraskevi Io, and Muldashev, Iskander
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- 2024
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13. Evidence for brittle deformation events at eclogite-facies P-T conditions (example of the Mt. Emilius klippe, Western Alps)
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Hertgen, Solenn, Yamato, Philippe, Morales, Luiz F.G., and Angiboust, Samuel
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- 2017
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14. Transient stripping of subducting slabs controls periodic forearc uplift
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Menant, Armel, Angiboust, Samuel, Gerya, Taras, Lacassin, Robin, Simoes, Martine, and Grandin, Raphael
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- 2020
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15. Hot subduction in the middle Jurassic and partial melting of oceanic crust in Chilean Patagonia
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Angiboust, Samuel, Hyppolito, Thais, Glodny, Johannes, Cambeses, Aitor, Garcia-Casco, Antonio, Calderón, Mauricio, and Juliani, Caetano
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- 2017
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16. Eclogite-, amphibolite- and blueschist-facies rocks from Diego de Almagro Island (Patagonia): Episodic accretion and thermal evolution of the Chilean subduction interface during the Cretaceous
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Hyppolito, Thais, Angiboust, Samuel, Juliani, Caetano, Glodny, Johannes, Garcia-Casco, Antonio, Calderón, Mauricio, and Chopin, Christian
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- 2016
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17. Stress-driven fluid flow controls long-term megathrust strength and deep accretionary dynamics
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Menant, Armel, Angiboust, Samuel, and Gerya, Taras
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- 2019
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18. Accretion and subduction mass transfer processes: Zircon SHRIMP and geochemical insights from the Carboniferous Western Series, Central Chile.
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Munoz-Montecinos, Jesus, Cambeses, Aitor, and Angiboust, Samuel
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GONDWANA (Continent) ,MASS transfer ,ZIRCON ,ACCRETIONARY wedges (Geology) ,SUBDUCTION ,SHRIMPS ,GEOCHEMISTRY ,GEOLOGICAL time scales ,HIGH temperatures - Abstract
In the region of Pichilemu (Central Chile), the exhumed roots of the Carboniferous paleo-accretionary wedge developed during subduction of an oceanic realm underneath the western Gondwana margin are exposed. We focus on the areas of Infiernillo beach and Punta de Lobos: the former representing a well-characterized transitional blueschist-facies coherent stack of metabasitic lithologies interlayered at the centimetre- to metre-scale within metasedimentary rocks and glaucophanites, whereas the latter corresponds to a massive, up to hundreds of metres thick, strained metapillow lavas edifice surrounded (not interlayered) by metasedimentary rocks. We provide new field, geochemical, Raman thermometry and zircon SHRIMP U-Th-Pb geochronology on the lithologies forming the Infiernillo-Punta de Lobos complex aiming at characterizing the sedimentary sources and the extent of mechanical mixing. Field observations suggest that the Infiernillo-Punta de Lobos complex can be considered as part of the same successions, subducted and basally accreted almost coherently at high pressure-low temperature (HP-LT) conditions. The geochemistry signal in metasedimentary rocks and maximum deposition ages point to a marked forearc source for all the metasedimentary and glaucophanite lithologies, whereas massive metapillow lavas and greenschists might represent volcanic products and oceanic roughnesses erupted near the trench when the oceanic material approached the Gondwana margin at c. 329 Ma. It is suggested that the interlayering now observed in the field is mostly the consequence of sedimentary and/or volcanic processes close to the trench environment, with minor tectonic reworking of the pre-subduction structures (e.g. lithological contacts). Our results suggest that the Punta de Lobos edifice is closely related to the subduction of large volumes of continent-derived, trench-filling sediments towards HP-LT conditions. Thus, in line with previous experimental and numerical simulations, we emphasize the potential role of oceanic roughness as stress perturbations that could contribute to the subduction of thick sedimentary sequences, and discuss their implications for seismogenesis. [ABSTRACT FROM AUTHOR]
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- 2024
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19. Subduction zone metamorphic pathway for deep carbon cycling: II. Evidence from HP/UHP metabasaltic rocks and ophicarbonates
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Collins, Nathan C., Bebout, Gray E., Angiboust, Samuel, Agard, Philippe, Scambelluri, Marco, Crispini, Laura, and John, Timm
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- 2015
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20. Subduction zone metamorphic pathway for deep carbon cycling: I. Evidence from HP/UHP metasedimentary rocks, Italian Alps
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Cook-Kollars, Jennie, Bebout, Gray E., Collins, Nathan C., Angiboust, Samuel, and Agard, Philippe
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- 2014
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21. In search of transient subduction interfaces in the Dent Blanche–Sesia Tectonic System (W. Alps)
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Angiboust, Samuel, Glodny, Johannes, Oncken, Onno, and Chopin, Christian
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- 2014
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22. Oxygen isotope record of oceanic and high-pressure metasomatism: a P–T–time–fluid path for the Monviso eclogites (Italy)
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Rubatto, Daniela and Angiboust, Samuel
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- 2015
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23. Blueschist-facies paleo-earthquakes in a serpentinite channel (Zagros suture, Iran) enlighten seismogenesis in Mariana-type subduction margins
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Muñoz-Montecinos, Jesús, Angiboust, Samuel, and Garcia-Casco, Antonio
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- 2021
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24. Effective rheology of a two-phase subduction shear zone: Insights from numerical simple shear experiments and implications for subduction zone interfaces
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Ioannidi, Paraskevi Io, Le Pourhiet, Laetitia, Agard, Philippe, Angiboust, Samuel, and Oncken, Onno
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- 2021
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25. Structural and biological control of the Cenozoic epithermal uranium concentrations from the Sierra Peña Blanca, Mexico
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Angiboust, Samuel, Fayek, Mostafa, Power, Ian M., Camacho, Alfredo, Calas, Georges, and Southam, Gordon
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- 2012
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26. Petrochronological close-up on the thermal structure of a paleo-subduction zone (W. Alps)
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Dragovic, Besim, Angiboust, Samuel, and Tappa, Michael J.
