郯庐断裂带中-南段走滑构造特征与变形规律  

STRUCTURAL AND GEOCHRONOLOGICAL EVIDENCE FOR MUL-TIPLE EPISODES OF DEFORMATION SINCE PALEOCENE ALONG THE AILAO SHAN-RED RIVER SHEAR ZONE, SOUTHEASTERN ASIA

作　　者：朱光[1] 徐佑德[1] 刘国生[1] 王勇生[1] 谢成龙[1] 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009

出　　处：《地质科学》2006年第2期226-241,255,共17页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金项目(批准号:40272094)资助。

摘　　要：在大别造山带东端和苏鲁造山带西端,郯庐断裂带存在着同造山期和早白垩世两期左旋走滑韧性剪切带,在张八岭隆起南段迄今为止只发现了早白垩世的走滑剪切带。这些剪切带由若干条小型韧性剪切带组成,带内糜棱岩都具有陡倾的糜棱面理和平缓的矿物拉伸线理。野外构造、显微构造及石英C轴组构皆指示了左旋走滑剪切指向。新生矿物组合和矿物变形行为分析显示大别山东端郯庐早、晚两期剪切带主要形成于中绿片岩相的变质温度环境,张八岭隆起南段剪切带主要形成于高绿片岩相的变质温度环境,苏鲁造山带西端郯庐早、晚两期剪切带则形成于高角闪岩相的变质温度环境。糜棱岩内基质中新生白云母的电子探针分析指示大别山东端和张八岭隆起南段出露的郯庐韧性剪切带形成于低压环境下,而苏鲁造山带西端的郯庐韧性剪切带形成于高压榴辉岩相环境。这些详细的构造研究显示:在华北与华南板块的碰撞造山期郯庐断裂带以左旋走滑构造型式存在,而在早白垩世太平洋构造域中它又再次发生了强烈的左行平移。Two phases of sinistral ductile shearing occurred along the eastern terminal of the Dabie orogen and western terminal of the Su-Lu orogen, which developed during the syn-orogenic period and Early Cretaceous respectively. Only Early Cretaceous sinistral shearing was found in southern part of the Zhangbaling Rise. These shear zones were composite ones, composed of several smaller ductile shear belts. The mylonites in the shear zones showed steep mylonitic foliation and gentle mineral elongation lineation. All of the filed surveys, microstructures and quartz C axis fabrics indicated a sinistral shear sense. Newly-formed mineral assemblages and mineral deformation behaviors demonstrated that both of the earlier and later shear zones along the eastern terminal of the Dabie orogen were developed under metamorphic temperature conditions of middle greenschist facies, the shear zone along southern part of the Zhangbaling Rise was formed under metamorphic temperature conditions of higher greenschist facies, and both of the earlier and later shear zones along the western terminal of the Su-Lu orogen were developed under metamorphic temperature conditions of higher amphibolite facies. Electron microprobe analysis on matrix white mica of the mylonites suggested that the shear zones along the eastern terminal of the Dabie orogen and southern part of the Zhangbaling Rise were developed under low-pressure conditions, and those along the western terminal of the Su-Lu orogen were formed under high-pressure eclogite facies conditions. These detailed structural studies demonstrated that the Tan-Lu fault zone appeared as sinistral strike-slip tectonics during the collision of the North and South China plates, and intense left-lateral displacement took place again along the fault zone in the circum-Pacific domain in the Early Cretaceous.

关 键 词：郯庐断裂带 构造特征 糜棱岩 温压环境 左旋走滑 

分 类 号：P542[天文地球—构造地质学]