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847 results on '"Géosciences Rennes (GR)"'

1. Core Complex Segmentation in North Aegean, A Dynamic View

Author: Brun, Jean Pierre, Sokoutis, Dimitrios, Tectonics, 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 ), Department of Geosciences [Oslo], University of Oslo ( UiO ), Tectonics, Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Institut Universitaire de France, The Netherlands Centre for Integrated Solid Earth Science, Géosciences Rennes (GR), Université de Rennes 1 (UR1), and 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)
Subjects: Aegean back-arc extension, 010504 meteorology & atmospheric sciences, North Anatolian Fault, Structural basin, 010502 geochemistry & geophysics, Neogene, 01 natural sciences, Paleontology, Geochemistry and Petrology, metamorphic core complex, 14. Life underwater, Clockwise, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, geography.geographical_feature_category, Rift, Rhodope, Metamorphic core complex, wide rifting, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, Sedimentary basin, Geophysics, Slab, acceleration of subduction rollback, Geology
Abstract: International audience; The core complexes of the North Aegean result from the gravity spreading of a thrust wedge, driven by the Hellenic slab rollback, since middle Eocene. The development of the Southern Rhodope Core Complex occurred in two stages: (i) core complex exhumation accommodated by the Kerdylion detachment and (ii) steep normal faulting controlling the deposition of Neogene sedimentary basins that segmented the core complex. Both stages have been controlled by a clockwise rotation of the detachment hanging wall. The bulk amount of extension along the Aegean coastline in Northern Greece reached 120 km. The transition between the two stages occurred in middle Miocene due to an increase in extensional displacement by a factor 5. This transition between two different modes of extension, from localized detachment (i.e., core complex mode) to distributed steep normal faulting (i.e., wide rift mode), occurred at Aegean scale as a result of an acceleration of slab rollback. The Neogene basins emplaced close to the detachment, where brittle upper crust was thin (around 7 km) but containing weak marble layers allowing the formation of ramp-flat extensional systems with rollover-type basin fill. Since Pliocene, the stretching direction changed, from NE-SW to NS, due to the propagation of the North Anatolian Fault in the North Aegean domain.
Published: 2018

2. Trench-parallel spreading ridge subduction and its consequences for the geological evolution of the overriding plate: Insights from analogue models and comparison with the Neogene subduction beneath Patagonia

Author: Joseph Martinod, Benjamin Guillaume, Christian Sue, Matías C. Ghiglione, Jean-Jacques Kermarrec, Méline Salze, Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), 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), Instituto de Estudios Andinos 'Don Pablo Groeber' (INDEAN), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET)-Facultad de Ciencias Exactas y Naturales [Buenos Aires] (FCEyN), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA), INSU-CNRS, A15-U02, ECOS-Sud, University of Bourgogne–Franche-Comté, Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Université de Franche-Comté ( UFC ) -Centre National de la Recherche Scientifique ( CNRS ), Institut des Sciences de la Terre ( ISTerre ), Université Joseph Fourier - Grenoble 1 ( UJF ) -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-PRES Université de Grenoble-Université Savoie Mont Blanc ( USMB [Université de Savoie] [Université de Chambéry] ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ), 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 ), INDEAN - Instituto de Estudios Andinos 'Don Pablo Groeber', Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Université de Rennes 1 (UR1), and 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)
Subjects: Lithosphere, 010504 meteorology & atmospheric sciences, 010502 geochemistry & geophysics, Geociencias multidisciplinaria, 01 natural sciences, Ciencias de la Tierra y relacionadas con el Medio Ambiente, SUBDUCTION, Analogue modeling, Asthenosphere, Patagonia, Oceanic ridge, Southernmost Andes, ANALOGUE MODELING, 0105 earth and related environmental sciences, Earth-Surface Processes, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, SLAB PULL FORCE, geography.geographical_feature_category, Volcanic arc, Subduction, Mid-ocean ridge, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, LITHOSPHERE, PATAGONIA, Geophysics, Ridge, Trench, Slab, SOUTHERNMOST ANDES, Slab pull force, OCEANIC RIDGE, Geology, Seismology, CIENCIAS NATURALES Y EXACTAS
Abstract: A series of 3-D asthenospheric-scale analogue models have been conducted in the laboratory in order to simulate the arrival of a spreading ridge at the trench and understand its effect on plate kinematics, slab geometry, and on the deformation of the overriding plate. These models are made of a two-layered linearly viscous system simulating the lithosphere and asthenosphere. We reproduce the progressive decrease in thickness of the oceanic lithosphere at the trench. We measure plate kinematics, slab geometry and upper plate deformation. Our experiments reveal that the subduction of a thinning plate beneath a freely moving overriding continent favors a decrease of the subduction velocity and an increase of the oceanic slab dip. When the upper plate motion is imposed by lateral boundary conditions, the evolution of the subducting plate geometry largely differs depending on the velocity of the overriding plate: the larger its trenchward velocity, the smaller the superficial dip of the oceanic slab. A slab flattening episode may occur resulting from the combined effect of the subduction of an increasingly thinner plate and the trenchward motion of a fast overriding plate. Slab flattening would be marked by an increase of the distance between the trench and the volcanic arc in nature. This phenomenon may explain the reported Neogene eastward motion of the volcanic arc in the Southern Patagonia that occurred prior to the subduction of the Chile Ridge. Fil: Salze, Méline. Universite de Bourgogne; Francia Fil: Martinod, Joseph. Université de Savoie Mont Blanc; Francia Fil: Guillaume, Benjamin. Universite de Rennes I; Francia Fil: Kermarrec, Jean Jacques. Universite de Rennes I; Francia Fil: Ghiglione, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Sue, Christian. Universite de Bourgogne; Francia
Published: 2018

3. Structural, metamorphic and geochronological insights on the Variscan evolution of the Alpine basement in the Belledonne Massif (France)

Author: Marc Poujol, Olivier Bruguier, Kévin Fréville, Olivier Blein, Wei Lin, Jérémie Melleton, Xian-Hua Li, Pierre Trap, Michel Faure, 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), Métallogénie - 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), Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), State Key Laboratory of Lithospheric Evolution (SKL), Institute of Geology and Geophysics [Beijing] (IGG), Chinese Academy of Sciences [Beijing] (CAS)-Chinese Academy of Sciences [Beijing] (CAS), Chinese Academy of Inspection And Quarantine (CAIQ), 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), Terre, Temps, Traçage, 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), ISTO, BRGMBRGM, Laboratoire Chrono-Environnement, Observatoire des Sciences de l'Univers en Région Centre, Institut des Sciences de la Terre d'Orléans - UMR7327 ( ISTO ), Bureau de Recherches Géologiques et Minières (BRGM) ( BRGM ) -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 ) -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 ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Université de Franche-Comté ( UFC ) -Centre National de la Recherche Scientifique ( CNRS ), Bureau de Recherches Géologiques et Minières (BRGM) ( BRGM ), State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Chinese Academy of Inspection And Quarantine ( CAIQ ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de Montpellier ( UM ) -Université des Antilles ( UA ) -Centre National de la Recherche Scientifique ( CNRS ), 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 ) -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 ), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-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)-Université de Rennes 1 (UR1), and 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)
Subjects: 010504 meteorology & atmospheric sciences, Geochemistry, Metamorphism, Thermobarometry, 010502 geochemistry & geophysics, 01 natural sciences, Nappe, Alpine External Crystalline Massifs, Lineation, SIMS and LA-ICP-MS dating, Metamorphic facies, 0105 earth and related environmental sciences, Earth-Surface Processes, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, geography.geographical_feature_category, Schist, Orogeny, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, Massif, Variscan Belt, Geophysics, Zircon and monazite dating, Geology, Zircon, Belledonne Massif
Abstract: International audience; A structural and petrochronological study was carried out in the southern part of the Belledonne crystalline massif. A first tectonometamorphic event, Dx, corresponds to the eastward thrusting of the Chamrousse ophiolitic complex characterized by a low-temperature–moderate-pressure metamorphism reaching 0.535 ± 0.045 GPa and 427.5 ± 17.5 °C. A subsequent D1 deformation is defined by a penetrative S1 foliation that mostly dips toward the west and displays an E–W- to NE–SW-trending mineral and stretching lineation L1. D1 is associated with a top-to-the east shearing and is responsible for the crustal thickening accommodated by the eastward nappe stacking and the emplacement of the Chamrousse ophiolitic complex upon the Rioupéroux-Livet unit. This event is characterized by an amphibolite facies metamorphism (0.58 GPa ± 0.06; 608 ± 14 °C) that attains partial melting at the base of the nappe pile (0.78 ± 0.07 GPa; 680.5 ± 11.5 °C). LA-ICP-MS U-Pb dating of monazite grains from the mica schists of the Rioupéroux-Livet unit constrain the age of D1 to 337 ± 7 Ma. The D2 tectono-metamorphic event is characterized by NE–SW trending, upright to NE-verging synfolial folding. Folding associated with D2 is pervasively developed in all lithotectonic units with the development of a steeply-dipping S2 foliation. In particular, D2 involves the uppermost weakly metamorphosed Taillefer unit. LA-ICP-MS U-Pb dating performed on detrital zircon grains shows that the Taillefer conglomerates was deposited during the Visean. A zircon SIMS U-Pb age of 352 ± 1 Ma from a plagioglase-rich leucocratic sill of the Rioupéroux-Livet unit is interpreted as the age of magmatic emplacement. Our results suggest that the D2 event took place between 330 Ma and 310 Ma. We propose a new interpretation of the tectonometamorphic evolution of the southern part of the Belledonne massif, focusing on the Middle Carboniferous stages of the Variscan orogeny.
Published: 2018

4. Geochronological constraints on the Trans-Hudsonian tectono-metamorphic evolution of the pre-Athabasca basement within the Wollaston-Mudjatik Transition Zone, Saskatchewan

Author: Marc Poujol, David Quirt, Patrick Ledru, Philippe Goncalves, Pierre Trap, Pauline Jeanneret, Cyril Durand, Didier Marquer, Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Laboratoire de Génie Civil et Géo-Environnement (LGCgE) - ULR 4515 (LGCgE), Université d'Artois (UA)-Université de Lille-Ecole nationale supérieure Mines-Télécom Lille Douai (IMT Lille Douai), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL), 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), Groupe AREVA, Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Laboratoire Génie Civil et géo-Environnement (EA 4515), 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 ), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Université de Rennes 1 (UR1), and 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)
Subjects: Uranium-enriched pegmatites, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, 010504 meteorology & atmospheric sciences, LA-ICP-MS monazite and zircon geochronology, Metamorphic rock, Wollaston-Mudjatik Transition Zone, Geochemistry, Partial melting, Geology, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, Trans-Hudson Orogen, 010502 geochemistry & geophysics, Migmatite, P-T-D-t evolution, 01 natural sciences, Basement (geology), Geochemistry and Petrology, Monazite, Shear zone, 0105 earth and related environmental sciences, Zircon, Gneiss
Abstract: International audience; The Hudsonian Pressure-Temperature- Deformation-time- (P-T-D-t) evolution of the pre-Athabasca crystalline basement (>∼1700 Ma) of the Wollaston-Mudjatik Transition Zone (WMTZ) highlights two major tectono-metamorphic events M1-D1 and M2-D2. The ages of these two event have been obtained by in-situ LA-ICPMS U-Th-Pb dating of monazite from Grt-Crd bearing pelitic gneiss and U-Pb analyses performed on zircons from pegmatites, using both exposed basement and drill cores from the Wolly–McClean exploration drilling project. The M1-D1 event, interpreted as the burial of the thinned Hearne margin via southward thrusting to pressures varying from 10 to 6 kbar, occurred between ca.1840 and 1813 Ma. The M2-D2 event, producing the northeast structural trend of the WMTZ, was formed in a sinistral transpressional tectonic regime during the late stage of the Hudsonian oblique collision between ca. 1813 and 1770 Ma. Thermobarometric estimates on the M2–D2 assemblages show that the entire studied area was reequilibrated at about 5 kbar and 750–825 °C. Trans-hudsonian pegmatites are viewed as the main proto-ore of the uranium-rich Athabasca unconformity-type deposits. Formation, transfer and differenciation of these Trans-hudsonian pegmatites are replaced in this P-T-D-t evolution. During the 1840-1813 Ma M1-D1 partial melting event, the first batches of melt produced in the deep crust are the most likely enriched in uranium. Then, these melts were transferred upwards to the upper crustal levels owing to the development of crustal scale steeply-dipping D2 shear zones, and finally were differentiated to form uranium-enriched pegmatites between 1813 and 1770 Ma. Some monazite and zircon grains within retrogressed migmatites recorded a later event at ca. 1720 Ma, interpreted as the terminal cooling event down to 300-400 °C responsible for partial retrogression of metamorphic assemblages. This age provides new insights into the timing of the onset of the Athabasca sedimentation that should therefore be at least 1710 Ma old or younger.
Published: 2017

