Oligocene thrust systems in central Xizang Plateau

Abstract：Regional thrusting occurred widely in Oligocene and formed large-scale thrust systems in the Xizang Plateau, such as South Kunlun Thrust (SKT), North Qiangtang Thrust (NQT), Lunpola-Amdo-Suoxian Thrust (LST), Gangdise Thrust System (GTS) and Main Central Thrust (MCT). Imbricate arrangement of faults indicates southward thrusting in Oligocene, which was evidently caused by northward subduction of India continental plate beneath Eurasia continent. According to isotopic dating of high resolution, thrusting in central Himalayas and Fenghuoshan area in north Qiangtang block started before 35 Ma, and thrusting in south Kunlun Mountains and granite emplacement was caused by thrusting in Fenghuo Mountain. Both occurred in 28.8-26.5 Ma. Major thrusting ended before the formation of Early Miocene lacustrine strata of Wudaoliang Group in central Xizang Plateau. Oligocene thrusting made great contribution to shortening and thickening of the crust and isostatic uplift of the Xizang Plateau.