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- 2020
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27. Set the cadence of basal-accretion events along the subduction interface: a geological monitoring of the Hellenic margin
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Menant, Armel, Glodny, Johannes, Angiboust, Samuel, Augier, Romain, Oncken, Onno, Jolivet, Laurent, Bessière, Eloïse, Gerya, Taras, Menant, Armel, German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), 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), École normale supérieure de Lyon (ENS de Lyon), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Géodynamique - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Institut des Sciences de la Terre de Paris (iSTeP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), and SGF, CNRS, Laboratoire de Géologie de Lyon ou l’étude de la Terre, des planètes et de l’environnement
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[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics ,[SDU] Sciences of the Universe [physics] ,High pressure ,Forearc topography ,Tectonic underplating ,Transient deformation ,[SDU]Sciences of the Universe [physics] ,[SDU.STU.TE] Sciences of the Universe [physics]/Earth Sciences/Tectonics ,[SDU.STU] Sciences of the Universe [physics]/Earth Sciences ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,low temperature metamorphism ,Hellenic subduction zone - Abstract
International audience; Subduction margins are the loci of a wide range of deformation processes occurring at different timescales along the plate interface and in the overriding forearc crust. Whereas long-term deformation is usually considered as stable over Myr-long periods, this vision is challenged by an increasing number of observations suggesting a long-term pulsing evolution of active margins. To appraise this emerging view of a highly dynamic subduction system and identify the driving mechanisms, detailed studies on now-exhumed, high pressure-low temperature (HP-LT) accretionary complexes are crucial as they open a window on the deformation history from the plate interface to the surface.In this study, we combine structural and petrological observations, Raman spectroscopy on carbonaceous material, Rb/Sr multi-mineral geochronology and thermo-mechanical numerical models to unravel with an unprecedented resolution the tectono-metamorphic evolution of the Late-Cenozoic HP-LT nappe stack cropping out in western Crete (Hellenic subduction zone). A consistent decrease of peak temperatures and deformation ages toward the base of the nappe pile allows us to identify a minimum of three basal accretion episodes between ca. 28 Ma and ca. 15 Ma. On the basis of structural evidences combined with numerical modeling results, we argue that this succession of mass-flux events triggered (i) pulses in the strain rate, sometimes associated with a switch of the stress regime (i.e., compressional/extensional) and (ii) vertical surface oscillations eventually resulting in the growth of a high forearc topography. This accretion-controlled, Myr-scale tectonic and topographic signal plays a part in active deformations monitored at subduction margins, though it may remain invisible to most of geodetic methods because of superimposed shorter- timescale transients, such as seismic-cycle-related events.
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- 2021
28. Fluids in the Earth's lithosphere: From petrology to geodynamics
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Angiboust, Samuel, Cambeses, Aitor, Fagereng, Ake, Menegon, Luca, Klein, Frieder, Raimondo, Tom, and Prigent, Cécile
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- 2023
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29. Permeability of subducted oceanic crust revealed by eclogite-facies vugs.
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Angiboust, Samuel and Raimondo, Tom
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OCEANIC crust , *PERMEABILITY , *RARE earth metals , *TRACE elements , *EARTH'S mantle , *FLOW meters - Abstract
We report the finding of rare eclogite-facies vugs forming millimeter- to centimeter-sized pockets in meta-ophiolites from the western European Alps. Euhedral garnet crystals covering the vug walls display oscillatory chemical zoning for a wide range of major and trace elements, including Cr, Mn, and rare earth elements. Thermodynamic modeling revealed that closed-system fluid production through the breakdown of prograde glaucophane, lawsonite, and chlorite between 505 °C and 525 °C can successfully explain porosity creation of ~4% and the mineralogical properties of the vugs. Available geologic and geochronologic constraints indicate that the eclogitization of the downgoing mafic crust spanned a window of at least 1 m.y. These observations can only be explained by the presence of extremely low permeability values (<10-22 m²) to keep the fluid confined at the meter scale within vugs on such time scales. Our field-based report of eclogite porosity provides the first in situ confirmation of previous experimental data and geophysical estimates on active margins. A substantial amount of fluid trapped in this porosity may be carried deeper than expected into Earth's mantle, with implications for volatile recycling budgets. [ABSTRACT FROM AUTHOR]
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- 2022
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30. Towards an integrated vision of tectonic underplating in subduction zones
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Menant, Armel, Angiboust, Samuel, Gerya, Taras, Lacassin, Robin, Simoes, Martine, Grandin, Raphael, 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), and Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)
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[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics ,[SDU]Sciences of the Universe [physics] ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences - Abstract
International audience; Study of now-exhumed ancient subduction zones revealed km-scale tectonic units of marine sediments and oceanic crust, which have been underplated (i.e. basally accreted) to the overriding plate at more than 10-km depth. However, geophysical observations of this deep process in active subduction zones (e.g. SW-Japan, Cascadia, Chile) are unclear and the dynamics as well as the existence of tectonic underplating along most of active margins remain controversial.Using high-resolution visco-elasto-plastic thermo-mechanical models, we present with unprecedented details the dynamics of formation, preservation and destruction of underplated crustal nappes at 10-40-km depth in subductions zones. Thus, we are able to characterize tectonic underplating from the plate interface where tectonic slicing is triggered, to the surface where topographic variations may be expected in response to such huge mass transfers.Our results show that subduction segments exhibiting an increasing frictional behaviour control deep accretionary dynamics and that the long-term frictional zonation of the plate interface is stable due to a positive feedback between fluid distribution and effective stress. As a result, successive underplating events are maintained during tens of Myr, leading to the formation of a high coastal relief. The rise of this relief is cadenced by an uplift-then-subsidence cycle, which characterizes each underplating event and the subsequent period of wedge re-equilibration. This periodical evolution is significantly modified by changing the rheological properties of the material entering the subduction zone, suggesting that tectonic underplating is likely a transient process active along most of active margins, depending on severe variations of the hydro-mechanical properties of the plate interface at Myr timescale.
