挤压造山带中的伸展构造及其成因——以滇中地区晚新生代构造为例  

EXTENSIONAL STRUCTURES WITHIN THE COMPRESSIONAL OROGENIC BELT AND ITS MECHANISM: A CASE STUDY FOR THE LATE CENOZOIC DEFORMATION IN CENTRAL YUNNAN

作　　者：王刚[1] 王二七[1] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029

出　　处：《地震地质》2005年第2期188-199,共12页Seismology and Geology

基　　金：国家重点基础研究发展规划项目(2002CB412601);中国科学院知识创新项目(KZCX2SW119)共同资助。

摘　　要：在印度和欧亚大陆晚新生代SN向陆内汇聚作用下,川滇地块沿鲜水河-小江左行走滑断裂和红河-哀牢山右行走滑断裂发生SE向逃逸和顺时针旋转,这必然造成其南缘的滇中、楚雄等地区地壳发生挤压缩短和隆升。然而,在滇中高原,SN向的小江断裂系发生张扭性运动,沿断裂出现众多的第四纪伸展和拉分盆地,这反映出滇中高原在晚新生代处于近EW向的伸展环境。力学分析与地质现象之间的矛盾暗示有一种尚未被揭示的伸展变形机制。文中根据该地区的地质和地貌特征论证了晚新生代滇中背形构造的存在,揭示出是背形构造的应力分布状态导致了滇中高原上部地壳EW向伸展的发生,从而使得小江断裂发生分裂并伴随伸展构造的发育。Under continuous N-S convergence between the Indian and Eurasian continents, the Sichuan-Yunnan block on the southeastern margin of the Tibetan Plateau has undergone southeastward extrusion and clockwise rotation since late Cenozoic along the right-lateral Red River to the southwest and left-lateral Xianshuihe-Xiaojiang Fault systems to the northeast. However, the surface deformation along the front part of the block in central Yunnan, where the Red River and Xianshuihe-Xiaojiang Fault systems join each other, is characterized by transtension instead of transpression, as indicated by the presence of a series of grabens and horsts along the Xiaojiang Fault system, penetrating the central Yunnan antiform in N-S direction. To explain such contradiction between the field data and theoretical modeling, a mechanic model is constructed in this study, based on the geologic and geomorphic features of the central Yunnan antiform, and the results illustrate that the generation of the E-W extension occurring along the Xiaojiang Fault strands is predominated by stress and strain patterns across the antiform.

关 键 词：伸展构造 新生代构造 挤压造山带 滇中地区 成因 晚新生代 滇中高原 应力分布状态 走滑断裂 顺时针旋转 欧亚大陆 川滇地块 拉分盆地 变形机制 地质现象 力学分析 地貌特征 小江断裂 哀牢山 鲜水河 断裂系 第四纪 SN 地壳 

分 类 号：P542.3[天文地球—构造地质学] P542.2[天文地球—地质学]