5. Two-stage partial melting during the Variscan extensional tectonics (Montagne Noire, France)

Author: Jean-Louis Paquette, Marc Poujol, Pavel Pitra, Jean Van Den Driessche, Romain Tartèse, Jean-Charles Poilvet, Gilles Ruffet, 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 ), Institut de minéralogie, de physique des matériaux et de cosmochimie ( IMPMC ), Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique ( CNRS ) -Muséum National d'Histoire Naturelle ( MNHN ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ), Laboratoire Magmas et Volcans ( LMV ), Université Blaise Pascal - Clermont-Ferrand 2 ( UBP ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université Jean Monnet [Saint-Étienne] ( UJM ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Université de Franche-Comté ( UFC ) -Centre National de la Recherche Scientifique ( CNRS ), 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 minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), 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), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE)
Subjects: 010504 meteorology & atmospheric sciences, Geochemistry, Earth and Planetary Sciences(all), 010502 geochemistry & geophysics, 01 natural sciences, Variscan, Extensional tectonics, U–Th–Pb dating, Monazite, LA-ICP-MS, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, geography.geographical_feature_category, Orogeny, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, Ar-Ar dating, Massif, Migmatite, Muscovite, Leucogranite, Montagne Noire, General Earth and Planetary Sciences, 40Ar-39Ar dating, Geology, Zircon, Gneiss
Abstract: One of the striking features that characterise the late stages of the Variscan orogeny is the development of gneiss and migmatite domes, as well as extensional Late Carboniferous and Permian sedimentary basins. It remains a matter of debate whether the formation of domes was related to the well-documented late orogenic extension or to the contractional tectonics that preceded. Migmatization and magmatism are expected to predate extension if the domes are compression-related regional anticlines, but they must both precede and be contemporaneous with extension if they are extensional core complexes. In the Montagne Noire area (southern French Massif Central), where migmatization, magmatism and the deformation framework are well documented, the age of the extensional event was unequivocally constrained to 300–290 Ma. Therefore, dating migmatization in this area is a key point for discriminating between the two hypotheses and understanding the Late Palaeozoic evolution of this part of the Variscan belt. For this purpose, a migmatite and an associated anatectic granite from the Montagne Noire dome were dated by LA-ICP-MS (U–Th–Pb on zircon and monazite) and laser probe 40Ar-39Ar (K–Ar on muscovite). Although zircon did not record any Variscan age unequivocally related to compression (380-330 Ma), two age groups were identified from the monazite crystals. A first event, at ca. 319 Ma (U–Th–Pb on monazite), is interpreted as a first stage of migmatization and as the emplacement age of the granite, respectively. A second event at ca. 298–295 Ma, recorded by monazite (U–Th–Pb) and by the muscovite 40Ar-39Ar system in the migmatite and in the granite, could be interpreted as a fluid-induced event, probably related to a second melting event identified through the syn-extensional emplacement of the nearby Montalet leucogranite ca. 295 Ma ago. The ages of these two events post-date the Variscan compression and agree with an overall extensional context for the development of the Montagne Noire dome-shaped massif. Comparison of these results with published chemical (EPMA) dating of monazite from the same rocks demonstrates that the type of statistical treatment applied to EPMA data is crucial in order to resolve different monazite age populations.
Published: 2017

6. Reorganization of Asian climate in relation to Tibetan Plateau uplift

Author: Fuli Wu, Xiaomin Fang, Yibo Yang, Guillaume Dupont-Nivet, Junsheng Nie, Frédéric Fluteau, Tao Zhang, Wenxia Han, Chinese Academy of Sciences [Beijing] (CAS), Lanzhou University, 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 (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), Linyi University, Second Tibetan Plateau Scientific Expedition and Research (2019QZKK0707), National Natural Science Foundation of China BSCTPES project (41988101-01), and Strategic Priority Research Program of Chinese Academy of Sciences (XDA20070201).
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Atmospheric Science, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Pollution, Nature and Landscape Conservation, Earth-Surface Processes
Abstract: International audience; Reorganization of the Asian climate from one dominated by global planetary wind systems to a regional monsoon climate is closely related to the surface uplift of the Tibetan Plateau (TP). However, evaluating this climatic reorganization is limited by difficulty in constraining the complex, multistaged uplift of the TP and contradictory evidence regarding Asian Monsoon onset. In this Review, we summarize proxy and model evidence for Asian Monsoon initiation at different latitudes to identify the main controls on monsoon evolution. Stratigraphy and palaeoclimate proxy records indicate that the Asian climate was reorganized in a two-stage northward expansion process. At ~41 million years ago (Ma), the monsoon advanced northwards from the tropic to the southern subtropical regions (~26° N, approximately present-day Yunnan), probably driven by central TP uplift, global cooling and rapid regression of the proto-Paratethys Sea. At ~26 Ma, the monsoon expanded northwards into temperate regions (~30–36° N, equivalent to the present-day Asian Monsoon boundary), likely driven by TP growth and global warming. Additional proxy records are needed to fill regional gaps, establishing more solid boundary conditions and improving parameter constraints for climate models.
Published: 2022

7. Reconstitution des environnements de dépôtdu Carbonifère supérieur/ Permien inférieurau Sud du bassin de Paris : implicationgéodynamique

Author: Hue, Charline, Rossignol, Camille, Bourquin, Sylvie, Beccaletto, Laurent, Pellenard, Pierre, Poujol, Marc, Ferrand, Myriam, Le Carlier de Veslud, Christian, Gastineau, Renaldo, 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 ), GéoHydrosystèmes COntinentaux ( GéhCO EA6293 ), Université de Tours, Bureau de Recherches Géologiques et Minières (BRGM) ( BRGM ), Biogéosciences [Dijon] ( BGS ), Université de Bourgogne ( UB ) -AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique ( CNRS ), Société Géologique de France, Dubigeon, Isabelle, 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), GéoHydrosystèmes COntinentaux (GéHCO EA6293), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Biogéosciences [UMR 6282] [Dijon] (BGS), Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement, 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), Université de Tours (UT), Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-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), Biogéosciences [UMR 6282] (BGS), and Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Gilbert delta, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, [SDU.STU.TE] Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.ST] Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, datation U/Pb, Sud bassin de Paris, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, Carbonifère, [ SDU.STU.ST ] Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Permien
Abstract: National audience; La période Carbonifère-Permien marque un changement drastiquede régime tectonique (fin de l’Orogenèse hercynienne -début d’une phase de rifting). Cette transition s’enregistre dansles bassins sédimentaires contemporains. En Europe de l’Ouest,ces bassins, principalement constitués de sédiments continentauxet de séries volcano-sédimentaires (largement sous-estimées),sont mal contraints sur beaucoup d’aspects (sédimentaire, tectonique,volcanique et corrélations spatio-temporelles). Le cadrechronologique de ces bassins est également mal connu dans lamesure où les principaux âges ont été estimés par palynologie àpartir de faciès floristiques ayant pu coexister dans le temps.Une étude sédimentologique détaillée a été réalisée dans le bassinpermien de Lucenay-lès-Aix (Nièvre). Ce bassin, situé sous lacouverture méso-cénozoïque du Bassin parisien (environ 250 md’épaisseur), est localisé à l’intersection de cinq bassins permocarbonifèresconnus à l’affleurement (Autun, Blanzy Le Creusot,Aumance, Décize et Bert).Sur la base d’un forage carotté, une série du Carbonifère-Permiende 350 m d’épaisseur, a été décrite au 1/50e afin de reconstituerles environnements de dépôt. Des niveaux de cinérite identifiés(tonsteins) ont été échantillonnés et datés (datations U-Pb/zirconpar LA-ICP-MS). Le calage des différents faciès sédimentaires entermes d’électrofaciès sur les données sismiques et diagraphiquesdisponibles a permis de réaliser des corrélations stratigraphiqueset d’étendre ces observations à l’échelle du bassin de Lucenay-lès-Aix.Les résultats obtenus permettent ainsi de discuter l’évolution tardivede l’Orogenèse hercynienne : la base de la série sédimentairedu bassin de Lucenay-lès-Aix donne un âge de 299 ± 2 Ma (limiteCarbonifère/Permien). Les environnements sont constitués degrands systèmes lacustres à rides de vague, avec des intercalationsde charbons massifs à la base de la série, et des arrivéespériodiques de conglomérats, décrivant une tendance généralerétrogradante. Pour la première fois dans ce type de bassin, nousproposons d’interpréter certains faciès observés en dépôt de typeGilbert delta. L’enregistrement sédimentaire montre que ce bassinétait soumis à un flux sédimentaire important dont la source, auvu des géométries imagées en sismique, était localisée à l’ouest.
Published: 2016

8. Subsidence de la plateforme de la Sonde(Asie du Sud-Est) : contraintes apportées parla modélisation des récifs

Author: Sarr , Anne-Clarisse, Pastier , Anne-Morwenn, Husson , Laurent, Elliot , Mary, Camilo Arias , Ruiz, Pedoja , Kevin, Institut des Sciences de la Terre ( ISTerre ), Université Joseph Fourier - Grenoble 1 ( UJF ) -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-PRES Université de Grenoble-Université Savoie Mont Blanc ( USMB [Université de Savoie] [Université de Chambéry] ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ), 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 ), Morphodynamique Continentale et Côtière ( M2C ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Rouen Normandie ( UNIROUEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ), Société Géologique de France, 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), 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), Morphodynamique Continentale et Côtière (M2C), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-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), Dubigeon, Isabelle, Université de Rennes 1 (UR1), and 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)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.TE] Sciences of the Universe [physics]/Earth Sciences/Tectonics, modeling, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, Sunda shelf, coral, subsidence
Abstract: National audience; En Asie du Sud-Est, la surrection domine la partie centrale(Est Indonésie) alors que les domaines de plateformes continentales,à l’Est et à l’Ouest, semblent être dominés par de la subsidence.Cela se traduit par des morphologies côtières contrastéesavec une prédominance de récifs barrières, de terrasses surélevéeset d’encoches marines dans les zones d’uplift alors que le contourdes plateformes est occupé par de larges plaines alluviales recouvertesde mangroves. Des études récentes sur la plateforme dela Sonde proposent par ailleurs qu’elle subit une subsidence dynamiqueliée à l’activation de la subduction Sumatra-Java depuisl’Eocene. Cependant, les taux de subsidences estimés sont rares,excepté à la marge de la plateforme et dans les bassins sédimentaires.Afin de contraindre les vitesses de subsidence, un modèlequi reproduit l’évolution de la morphologie récifale au coursdu temps a été utilisé. Il tient compte de la croissance récifale,des variations du niveau marin, de l’érosion sous-marine etde la sédimentation subséquente. Une étude paramétrique a étémenée afin de tenir compte de l’incertitude sur certains processus(pentes, vitesse verticale, taux de croissance). Les profils topographiquesobtenus comparés aux paramètres morphologiquesdu récif de l’ile de Belitung montrent que l’ile subside probablementà un taux compris entre 0,2 et 0,45 mm/an depuis le pleistocene.Etant donné la faible bathymétrie de la plateforme (- 120m maximum), cela implique qu’elle était en partie continuellementémergée, même en période de haut niveau marin.
Published: 2016

9. Effets de la subduction d’une dorsale sur ladynamique d’une plaque continentale :apports de la modélisation analogique

Author: Salze, Méline, Guillaume, Benjamin, Martinod, Joseph, Kermarrec, Jean-Jacques, Sue, Christian, Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), 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 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]), Société Géologique de France, Dubigeon, Isabelle, Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), 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 ), Institut des Sciences de la Terre ( ISTerre ), Université Grenoble Alpes ( UGA ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Savoie Mont Blanc ( USMB [Université de Savoie] [Université de Chambéry] ) -PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers ( INSU - CNRS ) -Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux ( IFSTTAR ) -Université Joseph Fourier - Grenoble 1 ( UJF ), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Université de Rennes 1 (UR1), and 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)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, dorsale, [SDU.STU.TE] Sciences of the Universe [physics]/Earth Sciences/Tectonics, modèles analogiques, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, Andes Australes, subduction, lithosphère
Abstract: National audience; Une série de modèles analogiques de subduction d’une plaqueocéanique sous une plaque continentale ont été reproduits àl’échelle du laboratoire, afin de mieux comprendre les relationsentre phénomènes profonds se produisant lors de la subductiond’une dorsale, et la réponse associée en surface. Ces modèles ontété réalisés au sein du laboratoire de modélisation analogique del’Univ. Rennes 1. Dans ces modèles, l’épaisseur de la plaqueocéanique augmente en direction de la fosse (plaque en forme debiseau), afin de simuler la variation d’épaisseur de la plaque depuisla dorsale jusqu’à la fosse où elle rentre en subduction. L’objectifde ces expériences est d’observer l’effet de la subduction d’uneplaque océanique de plus en plus jeune, et finalement de la subductiond’une dorsale, sur la géométrie de la subduction et la dynamiquedu système. Un exemple de subduction de dorsale peutêtre observé actuellement dans les Andes Australes, en Patagonie,où la dorsale du Chili plonge sous le continent sud-américainvers 47S. L’objectif de ce travail est de comprendre l’effet de lasubduction de cette dorsale sur la dynamique de la plaque continentale.Plusieurs paramètres (vitesse de convergence, largeur etforme de la plaque plongeante...) ont été testés afin de modéliserleur impact sur la subduction, sur l’évolution du pendage et surles déformations de la plaque continentale.
Published: 2016

10. Influence of spreading ridge's subduction on plate dynamics: insights fromlaboratory models

Author: Salze, Méline, Guillaume, Benjamin, Martinod, Joseph, Kermarrec, Jean-Jacques, Sue, Christian, Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), 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 ), Institut des Sciences de la Terre ( ISTerre ), Université Grenoble Alpes ( UGA ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Savoie Mont Blanc ( USMB [Université de Savoie] [Université de Chambéry] ) -PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers ( INSU - CNRS ) -Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux ( IFSTTAR ) -Université Joseph Fourier - Grenoble 1 ( UJF ), Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), 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 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]), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), 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)-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), and Dubigeon, Isabelle
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Analogue modeling, Patagonia, [SDU.STU.TE] Sciences of the Universe [physics]/Earth Sciences/Tectonics, ridge, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, lithosphere, subduction, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2016