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- 2019
31. The rise and demise of deep accretionary wedges: A long-term field and numerical modeling perspective.
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Angiboust, Samuel, Menant, Armel, Gerya, Taras, and Oncken, Onno
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SUBDUCTION zones , *CONTINENTAL crust , *MASS transfer , *STRESS concentration , *SOUND recordings - Abstract
Several decades of field, geophysical, analogue, and numerical modeling investigations have enabled documentation of the wide range of tectonic transport processes in accretionary wedges, which constitute some of the most dynamic plate boundary environments on Earth. Active convergent margins can exhibit basal accretion (via underplating) leading to the formation of variably thick duplex structures or tectonic erosion, the latter known to lead to the consumption of the previously accreted material and eventually the forearc continental crust. We herein review natural examples of actively underplating systems (with a focus on circum-Pacific settings) as well as field examples highlighting internal wedge dynamics recorded by fossil accretionary systems. Duplex formation in deep paleo-accretionary systems is known to leave in the rock record (1) diagnostic macro- and microscopic deformation patterns as well as (2) large-scale geochronological characteristics such as the downstepping of deformation and metamorphic ages. Zircon detrital ages have also proved to be a powerful approach to deciphering tectonic transport in ancient active margins. Yet, fundamental questions remain in order to understand the interplay of forces at the origin of mass transfer and crustal recycling in deep accretionary systems. We address these questions by presenting a suite of two-dimensional thermo-mechanical experiments that enable unravelling the mass-flow pathways and the long-term distribution of stresses along and above the subduction interface as well as investigating the importance of parameters such as fluids and slab roughness. These results suggest the dynamical instability of fluid-bearing accretionary systems causes either an episodic or a periodic character of subduction erosion and accretion processes as well as their topographic expression. The instability can be partly deciphered through metamorphic and strain records, thus explaining the relative scarcity of paleo-accretionary systems worldwide despite the tremendous amounts of material buried by the subduction process over time scales of tens or hundreds of millions of years. We finally stress that the understanding of the physical processes at the origin of underplating processes as well as the forearc topographic response paves the way for refining our vision of long-term plate-interface coupling as well as the rheological behavior of the seismogenic zone in active subduction settings. [ABSTRACT FROM AUTHOR]
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- 2022
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32. Field report: Sailing around the exhumed roots of the Mesozoic Patagonian paleo-accretionary wedge (Diego de Almagro Island, Chile)
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Angiboust, Samuel and Muñoz, Jesus
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- 2018
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33. Brittle deformation during Alpine basal accretion and the origin of seismicity nests above the subduction interface
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Menant, Armel, Angiboust, Samuel, Monié, Patrick, Oncken, Onno, and Guigner, Jean-Michel
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- 2018
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34. Deformation of high-pressure metamorphic rocks: mutual constraints from 2D cm-scale thermo-mechanical models and petrological observations
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Yamato, Philippe, Duretz, Thibault, Angiboust, Samuel, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-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), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), 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), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)
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[SDU.STU]Sciences of the Universe [physics]/Earth Sciences - Abstract
International audience; How rocks deform at depth during lithospheric convergence and what are the magnitude of stress levels theyexperience during burial/exhumation processes constitute fundamental questions for refining our vision ofshort-term (i.e. seismicity) and long-term tectonic processes in the Earth’s lithosphere.We here present a set of 2D numerical experiments of eclogitic rock deformation performed at cm-scale. The deformedmedium is composed of two mineral phases: omphacite and garnet. We carried out a series of experimentsfor different background strain-rates and for a range of realistic pressure and temperature conditions. Results showthat fracturing of the entire eclogite rock can occur under HP-LT conditions for strain-rates even smaller thanthose generally expected for seismic events.We also explore the ranges of parameters where garnet and omphaciteare deforming with a different deformation style (i.e. frictional vs. viscous) and discuss our modelling results atthe light of naturally deformed eclogitic samples. Finally, we show that in cases of fracturing, the first event offrictional strain localisation constitutes a precursor for ductile strain localisation and results from the conversionof the mechanical energy into heat (i.e. shear-heating).
