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5 results on '"India/Asia collision"'

1. Orocline and syntaxes formation during subduction and collision.

Author

Bajolet, Flora, Replumaz, Anne, and Lainé, Romain

Abstract

The present work investigates the formation of curved ranges and syntaxes with scaled laboratory experiments. We simulated subduction and collision processes comparable to India-Asia configuration involving a continental upper plate and a subducting plate composed of an oceanic lithosphere and a continental indenter. The experiments reveal that the shape of the mountain range (concave, straight, or convex) and the development of syntaxes are controlled by the subduction interface, the buoyancy number ( Fb) of the upper plate (i.e., thickness and viscosity), and the boundary conditions. Four end-members regimes of indentation can be defined depending on the range shape and dynamics of the upper plate. The curvature of the range is convex toward the subducting plate with syntaxes for a weak subduction fault and concave without syntaxes for a strong subduction fault. Convex curvature and syntaxes form by overthrusting of upper plate material on the subducting plate, which is faster at the center than at the extremities. They are associated with a rather flat slab (underthrusting) during continental collision. Low- Fb experiments show less pronounced curvatures associated to thickening comparable to the early stages of the India-Asia collision. In contrast, a thick and weak upper plate (high Fb) leads to gravity collapse that increases the amplitude of the curvature and lateral escape, similar to the late evolution of the Himalaya-Tibet system. Important lateral decoupling on the sides of the indenter enhances the indentation and produces sharper syntaxes. [ABSTRACT FROM AUTHOR]

Published
2013
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2. Crustal mass budget and recycling during the India/Asia collision

Author

Replumaz, Anne, Negredo, Ana M., Guillot, Stéphane, der Beek, Peter van, and Villaseñor, Antonio

Subjects
*CONTINENTAL drift, *SEISMIC tomography, *SUBDUCTION zones, *SUTURE zones (Structural geology), *GEOMORPHOLOGY, *EARTH sciences
Abstract

Abstract: The long-lasting collision between India and Asia has resulted in crustal and lithospheric deformation of both continents, providing unequalled opportunities to evaluate their long-term mechanisms of deformation. We have quantified a crustal mass budget for the collision by comparing the present-day and initial crustal volumes of the Indian and Asian continents involved in the collision. Initial crustal thickness was estimated from the non-deformed parts of the continents, whereas their initial extent was mapped from their contours at the onset of collision, using seismic tomography. We quantify the portion of the initial crustal thickness of both continents stored within the currently thickened crust or redistributed due to extrusion. For the Indian continent, this portion amounts to about 19km, far lower than the mean observed present-day crustal thickness of the Indian craton of about 38km. We conclude that between 40 and 50% of Indian crust has been recycled into the mantle by continental subduction, corresponding to a decoupling level at about 15–19km depth. For the Asian continent, the estimated crustal thickness stored during collision is about 33km, close to the initial Asian crustal thickness. We estimate that only 3% of the Asian crust was recycled into the mantle. This corresponds to one episode of continental subduction, occurring most probably soon after the initiation of collision along the Bangong suture. We identify the related slab using seismic tomography. The strong contrast between India and Asia implies an age-dependent capacity of the continental crust to be recycled into the mantle. This result has to be taken into account for further analysis of global crustal recycling during Earth''s history. [Copyright &y& Elsevier]

Published
2010
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3. Multiple episodes of continental subduction during India/Asia convergence: Insight from seismic tomography and tectonic reconstruction

Author

Replumaz, Anne, Negredo, Ana M., Guillot, Stéphane, and Villaseñor, Antonio

Subjects
*SUBDUCTION zones, *CONVERGENCE (Meteorology), *SEISMIC tomography, *STRUCTURAL geology, *COLLISIONS (Physics), *PALEOGEOGRAPHY
Abstract

Abstract: High wavespeed tomographic anomalies shallower than 1100km beneath the India/Asia collision zone are interpreted as continental slabs subducted during collision. Combining anomaly positions with paleogeographic reconstructions of India, we constrain the spatio-temporal evolution of multiple episodes of continental subduction likely related to these anomalies. This study highlights the different evolution at lithospheric scales of the western and eastern parts of the collision zone. The evolution of the western part is characterized by two episodes of steep subduction of the northern margin of India. The first episode, involving an area with a lateral extent as large as 1500km, started at about 40–30 and ended by a slab break-off process at ∼15Ma, The second episode consists on subduction beneath the Hindu Kush mountains since ∼8Ma. To the east of the collision zone, no anomaly related to steep subduction along the northern edge of India is found. We interpret two tomographic anomalies beneath the eastern border of the Indian plate, beneath Burma and beneath the Andaman Sea, as the result of two successive episodes of southeastward extrusion followed by subduction. We suggest that both extruded portions were initially located along the northern margin of India, and that they slid around the eastern syntaxis, then southward along the eastern boundary of Indian plate. Both portions subducted along the eastern border of India, south of the eastern syntaxis. We provide a rough estimate of the amount of Indian lithosphere consumed during these subduction and extrusion episodes. By comparing this amount with the total amount of Indian lithosphere at the onset of collision, we conclude that these processes accommodated most of the India/Asia convergence during collision. [Copyright &y& Elsevier]