11. Boris Choubert: Unrecognized visionary geologist, pioneer of the global tectonics

Author: Philippe Le Vigouroux, Anne-Marie Boullier, Dominik Letsch, Umberto G. Cordani, Benito Ábalos, Brian Upton, Jacques Kornprobst, Åke Johansson, Pierre Barbey, Roy H. Gabrielsen, Jean-Pierre Burg, José Ignacio Gil-Ibarguchi, David Corrigan, Stefan Claesson, Ramon Capdevila, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Universidad del Pais Vasco / Euskal Herriko Unibertsitatea [Espagne] (UPV/EHU), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), 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]), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), 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), Swedish Museum of Natural History (NRM), Universidade de São Paulo = University of São Paulo (USP), Geological Survey of Canada [Ottawa] (GSC Central & Northern Canada), Geological Survey of Canada - Office (GSC), Natural Resources Canada (NRCan)-Natural Resources Canada (NRCan), Department of Geosciences [Oslo], Faculty of Mathematics and Natural Sciences [Oslo], University of Oslo (UiO)-University of Oslo (UiO), Comité français d'histoire de la géologie (COFRHIGEO), Centre François Viète : épistémologie, histoire des sciences et des techniques - EA1161 (CFV), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Université de Brest (UBO)-Université de Nantes - UFR Lettres et Langages (UFRLL), Université de Nantes (UN)-Université de Nantes (UN), Grant Institute, University of Edinburgh, Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), 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), Universidade de São Paulo (USP), Université de Nantes (UN)-Université de Brest (UBO), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), 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)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), Université de Lorraine (UL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans ( LMV ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Université Jean Monnet [Saint-Étienne] ( UJM ) -Institut de Recherche pour le Développement et la société-Université Clermont Auvergne ( UCA ) -Centre National de la Recherche Scientifique ( CNRS ), Centre de Recherches Pétrographiques et Géochimiques ( CRPG ), Université de Lorraine ( UL ) -Centre National de la Recherche Scientifique ( CNRS ), Institut des Sciences de la Terre ( ISTerre ), Université Joseph Fourier - Grenoble 1 ( UJF ) -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-PRES Université de Grenoble-Université Savoie Mont Blanc ( USMB [Université de Savoie] [Université de Chambéry] ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ), Eidgenössische Technische Hochschule [Zürich] ( ETH Zürich ), 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 ) -Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique ( CNRS ), Swedish Museum of Natural History, Stockholm, Department of Geosciences, University of Oslo ( UiO ), Comité français d'histoire de la géologie ( COFRHIGEO ), Centre François Viète : épistémologie, histoire des sciences et des techniques, and Université de Nantes ( UN ) -Université de Brest ( UBO )
Subjects: Pangaea, PRÉ-CAMBRIANO, 010504 meteorology & atmospheric sciences, Paleozoic, 010502 geochemistry & geophysics, 01 natural sciences, tectonique des plaques, [SHS.HISPHILSO]Humanities and Social Sciences/History, Philosophy and Sociology of Sciences, Precambrian, Paleontology, dérive continentale, orogeny, ComputingMilieux_MISCELLANEOUS, [ SDU.STU.PE ] Sciences of the Universe [physics]/Earth Sciences/Petrography, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Wegener, lcsh:QE1-996.5, Précambrien, Geology, Orogeny, orogenèse, lcsh:Geology, Plate tectonics, Tectonics, Continental drift, Palaeozoic belts, Dérive continentale, Tectonique des plaques, Orogenèse, 13. Climate action, plate tectonics, continental drift, Geologist
Abstract: This work is a review of Boris Choubert’s paper (1935), which was published in French under the rather devalorizing title: “Research on the Genesis of Palaeozoic and Precambrian Belts.” Despite its innovative content, this article had no impact either at the time of its publication or even later. It begins with the construction of a remarkable fit of the circum-Atlantic continents. This was based on the −1.000 meters isobath instead of the shoreline. Thirty years before Bullard et al. (1965), it demonstrated in an indisputable way the reality of the continents motion on the surface of the Earth. Therefore, Choubert designated Wegener’s “continental drift” as the main cause of tectonics. Even going beyond Wegener’s theory, he argued that this mechanism was efficient well before the formation of the Triassic Pangæa, during the whole Palaeozoic to result in the building of the Caledonian and Hercynian mountains. Although he was still encumbered by the vocabulary of the time regarding geosynclines, Boris Choubert described tectonics based on the horizontal mobility of the Precambrian continental blocks. Oddly enough, he did not apply this model to the Precambrian structures, which he attributed to the effects of the Earth’s rotation on the continental crust during its solidification. At the time of its publication, this paper was a very important step towards understanding global tectonics. Unfortunately, Choubert’s contemporaries did not generally recognize its significance. Ce travail est une analyse de l’article de Boris Choubert (1935) paru en français sous le titre un peu réducteur: « Recherches sur la genèse des chaînes paléozoïques et antécambriennes. » Malgré son contenu novateur, cet article n’a eu aucun retentissement à l’époque de sa publication, ni même plus tard. Il débute par la construction d’un remarquable assemblage des continents péri-atlantiques fondé sur l’isobathe −1.000 mètres et non pas sur la ligne de rivage. Trente ans avant Bullard et al. (1965), il démontre de façon indiscutable la réalité du déplacement des masses continentales à la surface de la Terre. Dès lors, Choubert privilégie totalement la « dérive des continents » comme moteur de la tectonique. Allant au-delà même de la vision de Wegener, il fait jouer ce mécanisme bien avant la formation de la Pangée triasique, pendant toute la durée de l’ère primaire, au cours de l’érection des chaînes calédonienne et hercynienne. Bien que restant prisonnier du vocabulaire de l’époque sur les géosynclinaux, Boris Choubert décrit une tectonique fondée sur la mobilité des blocs continentaux précambriens. Curieusement, il n’applique pas ce modèle aux déformations précambriennes qu’il attribue aux effets de la rotation de la Terre sur une croûte continentale en voie de solidification. Lors de sa parution, cet article représentait un pas très important vers la compréhension de la tectonique globale et il est regrettable qu’il n’ait pas été mieux reçu par ses contemporains. ISSN:0037-9409 ISSN:1777-5817
Published: 2018

12. The 3.9 km-thick Carboniferous-Permian Brécy Basin (SW Paris Basin, France), a missing link between late Variscan basins in southern and northern Europe

Author: Laurent Beccaletto, Sylvie BOURQUIN, Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), 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), EGU, and European Geosciences Union
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU]Sciences of the Universe [physics], [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy
Abstract: From the end of the Carboniferous onwards, the over-thickened and hot Variscan crust collapsed (late-orogenic collapse), accompanied by the rise of high-grade metamorphic domes along low-angle detachment faults and the development of mainly half-graben or pull-apart type asymmetric intramountain coal basins.These Carboniferous-Permian late orogenic basins widely developed around 300 Ma and were filled with siliciclastic continental material, accompanied by a widespread intrusive and extrusive magmatic activity. These basins crop out in the internal parts of the belt south of the Variscan Front in several limited locations in and around the Variscan basement of Western Europe (Massif Central, Vosges-Black Forest, Alps, Harz). They occur as small isolated and disconnected “basins” with incomplete sedimentary series. Their present-day area does not reflect their initial extent and thickness, which can be explored by studying their subsurface prolongation beneath their Meso-Cenozoic sedimentary covers.We propose a geological overview of the late Variscan Carboniferous-Permian Brécy basin (SW Paris basin, France), based on the reprocessing and interpretation of vintage seismic lines and related deep boreholes. We aim (i) to discuss its sedimentary filling, which is hidden beneath the Meso-Cenozoic cover of the Paris basin, (ii) to present thickness maps of its 3.9 km-thick sedimentary filling, and (iii) to describe its structural extensional features related to a syn- to post-rift tectonic scenario. We finally compared our new results to other Carboniferous-Permian deposits in France (to discuss its lateral correlation with neighboring basins) and northwest Europe, suggesting that the Brécy Basin may represent - due to its thickness and location - a missing link between late Variscan basins in southern and northern Europe.
Published: 2023

13. Revealing the hidden signature of fault slip history in the morphology of degrading scarps

Author: Philippe Steer, Regina Holtmann, Rodolphe Cattin, Martine Simoes, 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), Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Université de Montpellier (UM), 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), ANR-18-CE01-0017,TOPO-Extreme,Dynamique des paysages à courte échelle de temps et signature topographique des évènements climatiques et tectoniques extrêmes(2018), ANR-18-CE31-0008,SLOWDEF,Aléas sismiques dans les orogènes à déformation lente(2018), ANR-18-IDEX-0001,Université de Paris,Université de Paris(2018), European Project: FEASIBLe, Institut de Physique du Globe de Paris (IPG Paris), and European Geosciences Union
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Multidisciplinary, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology
Abstract: Active faults accommodate tectonic plate motion through different slip modes, some stable and aseismic, others characterized by the occurrence of large earthquakes after long periods of inactivity. Although the slip mode estimation is of primary importance to improve seismic hazard assessment, this parameter inferred today from geodetic observations needs to be better constrained over many seismic cycles. From an analytical formulation developed for analyzing fault scarp formation and degradation in loosely consolidated material, we show that the final topographic shape generated by one earthquake rupture or by creep (i.e., continuous slip) deviates by as much as 10–20%, despite a similar cumulated slip and a constant diffusion coefficient. This result opens up the theoretical possibility of inverting, not only the cumulated slip or averaged slip rate, but also the number of earthquakes and their sizes from scarp morphologies. This approach is all the more relevant as the number of rupture events is limited. Estimating the fault slip history beyond a dozen earthquakes becomes very difficult as the effect of erosion on scarp morphology prevails. Our modeling also highlights the importance of trade-offs between fault slip history and diffusive processes. An identical topographic profile can be obtained either with a stable fault creep associated with rapid erosion, or a single earthquake rupture followed by slow erosion. These inferences, derived from the simplest possible diffusion model, are likely to be even more pronounced in nature.
Published: 2023

14. Southeastern Tibetan Plateau growth revealed by inverse analysis of landscape evolution model

Author: X. P. Yuan, R. Jiao, G. Dupont‐Nivet, X. Shen, China University of Geosciences [Wuhan] (CUG), University of Victoria [Canada] (UVIC), 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), University of Potsdam = Universität Potsdam, National Institute of Natural Hazards, Ministry of Emergency Management of China, Beijing, 100085, China, National Natural Science Foundation of China (NSFC) 42073052, and European Project: 649081,H2020,ERC-2014-CoG,MAGIC(2015)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Geophysics, General Earth and Planetary Sciences, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology
Abstract: The Cenozoic history of the Tibetan Plateau topography is critical for understanding the evolution of the Indian-Eurasian collision, climate, and biodiversity. However, the long-term growth and landscape evolution of the Tibetan Plateau remains ambiguous, it remains unclear if plateau uplift occurred soon after the India-Asia collision in the Paleogene or later in the Neogene. As the landscape evolution is controlled mainly by mountain uplift and surface processes, the present-day river profiles and the drainage basin geometries preserve important information that can be extracted to infer the long-term history of mountain uplift with numerical models. Here we focus on the southeastern (SE) Tibetan Plateau where three of the world’s largest rivers draining the Tibetan Plateau (the Yangtze, Mekong, and Salween Rivers, i.e., Three Rivers) have incised deep valleys with distinctive geomorphic signatures. We reproduce the uplift history of the SE Tibetan Plateau using a 2D landscape evolution model, which simultaneously solves fluvial erosion and sediment transport processes in the drainage basins of the Three Rivers region. Our model was optimized through a formal inverse analysis with a large number of forward simulations, which aims to reconcile the transient states of the present-day river profiles. The modeling results were ultimately compared to existing thermochronologic and paleoelevation datasets to help decipher between competing tectonic models that predict contrasting topographic evolutions. Our results suggest initially low elevations during the Paleogene, followed by a gradual southeastward propagation of topographic uplift of the plateau margin until present day. The modeling thus does not support Paleogene formation of the SE Tibetan Plateau with a major subsequent degradation via upstream fluvial erosion. The scenario with pre-existing high-elevation plateau or plateau degradation will result in much wider river channels with knickpoints that propagated upstream much further away from the plateau margin compared to observed river profiles. The quantitative constraints on landscape evolution achieved based on drainage patterns in SE Tibet indicate a powerful tool potentially applicable to other regions to infer important implications for the evolution of Indian-Eurasian collision, Asian monsoons, and biodiversity, as well as the geodynamic forces involved in collisional orogens.
Published: 2023

15. Fluid-pressure induced eclogitisation of a dry granulite: Insights from Hydro-Chemical model

Author: Erwan Bras, Philippe Yamato, Thibault Duretz, Stefan Schmalholz, Yury Podladchikov, 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), Goethe-Universität Frankfurt am Main, Université de Lausanne = University of Lausanne (UNIL), and European Geosciences Union
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography
Abstract: Eclogitization constitutes one of the most emblematic transformations in continental subduction zones, where conversion of initially dry lower crustal rocks into eclogite facies rocks correlates with the occurrence of seismogenic events. This reaction is generally considered to occur at high pressure conditions during hydration of dry granulite. Several models using « ad hoc » diffusion equation exist to model this hydration process and the consequences of reaction-induced changes in terms of rheology and density. However, to our knowledge, there is no quantitative model allowing to physically explain how fluids propagate inside a dry rock (i.e. with no porosity at all) and how reaction-induced alteration front widens over time. In this study, we therefore propose a new fully coupled hydro-chemical model wherein a two-phase flow model is coupled with the eclogitization reaction. We use a mass conservative approach, solving total mass and solid mass equations, in a closed isothermal system. Fluid and solid densities are calculated with lookup tables from equilibrium thermodynamics. Our model shows that a fluid pressure pulse generates a pressure gradient that can be associated with the densification reaction when the pressure required for the eclogitization is reached. This reaction generates a large increase in porosity (0 to ~16%) and subsequent porous fluid flow inside the initially dry granulite. This process is then sustained as long as the fluid pulse is maintained, and ends shortly after the fluid pressure pulse stops. However, high pressure within the reacted area can persist for a long period of time. A parametric study allowing to constrain both the duration and the widening of the reaction area is proposed as well as an application to the emblematic case study of the eclogitized granulites of Holsnoy (Bergen Arcs, Norway).
Published: 2023

16. A systematic study of mantle drag effect on subduction dynamics and overriding plate deformation

Author: Thomas Geffroy, Guillaume Benjamin, Replumaz Anne, Simoes Martine, Lacassin Robin, Kermarrec Jean-Jacques, Habel Tania, 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 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), Institut de Physique du Globe de Paris (IPG Paris), 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), and European Geosciences Union
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics
Abstract: International audience; Plates and the convective mantle interact with each other over geological time scales, leading to mantle flow, plate motion, and deformation along plate boundaries. At convergent boundaries undergoing subduction, the role played by mantle drag remains poorly understood despite its potential impact on subduction dynamics, and in turn on the deformation regime of the overriding plate. Previous studies were generally conducted in two dimensions, limiting their ability to faithfully reproduce processes taking place on Earth. Instead, in this study, we present 11 three-dimensional analog models of subduction at the scale of the upper mantle, including an overriding plate, and in which we control mantle drag at the base of the lower or upper plate by imposing a controlled unidirectional background mantle flow perpendicular to the trench. We systematically vary the velocity and the direction of the imposed horizontal mantle flow and quantify its impact on horizontal and vertical upper plate deformations, plate and subduction velocities, and the geometry of the slab. The geometry of the slab is only marginally affected by the velocity and direction of the mantle flow. In the absence of mantle flow, slab rolls back and deformation is accommodated by trench-orthogonal stretching in the upper plate. Instead, the addition of a background flow dragging the lower or upper plate toward the trench systematically results either in the absence of upper plate deformation, or in trench-orthogonal shortening with strain rates that increase linearly with increasing mantle flow. We show that the upper plate strain rate is primarily controlled by the velocity of the free plate in the model, which itself results from the drag exerted by the mantle at the base of the plate. Coupling between mantle and plate is larger for models with flow directed toward the upper plate, resulting in strain rates that are about three times larger than for equivalent models with flow directed toward the lower plate. This systematic study provides a better understanding of the effect of mantle drag on plate displacements and deformation along subduction zones, leading to a better understanding of the ingredients required to form Andean-type mountain ranges.
Published: 2023