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- 2018
35. Evidence for brittle deformation events in eclogite-facies (example from the Mt. Emilius klippe, W. Alps)
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Hertgen, Solenn, Yamato, Philippe, Morales, Luiz, Angiboust, Samuel, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), 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)
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[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics - Abstract
International audience; Eclogitic rocks are crucial for our knowledge of the subduction interface because they provide key constraints on both the evolution (P-T-t paths) and the deformation modes sustained by rocks in subduction zones. We herein focus on eclogitised flattened mafic bodies exposed within granulites from the continental basement slice of the Mt. Emilius klippe (W. Alps, Italy).These eclogites exhibit highly deformed garnetite and clinopyroxenite layers. In some places, these deformed rocks (up to mylonitic) can be found as clasts within meter-thick brecciated fault rocks formed close to the metamorphic peak conditions in the lawsonite-stable eclogite facies (at P 2.2-2.4 GPa and T 500-550°C).The garnet-rich layers tend to show brittle features, whereas deformation within clinopyroxene-rich layers is accommodated by both dislocation creep and fracturing. We present a petro-structural study of these eclogites allowing to track the brittle deformation mode associated with the chemical evolutionfrom the outcrop to the microscopic scale. We propose a new tectono-metamorphic model for the deformation of these rocks, related to the alpine eclogitic stage.This model is consistent with the coexistence of both ductile and brittle features that developed in the same metamorphic facies, and closely associated with fluid circulations. Our study shows therefore that the crustal material, along the subduction interface at HP-LT conditions, can record several successive brittle events in places where deformation is classically envisioned as ductile. This brings new constraints in our understanding of the mechanical processes in the subduction zone interface.
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- 2018
36. Drainage of subduction interface fluids into the forearc mantle evidenced by a pristine jadeitite network (Polar Urals).
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Angiboust, Samuel, Glodny, Johannes, Cambeses, Aitor, Raimondo, Tom, Monié, Patrick, Popov, Michael, and Garcia‐Casco, Antonio
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SUBDUCTION , *LONG-Term Evolution (Telecommunications) , *DRAINAGE , *FLUIDS , *SUBDUCTION zones , *DIKES (Geology) , *HIGH temperatures , *PERIDOTITE - Abstract
The physical and mechanical processes rooted in the hydrated, serpentinized mantle above subduction zones remain insufficiently explored despite fundamental implications for our understanding of rheology and fluid recycling along subduction interfaces. Through a field‐based investigation, serpentinized peridotites and jadeitite samples from a fossil forearc mantle in the Polar Urals (Russia) are studied here to document fluid–rock interaction processes in the high‐P field, as well as the long‐term evolution of the base of the mantle wedge. Petrographic, geochemical and microstructural observations reveal a complex, protracted evolution of the jadeitite‐forming fluid pathway throughout the gradual cooling of the forearc mantle and increasing serpentinization of the host. It is shown that the jadeitite lenses in the studied locality (a) derive for a large part from a trondhjemitic dyke earlier emplaced in a warm subduction environment, and (b) record the cooling of the subduction hangingwall under high‐P conditions associated with increasing host serpentinization. In the studied locality, the majority of the jadeitites formed at relatively high temperatures (>600°C) by the influx of Na–Al‐rich, slab‐derived metamorphic fluids that were drained along the base of the mantle wedge, parallel to the subduction interface. Changes in bulk‐rock geochemical signatures and in paragenetic sequences also constrain the compositional evolution of the fluid channelized along this drainage, with an increasing sedimentary component. The phlogopite‐bearing walls of the dyke exhibit Rb–Sr and Ar–Ar ages ranging between c. 405 and c. 390 Ma, a range partly overlapping within uncertainty with the previously dated zircons from the jadeitite core (410–400 Ma; U–Pb). This study opens a unique window on the pristine structures formed above the plate interface by melting and fluid–rock interaction in the early subduction stages, as well as their evolution during secular cooling of the base of the mantle wedge. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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37. Seamount subduction at seismogenic depths: Structural and metamorphic evidence from the Zagros Suture Zone
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Bonnet, Guillaume, Agard, Philippe, Angiboust, Samuel, Fournier, Marc, Omrani, Jafar, and Bonnet, Guillaume
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[SDU] Sciences of the Universe [physics] - Published
- 2018
38. Multiple veining in a paleo-accretionary wedge: The metamorphic rock record of prograde dehydration and transient high porefluid pressures along the subduction interface (Western Series, central Chile).
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Muñoz-Montecinos, Jesús, Angiboust, Samuel, Cambeses, Aitor, and García-Casco, Antonio
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METAMORPHIC rocks , *SOUND recordings , *SUBDUCTION zones , *SUBDUCTION , *DEHYDRATION reactions , *VEINS , *QUARTZ - Abstract
High pressure-low temperature metamorphic rocks from the late Paleozoic accretionary wedge exposed in central Chile (Pichilemu region) are characterized by a greenschist-blueschist lithological association with interbedded metasediments that reached peak burial conditions of ~400 °C and 0.8 GPa during late Carboniferous times. We herein combine new extensive field observations, structural measurements, and geochemical and petrological data on vein and matrix material from Pichilemu transitional greenschist-blueschist facies rocks. The studied veins were first filled by albite, followed by quartz and calcite as well as glaucophane and winchite. Field, structural, and microscopic zoning patterns show that these rocks underwent a protracted sequence of prograde vein-opening events, which have been largely transposed to the main foliation before and during underplating in the basal accretion site near 25-30 km depth. While some of the earliest albite-filled vein sets may have formed after prograde breakdown of sub-greenschist facies minerals (<250 °C), our thermodynamic modeling shows that relatively minor amounts of fluid are produced in the subducted pile by dehydration reactions between 250 and 400 °C along the estimated geothermal gradient. It also confirms that the formation of interlayered blueschist and greenschist layers in Pichilemu metavolcanics is a consequence of local bulk composition variations, and that greenschists are generally not formed due to selective exhumation-related retrogression of blueschists. The early vein sets are a consequence of prograde internal fluid production followed by sets of hydrofractures formed at near-peak burial that are interpreted as a record of external fluid influx. We postulate that such a fractured sequence represents a close analogue to the high-Vp/Vs regions documented by seismological studies within the base of the seismogenic zone in active subduction settings. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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39. Deformation along the roof of a fossil subduction interface in the transition zone below seismogenic coupling: The Austroalpine case and new insights from the Malenco Massif (Central Alps).
