东昆仑南部晚新生代逆冲推覆构造系统

Late Cenozoic overthrust system in the southern East Kunlun Mountains, China

通过对东大滩—东温泉地区的路线地质观测与构造填图,在东昆仑南部发现晚新生代大型逆冲推覆构造系统。沿低角度逆冲断层,早二叠世大理岩和早三叠世砂板岩自北向南逆冲推覆于古新统—始新统风火山群紫红色砾岩和渐新世砖红色砂砾岩之上,形成大量不同规模的飞来峰;沿主逆冲断层发育厚层断层角砾岩与断层泥,局部形成碳酸盐质糜棱岩。东昆仑南部逆冲推覆构造的发育时代为渐新世晚期—中新世早期,主要形成、活动时期为26～13.5Ma;估算最小逆冲推覆距离为30～35km,最小逆冲推覆运动速率为2.4～2.8mm/a。东昆仑南部晚新生代逆冲推覆构造运动与现今山脉快速隆升存在着动力学成因联系。

A large-scale Late Cenozoic overthrust system has been found in the southern East Kunlun Mountains through tectonic mapping and geological reconnaissance in the Dongdatan-East Wenquan area. Along the low-angle overthrnst Early Permian marble and Early Triassic sandy slate were thrust southward over Paleocene-Eocene purplish red conglomerate of the Paleocene-Eocene Fenghuoshan Group and brick-red sandy conglomerate of the Oligocene Yaxicuo Group, forming many ldippen of varying scales, and thick fault breccia and gouge and locally carbonate mylonite formed along major thrust faults. The overthrusting in the southern East Kunlun Mountains occurred in the late Oligocene-early Miocene, mainly at 26-13.5 Ma. The minimal displacement and average rate of southward overthrusting are estimated to be ～30-35 km and 2.4-2.8 mm/a respectively. The Late Cenozoic overthrusting in the southern East Kunlun is inferred to have dynamic relation to the rapid uplift of the present-day Kunlun Mountains.