The Late Triassic Collision and Sedimentary Responses at Western Segment of Jinshajiang Suture, Tibet
LI Yong 1,2 WANG Cheng-shan1 YI Hai-sheng1 1 (The Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059) 2 (Hydroelectric Engineering College, Sichuan University, Chengdu 610065)
Qinghai-Tibetan Plateau is composed of many sutures and basins. The late Triassic northern Qiangtang foreland basin system is peripheral foreland system in the front of Jinshajiang suture and can be divided into four tectonic units from north to south, including the Jinshajiang suture, Hoh Xil thrust belt, Qiangtang foreland basin and the forebulge (center uplift). The Late Triassic northern Qiangtang foreland basin is filled with more than 2500 m strata and can be divided into two tectonic sequences bounded by unconformities. In a transverse section there is wedge-shaped sedimentary body and the depocenter was located in north part of the basin . There were double paleocurrent and double provenances in the basin. Based on the youngest age of ophiolite, collision granite, Flysch, Molasss, carbonate ramp on forebulge and clast in sandstone and conglomerate, unconformity between Flysch facies and Molasse facies, it has been suggested that the time of the major collision between Qiangtang block and Euasian block is between Norian and Rhaetian.