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Ioannidi, Paraskevi Io, Angiboust, Samuel, Oncken, Onno, Agard, Philippe, Glodny, Johannes, and Sudo, Masafumi
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SUBDUCTION zones , *MUSCOVITE , *SHEAR zones , *FOSSILS , *GEOLOGICAL time scales , *SUBDUCTION , *FOSSIL collection - Abstract
A network of fossil subduction plate interfaces preserved in the Central Alps (Val Malenco, N Italy) is herein used as a proxy to study deformation processes related to subduction and subsequent underplating of continental slices (in particular the Margna and Sella nappes) at depths reported to in the former brittle-ductile transition. Field observations, microfabrics, and mapping revealed a network of shear zones comprising mostly mylonites and schists but also rare foliated cataclasites. These shear zones are either located at the contacts of the two nappes or within the boundaries of the Sella unit. Microprobe results point to two different white mica generations, with higher-pressure (Si-rich) phengites rimming lower- pressure (Si-poor) phengites. Garnet is locally observed overgrowing resorbed pre-Alpine cores. Pressure-temperature estimates based on pseudosection modeling point to peak burial deformation conditions of ~0.9 GPa and 350-400 °C, at ~30 km depth. Rb/Sr geochronology on marbles deformed during the Alpine event yields an age of 48.9 ± 0.9 Ma, whereas due to incomplete recrystallization, a wide range of both Rb/Sr and 40Ar/39Ar apparent ages is obtained from deformed orthogneisses and micaschists embracing 87-44 Ma. Based on our pressure-temperature, structural and geochronological observations, the studied shear zones last equilibrated at depths downdip of the seismogenic zone in an active subduction zone setting. We integrate these new results in the frame of previous studies on other segments of the same Alpine paleosubduction interface, and we propose that this system of shear zones represents deformation conditions along the subduction interface(s) in the transition zone below the seismogenic zone during active subduction. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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40. Zagros blueschists: Episodic underplating and long-lived cooling of a subduction zone
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Angiboust, Samuel, Agard, Philippe, Glodny, Johannes, Omrani, Jafar, and Oncken, Onno
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- 2016
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41. Structure and metamorphism of a subduction mélange (Sistan, Eastern Iran): a close-up on subduction channel processes
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Bonnet, Guillaume, Agard, Philippe, Angiboust, Samuel, Monie, Patrick, Whitechurch, Hubert, Fournier, Marc, Jentzer, Michael, and Bonnet, Guillaume
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[SDU] Sciences of the Universe [physics] - Published
- 2017
42. Evidences for brittle deformation events ineclogite-facies conditions: the case of theMt. Emilius kilppe (Western Alps)
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Hertgen, Solenn, Yamato, Philippe, Morales, Luis, Angiboust, Samuel, Géosciences Rennes (GR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), Société Géologique de France, Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), and Dubigeon, Isabelle
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eclogite breccia ,[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics ,brittle ,rock interactions ,ductile deformation ,[SDU.STU.TE] Sciences of the Universe [physics]/Earth Sciences/Tectonics ,subduction zone ,[SDU.STU.MI] Sciences of the Universe [physics]/Earth Sciences/Mineralogy ,fluid ,[SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy - Abstract
National audience; Eclogitic rocks are crucial in tectonics as they provide key constraintson both the evolution (P-T-t paths) and the deformationmodes sustained by the rocks in subduction zones. We herein focuson eclogitized flattened mafic bodies remnants exposed withingranulites from the continental basement slice of the Mt. Emiliusklippe (Western Alps, Italy). These eclogites exhibit highly deformed(up to mylonitic) garnetite and clinopyroxenite levels foundas clasts within meter-thick eclogitic shear zone formed close tothe metamorphic peak conditions under lawsonite bearing eclogitefacies conditions. The garnet-rich levels tend to behave in abrittle fashion while deformation within clinopyroxene-rich levels ismostly accommodated by creep, as evidenced by the presence ofelongated grains, subgrains boundaries and intense grain size reduction.Especially, crystallographic preferred orientation (CPO)measurements in garnet indicate a quasi-random distribution. Inmost of the clinopyroxene levels nevertheless, the CPO is relativelystrong, with multiples of uniform distribution varying from4 to 5.5 (value of 1 is random texture). This CPO is characterizedby a strong alignment of poles of the planes (001) parallelto the lineation and poles of the planes (100) and directions ofthe planes [010] distributed along girdles cross-cutting the foliationplane. Based on a petrological study, from the outcrop tothe microscopic scale, we propose a tectono-metamorphic historyof the Mt. Emilius eclogites. This history related to the alpineeclogitic event, allow to link the metamorphic P-T path and thedeformation processes in association with the chemical evolutionsthat could lead to the formation of the Mt. Emilius brecciatedeclogites in the Arbole region. This model is consistent with thealternating ductile and brittle events that developed in the samemetamorphic facies, at P~2.0-2.5 GPa and T~500-550C, closelyassociated to metamorphic fluid circulations. Thus, our study atteststhat the material along the subduction interface, at HP-LTconditions, can locally be brittle where deformation is classicallyenvisioned as ductile.