17. Phase transition induced stresses and their implications for deep earthquakes

Author: Marcel Thielmann, Einat Aharonov, Philippe Yamato, Thibault Duretz, Universität Bayreuth, Christian-Albrechts-Universität zu Kiel (CAU), University of Jerusalem, 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), Goethe-Universität Frankfurt am Main, and European Geosciences Union
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology
Abstract: International audience; The nucleation and rupture processes of deep-focus earthquakes have remained enigmatic ever since their discovery. These earthquakes occur mostly within the mantle transition zone where brittle failure is extremely unlikely due to the elevated pressures at these depths. Hence, other mechanisms have to be invoked to explain the occurrence of these events. To date, two main hypotheses have been put forward to explain deep focus earthquakes: transformational faulting (due to the polymorphic phase change of metastable olivine to either wadsleyite or ringwoodite) and thermal runaway (due to the conversion of deformational work to heat). More recently, it has been proposed that the feedback between those two mechanisms may explain the observed two-stage ruptures of large deep-focus earthquakes.To better understand the potential feedback between transformational faulting and thermal runaway, it is necessary to determine the stresses induced by the phase change due to i) the grain size reduction and corresponding viscosity reduction of the transformed material and ii) the volume reduction of the transformed phase. The former process triggers a stress transfer from the transformed material to the untransformed material, whereas the latter results in elevated stresses around the transformed phase.In this study, we employ numerical models with a viscoelastic compressible rheology to quantify the stress levels and patterns resulting from both processes. To gain a better understanding of the parameters controlling the stress transfer from transforming regions to the surrounding matrix, we employ simplified numerical models where transforming regions are approximated using elliptical inclusions. In a second step, more realistic model geometries are used to additionally study the effect of the morphology of transformed regions on stress levels and heterogeneities.Results show that both processes result in significantly different stress evolution upon a phase transition. Whereas a phase transition affecting only the viscosity of the transformed material results in moderate stress increases which occur on relatively long timescales, a phase transition affecting both viscosity and density results in significantly larger stresses, which also exhibit a significantly faster build-up. In both cases, the attained stress are sufficiently large to activate additional ductile weakening mechanisms that could trigger ductile ruptures. The higher stress levels resulting from the combined effect of a viscosity and density change would likely result in stronger weakening effects and faster occurrence of ductile failure
Published: 2023

18. Subobduction: subduction plate boundary hiccups revealed by blueschists, eclogites and ophiolites

Author: Philippe Agard, Mathieu Soret, Guillaume Bonnet, Dia Ninkabou, Alexis Plunder, Cécile Prigent, Philippe Yamato, 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), 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), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), 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), 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), and European Geosciences Union
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics
Abstract: Fragments of ancient oceanic lithosphere preserved in mountain belts, though volumetrically subordinate, provide essential insights into past geodynamics and formation and destruction of oceanic lithosphere. This contribution shows how the two types of oceanic fragments, blueschists and eclogites, on one hand, and ophiolites on the other, preserve crucial information on the dynamics of oceanic convergence, i.e. subduction and obduction.Their mutual relationships, as well as the similarities and differences in the mechanisms leading to their preservation, allow tracking the evolution of the subduction process through time, from the onset of intra-oceanic subduction to the cessation of continental subduction – and, in some cases, to the obduction of ophiolites.Fragments located at the base and immediately below unmetamorphosed (true) ophiolites represent witnesses of intra-oceanic subduction initiation and reveal, in particular, initial mechanical resistance to subduction, subsequent cooling and gradual strain localization. Subducted fragments of oceanic lithosphere metamorphosed as blueschists and eclogites, scraped off the downgoing slab episodically, at shallow or great depths, provide direct access to the composition, structure and rheology of rocks at the plate interface.Both types reflect the mechanical behavior and 'hiccups' of the subduction plate boundary, during subduction initiation and mature subduction respectively.
Published: 2023

19. Upper-plate shortening and Andean-type mountain-building in the context of mantle-driven oceanic subduction

Author: Robin Lacassin, Tania Habel, Anne Replumaz, Benjamin Guillaume, Martine Simoes, Thomas Geffroy, Jean-Jacques Kermarrec, 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 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), 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 (IPG Paris), and European geosciences Union
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics
Abstract: To explore the conditions that lead to mountain-building in the case of an oceanic subduction, we conduct analog experiments (with silicon putty upper and lower plates, glucose syrup upper mantle) where subduction is driven by slab pull but also by an underlying mantle flow. Here, plate displacement is not imposed as in most models, but is controlled by the overall balance of forces in the system. We simulate three scenarios: no mantle flow (slab-pull driven subduction), mantle flow directed toward the subducting plate, and mantle flow directed toward the overriding plate. In the case of this latter scenario, we also test the influence of pre-existing rheological contrasts in the upper plate to best reproduce natural cases where inheritance is common. Our experiments show that when plate convergence is also driven by a background mantle flow, the continental plate deforms with significant trench-orthogonal shortening (up to 30% after 60 Myr), generally associated with thickening. We further identify that upper plate shortening and thickening is best promoted when the mantle flow is directed toward the fixed overriding continental plate. The strength of the upper plate is also a key factor controlling the amount and rates of accommodated shortening. Deformation rates increase linearly with decreasing bulk strength of the upper plate, and deformation is mostly localized where viscosity and strength are lower. When compared to the particular natural case of the Andes, our experiments provide key insights into the geodynamic conditions that lead to the building of this Cordilleran orogen since the Late Cretaceous - Early Cenozoic.
Published: 2023

20. Influence of magma-poor versus magma-rich passive margins on subduction initiation

Author: Antoine Auzemery, Kristóf Porkoláb, Liviu Matenco, Philippe Yamato, Ernst Willingshofer, T. Duretz, Utrecht University [Utrecht], 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 Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Institut für Geowissenschaften [Frankfurt am Main], Goethe-Universität Frankfurt am Main, Institute of earth physics and space science [Sopron], European Project: 674899,H2020,H2020-MSCA-ITN-2015,SUBITOP(2016), 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 Tectonics
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, 010504 meteorology & atmospheric sciences, Subduction, Passive margins rheological coupling, Continental crust, Hellenides/Dinarides, Alps, Geology, 010502 geochemistry & geophysics, passive margins rheological coupling, 01 natural sciences, Subduction initiation, Mantle (geology), Magma-rich and magma-poor passive margins, Continental margin, Lithosphere, Passive margin, Magma, magma-rich and magma-poor passive margins, Shear zone, Petrology, 0105 earth and related environmental sciences
Abstract: International audience; We present a new numerical modelling study of subduction initiation at (hyper-extended) magma-poor and magma-rich continental passive margins. In particular, we test how the structure and rheological stratification of these two end-member types control the formation and thermo-mechanical evolution of subduction zones. The serpentinization of mantle lithosphere in a magma-poor continental rifted margin leads to rheological decoupling at the base of the continental crust, which induces shear localization during subsequent shortening. Under these conditions, a shear zone propagates into the mantle lithosphere and leads to subduction initiation at the transition between ocean and passive margin. In contrast, a magma-rich rifted continental margin is rheologically coupled, which creates a buttressing effect and transfer of deformation into the oceanic domain during shortening, where the subduction zone initiates. These results are quantitatively compared and in agreement with the geological record of subduction initiation in the Alps and Dinarides – Hellenides, where the relics of end-member types of continental rifted margins of the same Adriatic micro-continent bordering the Alpine Tethys and Neotethys oceans, respectively, are observed.
Published: 2022

21. Eclogitisation of dry and impermeable granulite by fluid flow with reaction-induced porosity: insights from hydro-chemical modelling

Author: Bras, Erwan, Yamato, Philippe, Schmalholz, Stefan, Duretz, Thibault, Podladchikov, Yury, 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), Institute of Earth Sciences, Géopolis, University of Lausanne, CH-1015 Lausanne, Switzerland., Université de Lausanne = University of Lausanne (UNIL), J.W. Goethe Universität, Institut für Geowissenschaften, Altenhöferallee 1, D-60438 Frankfurt am Main, Germany, Lomonosov Moscow State University (MSU), INSU SYSTER program (AO Tellus), Institut Universitaire de France, and Université de Lausanne
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, hydro-chemical modelling, hydration front, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, reaction-induced porosity, Eclogitization
Abstract: International audience; Eclogitisation is a major metamorphic process of continental subduction zones, where transformation of dry lower crustal rocks into eclogites seem to correlate with seismogenic events. Eclogitisation can occur at high pressure during hydration of granulite, but the physical processes controlling the hydration of dry, impermeable granulite remain poorly understood. Here, we present a new fully coupled hydro-chemical model of a non-deforming porous rock which undergoes metamorphic reactions in response to fluid pressure variations. Conservation equations for total and solid mass are solved, and fluid and solid densities are calculated with look-up tables computed from models relying on equilibrium thermodynamics. Our model shows that a fluid pressure pulse generates a pressure gradient that causes densification when the pressure required for eclogitisation is reached. The reaction generates porosity and subsequent porous fluid flow into the initially non-porous impermeable granulite. This process lasts as long as the pressure pulse is maintained, but high pressure within eclogite can persist for a longer time. The hydration front propagates tens of centimetres into the granulite in the order of weeks to months. We show that propagation of a hydration-reaction front is effectively a diffusive process, with diffusivity in the order of 10 −9 m 2 •s −1 for eclogitisation as in Holsnøy, Norway. Reactive hydration of impermeable granulite is possible because its solid density is smaller than that of eclogite. We discuss the application of our model for eclogitisation and also for other reactions for which hydration of impermeable rock is possible.
Published: 2023

22. The role of H2O on metamorphism and deformation at high pressure: A combined petrological and thermo-mechanical study based on the Gran Paradiso Unit, Western Alps

Author: Cindy Luisier, Michel Ballèvre, Thibault Duretz, 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), and Goethe-University Frankfurt am Main
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Fluids, Kinetics, Geochemistry and Petrology, Gran Paradiso Unit, Thermo-mechanical modelling, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, Geology, High-pressure metamorphism, Rheology, Thermodynamic modelling
Abstract: Quantitative phase petrology analysis of two samples showing variable strain record and different peak pressure (P) conditions show that H2O is a key parameter in the development of contrasting high-pressure (HP) peak conditions in adjacent polymetamorphic rocks. A shear zone in a paragneiss from the Gran Paradiso nappe, Western Alps, shows an Alpine foliation and records a peak P of 1.9 GPa, for a temperature of 500 to 520 °C. A few tens of meters away from the shear zone, a paragneiss showing no apparent Alpine age deformation records a peak P of maximum 1.4 GPa for the temperature range of 500 to 520 °C. The H2O content of the latter has potentially been reduced to low contents following the pre-Alpine, Variscan amphibolite facies, and the absence of re-hydration prior to Alpine orogeny could have inhibited the formation of HP mineral assemblages. The validity of this interpretation is questioned here by considering the mechanical effect of H2O undersaturated rocks on deformation and P during deformation. Based on a thermo-mechanical numerical modelling study, we show that heterogeneities in fluid saturation conditions between rocks lead to strength contrasts that are sufficient to trigger a dynamic P in the range of several hundreds of MPa. In particular, the models successfully reproduce the measured peak P between the two paragneiss studied. This model could be applied to other H2O deficient rocks from HP tectonic units to further explore the role of H2O on the rheology and hence assess its potential impact in the preservation of low P bodies in otherwise HP units from continental collision settings.
Published: 2023

23. Spatiotemporal Evolution of Central Qilian Shan (Northwest China) Constrained by Fission-Track Ages of Detrital Grains from the Huangshui River

Author: Lin, Xu, Jolivet, Marc, Cheng, Feng, China Three Gorges University, 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), Peking University [Beijing], and National Natural Science Foundation of China (grant 41972212)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, detrital zircon, Tibetan Plateau, fission track, Central Qilian Shan, LA-ICP-MS, Huangshui River
Abstract: International audience; The emergence of the Tibetan Plateau is one of the most significant geological events in East Asia. The Central Qilian Shan connects North and South Qilian Shan in the northeastern part of the Tibetan Plateau. However, the exhumation history of the Central Qilian Block from the Mesozoic to Cenozoic remains unclear. Determining the cooling ages of detrital zircon and apatite in modern river sediments is an ideal method for tracing the evolutionary processes of orogenic belts. In this study, we present the first single-grain detrital apatite (153) and zircon fission-track (108) data for the Huangshui River sediments from the Central Qilian Shan. The decomposition of the dataset revealed major Mesozoic and Cenozoic age peaks at ca. 145–93, and 11 Ma. The Central Qilian Shan entered the intracontinental orogeny stage dating back to the Cretaceous (ca. 145–93 Ma) and Late Cenozoic (ca. 11 Ma) caused by the subduction of the Neo-Tethys and Indian–Asian collision. Therefore, we propose that the geomorphic framework of the northeastern margin of the Tibetan Plateau was initially established during the Mesozoic and further consolidated in the Late Miocene.
Published: 2023

24. A tectonic model for the juxtaposition of granulite- and amphibolite-facies rocks in the Eburnean collision in the orogenic belt (Sassandra-Cavally domain, Côte d’Ivoire)

