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

Abstract

[1] 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.

A tectonic model reconciling evidence for the collisions between India, Eurasia and intra-oceanic arcs of the central-eastern Tethys

“…This coincides with the significant drop in India-Eurasia convergence from 60-50 Ma (India-Kohistan/KLA, Fig. 7b) (Zahirovic et al, 2012) and was likely due to the buoyancy of Indian continental crust impeding subduction at the intra-oceanic arc. Andean-style subduction re-initiated along southern Lhasa by 65 Ma (Fig.…”

“…6k), and coincides with a second significant drop in India-Eurasia convergence rates at ~43 Ma (Fig. 7b) and reorganization of seafloor spreading in the Indian Ocean (Lee and Lawver, 1995;Zahirovic et al, 2012), coupling Indian and Australian plates (Liu et al, 1983), which began to move to north-…”

“…GPlates (Boyden et al, 2011), to create a regionally-constrained global plate model based on combining the seafloor-spreading histories from ocean basins (Seton et al, 2012) and our extensive review of the regional onshore geology, outlined in the previous section. open-source, community-driven online repository .…”

Tectonic speed limits from plate kinematic reconstructions

“…Such an approach can be verified by linking geodynamic models to plate reconstructions in order to reproduce present-day mantle structure that can be validated using seismic tomography. Interpretations of subducted slab volumes have shown that alternative subduction scenarios can be tested (Van der Voo et al, 1999;Zahirovic et al, 2012), whilst also providing a possible absolute reference frame in the absence of reliable hotspot tracks in premid-Cretaceous times (van der Meer et al, 2010).…”

The Indian Promontory: A Bridge between Plate Tectonics and Life Evolution Models

“…such as in [6,20]), preventing slab pull to be transmitted. In such case, the necessary geodynamic force to move India northward would be annihilated.…”