东亚大陆西缘侏罗纪变形--以班公湖-怒江带中段韧性变形为例  

JURASSIC DEFORMATION AT THE WESTERN MARGIN OF THE EAST ASIA CONTINENT: A CASE STUDY OF DUCTILE DEFORMATION IN THE CENTRAL SEGMENT OF THE BANGONG CO-NUJIANG BELT

作　　者：施炜[1] 董树文[2] 黄兴富[1] 陈虹[1] 崔建军[1] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]南京大学地球科学与工程学院,江苏南京210093

出　　处：《地质力学学报》2017年第4期515-525,共11页Journal of Geomechanics

基　　金：国家重点研发计划项目(2017YFC0601402);中国地质调查局项目(1212011120184,1212011221111)

摘　　要：班公湖-怒江带作为羌塘地块与拉萨地块晚中生代聚合而形成巨型构造带,其形成时代与如何汇聚是构造研究关键所在。本次研究选择班公湖—怒江带中段的安多—聂荣地块发育为研究区,对地块内部基底发育的近东西走向的韧性剪切带,开展了韧性剪切变形分析与同构造年代学研究。剪切带面理和线理测量分析指示北东—南西向构造挤压,其同构造矿物40Ar/39Ar的测试分析获得年龄约为167 Ma,表明班公湖-怒江带中段形成于中侏罗世中期北东—南西向汇聚的构造背景下。结合区域构造分析,东亚大陆西缘羌塘地块与拉萨地块在中侏罗世中期以北东—南西向碰撞聚合的构造方式完成大陆拼接,为东亚大陆西缘中侏罗世变形提供了直接构造证据。The Bangong Co-Nujiang belt resulted from the convergence and collision between the Chiangtang and Lhasa blocks in late Mesozoic. The key issue in this tectonic study is when and how the belt was formed. With the Ando-Nyainrong block of the central segment of the Bangong Co-Nujiang belt as the study area, the ductile shear belts with approximately E-W strike developed in the internal basement of the block are studied based on ductile shear deformation analysis and syntectonic geochronology. The foliation and lineation measurement and analysis of the shear belts indicate tectonic compression with NE-SW strike. Through the test analysis of 40Ar/39 Ar in syntectonic minerals, the age is worked out as 167 Ma. All the evidence shows that the central segment of the Bangong Co-Nujiang belt was caused under the convergence and collision between the Chiangtang and Lhasa blocks in the middle of Middle Jurassic, which provides direct tectonic evidence for the Jurassic deformation at the western margin of the East Asian continent.

关 键 词：东亚大陆 班公湖—怒江带 安多—聂荣地块 韧性剪切变形 侏罗纪 

分 类 号：P542[天文地球—构造地质学]