Author: Augustin Yao Koffi, Lenka Baratoux, Pavel Pitra, Alain Nicaise Kouamelan, Olivier Vanderhaeghe, Nicolas Thébaud, Olivier Bruguier, Sylvain Block, Hervé Jean-Luc Fossou Kouadio, Jacques Kone, 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), and 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)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, Geology
Abstract: The Sassandra-Cavally (SASCA) domain (SW Côte d’Ivoire) marks the transition between the Archaean Kenema-Man craton and the Palaeoproterozoic (Rhyacian) Baoule-Mossi terranes. It is characterized by the tectonic juxtaposition of granulite-facies and amphibolite-facies rocks. Migmatitic grey gneisses, garnet-cordierite-sillimanite migmatitic paragneisses and garnet-staurolite-bearing micaschists reached peak pressure conditions ranging from ~6.6 kbar at 620°C to ~10 kbar at 820°C. These conditions are associated with the first recorded deformation D1 and correspond to a Barrovian geothermal gradient of ~25°C/km. Subsequent exhumation, associated with a second deformation D2, was marked by decompression followed by cooling along apparent geothermal gradients of ~40°C/km. A D3 deformation phase is marked by folding and local transposition of the regional S1/S2 foliation by E-W trending shear zones. LA-ICP-MS U-Pb dating of monazite, which displays complex internal structures, reveals four age groups as a function of their textural position: 1) Rare relictual zones yield dates at the Archaean-Palaeoproterozoic transition (c. 2400–2600 Ma); 2) a cluster of dates centered at c. 2037 Ma. This cluster includes dates from crystals located in the S2 foliation of the migmatitic grey gneiss, which suggests that this is the age for the D2 exhumation; 3) a cluster of dates centered at c. 2000 Ma, and 4) dates spreading from c. 1978 to 1913 Ma, documented for the first time in the West African Craton monazites. The ages of the latter two groups are similar to the ones identified in the Guiana Shield, and could be attributed to a disturbance by fluids, to a periodic opening of U-Pb system or to an episodic crystallization of monazite during slow cooling lasting several tens of Myrs. These data bring new petro-tectonic and geochronological constraints on the contact between the Rhyacian Baoule-Mossi terrains and the Archaean Kenema-Man nucleus, and confirm the collisional character of the polyphase tectono-metamorphic evolution of the SASCA domain during the Eburnean orogeny. They suggest a transitional regime between the predominance of gravitational instabilities and modern plate tectonics. The exhumation of the granulite- and amphibolite-facies rocks results from a combination of crustal-scale folding associated with lateral flow and regional transcurrent shear zones, which would explain the juxtaposition of rocks that reached significantly different P–T conditions.
Published: 2023

25. Chapitre 5 : la zone nord-pyrénéenne : un rift à croûte hyperamincie et manteau dénudé

Author: Lagabrielle, Yves, 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), and 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)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics
Abstract: International audience
Published: 2023

26. Chapitre 4 : les brèches sédimentaires synextension dans le nord-est des Pyrénées

Author: Kernif, Tarik, Nalpas, Thierry, Bousquet, Romain, Chelalou, Roman, 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), and 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)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy
Abstract: International audience
Published: 2023

27. Fluids Circulation in Subduction Zones: How Fluids Impact Seismic/Aseismic Slip in Ecuador ?

Author: Galve, Audrey, Rietbrock, Andreas, Ribodetti, Alessandra, Laigle, Mireille, Michaud, François, Géli, Louis, Lebrun, Jerome, Cubas, Nadaya, Proust, Jean-Noël, Skrubej, Alexandra, Segovia, Monica, Paulatto, Michele, Wallace, Laura, 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]), Karlsruhe Institute of Technology (KIT), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Informatique, Signaux, et Systèmes de Sophia-Antipolis (I3S) / Equipe SIGNAL, Signal, Images et Systèmes (Laboratoire I3S - SIS), Laboratoire d'Informatique, Signaux, et Systèmes de Sophia Antipolis (I3S), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA)-Laboratoire d'Informatique, Signaux, et Systèmes de Sophia Antipolis (I3S), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Université Côte d'Azur (UCA), 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), 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), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-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), University of Oxford [Oxford], and University of Texas at Austin [Austin]
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics
Abstract: International audience; Identifying the circulation of fluids in subduction zone system and understanding their role on the megathrust fault slip modes remains one of the outstanding challenges in Earth Sciences. As these faults have the capacity to generate mega-earthquakes, the associated hazard to the society is significant.In recent years, studies in Japan, Costa Rica and New Zealand try to find the processes that control slip behaviours through marine campaigns and IODP drillings. The Ecuadorian margin is an exceptional laboratory to continue this international effort by adding a subduction zone to the list of those with contrasted slips at shallow depth. In April 2016, a Mw 7.8 earthquake broke the southern part of the 1906 earthquake rupture zone, causing hundreds of deaths and millions of dollars in damages along an increasingly populated coastline. The seismological and geodetic network in place since several years and a dense post-seismic deployment, contributed to observe and define the rupture zone and areas affected by aseismic slip on the shallowest portion of the megathrust fault.Thanks to two marine campaigns (HIPER and SUPER) and other existing onshore/offshore data acquisition, our project Fluid2Slip will participate to determine the exact role of fluids on slip behaviour around the updip part of the seismogenic megathrust fault by localizing fluids and seismicity, imaging fault properties and deformation. Our large experiment allowed a high density onshore/offshore deployment to perform shots and earthquakes FWI (Full Waveform Inversion) and obtain sufficient resolution to tackle the role of fluids with respect to interplate roughness, the nature of sediments, upper plate and lower plate’s structural heterogeneity in seismic/aseismic slip behavior. In addition, subsurface observation and fluid geochemistry will help detect fluid flow and discuss the path they take through the upper plate.
Published: 2022

28. Mixing in a turbulent thermal and implications for metal-silicate equilibrium during Earth's formation

Author: Huguet, Ludovic, Lherm, Victor, Deguen, Renaud, Le Borgne, Tanguy, Heyman, Joris, Université Grenoble Alpes (UGA), École normale supérieure de Lyon (ENS de Lyon), Institut des Sciences de la Terre (ISTerre), 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 Gustave Eiffel-Université Grenoble Alpes (UGA), 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), and 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)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics
Abstract: International audience; During the differentiation of terrestrial planets, the metal phase from the impactor core segregates from the silicate phase of the magma ocean. This buoyant mass forms a turbulent thermal and settles toward the proto-core. During this descent, turbulent motions induce stirring of the metallic phase and entrainment of silicates. Thermal and chemical exchanges may occur at the boundary of the stirred phases. However, homogenization between the two phases only occurs when the metallic phase reaches the diffusive length scale, where mass or heat transfer became irreversible. Based on laboratory fluid dynamic experiments and on 3D direct numerical simulations mimicking the settling of the thermal turbulent, we used the “lamellar” description of the mixing by advecting a Lagrangian material line based on velocity fields. 3D simulations strengthen the results obtained from the experimental dataset, which is only 2D. We have tracked the evolution of the material elongated as lamellae by the turbulent stirring. We have characterized the elongation rate, the aggregation of lamellae, and the probability density function of the elongation and concentration, which are not accessible from direct measurements in the experiments. We have also investigated the effect of the Reynolds and Péclet number on these quantities. Based on these results, we have produced a stochastic model able to predict the temporal evolution of the concentration field, which can be used for understanding the equilibrium between metals and silicates during the accretion of terrestrial planets.
Published: 2022

29. Paleoproterozoic crustal evolution and Mesoproterozoic overprint in the Roosevelt-Guariba Transpressive Belt, Juruena Terrain, Southeastern Amazonas, Brazil

Author: Almeida, Marcelo, Oliveira, Antonio, Orestes Santos, Joao, Rodrigues, Joseneusa, Ruffet, Gilles, Geological Survey of Brazil (CPRM), Federal University of Amazonas, The University of Western Australia (UWA), 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), and GSB-CPRM (Sumaúma-Mutum-Roosevelt Project)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Southeastern Amazonas, Tectonothermal Events, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Geochronology, Rondônia-Juruena Southeastern Amazonas Tectonothermal Events Geochronology, Rondônia-Juruena
Abstract: International audience; The Juruena Terrain (Rondônia-Juruena Province) in the southeastern Amazonas State shows a NW-SE dextral shear zones system denominated Roosevelt-Guariba Transpressive Belt (RGTB). The RGTB was generated in response to intracontinental crustal reworking, juxtaposing Paleoproterozoic Juruena granitic-gneiss and coeval supracrustal associations. This granitic-gneiss basement shows high-K calcalkaline (Teodósia Suite) to transitional I-to A-type (Igarapé das Lontras Suite) signatures, produced in a continental magmatic arc setting around 1760-1740 Ma (zircon, titanite; U-Pb SHRIMP, LA-ICP-MS). New geochronological data about of the deformation and metamorphic rocks in the RGTB were obtained from migmatite paragneisses, amphibolites, S-type leucogranite (Quatro Cachoeiras Complex and Itamaraty Suite; zircon U-Pb SHRIMP) and protomylonites and mylonites (Igarapé das Lontras and Teodosia protoliths; amphibole-muscovite-sericite Ar-Ar step heating). The results suggest that Southeastern Amazonas (northern Juruena Terrain) was metamorphosed/deformed during 1530-1460 Ma under temperatures of 900 o C (zircon) to 580 o C (hornblende) and 420 o C (muscovite). The geochronological data show that the granite-gneiss basement (continental magmatic arc) and supracrustal rocks (foreland basin) were reworked by a regional event with an age interval of 1530 Ma (high grade and anatexis) to 1460 Ma (medium grade). Finally, the Juruena Terrain is affected by a younger low-T event (1300 Ma, muscovite Ar-Ar step heating) with wide NE-trending structures (e.g. Buiuçu Shear Zone). This 1.3 Ga event suggests a continental reactivation caused by the pericratonic deformation related to Candeias/ Sunsás Orogeny during the Columbia Supercontinent break-up, before the Rodinia Supercontinent assembly. In summary, the Juruena Terrain in the southeast Amazonas shows a complex metamorphic and structural intracontinental evolution, involving polycyclic events from late Orosirian to Ectasian in a convergent tectonic setting. Therefore, the Juruena Terrain shows similar accretionary histories with other orogens and has apparent long-lived connections with Laurentia (Yavapai Province) and Baltica (Transscandinavian Igneous Belt), forming the core of the Columbia Supercontinent.
Published: 2022

30. Peak metamorphic temperatures in the Alpine tectonic wedge, south Cottian Alps, Italy

Author: Lahfid, Abdeltif, Michard, André, Chopin, Christian, Schmid, S.M., Dana, D., Ballèvre, Michel, Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Université Paris-Sud - Paris 11 (UP11), 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), Departement Physik [ETH Zürich] (D-PHYS), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Università degli studi di Torino = University of Turin (UNITO), 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), Società Geologica Italiana, Université Paris-Saclay, Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), Université Paris sciences et lettres (PSL), Institut für Geophysik [Zürich], Italian Geological Society (SGI), and Italian Society of Mineralogy and Petrology (SIMP)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Raman Spectroscopy of Carbonaceous Material (RSCM), [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, blueschist-facies metamorphism, Western Alps, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, [SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology, [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy
Abstract: International audience; In the south Cottian Alps, the metamorphic wedge of the Western Alps is widely exposed. It includes, fromSW to NE, the Briançonnais internal border (Acceglio units), the ophiolitic Schistes lustrés nappes (Piemonte-Liguria Ocean) and the southern Dora-Maira units derived from the Briançonnais s.l. basement (Michard et al.,2022, and references therein). Located between the Acceglio and Dora-Maira units, the Val Maira-Sampeyreand Val Grana Allochthons (MGA) consist of a Permo-Triassic to Mid Jurassic “Prepiemonte”-type sequencedetached from the Briançonnais s.l. basement. The peak metamorphic grade of these tectonic complexesevolves from blueschist- to coesite-eclogite (Brossasco-Isasca unit of Dora-Maira). Here we report new peaktemperatures by carrying the RSCM geothermometry approach (see Lahfid et al., 2019) on most of the southCottian transect with emphasis on the MGA and on the intervening mélange shear zones. TRSCM valuesrange from ~400°C to >500°C, going from the most external Val Grana unit and overlying Queyras schiststo the uppermost Dora-Maira unit. We present a new metamorphic map and profiles based on published andnew data, including our new thermometric data. We note an overall fit between our TRSCM results and thoseinferred from the mineral assemblages, where available. The thermal anomaly linked to the rifting evolutionthat gave birth to the Piemonte-Liguria Ocean was recognized in the poorly metamorphic Adriatic margin SEof the Periadriatic line (Beltrando et al., 2015), but cannot be evidenced in the studied Briançonnais-derivedunits due to their high metamorphic grade.Beltrando M., Stockli D.F., Decarlis A. & Manatschal G. (2015) - A crustal-scale view at rift localization along the fossilAdriatic margin of the Alpine Tethys preserved in NW Italy. Tectonics, 34, 1927-1951.Lahfid A., Baidder L., Ouanaimi H., Soulaimani A., Hoepffner C., Farah A., Saddiqi O. & Michard A. (2019) - Fromextension to compression: high geothermal gradient during the earliest Variscan phase of the Moroccan Meseta; a firststructural and RSCM thermometric study. Eur. J. Mineral., 31, 695-713.Michard A., Schmid S.M., Lahfid A., Ballèvre M., Manzotti P., Chopin C., Iaccarino S. & Dana D. (2022) - The Maira-Sampeyre and Val Grana Allochthons (south Western Alps): review and new data on the tectonometamorphic evolutionof the Briançonnais distal margin. Swiss J. Geosci. (in press).
Published: 2022

31. A journey towards the forbidden zone: a new, cold, UHP unit in the Dora-Maira Massif(Western Alps)

Author: Manzotti, Paola, Schiavi, F., Nosenzo, Francesco, Pitra, Pavel, Ballèvre, Michel, Stockton University (Stockton), Université Clermont Auvergne (UCA), Stockholm University, 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), Czech Geological Survey [Praha], Società Geologica Italiana, and Dubigeon, Isabelle
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.TE] Sciences of the Universe [physics]/Earth Sciences/Tectonics, chloritoid, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, [SDU.STU.PE] Sciences of the Universe [physics]/Earth Sciences/Petrography, Dora-Maira, coesite
Abstract: International audience; The distribution of ultrahigh-pressure metamorphism (UHP) at the scale of a mountain belt is of primeimportance for deciphering its past subduction history. In the Western Alps, coesite has been recognized in thesouthern Dora-Maira massif, in the lens-shaped Brossasco-Isasca Unit, but has not been found up to now inthe other parts of the massif. We report the discovery of a new UHP unit in the northern Dora-Maira Massif(Western Alps), named Chasteiran Unit. It is only a few tens of metres thick and consists of garnet-chloritoidmicaschists. Garnet inclusions (chloritoid, rutile) and its growth zoning allow to precisely model the P-Tevolution. Coesite crystals, which are pristine or partially transformed to palisade quartz occur as inclusionsin the garnet outer cores. According to thermodynamic modelling, garnet displays a continuous record ofgrowth during the prograde increase in P and T (25-27 kbar 470-500°C) (stage 1), up to the coesite stabilityfield (27-28 kbar 520-530°C) (stage 2), as well as sub-isothermal decompression of about 10 kbar (down to15 kbar 500-515°C) (stage 3). The main regional, composite, foliation, marked by chloritoid and rutile, beganto develop during this stage, and was then overprinted by chlorite-ilmenite (stage 4). The Chasteiran Unit isdiscontinuously exposed in the immediate hangingwall of the Pinerolo Unit, and it is located far away from,and without physical links to the classic UHP Brossasco-Isasca Unit. Moreover, it records a different, muchcolder, P-T evolution, showing that different slices were detached from the downgoing subduction slab. TheChasteiran Unit is the fourth and the coldest Alpine UHP unit known so far in the entire Alpine belt. Its P-Tconditions are comparable to the ones of the Tian Shan coesite-chloritoid-bearing rocks.
Published: 2022

