大别造山带西段南部构造几何学和运动学初步分析  

BASICAL GEOMETRIC AND KINEMATIC ANALYSIS OF SOUTHWESTERN DABIE OROGEN

作　　者：黄少英[1] 王志民[1] 徐备[1] 

机构地区：[1]北京大学地球与空间科学学院,北京100871

出　　处：《大地构造与成矿学》2002年第3期240-246,共7页Geotectonica et Metallogenia

基　　金：国家重点基础研究发展规划项目(编号:G1999075511)二级课题"大陆深俯冲动力学机制"研究成果.

摘　　要：根据红安—大悟地区构造填图的结果,结合室内显微镜分析,给出了研究区的构造演化序列、变形几何学特征和运动学方向。本地区经历了两期构造变形,早期变形(D1)是发生在地壳中部层次向北的韧性剪切推覆,形成了区域性、透入性的面理和线理构造,第二期变形(D2)是向较浅层次的向北东方向的逆冲推覆,形成了控制地层分布的区域性褶皱和各种露头尺度的小褶皱。结合已有的构造年代学结果,西大别南部的变形历史可分两个阶段:第一阶段为240Ma到225～210Ma的韧性剪切变形;第二阶段为早于195Ma的褶皱变形,二者均表现为总体由南向北的运动学特征,揭示出大别造山带折返过程的动力学背景。The result of detailed structural in vestigation of the Dawu-Hong'an area,southwestern Dabie has been reported in this paper.Accordi ng to our fieldwork and indoor micro-tectonic analysis,we have obtained the structural evolution phases,geometry of deformation and kinematic of this area.Two deformation phases have been recognized,the earlier one is a top-to-north simple shear,which formed both the pene-trative foliations and lineation of this area;the later one is also a northeast shear deformation phase,whic h formed different scale of folds in th is zone and controlled the distribut ions of the formations at southweste rn Dabie.Combining with others'geochronology,we suggest a two step s deformation history of the west Dab ie,which includes:(1)240Ma to 225-210Ma,plastic deforma tion at middle crust;(2)before 195Ma,plastic to elastic folding at upper c rust.Both show a south to north kinem atic character and reflect the kinematic setting of southwestern D abie orogen during exhumation.

关 键 词：大别造山带 几何学 运动学 构造演化序列 韧性剪切带 

分 类 号：P542.2[天文地球—构造地质学]