Published
2010
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4. Crustal mass budget and recycling during the India/Asia collision

Author

Antonio Villaseñor, Ana M. Negredo, Stéphane Guillot, Anne Replumaz, Peter van der Beek, Laboratoire de Géodynamique des Chaines Alpines (LGCA), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-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)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Department of Geophysics [Madrid], Universidad Complutense de Madrid [Madrid] (UCM), Institute of Earth Sciences Jaume Almera, Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), and Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)

Subjects
geography, geography.geographical_feature_category, Continental subduction, 010504 meteorology & atmospheric sciences, Subduction, Continental collision, Continental crust, Crustal recycling, Crustal budget, Crust, Geophysics, 010502 geochemistry & geophysics, 01 natural sciences, India/Asia collision, Craton, Ancient plate boundary inferred from tomography, 13. Climate action, Lithosphere, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, Petrology, Eclogitization, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

International audience; The long-lasting collision between India and Asia has resulted in crustal and lithospheric deformation of both continents, providing unequalled opportunities to evaluate their long-term mechanisms of deformation. We have quantified a crustal mass budget for the collision by comparing the present-day and initial crustal volumes of the Indian and Asian continents involved in the collision. Initial crustal thickness was estimated from the non-deformed parts of the continents, whereas their initial extent was mapped from their contours at the onset of collision, using seismic tomography. We quantify the portion of the initial crustal thickness of both continents stored within the currently thickened crust or redistributed due to extrusion. For the Indian continent, this portion amounts to about 19 km, far lower than the mean observed present-day crustal thickness of the Indian craton of about 38 km. We conclude that between 40 and 50% of Indian crust has been recycled into the mantle by continental subduction, corresponding to a decoupling level at about 15–19 km depth. For the Asian continent, the estimated crustal thickness stored during collision is about 33 km, close to the initial Asian crustal thickness. We estimate that only 3% of the Asian crust was recycled into the mantle. This corresponds to one episode of continental subduction, occurring most probably soon after the initiation of collision along the Bangong suture. We identify the related slab using seismic tomography. The strong contrast between India and Asia implies an age-dependent capacity of the continental crust to be recycled into the mantle. This result has to be taken into account for further analysis of global crustal recycling during Earth's history.

Published
2010

5. Multiple episodes of continental subduction during India/Asia convergence: Insight from seismic tomography and tectonic reconstruction

Author

Stéphane Guillot, Anne Replumaz, Ana M. Negredo, Antonio Villaseñor, Laboratoire de Géodynamique des Chaines Alpines (LGCA), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Geophysics [Madrid], Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Institute of Earth Sciences Jaume Almera, Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-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)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Universidad Complutense de Madrid [Madrid] (UCM), and Consejo Superior de Investigaciones Científicas [Spain] (CSIC)

Subjects
010504 meteorology & atmospheric sciences, Continental collision, [SDE.MCG]Environmental Sciences/Global Changes, 010502 geochemistry & geophysics, 01 natural sciences, Lithospheric extrusion, Burma, Underthrusting, Lithosphere, Tomography, 0105 earth and related environmental sciences, Earth-Surface Processes, First episode, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Continental subduction, Subduction, Syntaxis, Break-off, Collision zone, India/Asia collision, Tectonics, Geophysics, Seismic tomography, Andaman Sea, Convergence, Geology, Seismology
Abstract

International audience; High wavespeed tomographic anomalies shallower than 1100 km beneath the India/Asia collision zone are interpreted as continental slabs subducted during collision. Combining anomaly positions with paleogeographic reconstructions of India, we constrain the spatio-temporal evolution of multiple episodes of continental subduction likely related to these anomalies. This study highlights the different evolution at lithospheric scales of the western and eastern parts of the collision zone. The evolution of the western part is characterized by two episodes of steep subduction of the northern margin of India. The first episode, involving an area with a lateral extent as large as 1500 km, started at about 40–30 and ended by a slab break-off process at not, vert, similar 15 Ma, The second episode consists on subduction beneath the Hindu Kush mountains since not, vert, similar 8 Ma. To the east of the collision zone, no anomaly related to steep subduction along the northern edge of India is found. We interpret two tomographic anomalies beneath the eastern border of the Indian plate, beneath Burma and beneath the Andaman Sea, as the result of two successive episodes of southeastward extrusion followed by subduction. We suggest that both extruded portions were initially located along the northern margin of India, and that they slid around the eastern syntaxis, then southward along the eastern boundary of Indian plate. Both portions subducted along the eastern border of India, south of the eastern syntaxis. We provide a rough estimate of the amount of Indian lithosphere consumed during these subduction and extrusion episodes. By comparing this amount with the total amount of Indian lithosphere at the onset of collision, we conclude that these processes accommodated most of the India/Asia convergence during collision.

Published
2010

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