32. Effect of aseismic ridge subduction on slab geometry and overriding plate deformation: Insights from analogue modeling

Author: Joseph Martinod, Benjamin Guillaume, Francesca Funiciello, Claudio Faccenna, Nicolas Espurt, Vincent Regard, 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), Systèmes Tectoniques, 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)-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 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 européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratory of Experimental Tectonics, Università degli Studi Roma Tre = Roma Tre University (ROMA TRE), INSU, 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), 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), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Università degli Studi Roma Tre, Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), 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)-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)-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)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Martinod, J, Guillaume, B, Espurt, E, Faccenna, Claudio, Funiciello, Francesca, and Regard, V.
Subjects: 010504 meteorology & atmospheric sciences, [SDE.MCG]Environmental Sciences/Global Changes, 010502 geochemistry & geophysics, 01 natural sciences, topography, oceanic ridge, slab dip, 0105 earth and related environmental sciences, Earth-Surface Processes, Slab suction, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, geography.geographical_feature_category, Subduction, Mid-ocean ridge, indentation, Geophysics, Ridge push, Trench, Slab window, Ridge (meteorology), Slab, analogue models, subduction, Geology, Seismology
Abstract: We present analogue models simulating the subduction of a buoyant ridge oriented perpendicularly or obliquely with respect to the trench, beneath an advancing overriding plate. The convergence velocity is imposed by lateral boundary conditions in this experimental set. We analyze the three-dimensional geometry of the slab, the deformation and topography of the overriding plate. Experiments suggest that ridge subduction diminishes the dip of the slab, eventually leading to the appearance of a horizontal slab segment in case boundary conditions impose a rapid convergence. This result contrasts with that obtained in free subduction experiments, in which ridge subduction diminishes the convergence velocity which, in turn, increases the dip of the slab beneath the ridge. The slab dip decrease is accompanied by the indentation of the overriding plate by the ridge, resulting in arc curvature. Experiments suggest that indentation is larger for small convergence velocity and large slab dip. Ridge subduction also uplifts the overriding plate. Uplift first occurs close to the trench (~ fore-arc area) and is accompanied by the flexural subsidence of the overriding plate behind the uplifted area (~ back-arc subsidence). The uplifted area migrates within the overriding plate interiors following the appearance of a horizontal slab segment. These results are compared with natural examples of ridge subduction in the circum-Pacific area. They explain why ridge subduction may have contrasted effects on the overriding plate dynamics depending on the global conditions that constrain the converging system.
Published: 2013

33. Passive margins getting squeezed in the mantle convection vice

Author: Yamato, P., Husson, L., Becker, T.W., Pedoja, Kevin, Systèmes Tectoniques, Géosciences Rennes (GR), 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), 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)-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 Rennes (GR), Department of Earth Sciences [USC Los Angeles], University of Southern California (USC), Morphodynamique Continentale et Côtière (M2C), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), 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 ) -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 ), Laboratoire de Planétologie et Géodynamique de Nantes ( LPGN ), Université de Nantes ( UN ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Nantes ( UN ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Géosciences Rennes ( GR ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS ), Department of Earth Sciences, University of Southern California ( USC ), Morphodynamique Continentale et Côtière ( M2C ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Rouen Normandie ( UNIROUEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ), 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), Institut des Sciences de la Terre ( ISTerre ), Université Joseph Fourier - Grenoble 1 ( UJF ) -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-PRES Université de Grenoble-Université Savoie Mont Blanc ( USMB [Université de Savoie] [Université de Chambéry] ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ), Institut des Sciences de la Terre (ISTerre), Université Joseph Fourier - Grenoble 1 (UJF)-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-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Université Joseph Fourier - Grenoble 1 (UJF)-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])
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [ SDE.MCG ] Environmental Sciences/Global Changes, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [ SDU.STU ] Sciences of the Universe [physics]/Earth Sciences, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics
Abstract: International audience; Passive margins often exhibit uplift, exhumation and tectonic inversion. We speculate that the compression in the lithosphere gradually increased during the Cenozoic. In the same time, the many mountain belts at active margins that accompany this event seem readily witness this increase. However, how that compression increase affects passive margins remains unclear. In order to address this issue, we design a 2D viscous numerical model wherein a lithospheric plate rests above a weaker mantle. It is driven by a mantle conveyor belt, alternatively excited by a lateral downwelling on one side, an upwelling on the other side, or both simultaneously. The lateral edges of the plate are either free or fixed, representing the cases of free convergence, and collision or slab anchoring, respectively. This distinction changes the upper boundary condition for mantle circulation and, as a consequence, the stress field. Our results show that between these two regimes, the flow pattern transiently evolves from a free-slip convection mode towards a no-slip boundary condition above the upper mantle. In the second case, the lithosphere is highly stressed horizontally and deforms. For an equivalent bulk driving force, compression increases drastically at passive margins provided that upwellings are active. Conversely, if downwellings alone are activated, compression occurs at short distances from the trench and extension prevails elsewhere. These results are supported by Earth-like 3D spherical models that reveal the same pattern, where active upwellings are required to excite passive margins compression. These results support the idea that compression at passive margins, is the response to the underlying mantle flow, that is increasingly resisted by the Cenozoic collisions.
Published: 2013

34. Present-day trends of vertical ground motion along the coast lines

Author: Cécile Robin, Laurent Husson, Gaël Choblet, Kevin Pedoja, Emilie Ostanciaux, 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), 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), Morphodynamique Continentale et Côtière (M2C), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), 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 ) -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 ), Laboratoire de Planétologie et Géodynamique de Nantes ( LPGN ), Université de Nantes ( UN ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Nantes ( UN ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Géosciences Rennes ( GR ), Université de Rennes ( UNIV-RENNES ) -Université de Rennes ( UNIV-RENNES ) -Observatoire des Sciences de l'Univers de Rennes ( OSUR ) -Centre National de la Recherche Scientifique ( CNRS ), Université de Nantes ( UN ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Morphodynamique Continentale et Côtière ( M2C ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Rouen Normandie ( UNIROUEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ), 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), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)
Subjects: 010504 meteorology & atmospheric sciences, Ground motion, [SDE.MCG]Environmental Sciences/Global Changes, Context (language use), Present day, 010502 geochemistry & geophysics, 01 natural sciences, Sea level, Satellite altimetry, Postglacial rebound, 14. Life underwater, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Subduction, Transform fault, Subsidence, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, Post-glacial rebound, [ SDE.MCG ] Environmental Sciences/Global Changes, Tide gauges, 13. Climate action, Climatology, General Earth and Planetary Sciences, Tide gauge, Geology
Abstract: International audience; Vertical ground motion (VGM) rates stand as crucial information, either for predicting the impact of the actual sea level rise along low-lying coasts or refining geodynamic problems. Because present day VGM rates have a magnitude smaller than 10 mm/yr, they remain challenging to quantify and often elusive. We focus on the quantification of global-scale VGM rates in order to identify global or regional trends. We computed VGM rates by combining tide gauges records and local satellite altimetry, which yield a new dataset of 634 VGM rates. We further compare this database to previous studies that use geodetic techniques and tide gauges records in order to evaluate the consistency of both our results and previous ones. The magnitudes differ by less than 5 mm/yr, and similar subsidence and uplift general tendencies appear. Even if the asset of our database stands in the greater number of sites, the combination of all studies, each with different pros and cons, yields a hybrid dataset that makes our attempt to extract VGM trends more robust than any other, independent study. Fennoscandia, the West coast of North America, and the eastern coast of Australia are uplifting, while the eastern coast of North America, the British Isles and Western Europe, the eastern Mediterranean Sea, Japan, and the western coast of Australia are subsiding. Glacial Isostatic Adjustment (GIA) is expected to provide a major contribution to the present-day signal. Aside from Fennoscandia, observed VGM often depart from the GIA model predictions of Peltier (2004). This either results from an underestimate of the model predictions or from the influence of other processes: indeed, the influence of the geodynamic setting appears in particular along the coasts of western North America or Japan, where the alternation of transform faults and subduction zones makes it possible to assign contrasted behaviours to the local geodynamic context. Local mechanisms like anthropogenic processes or sediment compaction, also contribute to VGM. This remains true for the critical cases of Venice, the Gulf of Mexico, the Ganges delta, and the Maldives, which are particularly exposed to the current sea level rise.
Published: 2012

35. The role of slabs and oceanic plate geometry in the net rotation of the lithosphere, trench motions, and slab return flow

Author: Gerault, M., Becker, T. W., Kaus, B., Faccenna, Claudio, Moresi, Louis, Husson, Laurent, Systèmes Tectoniques, Department of Earth Sciences [USC Los Angeles], University of Southern California (USC)-University of Southern California (USC)-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)-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), University of Southern California (USC), Università degli Studi Roma Tre, School of Mathematical Sciences [Clayton], Monash University [Clayton], 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)-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 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), and Università degli Studi Roma Tre = Roma Tre University (ROMA TRE)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, trench motions, slab dynamics, [SDE.MCG]Environmental Sciences/Global Changes, lithosphere-mantle interactions, net rotation of the lithosphere
Abstract: International audience; [1] Absolute plate motion models with respect to a deep mantle reference frame (e.g., hot spots) typically contain some net rotation (NR) of the lithosphere. Global mantle flow models for the present-day plate setting reproduce similarly oriented NRs but with amplitudes significantly smaller than those found in some high NR Pacific hot spot reference frames. It is therefore important to understand the mechanisms of NR excitation, which we attempt here with two-dimensional cylindrical models of an idealized Pacific domain. We study the influence of slab properties, oceanic ridge position, continental keels, and a weak asthenospheric layer on NR and trench migration. Fast slab return flow develops in models with stiff slabs and moderate slab dips. Rapid NRs, comparable to the high NR Pacific hot spot reference frames, are primarily induced by asymmetric slab dips, in particular a shallow slab beneath South America and a steep slab in the western Pacific. A scaling relationship links the amplitude of NR to plate size, slab dip angle, and slab viscosity. Asymmetric ridge positions also promote NR through asymmetric plate sizes. Continental keels have less impact, in contrast to what has been found in earlier global studies. Several models yield unidirectional Pacific trench motions, such as slab advance in the western Pacific and, simultaneously, slab retreat in the eastern Pacific. Our model provides a physical explanation for NR generation in the present-day Pacific setting and hints at mechanisms for the temporal evolution of the basin.
Published: 2012

36. Uplift of quaternary shorelines in eastern Patagonia: Darwin revisited

Author: Pierre Weill, Joseph Martinod, Enrique Fucks, Benjamin Guillaume, Maximiliano Iglesias, Kevin Pedoja, Laurent Husson, Vincent Regard, Morphodynamique Continentale et Côtière (M2C), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Mécanismes et Transfert en Géologie (LMTG), 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), Géosciences Rennes (GR), 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), 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), Dipartimento di Scienze Geologiche [Roma TRE], Università degli Studi Roma Tre, Universidad Nacional de la Plata [Argentine] (UNLP), Universidad Nacional de la Patagonia Austral (UNPA), Université de Toulouse (UT)-Université de Toulouse (UT)-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), 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), Università degli Studi Roma Tre = Roma Tre University (ROMA TRE), Morphodynamique Continentale et Côtière ( M2C ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Rouen Normandie ( UNIROUEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ), Laboratoire des Mécanismes et Transfert en Géologie ( LMTG ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Systèmes Tectoniques, 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 ) -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 ) -Laboratoire de Planétologie et Géodynamique de Nantes ( LPGN ), and Université de Nantes ( UN ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Nantes ( UN ) -Centre National de la Recherche Scientifique ( CNRS )
Subjects: 010504 meteorology & atmospheric sciences, Pleistocene, [SDE.MCG]Environmental Sciences/Global Changes, Argentina, 010502 geochemistry & geophysics, [ SDU.STU.ST ] Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, 01 natural sciences, passive margin, Uplift, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Quaternary, coastal sequences, Paleontology, Passive margin, South American Plate, Patagonia, 14. Life underwater, Chronostratigraphy, 0105 earth and related environmental sciences, Earth-Surface Processes, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, quaternary, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, South America, Plate tectonics, [ SDE.MCG ] Environmental Sciences/Global Changes, uplift, Coastal sequences, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Interglacial, Cenozoic, Geology
Abstract: International audience; During his journey on the Beagle, Darwin observed the uniformity in the elevation of coastal Eastern Patagonia along more than 2000 km. More than one century later, the sequences of Quaternary shorelines of eastern Patagonia have been described and their deposits dated but not yet interpreted in terms of geodynamics. Consequently, we i) mapped the repartition of the Quaternary coastal sequences in Argentinean Patagonia, ii) secured accurate altitudes of shoreline angles associated with erosional morphologies (i.e. marine terraces and notches), iii) took into account previous chrono-stratigraphical interpretations in order to calculate mean uplift rates since ~440 ka (MIS 11) and proposed age ranges for the higher and older features (up to ~180 m), and iv) focused on the Last Interglacial Maximum terrace (MIS 5e) as the best constrained marine terrace (in terms of age and altitude) in order to use it as a tectonic benchmark to quantify uplift rates along the entire passive margin of Eastern South America. Our results show that the eastern Patagonia uplift is constant through time and twice the uplift of the rest of the South American margin. We suggest that the enhanced uplift along the eastern Patagonian coast that interested Darwin during his journey around South America on the Beagle could originate from the subduction of the Chile ridge and the associated dynamic uplift.
Published: 2011