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- 2016
43. Accretion/underplating, detachment and exhumation: short/long-term rheology of the subduction plate interface
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Agard, Philippe, Angiboust, Samuel, Plunder, Alexis, Guillot, Stéphane, Yamato, Philippe, Al., Et, Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), Institut des Sciences de la Terre (ISTerre), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), European Geosciences Union, Dubigeon, Isabelle, Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)
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[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics ,[SDU.STU.TE] Sciences of the Universe [physics]/Earth Sciences/Tectonics - Abstract
International audience; The presence of km-scale accreted terranes/units in both ancient and present-day subduction zones attests tochanges in strain localization along the plate interface, whereby these terranes/units get detached from the downgoingslab (or, in places, are eroded away from the tip of the upper plate) and either directly exhumed or accreted/underplated below the upper plate before final exhumation. The rock record (P-T-t data) indicates that, for agiven subduction zone, exhumation is episodic: no more than a few My compared to the 100 My lifetime of typicalsubduction zones. Not much is known, however, regarding this process and important open questions remain:what exactly is episodic (i.e. detachment from the slab and/or exhumation?), for how long and where? How is mechanicalcoupling impacted by the initial structure of the incoming plates (structural/lithological heterogeneities,thermo-fluid regime, geodynamic boundary conditions, etc...)?We herein present both new and literature structural and P-T-t data ranging from shallow (i.e. 15-20 km) to intermediatedepths (100 km) along the subduction interface, that span a range from long-term to short-lived eventsof underplating and/or exhumation, and confront them with the recent wealth of geophysical data gathered onsubduction zones. Structural and petrological data indicate that the slicing of km-scale units mostly occurs atspecific depths where major mechanical changes occur along the plate interface: at 30-40 km (downdip of theseismogenic zone) and 70-80 km (where mechanical coupling between the two plates resumes and where eclogitesget critically dense). This suggests that switches in mechanical coupling (i.e. in the rheology of the material)are key in controlling the ability to detach pieces from the slab (and that later exhumation is rather controlledby large-scale, lithospheric-scale boundary conditions). The study of rock remnants detached from the slab andunderplated during subduction infancy (i.e. metamorphic soles) further illustrates how changing rheologies (crustv. mantle) and increased mechanical coupling affect the potential to retrieve rocks/units and emphasize the role offluids (and of the mantle wedge). Fully-coupled thermo-mechanical models taking into account variable hydrationconditions strengthen these conclusions. From these observations, we infer that long-term mechanical couplingprobably varies throughout subduction lifetime, from strong to weak, as a function of the contrast of effective viscosityon either side of the subduction interface: a young and wet interface will promote strong viscous coupling,metamorphic sole accretion and the formation of high-temperature (eclogite) knockers, whereas a fluid-present yetdrier and colder one will mainly promote underplating of metasedimentary material and, occasionally, large-scaleslivers of oceanic lithosphere. We finally discuss the possible link between strain localization mechanisms leadingto tectonic slicing and seismicity (regular or slow earthquakes), particularly in the light of the recent finding ofeclogite breccias.
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- 2016
44. Brittle/Ductile deformation at depth during continental crust eclogitization (Mont-Emilius klippe,Western Internal Alps)
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Hertgen, Solenn, Yamato, Philippe, Morales, Luiz, Angiboust, Samuel, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), European Geosciences Union, Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), and Dubigeon, Isabelle
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[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics ,[SDU.STU.TE] Sciences of the Universe [physics]/Earth Sciences/Tectonics - Abstract
International audience; Eclogitic rocks are important for understanding tectonics at large scale as they provide key constraints on boththe evolution (P-T-t-" paths) and the deformation modes of the crust along the subduction interface. We hereinfocus our study on eclogitized mafic dykes remnants exposed within granulites from the continental basementsilver of the Mt. Emilius klippe (Western Internal Alps, Italy). These eclogites exhibit highly deformed garnetiteand clinopyroxenite levels. In some places, these rocks with a mylonitic aspect can be found as clasts withinmeter-thick brecciated fault rocks formed close to metamorphic peak conditions in eclogite facies. Especially, thegarnet-rich levels tend to behave in a brittle fashion while deformation within clinopyroxene-rich levels is mostlyaccommodated by creep. This is evidenced by the presence of elongated grains, subgrain boundaries and intensegrain size reduction close to rigid garnets. Crystallographic preferred orientation (CPO) measurements in garnetsindicate a quasi-random distribution. In most of the clinopyroxenes levels nevertheless, the CPO is relativelystrong, with multiples of uniform distribution varying from 4 to 5.5 (value of 1 is random texture). This CPO ischaracterized by a strong alignment of poles (001) parallel to the lineation and (100) and [010] distributed alonggirdles cross-cutting the foliation plane. Our study thus attests that the materials along the subduction interfaceat P2.0-2.5 GPa and T500-550C can locally be brittle where deformation is classically envisioned as ductile.In addition to this deformation analysis, we present a petrological study of these eclogites, from the outcrop tothe microscopic scale, tracking the chemical evolution associated to the observed deformation. Based on all thesedata, we finally propose a tectono-metamorphic history for these rocks allowing to explain the co-existence ofductile and brittle features developed in the same metamorphic facies, and closely associated to the circulation ofmetamorphic fluids.
