新疆天山中段地壳和上地幔顶部P波速度结构研究  

P-wave velocity structure of the crust and uppermost mantle in the middle of Tianshan

作　　者：刘建明 吴传勇[3] 余怀忠 王琼 刘代芹[1,2,4] 赵彬彬 高荣[1,2] 高歌[1,2] 孔祥艳 LIU JianMing;WU ChuanYong;YU HuaiZhong;WANG Qiong;LIU DaiQin;ZHAO BinBin;GAO Rong;GAO Ge;KONG XiangYan(Xinjiang Pamir Intracontinental Subduction National Field Observation and Research Station,Urumqi 830011,China;Earthquake Agency of Xinjiang Uygur Autonomous Region,Urumqi 830011,China;Institute of Disaster Prevention,Langfang Hebei 065201,China;Urumqi Institute of Central Asia Earthquake,China Earthquake Administration,Urumqi 830011,China;China Earthquake Networks Center,Beijing 100045,China;School of Information Engineering,Xinjiang Institute of Engineering,Urumqi 830023,China)

机构地区：[1]新疆帕米尔陆内俯冲国家野外科学观测研究站,乌鲁木齐830011 [2]新疆维吾尔自治区地震局,乌鲁木齐830011 [3]防灾科技学院,河北廊坊065201 [4]中国地震局乌鲁木齐中亚研究所,乌鲁木齐830011 [5]中国地震台网中心,北京100045 [6]新疆工程学院信息工程学院,乌鲁木齐830023

出　　处：《地球物理学报》2023年第4期1348-1362,共15页Chinese Journal of Geophysics

基　　金：新疆维吾尔自治区自然科学基金面上项目(2020D01A84);新疆维吾尔自治区重点研发专项(2020B03006-2,2022B03001-1);国家重点研发计划(2018YFE0109700);国家自然科学基金地震联合基金(U2039205);新疆地震局科技创新团队计划(XJDZCXTD2020-3);地震科技星火计划(XH22007YA,XH20066)共同资助。

摘　　要：天山造山带一直以来是研究盆山耦合作用的理想场所,深入理解这一地区的壳幔结构对认识天山造山带深部动力学过程具有重要意义.本研究基于2009—2020年新疆区域数字地震台网固定台站、震后架设应急流动台站以及部分宽频带流动地震台站记录到的MS≥1.5地震到时资料,采用双差地震层析成像方法反演获得了新疆天山中段精细的地壳和上地幔顶部三维P波速度结构和地震震源参数.结果显示:新疆天山中段具有复杂的深浅构造关系,地壳浅部及上地壳P波速度结构与地表地质构造密切相关,高速异常区对应于天山造山带,低速异常区对应于沉积盆地.研究区中东段中地壳和下地壳存在较大范围低速区,与两侧准噶尔盆地和塔里木盆地上地壳和中地壳低速区相连,且准噶尔盆地和塔里木盆地下地壳及上地幔顶部双向均向新疆天山中段下方倾斜.结合前人诸多研究成果推测,在南北向构造挤压作用下,塔里木盆地与准噶尔盆地双向向天山造山带壳幔岩石圈发生"层间插入与俯冲削减".重定位后地震分布显示,地震震源深度优势范围为0~25 km,主要沿断裂带、盆山结合部以及不同块体接触部位分布,且与壳内低速体有较好的相关性.这些结果可能为研究新疆天山中段地壳和上地幔顶部速度结构和动力学过程提供参考依据.The Tianshan is an ideal location to study the effects of mountain-basin coupling.Examining the crust-mantle structure in this area provides a basis for understanding the deep dynamics of the Tianshan Orogen.Based on arrival time data of MS≥1.5 earthquakes from 2009 to 2020 recorded by the permanent stations of the Xinjiang regional digital seismic network,emergency mobile stations,and some broadband seismic stations,this study examined the high-resolution 3D P-wave velocity structures of the crust and uppermost mantle in the study area along with hypocentral relocations via the double-difference tomography method.The results showed that the P-wave velocity structure of the shallow crust and deep crust in the middle of the Tianshan Mountains is closely related to the surface geological structure,with high velocity corresponding to the Tianshan and low velocity corresponding to the sedimentary basin.In the middle-eastern part of the study area,low velocity zones exist in both the middle and lower crust.These low-velocity zones are connected on both sides to upper-middle crust low-velocity zones of the Junggar Basin and Tarim Basin,and the lower crust-upper mantle plane is inclined toward the lower part of the Tianshan.In consideration of previous research results,we inferred that the Tarim Basin and Junggar Basin subduct and are inserted into the Tianshan at different levels as a result of the north-south compression of the Tianshan.The relocated earthquakes are mainly along fault zones,basin-mountain junctions,and different blocks.These results provide a reference for studying the velocity structure and dynamic processes of the crust and uppermost mantle in the middle Tianshan Mountains in Xinjiang.

关 键 词：新疆天山中段 塔里木盆地 准噶尔盆地 双差地震层析成像 P波速度结构 

分 类 号：P315[天文地球—地震学]