桂东北地区鹰扬关韧性剪切带的厘定及其构造意义  

Discovery of Yingyangguan Ductile Shear Zone in Northeastern Guangxi and Its Tectonic Significances

作　　者：秦亚[1,2] 冯佐海[1,2] 吴杰[1,2] 薛云峰 胡乔帆 白玉明 周鹏程 QIN Ya;FENG Zuo-hai;WU Jie;XUE Yun-feng;HU Qiao-fan;BAI Yu-ming;ZHOU Peng-cheng(Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources by the Province and Ministry,Guilin University of Technology,Guilin,Guangxi 541006;Guangxi Key Laboratory of Exploration for Hidden Metallic Ore Deposits,Guilin University of Technology,Guilin,Guangxi 541006;Henan Geological Bureau of China Chemical Geology and Mine Bureau,Zhengzhou,Henan 450000;China Nonferrous Metals(Guilin)Geology and Mining Co.,Ltd.,Guilin,Guangxi 541006)

机构地区：[1]桂林理工大学有色隐伏金属矿产勘查与资源高效利用省部共建协同创新中心,广西桂林541006 [2]桂林理工大学广西隐伏金属矿产勘查重点实验室,广西桂林541006 [3]中化地质矿山总局河南地质局,河南郑州450000 [4]中国有色桂林矿产地质研究院有限公司,广西桂林541006

出　　处：《地球学报》2023年第3期434-454,共21页Acta Geoscientica Sinica

基　　金：国家自然科学基金项目(编号:42072259,42162018);广西自然科学基金项目(编号:2022GXNSFAA035570,2019GXNSFDA245009)联合资助。

摘　　要：论文通过宏-微观构造、磁组构、热液锆石和石英EBSD组构等,厘定鹰扬关韧性剪切带并讨论其构造意义。鹰扬关韧性剪切带具有宏-微观韧性变形组构,发育糜棱岩、拉伸线理、S-C组构、旋转碎斑系、书斜构造、压力影和石英的动态重结晶等。磁组构和宏-微观构造表明,鹰扬关韧性剪切带呈NNE向延伸超过40 km,宽2.5~8 km。糜棱C面理的极密点产状127°∠50°;磁面理的极密点产状107°∠83°。宏-微观构造研究表明,鹰扬关韧性剪切带具有早期左旋逆冲剪切,晚期右旋正滑剪切的运动学性质。石英EBSD组构表明,鹰扬关韧性剪切带具有晚期中低温变形(400~550℃)叠加于早期中高温变形(550~650℃)的特征。年代学研究表明,鹰扬关韧性剪切带早期左旋逆冲剪切的时代为(441.1±2.3)Ma,晚期右旋正滑剪切的时代应晚于420 Ma,区域构造应力由挤压转为伸展的时限为420 Ma。在磁组构、石英EBSD组构和热液锆石定年的基础上,结合区域地质资料,认为鹰扬关韧性剪切带形成于华夏陆块自SE向扬子陆块造山挤压的构造背景。早期造山挤压,产生压扁型应变和中高温左旋逆冲剪切;晚期造山后伸展,产生拉伸型应变和中低温右旋正滑剪切。鹰扬关韧性剪切带的上述认识暗示其形成与早古生代扬子和华夏陆块的造山作用有关,而非构造混杂作用的产物。Based on macro-micro structure,magnetic fabric,hydrothermal zircon and quartz EBSD fabric,the Yingyangguan ductile shear zone was determined and its tectonic significance is discussed.The Yingyangguan ductile shear zone has typical macro-micro structural characteristics,such as mylonite,stretching lineation,S-C fabric,rotating porphyry system,domino structures,pressure shadow structure and dynamic recrystallization of quartz.Magnetic fabric measurement and field geological survey showed that the Yingyangguan ductile shear zone extends over 40 km in NNE direction and is 2.5-8 km wide.The extremely dense point occurrence of the C folication of the mylonite is 127°∠50°,and the occurrence of extremely dense points of magnetic foliation is 107°∠83°.Analysis of the macro-micro structure showed that the Yingyangguan ductile shear zone has kinematic properties of early sinistral thrust shear and late dextral normal slip shear.Quartz EBSD fabric analysis revealed that the Yingyangguan ductile shear zone is characterized by late mid-low temperature deformation(400-550℃)superimposed on early mid-high temperature deformation(550-650℃).The geochronology showed that the age of the early sinistral thrust shear is(441.1±2.3)Ma,and the age of late dextral normal slip shear is later than 420 Ma.The time limit of regional tectonic stress from compression to extension is 420 Ma.Analysis of the magnetic fabric,quartz EBSD fabric,and hydrothermal zircon dating,combined with regional geological data,revealed that the Yingyangguan ductile shear zone formed in the tectonic background of the collision of the Cathaysia block from the SE to the Yangtze block.In the early stage of extrusion and collision,flattening strain was generated and mid-high temperature sinistral thrust shear was formed.After the late orogenic extension,tensile strain was generated,and dextral normal slip shear was formed at mid-low temperature.The strain characteristics,deformation temperature,deformation age,and dynamic setting of the Yingyangguan ducti

关 键 词：磁组构 石英EBSD组构 热液锆石 韧性剪切带 桂东北鹰扬关地区 

分 类 号：P542[天文地球—构造地质学]