Silurian Sedimentation in the South Qilian Belt: Arc-Continent Collision-related Deposition in the NE Tibet Plateau?  

作　　者：YAN Zhen FU Changlei Jonathan CAITCHISON ZHOU Renjie Solomon BUCKMAN CHEN Lei 

机构地区：[1]Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China [2]School of Earth and Environmental Sciences,University of Queensland,Brisbane,Queensland,4072,Australia [3]School of Earth&Environmental Science,University of Wollongong,NSW 2522,Australia

出　　处：《Acta Geologica Sinica(English Edition)》2020年第4期901-913,共13页地质学报（英文版）

基　　金：the National Natural Science Foundation of China(Grants 41672221,41872241);China Geological Survey(Grants DD20190006,DD2016020104);IGGCAS Open Research Foundation(SKLK201702)。

摘　　要：The South Qilian belt mainly comprises an early Paleozoic arc-ophiolite complex, accretionary prism, microcontinental block, and foreland basin. These elements represent accretion-collision during Cambrian to Silurian time in response to closure of the Proto-Tethyan Ocean in the NE of the present-day Tibet Plateau. Closure of the Proto-Tethyan Ocean between the Central Qilian block and the Oulongbuluke block and the associated collision took place from NE to SW in a zipper-like style. Sediment would have been dispersed longitudinally SW-ward with a progressive facies migration from marginal alluvial sediments toward slope deep-water and deep-sea turbidites. This migration path indicates an ocean basin that shrank toward the SW. The Balonggongga'er Formation in the western South Qilian belt represents the fill of a latest Ordovician-Silurian remnant ocean basin that separated the Oulongbuluke block from the Central Qilian block, and records Silurian closure of the Proto-Tethyan Ocean and subduction beneath the Central Qilian block. However, alluvial deposits in the Lajishan area were accumulated in a retro-foreland basin, indicating that continent-continent collision in the eastern South Qilian belt occurred at c. 450–440 Ma. These results demonstrate that the Proto-Tethyan Ocean closed diachronously during early Paleozoic time.

关 键 词：remnant ocean basin Qilian Orogen arc-continental collision Proto-Tethyan Ocean 

分 类 号：P542[天文地球—构造地质学] P512.2[天文地球—地质学]