Cenozoic tectonic evolution of Asia: A preliminary synthesis

Asia has been a major testing ground for various competing models of continental deformation due to its relatively well-understood plate boundary conditions in the Cenozoic, exceptional exposure of active structures, and strain distribution, and widespread syn-collisional igneous activity as a proxy for the thermal state of the mantle and crust. Two Cenozoic orogens dominate the continent: the Himalayan–Tibetan orogen in the east induced by the India–Asia collision and the Turkish–Iranian–Caucasus orogen in the west induced by the Arabia–Asia collision. The development of the two orogens was accomplished by shortening in the early stage followed by strike-slip faulting and extension in the late stage. In the Himalayan–Tibetan orogen, shortening across two discrete thrust belts at 55–30 Ma in southern and northern Tibet created a large intracontinental basin (the Paleo-Qaidam basin) in between. Subsequent crustal thickening and a possible thermal event in the mantle (e.g., convective removal of central Tibetan mantle lithosphere) may have raised the elevation of this early intra-plateau basin up to ~ 2–3 km to its current height. Collision between India and Asia also caused lateral extrusion of southeast Asia between 32 Ma and 17 Ma. The latest stage of the India–Asia collision was expressed by north-trending rifting and the development of trench-facing V-shaped conjugate strike-slip faults in central Mongolia, central Tibet, eastern Afghanistan and southeast Asia. In the Turkish–Iranian–Caucasus orogen, early crustal thickening in the orogenic interior began at or prior to 30–20 Ma. This style of deformation was replaced by strike-slip faulting at ~ 15–5 Ma associated with further northward penetration of Arabia into Asia, westward extrusion of the Anatolia/Turkey block, and rapid extension across the Sea of Crete and Sea of Aegean. The late stage extension in both orogens was locally related to extensional core-complex development. The continental-margin extension of east Asia was developed in two stages: initially in a widely distributed zone that has an east-west width of 500–800 km during 65–35 Ma, which was followed by localized extension and opening of back-arc basins associated with the development of spreading centers at 32–17 Ma (e.g., Japan Sea or East Korea Sea, Bohai Bay, and South China Sea). Opening of the back-arc basins could be induced by (1) rapid eastward migration of the western Pacific trench system or (2) oblique subduction of Pacific