东昆仑造山带东段阿拉克湖地区侏罗系羊曲组地质特征及其构造意义

摘要

The early Jurassic Yangqu Formation,newly identified at Alake Lake area during the process of 1 ∶ 50000 geological mapping in the eastern part of East Kunlun orogenic belt,is observed and depicted carefully both outdoor and indoor in the view of sedimentary faciology,which has been subdivided into 3 lithology beds according to their lithological differences from bottom to top,namely,conglomerate lithology bed (J1y1),sandstone and siltstone lithology bed (J1y2) and rhythmic lithology bed (J1 y3).This Formation can be summarized as a stratigraphic sequence of continental faciology with fluvial deposits-lacustrine deposits-fluvial deposits.Based on the regional data,it is supposed that this strata may be the sedimentary response to the strength field transition from compression to extension for the eastern part of East Kunlun orogenic belt during middle Triassic-early Jurassic.%从沉积相角度入手,对1∶50000地质填图过程中新识别出的东昆仑造山带东段阿拉克湖地区下侏罗统羊曲组进行了详细的野外观测和剖面描述,将其按岩性由老到新划分为3个岩性段,分别为下段砾岩段(J1y1)、中段砂泥岩段(J1 y2)以及上段韵律层段(J1 y3)等.岩石组合及沉积结构构造表明,其为一套由河流相-湖泊相-河流相组成的陆相沉积地层序列.通过区域对比及研究得出,该套地层可能是对中三叠世晚期—早侏罗世东昆仑造山带东段由挤压向伸展转换的构造事件的沉积响应.