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- 2016
45. Dynamique d’écaillage et d’exhumation des unités océaniques subductées du Sistan (Iran oriental)
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Bonnet, Guillaume, Agard, Philippe, Angiboust, Samuel, Monie, Patrick, Jentzer, Michael, Fournier, Marc, and Bonnet, Guillaume
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[SDU] Sciences of the Universe [physics] - Published
- 2016
46. Detachment, accretion/underplating and short- vs. long-term rheology of the subduction plate interface
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Agard, Philippe, Angiboust, Samuel, Plunder, Alexis, Bonnet, Guillaume, Ruh, Jonas B., and Bonnet, Guillaume
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[SDU] Sciences of the Universe [physics] - Published
- 2016
47. Middle to Late Miocene Age for the End of Amphibolite‐Facies Mylonitization of the Alpine Schist, New Zealand: Implications for Onset of Transpression Across the Alpine Fault.
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Ring, Uwe, Glodny, Johannes, Angiboust, Samuel, Little, Tim, and Lang, Karl A.
- Abstract
We report five new Rb‐Sr muscovite‐based isochron ages, which are the first to constrain the timing of amphibolite‐facies mylonitization of the Alpine Schist in the Southern Alps of New Zealand. The ages range from 13.1 ± 4.3 to 8.9 ± 3.2 Ma (2σ uncertainties) for mylonite directly above the Alpine Fault. The weighted mean age of 10.74 ± 0.57 Ma is within uncertainty of a published 40Ar/39Ar illite/mica upper‐intercept age of 11.5 ± 0.5 Ma measured at the same locality. The end of amphibolite‐facies mylonitization occurred at metamorphic conditions of ~560–570 °C and ~0.9–1.1 GPa as derived from pseudosection analysis in the NCTiKFMASH system. We interpret Miocene metamorphism to reflect transpressional crustal thickening and formation of a thick crustal root supporting early Southern Alps topography at or prior to 10.74 ± 0.57 Ma. Additional ~2–1 Ma Rb‐Sr biotite, 40Ar/39Ar muscovite, and 40Ar/39Ar biotite ages reflect isotopic closure during rapid cooling along the Alpine Fault in the Pleistocene. The Miocene mylonitization ages and the Pleistocene cooling ages define a distinct two‐stage cooling and exhumation history for the Alpine Schist with initial cooling of ~10 °C/Myr and exhumation rates of 2–4 km/Myr. Final cooling since ~2 Ma was >100 °C/Myr at exhumation rates of ~5–6 km/Myr. We interpret the two‐phase cooling history by movement of the mylonite through a strongly nonlinear thermal structure. An older 60.5 ± 0.7 Ma metamorphic event is also preserved as a Rb‐Sr crystallization age of a predeformational muscovite‐plagioclase assemblage in a sheared pegmatite. Key Points: We present the first quantitative data constraining the timing of Cenozoic Alpine Schistmylonitization and metamorphismWe present evidence for middle Miocene crustal thickening in the Southern Alps of New ZealandThe Alpine Schist has a distinct two‐phase cooling history [ABSTRACT FROM AUTHOR]
- Published
- 2019
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48. A 100-m.y.-long window onto mass-flow processes in the Patagonian Mesozoic subduction zone (Diego de Almagro Island, Chile).
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Angiboust, Samuel, Cambeses, Aitor, Hyppolito, Thais, Glodny, Johannes, Monié, Patrick, Calderón, Mauricio, and Juliani, Caetano
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GRANULITE , *SUBDUCTION , *PLATE tectonics , *ACCRETION (Chemistry) , *MESOZOIC Era - Abstract
Diego de Almagro Island was formed by the subduction and accretion of several seafloor-derived tectonic slices with very heterogeneous ages and pressure-temperature-time (P-T-t) paths. The highest element of the pile (the Lazaro unit) evidences subduction in the high-P granulite field (~1.3 GPa, 750 °C) at ca. 163 Ma. Below it, a thin tectonic sliver (the Garnet Amphibolite unit) preserves eclogitefacies remnants (~570 °C and ~1.7 GPa) formed at ca. 131 Ma (in situ U-Pb zircon rim ages). Peak assemblages were nearly fully amphibolitized during decompression down to ~1.2 GPa and ~600 °C at 125-120 Ma (Rb-Sr multimineral dating). The underlying Blueschist unit has ~50 m.y. younger metamorphic ages and exhibits slightly cooler peak burial conditions (~520 °C, 1.7 GPa; ca. 80 Ma, in situ white mica Ar-Ar ages and multimineral Rb-Sr dating) and is devoid of amphibolitization. The mylonites from the sinistral strike-slip Seno Arcabuz shear zone bounding Diego de Almagro Island to the east also exhibit amphibolite-facies (~620 °C and ~0.9 GPa) deformation at ca. 117 Ma (multimineral Rb-Sr ages). In situ white mica Ar-Ar dating and multimineral Rb-Sr dating of low-T mylonites (~450 °C) along the base of the Lazaro unit reveal partial resetting of high-T assemblages during tectonic displacement between 115 and 72 Ma and exhumation of the slice stack. Detrital zircon U-Th-Pb ages indicate that the material accreted on Diego de Almagro Island has been mostly recycled from a Permian-Triassic accretionary wedge (Madre de Dios accretionary complex) exposed along the subduction buttress. Geological and geochronological constraints suggest that the rocks of the Seno Arcabuz shear zone and the Lazaro unit were tectonically eroded from the buttress, while the underlying Garnet Amphibolite and Blueschist units instead derive from the subducted oceanic basin, with increasingly younger maximum depositional ages. The very long residence time of the rocks (~90 m.y. for the Lazaro unit) along the hanging wall of the subduction interface recorded long-term cooling along the Patagonian subduction zone during the Mesozoic. Diego de Almagro Island therefore represents a unique window onto long-term tectonic processes such as subduction interface down-stepping, tectonic erosion, and episodic underplating near the base of an accretionary wedge (40-50 km). [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