37. HP-UHP metamorphism as an indicator of slab dip variations in the Alpine arc

Author: Jean-Pierre Brun, Frédéric Gueydan, Didier Marquer, Nicolas Carry, Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Université de Franche-Comté ( UFC ) -Centre National de la Recherche Scientifique ( CNRS ), Sytèmes Tectoniques, 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 ) -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 ), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), 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)-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), Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), 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)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Continental subduction, HP-UHP metamorphism, 010504 meteorology & atmospheric sciences, Subduction, Continental collision, [SDE.MCG]Environmental Sciences/Global Changes, Alps, Metamorphism, Magnetic dip, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, 010502 geochemistry & geophysics, 01 natural sciences, Nappe, Nappe stacking, [ SDE.MCG ] Environmental Sciences/Global Changes, Slab, General Earth and Planetary Sciences, Eclogitization, Geomorphology, Geology, 0105 earth and related environmental sciences, Terrane
Abstract: International audience; HP/UHP and LT metamorphic units that commonly occur in the inner parts of mountain belts result from the subduction of continental and oceanic material, most often exhumed prior to continental collision. The prograde pressure-temperature history of HP-UHP rocks strongly depends on the convergence rate and on the subduction zone geometry. The maximum pressure recorded provides a proxy for the depth of shearing off and stacking of HP metamorphic nappes. A 2-D thermal model of continental subduction at lithospheric scale is used to compute the length and pressure peak of detached HP metamorphic units as a function of the slab dip angle and the convergence rate. Model results are applied to the metamorphic nappe pile of the inner Alps. A mean convergence rate of 1 cm/year during the subduction of the Briançonnais terrane is indicated by the paleogeographic reconstructions between 46 and 38 Ma. On this basis, the available petrological data and lengths of metamorphic units are used to compute the variations of the slab dip angle. The slab dip angle is shown to increase, from the northeast to the southwest, along the Alpine arc with estimated values of 20° for Suretta, 30-45° for Monte Rosa and Gran Paradiso, and 60° for Dora Maira. From Eocene to Oligocene times, the increase in slab dip angle is controlled by changes of buoyancy, due to the spatial configuration of the Valaisan trough and the incoming of crustal material within the subduction zone
Published: 2011

38. A journey towards the forbidden zone: a new, cold, UHP unit in the Dora-Maira Massif (Western Alps)

Author: Paola Manzotti, Federica Schiavi, Francesco Nosenzo, Pavel Pitra, Michel Ballèvre, Stockholm University, Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), 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), and 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)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Geophysics, Geochemistry and Petrology, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography
Abstract: The distribution of ultrahigh-pressure metamorphism (UHP) at the scale of a mountain belt is of prime importance for deciphering its past subduction history. In the Western Alps, coesite has been recognized in the southern Dora-Maira massif, in the lens-shaped Brossasco-Isasca Unit, but has not been found up to now in the other parts of the massif. We report the discovery of a new UHP unit in the northern Dora-Maira Massif (Western Alps), named Chasteiran Unit (Manzotti et al. 2022). It is only a few tens of metres thick and consists of garnet-chloritoid micaschists. Garnet inclusions (chloritoid, rutile) and its growth zoning allow to precisely model the P–T evolution. Coesite crystals, which are pristine or partially transformed to palisade quartz occur as inclusions in the garnet outer cores. According to thermodynamic modelling, garnet displays a continuous record of growth during the prograde increase in P and T (25–27 kbar 470–500 °C) (stage 1), up to the coesite stability field (27–28 kbar 520–530 °C) (stage 2), as well as sub-isothermal decompression of about 10 kbar (down to 15 kbar 500–515 °C) (stage 3). The main regional, composite, foliation, marked by chloritoid and rutile, began to develop during this stage, and was then overprinted by chlorite-ilmenite (stage 4). The Chasteiran Unit is discontinuously exposed in the immediate hangingwall of the Pinerolo Unit, and it is located far away from, and without physical links to the classic UHP Brossasco-Isasca Unit. Moreover, it records a different, much colder, P–T evolution, showing that different slices were detached from the downgoing subduction slab. The Chasteiran Unit is the fourth and the coldest Alpine UHP unit known so far in the entire Alpine belt. Its P–T conditions are comparable to the ones of the Tian Shan coesite-chloritoid-bearing rocks. Manzotti, P., Schiavi, F., Nosenzo, F., Pitra, P., Ballèvre, M. (2022). A journey towards the forbidden zone: a new, cold, UHP unit in the Dora-Maira Massif (Western Alps). Contributions to Mineralogy and Petrology, in press.
Published: 2022

39. From Long‐ to Short‐Term Inter‐Plate Coupling at the Subducted Carnegie Ridge Crest, Offshore Central Ecuador

Author: J.‐Y. Collot, J.‐N. Proust, J.‐M. Nocquet, C. Martillo, F. Michaud, J.‐F. Lebrun, L. Schenini, S. Popescu, M.‐J. Hernandez, G. Ratzov, 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]), 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), Escuela Superior Politécnica del Litoral [Guayaquil] (ESPOL), Institut des Sciences de la Terre (ISTerre), 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 Gustave Eiffel-Université Grenoble Alpes (UGA), Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA), Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Université de Montpellier (UM), Escuela Politécnica Nacional (EPN), Institut de Recherche pour le Developpement (IRD), Institut National des Sciences de l'Univers (INSU), Institut Francais pour l'Exploitation de la Mer (IFREMER), 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), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-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 Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous)
Abstract: We investigate the relationship between the long-term (Quaternary) interplate coupling and the short-term geodetically derived interseismic coupling at the Central Ecuador subduction zone. At this nonaccretionary margin, the Cabo Pasado shelf promontory and coastal area are associated with two inter-plate geodetically locked patches. The deepest patch ruptured co-seismically during the Mw7.8-2016 Pedernales earthquake, while the shallowest underwent dominantly after-slip. Marine geophysical and chronostratigraphic data allow reconstructing the Quaternary tectonic evolution of the shelf promontory and substantiating variation of the long-term inter-plate coupling that led to the geodetically locked patches. Prior to ∼1.8 Ma, the outer-wedge inter-plate coupling was strong enough to activate trench-subparallel strike-slip faults. Then, between ∼1.8-0.79 Ma, shortening and uplift affected the shelf promontory, implying a locally increased inter-plate coupling. After a short, post-0.79 Ma period of subsidence, shortening and uplift resumed denoting a high inter-plate coupling that endured up to the present. The synchronicity of the structural evolution of the shelf promontory with the subduction chronology of two reliefs of the Carnegie Ridge crest suggests that the locked patches are caused by a geometrical resistance to subduction that propagates landward causing permanent deformation. In 2016, the deepest subducted relief localized stress accumulation and high seismic slip, while the shallowest relief, which is associated with a weakened outer-wedge, prevented updip rupture propagation. Thus, at nonaccretionary margins, active outer-wedge strike-slip faults might be considered a proxi of near-trench coupling, and subducted relief a cause of plate coupling but an obstacle to the tsunami genesis when the relief is shallow. Key Points A trench-parallel strike-slip fault and its earthquake-controlled fault scarps substantiate a pre-1.8 Ma, outer-wedge inter-plate coupling From 1.8 Ma, a robust shelf uplift caused by subducted reliefs highlights a long-term coupling that led to geodetically locked patches The shallowest subducted relief likely impeded the generation of a major tsunami during the Mw7.8, 2016 event Plain Language Summary The 2016-Ecuador earthquake ruptured a subduction fault segment previously locked for decades beneath the coastline. The rupture was arrested updip by another locked fault segment called locked patch, which instead slipped slowly. To understand the cause of the locked patches, their rupture behaviors, and whether the decadal fault locking and long-term subduction processes are related, we reconstructed the Quaternary tectonic evolution of the margin offshore Central Ecuador using geophysical data. We consider that tectonic deformation reflects the long-term inter-plate coupling, which is the ability of the fault to transfer long-term stress and strain to the margin. Prior to ∼1.8 Ma, a trench-subparallel fault accommodating lateral displacement indicates a shallow plate coupling, which increased locally between ∼1.8-0.79 Ma as shown by margin shortening. After a brief subsidence, shortening resumed, denoting a strong coupling that persisted until today in the form of the locked patches. Although many physical factors have been proposed to control plate coupling, here we find that the locked patches are caused by the subduction of two reliefs of a submarine ridge. Remarkably, in 2016, the deepest relief released high elastic strain, while the shallower relief, thrust under a weakened outer-margin, damped updip rupture propagation, impeding a significant tsunami.
Published: 2022

40. Gondwana break‐up controlled by tectonic inheritance and mantle plume activity: insights from Natal rift development (South Mozambique, Africa)

Author: Vincent Roche, Sylvie Leroy, Sidonie Revillon, François Guillocheau, Gilles Ruffet, William Vétel, 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), Sedisor, 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), TotalEnergies, and Total et IFREMER (PAMELA)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Geology
Abstract: International audience; The breakup of Eastern Gondwana started during the Early Jurassic with the separation of Antarctica and Madagascar from Africa. While margins architecture has been described along the Western Somalia Basin and the central Mozambique, the spatial extent of rifting further south – i.e. the Natal Valley – remains poorly documented. Seismic reflection profiles interpretation, 40Ar/39Ar ages and isotopic data show the existence of a plume related magma-rich margin – the Natal segment – characterized by a large volume of seaward dipping reflectors inferred to be basalts. In particular, the contrast in lithosphere rheology, probably caused by a Meso-Neoproterozoic belt between the Kaapval and Grunehogna Archean cratons, favored extension and upwelling from a deep mantle thermomechanical anomaly, the so-called Karoo superplume that started at around 180 Ma. Further, the presence of stretched continental crust at around 30°S implies a more southerly position of Antarctica which will need to be considered in future kinematic models.
Published: 2022

41. Mechanical decoupling of high-pressure crustal units during continental subduction

Author: Nicolas Carry, Frédéric Gueydan, Didier Marquer, Jean-Pierre Brun, 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 ) -Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), 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)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement - CNRS - UFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Laboratoire Chrono-environnement (UMR 6249) (LCE), 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)
Subjects: 010504 meteorology & atmospheric sciences, HPLT metamorphism, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Continental margin, Geochemistry and Petrology, Lithosphere, Passive margin, Earth and Planetary Sciences (miscellaneous), Eclogitization, Petrology, 0105 earth and related environmental sciences, [ SDU.STU.PE ] Sciences of the Universe [physics]/Earth Sciences/Petrography, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Subduction, Crustal recycling, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, Geophysics, HP-LT metamorphism, [ SDE.MCG ] Environmental Sciences/Global Changes, lithosphere strength, numerical modeling, 13. Climate action, Space and Planetary Science, Slab, Geology
Abstract: International audience; The mechanics of the transition from continental subduction toward upper crustal nappe stacking is still poorly understood and is studied here through a 2D thermal and strength numerical modelling of a subducted passive margin. Geological observations in the core of most mountain belts show the piling up of several HP-LT upper crustal units that are most likely related to the detachment of upper crustal units from the subducted continental margin and to the subsequent stacking of the detached units at depths. The Adula unit (Lepontine dome, Central Alps, Switzerland) is a long and thin upper crustal unit and is used here as a natural case-study as it provides a well-documented example of these units. 2D thermal modeling shows that two steps, successive in time, characterized the burial history of the passive margin undergoing continental subduction: 1-an increase in the margin strength due to an increase in the confining pressure during the first million years of the margin subduction and 2-the progressive heating of the subducted margin from the overlying lithosphere leads to a decrease in the margin strength due to thermal weakening, which progressively counter-balances the increase in confining pressure. Two strength gradients develop within the subducted lithosphere: 1-along the slab, the strength decreases with increasing burial depth and 2-perpendicular to the slab, the strength increases with depth due to an inverse temperature distribution. The detachment of HP-LT continental units from the subducted margin could occur when the slab strength becomes lower than the applied net stress. This allows the detachment of ductile weakened thin and long upper-crustal units. The thickness and length of the detached crustal units are controlled by the following parameters, in order of their importance: subduction dip angle, crustal rheology, mantle heat flux and subduction velocity. The comparison of our model results with the geometry and PT conditions of the Adula unit yields an estimate of the Alpine subduction dip angle at the time of deformation and metamorphism.
Published: 2009

42. P/T ratio in high-pressure rocks as a function of dip and velocity of continental subduction

Author: Gueydan , Frédéric, Le Garzic , Edouard, Carry , Nicolas, 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 ) -Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique ( CNRS ), Ecole et Observatoire des sciences de la terre de Strasbourg ( EOSTS ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Université de Franche-Comté ( UFC ) -Centre National de la Recherche Scientifique ( CNRS ), 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), Institut de physique du globe de Strasbourg (IPGS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), 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 Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), and Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [ SDE.MCG ] Environmental Sciences/Global Changes, [SDE.MCG]Environmental Sciences/Global Changes, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2009

43. Geometry and kinematics of continental subduction inferred from 1D thermal modelling of prograde PT path

Author: Gueydan, Frédéric, Le Garzic, Edouard, Carry, Nicolas, 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 ) -Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique ( CNRS ), Ecole et Observatoire des sciences de la terre de Strasbourg ( EOSTS ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Chrono-environnement ( LCE ), Université Bourgogne Franche-Comté ( UBFC ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), 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)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS), Ecole et Observatoire des sciences de la terre (EOST), Institut national des sciences de l'Univers (INSU - CNRS)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), 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 Chrono-environnement (UMR 6249) (LCE), Dubigeon, Isabelle, Centre National de la Recherche Scientifique (CNRS)-Université Louis Pasteur - Strasbourg I-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire Chrono-environnement - UFC (UMR 6249) (LCE), and Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDE.MCG] Environmental Sciences/Global Changes, [ SDE.MCG ] Environmental Sciences/Global Changes, [SDE.MCG]Environmental Sciences/Global Changes, [SDU.STU.TE] Sciences of the Universe [physics]/Earth Sciences/Tectonics, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2008

44. Peak Alpine metamorphic conditions from staurolite‐bearing metapelites in the Monte Rosa nappe (Central European Alps) and geodynamic implications

