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Journal Articles Tectonophysics Year : 2010

Crustal mass budget and recycling during the India/Asia collision

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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 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.
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insu-00549821 , version 1 (22-12-2010)

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Anne Replumaz, Ana M. Negredo, Stéphane Guillot, Peter van Der Beek, Antonio Villaseñor. Crustal mass budget and recycling during the India/Asia collision. Tectonophysics, 2010, 492, pp.99-107. ⟨10.1016/J.TECTO.2010.05.023⟩. ⟨insu-00549821⟩
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