Burma Terrane part of the Trans-Tethyan Arc during collision with India according to palaeomagnetic data.

Abstract

Convergence between the Indian and Asian plates has reshaped large parts of Asia, changing regional climate and biodiversity. Yet geodynamic models fundamentally diverge on how convergence was accommodated since the India-Asia collision. Here we report paleomagnetic data from the Burma Terrane, at the eastern edge of the collision zone and famous for its Cretaceous amber biota, to better determine the evolution of the India-Asia collision. The Burma Terrane was part of a Trans-Tethyan island arc and stood at a near-equatorial southern latitude at ~95 Ma, suggesting island endemism for the Burmese amber biota. The Burma Terrane underwent significant clockwise rotation between ~80-50 Ma, causing its subduction margin to become hyper-oblique. Subsequently, it was translated northward on the Indian Plate, by an exceptional distance of at least 2000 km, along a dextral strike-slip fault system in the east. Our reconstructions are only compatible with geodynamic models involving a first collision of India with a near-equatorial Trans-Tethyan subduction system at ~60 Ma, followed by a later collision with the Asian margin.