基于小震定位与震源机制解信息的阿尔金断裂带东段构造转换研究  

Study of tectonic transformation along the eastern Altyn Tagh fault zone based on small earthquake relocation and focal mechanism solutions

作　　者：刘亢[1] 李海兵[2] 王长在[3] 张辉[4] 肖根如[5] 李红光[1] 张凌[1] LIU Kang;LI HaiBing;WANG ChangZai;ZHANG Hui;XIAO GenRu;LI HongGuang;ZHANG Ling(National Earthquake Response Support Service,Beijing 100049,China;Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Lanzhou Institute of Seismology,China Earthquake Administration,Lanzhou 730000,China;Key Laboratory for Digital Land and Resources of Jiangxi Province,East China University of Technology,Nanchang 330013,China)

机构地区：[1]中国地震应急搜救中心,北京100049 [2]自然资源部深地动力学重点实验室,中国地质科学院地质研究所,北京100037 [3]中国地震局地球物理研究所,北京100081 [4]中国地震局兰州地震研究所,兰州730000 [5]东华理工大学江西省数字国土重点实验室,南昌330013

出　　处：《地球物理学报》2018年第11期4459-4474,共16页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41502206,41504043,41631073);东华理工大学江西省数字国土重点实验室开放研究基金项目(DLLJ201616)资助.

摘　　要：阿尔金断裂带东段地区的造转换及其动力学机制研究一直是地学工作者关注的焦点.本文利用双差定位法获取研究区域2008—2017年间6013次地震事件的精确定位数据;整理筛选前人震源机制解36个,并采用P/S波振幅比方法计算获得221个以及CAP方法获得25个震源机制解信息.选择野马河—大雪山断裂作为研究区构造转换研究的突破口,综合小震定位数据与震源机制解信息,并开展野外地质调查进行验证,清晰刻画出该断裂的深部构造形态以及现今的运动特征:由阿尔金断裂带向祁连山方向过渡,断层产状由近直立逐渐转变为倾向南,倾角变缓,震源机制解由走滑性质为主转变为逆冲性质为主,是一个连续渐变的过程,为研究区的构造转换研究提供了直接证据.The tectonic transformation and kinetic mechanism of the eastern Altyn Tagh fault zone have been a focus issue of geologists.In this work,6013 earthquakes from 2008 to 2017 in study region were relaocted using the double-difference location algorithm.Meanwhile,we selected 36 focal mechanism solutions from previous study,and determined 221 focal mechanism solutions by using the method of the maximum amplitude ratio between P and S waves,and 25 focal mechanism solutions by the Cut and Paste(CAP)method.The Yemahe-Daxueshan fault zone was selected as an example of the tectonic transformation in study region.Based on these data of small earthquake relocation and focal mechanism solutions,as well as field geological investigations,spatial distribution of the faults and the current movement characteristics of the study area were described in detail.Results suggest that from the Altyn Tagh fault zone to the Qilian mountains,the faults gradually change from nearly-vertical to southward dipping and the focal mechanism solutions also chang from strike slip to dominant thrust,experiencing a continuous transition,which provides direct evidence for the tectonic transformation research.

关 键 词：阿尔金断裂带 祁连山断裂带 小震重新定位 震源机制解 构造转换 

分 类 号：P315[天文地球—地震学] P541[天文地球—固体地球物理学]