Author: Joshua D. Vaughan-Hammon, Cindy Luisier, Stefan M. Schmalholz, Lukas P. Baumgartner, Institute of Earth Sciences [Lausanne], Université de Lausanne = University of Lausanne (UNIL), 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), Swiss National Foundation grant numbers 200021-165756, University of Lausanne (UNIL), 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)
Subjects: 010504 meteorology & atmospheric sciences, high-pressure metamorphism, Lithology, Metamorphic rock, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, Geochemistry, Zn-staurolite, engineering.material, Mélange, 010502 geochemistry & geophysics, 01 natural sciences, Nappe, Geochemistry and Petrology, metapelite, Chloritoid, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, tectonic pressure, Geology, Phengite, Central European Alps, 13. Climate action, visual_art, Whiteschist, Staurolite, engineering, visual_art.visual_art_medium
Abstract: International audience; The tectono-metamorphic evolution of the European Alps is still contentious. The Monte Rosa tectonic unit is a prominent nappe in the Central European Alps and estimates of its peak Alpine pressure (P) and temperature (T) conditions are essential for reconstructing its tectonometamorphic evolution. However, the reported peak Alpine P and T estimates vary considerably between 1.2 and 2.7 GPa and 490 and 640 °C for a variety of lithologies. Here, we show petrology and pseudosection modelling of metapelitic assemblages from the western portions of the Monte Rosa nappe (upper Ayas valley, Italy). We present newly discovered staurolite-chloritoid bearing metapelitic assemblages. These assemblages exhibit an Alpine high-P metamorphic overprint of a former contact-metamorphic mineral assemblage generated by post-Variscan granitic intrusions. Staurolite contains major amounts of Zn (up to 1.0 atoms per formula units), which is currently, in contrast to Fe-and Mg-staurolite end-members, not considered in any thermodynamic database. We employ two end-member mixing models for Zn in staurolite, site mixing and molecular mixing. Both models enlarge the P and T stability range for the observed assemblage, where site mixing has the largest influence of  0.2 GPa and  20 C. Our results for three metapelite assemblages, with and without staurolite, indicate peak Alpine P of 1.6 ± 0.2 GPa and peak T of 585  20 C. These peak P estimates agree with previously published estimates for metagranites in the nappe, and are in stark contrast with peak P obtained from talc, chloritoid, phengite and quartz bearing lithologies termed 'whiteschists' (>2.2 GPa). Our results confirm a variation of peak Alpine P of 0.6 ± 0.2 GPa between metagranite/metapelite lithologies and a nearby whiteschist lens (>2.2 GPa) within the metagranite. Field observations indicate that the studied region is structurally coherent and that the whiteschist is not a tectonic slice formed by tectonic mélange. We suggest that the consistent peak P for metapelite and metagranite assemblages represents the regional peak P and that the higher pressure recorded in the whiteschist lens is likely due to dynamic pressure, possibly resulting from tectonic and/or reaction-induced stresses. If the calculated P of 1.6 ± 0.2 GPa represents regional peak Alpine conditions, then the Monte Rosa nappe was exhumed from a significantly shallower depth than previously assumed, based on peak P estimates >2.2 GPa for whiteschist lithologies.
Published: 2021

45. Controls of continental and oceanic rheologies on reactivation of passive margin

Author: Dauteuil , Olivier, Leroy , M., Guiraud , Michel, Rouby , Delphine, 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)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS), Biogéosciences [UMR 6282] [Dijon] (BGS), Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement, European Geosciences Union, 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 ) -Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique ( CNRS ), Biogéosciences [Dijon] ( BGS ), AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Université de Bourgogne ( UB ) -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), Biogéosciences [UMR 6282] (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), and Dubigeon, Isabelle
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.TE] Sciences of the Universe [physics]/Earth Sciences/Tectonics, [ SDU.STU.TE ] Sciences of the Universe [physics]/Earth Sciences/Tectonics, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2006

46. Control of inheritance, crustal strength and relative rate of extrusion/indentation on 3D strain distribution and basin reactivation: insights from laboratory models

Author: Guillaume, Benjamin, Gianni, Guido, 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), Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires] (CONICET), European Geosciences Union, and Dubigeon, Isabelle
Subjects: [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; Cases where multiple tectonic regimes acted closely in space and time have been long recognized. The coexistence of thrust, strike-slip, and normal faulting has been documented in thick orogenic regions, in oblique convergent settings associated with strain partitioning, in areas of indentation tectonics and lateral escape, and synorogenic foreland rifting/transtension settings, where extension-transtension takes place in close spatiotemporal relation with plate-margin shortening. Here, we use analogue models to test how parameters like the crustal strength, basement inheritances, and relative rate of extrusion/indentation can be effective mechanisms to explain the coeval emplacement of thrust, strike-slip, and normal faults. We also investigate their effect on fault reactivation in previously extended basins.We show that a strong crust can exhibit coeval thrust faults, strike-slip faults and normal faults for ratios of extrusion over indentation rates in between 1.4 and 2, as orientation and magitude of principal stresses spatially vary within the model. For a weaker crust, normal faults and thrusts faults cannot coexist at the same time. Inheritance, which is implemented through the presence of a seed simulating a preexisting weakness zone or through an initial phase of extension, controls the geometry of strike-slip faults, whose orientation departs from the Coulomb fracture criterion. Reactivation of former normal faults as normal faults is only possible for ratios of extrusion over indentation rates over 1, for both weak and strong crusts. For lower rates, pre-existing normal faults are reactivated as indentation-parallel strike-slip faults. Our experimental results are then compared with the tectonic evolution of the Eastern Anatolia, the Alps and the Central Patagonia.
Published: 2022

47. Numerical modelling of lithospheric deformations with frictionalplasticity

Author: Duretz, Thibault, de Borst, René, Räss, Ludovic, Yamato, Philippe, Hageman, Tim, Le Pourhiet, Laëtitia, 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), Goethe-Universität Frankfurt am Main, University of Sheffield [Sheffield], ETH Zürich Laboratory of Hydraulics, Hydrology and Glaciology, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Department of Civil and Environmental Engineering [Imperial College London], Imperial College London, 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), European Geosciences Union, and Dubigeon, Isabelle
Subjects: [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; Strain localisation is a key process that allows for the emergence of tectonic plates and controlstheir long-term deformation. Upper crustal levels are relatively cold and their rheology is thusgoverned by frictional plasticity. In order to predict the formation of tectonic plates and quantifythe deformation of the Earth's upper shell, geodynamic modelling simulation tools must reliablyaccount for deformation in the frictional plastic realm.Nevertheless, the simulation of frictional plastic strain localisation poses severe issues.Commonly employed implementations (visco-plastic and visco-elasto-plastic) often fail toaccurately satisfy force balance and suffer from a lack of convergence upon mesh refinement.These problems are intimately linked to the fact that commonly employed models do notencompass any characteristic spatial or temporal scales of localisation. Various regularisationtechniques can thus be used as a remedy. Here we investigate three popular regularisationtechniques, namely viscoplasticity, gradient plasticity and the use of a Cosserat medium, anddiscuss their potential application for geodynamic modelling.Powered by
Published: 2022

48. Evolution of the Nile River since 70 Ma: insights from surface processes and anorogenic reliefs controlled by mantle dynamics

Author: Iwan Setiawan, François Guillocheau, Cécile Robin, Jean Braun, 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), and European Geosciences Union
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy
Abstract: Anorogenic reliefs (plateaus and plains) made up about 70% of the total emerged reliefs on Earth. They are characterized by nearly flat erosional surfaces upstream bounded by escarpments, called pediments/pediplains. Africa’s landforms are constituted by very long (several thousands of kilometers) wavelength relief of broad “basins” (depressions) and swells (Holmes, 1944) possibly controlled by mantle dynamics. This "basin" and swell pattern caused Africa to be consisted of numerous endorheic and exorheic systems. Consequently, the Nile River, the longest river on Earth and main object of this study, crosses today a set of two former endorheic systems (Ugandese and Sudanese “Basins”) and one exorheic system (Egyptian Margin) along its courses to the Mediterranean Sea. Our objective is here to unravel the paleorouting systems of the Nile River through relief growth, tectonic, and climate since the uppermost Cretaceous.Several generations of stepped pediments, proxies of relief growth, were characterized and mapped on DEM and satellite images and dated using their geometrical relationships with dated magmatic rocks. To better constrain periods of relief uplift and the deformation wavelength through time, the stratigraphic record of the sedimentary basins located in between two swells were studied using biostratigraphy and sequence stratigraphy. The originality of the approaches is to integrate data of all the source-to-sink (S2S) systems to produce a coherent scenario of the evolution of the Nile.We proposed the following model for the evolution of the Nile River. First, a main large pediplain is formed during the uppermost Cretaceous (?75-66 Ma), acting as a base of any kind of landforms that would be formed afterwards, bounded westward by the Darfur-Ennedi crest. Second, a major marine flooding during late Paleocene time (58-57 Ma) reached a subtle high bounding northward the endorheic Sudanese “Basin”. Third, Pre-Eonile started to form during the uppermost Eocene (~37 Ma) with a divide limited to the Egyptian Margin. Fourth, the Eonile was incised during late Miocene (~10 Ma) at time of a major uplift at the scale of north-east Africa. Finally, the Nile captured first the Sudanese endorheic system in the Early Pliocene (~4 Ma) and altered the Ugandese one in the Middle-Late Pleistocene (less than 1 Ma).
Published: 2022

49. Brittle failure at high-pressure conditions: the key role of reactioninducedvolume changes

Author: Yamato, Philippe, Duretz, Thibault, Baîsset, Marie, Luisier, Cindy, 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 Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Goethe-Universität Frankfurt am Main, 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), Goethe-University Frankfurt am Main, European Geosciences Union, and Dubigeon, Isabelle
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.TE] Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDU.STU.PE]Sciences of the Universe [physics]/Earth Sciences/Petrography, [SDU.STU.PE] Sciences of the Universe [physics]/Earth Sciences/Petrography
Abstract: International audience; Metamorphic reactions can lead to drastic changes in rocks mechanical properties. Indeed, duringsuch transformations, the nucleation of new phases with different strength, grain size and/ordensity compared to the primary phases is enhanced, and transient processes due to the ongoingreaction are then activated.Eclogitization of lower crustal rocks during continental subduction constitutes an emblematictransformation illustrating these processes. In such tectonic context, it has been shown thateclogitization seems to be closely associated with the occurrence of seismogenic events. However,the mechanisms that trigger brittle failure in such high pressure environments remain highlydebated. Indeed, whether the change in density or the change in rheology can lead toembrittlement is still enigmatic.By using 2D compressible mechanical numerical models we studied the impact of the strongnegative volume change of the eclogitization reaction on the rocks rheological behaviour. We showthat eclogitization-induced density change occurring out of equilibrium can, by itself, generatessufficient shear stress to fail the rocks at high-pressure conditions.Rupture initiation at depth in continental subduction zones could therefore be explained byvolume changes, even without considering the modifications of the rheological properties inducedby the transformation. Our results also indicate that the negative volume change associated withbrittle failure can enhance the propagation of the eclogitization process by a runaway mechanismas long as the reaction is not limited by the lack of reactants.Powered by
Published: 2022

50. Sharing data and facilities in the analogue modelling community: the EPOS Multi-Scale Laboratories Thematic Core Service

Author: Funiciello, Francesca, Matthias, Rosenau, Dominguez, Stephane, Willingshofer, Ernst, ter Maat, Geertje, Zwaan, Frank, Corbi, Fabio, Olivier Eisermann, Jan, Guillaume, Benjamin, Al., Et, Università degli Studi Roma Tre = Roma Tre University (ROMA TRE), German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Université de Montpellier (UM), Utrecht University [Utrecht], University of Bern, Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome] (UNIROMA), Université de Hambourg, 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), and European Geosciences Union
Subjects: [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics
Abstract: International audience; EPOS, the European Plate Observing System, is a unique e-infrastructure and collaborative environment for the solid earth science community in Europe and beyond (https://www.epos-eu.org/). A wide range of world-class experimental (analogue modelling and rock and melt physics) and analytical (paleomagnetic, geochemistry, microscopy) laboratory infrastructures are concerted in a “Thematic Core Service” (TCS) labelled “Multi-scale Laboratories” (MSL) (https://www.epos-eu.org/tcs/multi-scale-laboratories). Setting up mechanisms allowing for sharing metadata, data, and experimental facilities has been the main target achieved during the EPOS implementation phase. The TCS Multi-scale Laboratories offers coordination of the laboratories’ network, data services, and Trans-National access to laboratory facilities.In the framework of data services, TCS Multi-Scale Laboratories promotes FAIR (Findable-Accessible-Interoperable-Re-Usable) (FAIR) sharing of experimental research data sets through Open Access data publications. Data sets are assigned with digital object identifiers (DOI) and are published under the CC BY license. Data publications are now conventionally citable in scientific journals and develop rapidly into a common bibliometric indicator and research metric. A dedicated metadata scheme (following international standards that are enriched with disciplinary controlled community vocabulary) facilitates ease exploration of the various data sets in a TCS catalogue (https://epos-msl.uu.nl/). Concerning analogue modelling, a growing number of data sets includes analogue material physical and mechanical properties and modelling results (raw data and processed products such as images, maps, graphs, animations, etc.) as well as software (for visualization, monitoring and analysis). The main geoscience data repository is currently GFZ Data Services, hosted at GFZ German Research Centre for Geosciences (https://dataservices.gfz-potsdam.de), but others are planned to be implemented within the next years.In the framework of Trans-National access (TNA), TCS Multi-scale laboratories’ facilities are accessible to any researchers, creating new opportunities for synergy, collaboration and scientific innovation, according to TNAtrans-national access rules. TNA can be realized in the form of physical access (on-site experimenting and analysis), remote service (sample analysis) and virtual access (remotely operated processing). After three successful TNA calls, the pandemic has forced a moratorium on the TNA program.The EPOS TCS Multiscale Laboratories framework is also providing the foundation for a comprehensive database of rock analogue materials, a dedicated bibliography, and facilitates the organization of community-wide activities (e.g., meetings, benchmarking) to stimulate collaboration among analogue laboratories and the exchange of know-how. Recent examples of these community efforts are also the contributions to the monthly MSL seminars, available on the MSL YouTube channel (https://www.youtube.com/channel/UCVNQFVql_TwcSBqgt3IR7mQ/featured), as well as the Special Issue on basin inversion in Solid Earth that is currently open for submissions (https://www.solid-earth.net/articles_and_preprints/scheduled_sis.html#1160).
Published: 2022

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