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Published April 4, 2012 | Published
Journal Article Open

Insights on the kinematics of the India-Eurasia collision from global geodynamic models

Abstract

The Eocene India-Eurasia collision is a first order tectonic event whose nature and chronology remains controversial. We test two end-member collision scenarios using coupled global plate motion-subduction models. The first, conventional model, invokes a continental collision soon after ∼60 Ma between a maximum extent Greater India and an Andean-style Eurasian margin. The alternative scenario involves a collision between a minimum extent Greater India and a NeoTethyan back-arc at ∼60 Ma that is subsequently subducted along southern Lhasa at an Andean-style margin, culminating with continent-continent contact at ∼40 Ma. Our numerical models suggest the conventional scenario does not adequately reproduce mantle structure related to Tethyan convergence. The alternative scenario better reproduces the discrete slab volumes and their lateral and vertical distribution in the mantle, and is also supported by the distribution of ophiolites indicative of Tethyan intraoceanic subduction, magmatic gaps along southern Lhasa and a two-stage slowdown of India. Our models show a strong component of southward mantle return flow for the Tethyan region, suggesting that the common assumption of near-vertical slab sinking is an oversimplification with significant consequences for interpretations of seismic tomography in the context of subduction reference frames.

Additional Information

© 2012 by the American Geophysical Union. Received 22 September 2011; Revised 22 February 2012; Accepted 22 February 2012; Published 4 April 2012. Numerical models were run on the CiTerra cluster at Caltech and the Australian National Computational Infrastructure (NCI). CitcomS was obtained from the Computational Infrastructure for Geodynamics (www.geodynamics.org). All figures were created using GPlates (www.gplates.org) and Generic Mapping Tools (GMT, gmt.soest.hawaii.edu). This project was supported by Statoil and ARC grants FL0992245 and DP0987713, the National Science Foundation under EAR-0810303, and by the Gordon and Betty Moore Foundation (through the Caltech Tectonics Observatory). We are thankful for the constructive suggestions of two anonymous reviewers and the Editors that considerably improved the original manuscript.

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