49. Effect of fluid release on intermediate depth subduction processes: Insights from fully-coupled numerical modelling
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Angiboust, Samuel, Wolf, Sylvie, Burov, Evgenii, Agard, Philippe, Yamato, Philippe, Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Systèmes Tectoniques, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Dubigeon, Isabelle, Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS), and Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS)
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[SDU.STU] Sciences of the Universe [physics]/Earth Sciences ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience; A wide range of geophysical/petrological data indicates that large amounts of water are released in subduction zones during the burial of oceanic lithosphere through metamorphism and associated dehydration reactions. Large volumes of aqueous fluids are expected and observed in the mantle wedge, just below the continental Moho. Recent estimates suggest that the mantle wedge is heterogeneously serpentinized (generally 20-30%). This serpentinization is believed to cause a significant weakening of the mantle wedge and therefore may critically control the depth of interplate seismogenic coupling. However, data constraining mechanisms driving deep (50-200km) fluid circulation are lacking and fluid-rock interaction processes remain weakly constrained at the km-scale. We herein propose a new fluid migration algorithm based on thermodynamic modelling (PerpleX) where fluids are free to migrate, driven by rock fluid concentration, non-lithostatic pressure gradients and deformation. Oceanic subduction is modelled using a forward visco-elasto-plastic thermomechanical code (FLAMAR algorithm) based on previous work by Yamato et al. (2007). After 15 Ma of convergence between the two plates, we show that deformation is accommodated along a low-strength shear zone in the wall of the subduction thrust interface, characterized by a weak (10-25% serp.) and relatively narrow (between 3-6km) serpentinized front/channel. Our results also show that dehydration associated with eclogitization of oceanic crust (60-75km) and serpentinite breakdown (110- 130km) significantly weakens the mantle wedge at these depths, thereby favouring deep sedimentary accretion in the deep mantle wedge. We finally show that dehydration causes significant fluid overpressures in the downgoing oceanic lithosphere. These results bring new critical constraints on the location of intermediate-depth seismicity and dehydration-embrittlement processes reported by geophysical studies.
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- 2012
50. Eclogitized Oceanic Crust During Subduction: Implications for Subduction Zone Dynamics
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Angiboust, Samuel, Agard, Philippe, Langdon, Ryan, Waters, Dave, Raimbourg, Hugues, Yamato, Philippe, Chopin, Christian, Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Systèmes Tectoniques, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géologie de l'ENS (LGENS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Dubigeon, Isabelle, Université de Tours-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris)
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[SDU.STU] Sciences of the Universe [physics]/Earth Sciences ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences - Abstract
International audience; The Monviso ophiolite is composed of two main tectonic slices: the Monviso Unit (MU) to the west, which overlies the Lago Superiore Unit (LSU). Our PT estimates show that the MU has been subducted down to 480°C-23kbar (~70km) during Alpine subduction while the LSU reached slightly deeper conditions (540°C-26kbar, i.e. ~80km). This ophiolite, which comprises large (10-20km long) ophiolite fragments therefore does not correspond to a serpentinite mélange, and may be the southern extension of the Zermatt-Saas ophiolite (Angiboust et al., 2009; 2011). The well-preserved LSU constitutes an almost continuous upper fragment of oceanic lithosphere subducted between 50 and 40 Ma and later exhumed along the subduction interface. It therefore provides a unique opportunity to study strain partitioning and deep mechanical behaviour of the subducting lithosphere. The LSU comprises (i) several hundred meters of eclogitized basaltic crust (+ minor calcschist lenses) overlying a 100-400m thick metagabbroic body and (ii) a serpentinite sole (c. 1km thick). We herein focus on eclogite-facies shear zones, which are found at the boundary between basalts and gabbros, and between gabbros and serpentinites, i.e. between material with marked rheological contrasts. Eclogite facies blocks within the shear zones display intense fracturation, fragment rotation and dispersion in the serpentinite schists which line up the shear zones. We also report the first finding of eclogite-facies breccias, constituted of rotated eclogite mylonitic clasts cemented within an eclogite-facies matrix. Local fracturation of garnet within these breccias is attested by the presence of numerous fracture networks within garnet, generally healed by a Mg-enriched composition. The shear zones also preserve clear evidence of pervasive and channelized fluid flow (of variable duration) leading to alteration of bulk rock composition, weakening of the rock and widespread crystallization of lawsonite. Our results provide new constraints for deep mechanical coupling processes and meter-scale fluid-rock interaction occurring at depth in present-day subduction zones. In particular, we emphasize that (i) rheological contrasts in the field qualitatively support those inferred from experimental flow laws, (ii) fluid flow is channelized along deep eclogite facies shear zones (iii) brittle fracturing recorded by eclogite breccias and garnet fractures could be associated with deep interplate seismicity.
- Published
- 2011
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