Abstract
The India-Asia collision has formed the highest mountains on Earth and is thought to account for extensive intraplate deformation in Asia. The prevailing explanation considers the role of the Pacific and Sunda subduction zones as passive during deformation. Here we test the hypothesis that subduction played an active role and present geodynamic experiments of continental deformation that model Indian indentation and active subduction rollback. We show that the synchronous activity and interaction of the collision zone and subduction zones explain Asian deformation, and demonstrate that east-west extension in Tibet, eastward continental extrusion and Asian backarc basin formation are controlled by large-scale Pacific and Sunda slab rollback. The models require 1740 ± 300 km of Indian indentation such that backarc basins form and central East Asian extension conforms estimates. Indentation and rollback produce ~260–360 km of eastward extrusion and large-scale clockwise upper mantle circulation from Tibet towards East Asia and back to India.
Highlights
The India-Asia collision has formed the highest mountains on Earth and is thought to account for extensive intraplate deformation in Asia
Our models reveal that the synchronous activity and interaction of the collision zone and subduction zones are crucial for explaining the entire deformation field in Central, East and Southeast Asia and demonstrate that enigmatic east–west extension in Tibet, eastward continental extrusion and backarc basin formation along the East and Southeast Asian margins are controlled by large-scale Pacific and Sunda slab rollback
We implement length scaling and geometrical aspect ratios such that, for the first time, the model components accurately represent the size of the Indian indenter (~2400 km), the western Pacific subduction margin (~8000 km), the Sunda subduction zone (~4000 km) and the Asian lithospheric thickness (~104 km) at the onset of collision
Summary
We show that the synchronous activity and interaction of the collision zone and subduction zones explain Asian deformation, and demonstrate that east-west extension in Tibet, eastward continental extrusion and Asian backarc basin formation are controlled by large-scale Pacific and Sunda slab rollback. In the current paradigm for the Cenozoic evolution of this intraplate zone, all deformation, including shortening, strike-slip and extensional deformation (Fig. 1a), is ascribed to the collision and progressive indentation of the Indian subcontinent into the Eurasian plate[1,9,11,12]. In the past two decades, conceptual models have been proposed that argue for an active role of the Pacific subduction margin in driving East Asian extension through slab rollback[10,19,20]. Such models involved a relatively limited spatial domain of Asian continental lithosphere and excluded the Western Pacific subduction margin and most of the
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