巴东-秭归地区地壳密度反演及其构造特征  

Crustal Density Inversion and Its Tectonic Structure in Badong-Zigui Area

作　　者：王泽 吴云龙[1,2] 张毅 姚运生[2] WANG Ze;WU Yunlong;ZHANG Yi;YAO Yunsheng(Key Laboratory of Seismic Geodesy,Institute of Seismology,China Earthquake Administration,Wuhan 430071,China;School of Geological Engineering,Institute of Disaster Prevention,Sanhe 065201,China)

机构地区：[1]中国地震局地震研究所地震大地测量重点实验室,湖北武汉430071 [2]防灾科技学院地质工程学院,河北三河065201

出　　处：《武汉大学学报（信息科学版）》2020年第11期1763-1770,共8页Geomatics and Information Science of Wuhan University

基　　金：国家重点研发计划(2018YFC1503503-01);国家自然科学基金(41931074,41572354,41974096,41704082);湖北省自然科学基金(2017CFB435);中国地震局地震研究所基本科研业务费专项;中国地震局地壳应力研究所基本科研业务费专项(IS201616249);国家国防科技工业局民用航天技术预先研究项目(D010103)。

摘　　要：巴东-秭归盆地位于三峡地区西部,南侧为雪峰山厚皮构造带,北侧为秦岭造山带,东部近邻黄陵背斜,西部为四川盆地的东延部分。巴东-秭归盆地为南北轴向的向斜构造,盆地内沉积物以晚三叠-晚侏罗世沙泥质岩为主,特殊的构造环境造成盆地内构造活动强烈。利用三维重力反演,得到巴东-秭归一线及邻区地下三维密度结构。结果表明:秭归盆地较周边区域密度更低,东部沉积厚度较西部深,沉积密度较西部小,区内中小地震基本集中在地下4~12 km,沉积活动强烈;盆地内有东部低密度物质向西部搬运进积,同时受到四川盆地的向东延伸挤压,推测盆地内有东西相互运动挤压的趋势。Objectives:The Badong-Zigui Basin is located in the west of the Three Gorges area,and it is surrounded by four different tectonic units:With the Xuefengshan thick-soil tectonic belt on the south,the Qinling orogenic belt on the north,the Huangling anticline on the east,and the eastern extension of the Sichuan Basin in the west.The Badong-Zigui basin is a north-south syncline structure,the sediments in the basin are dominated by Late Triassic-Late Turassic argillaceous rocks,and the special tectonic setting causes strong tectonic activities in the basin.Methods:Using a three-dimensional gravity inversion algorithm based on Lagrangian multiplier constraints,the local Bouguer gravity anomaly in Badong-Zigui area is inverted,and the underground three-dimensional density structure of Badong-Zigui and adjacent areas is obtained.Results:The inversion results show that the Zigui Basin is a low-density area compared with the surrounding area.The sedimentation thickness in the east is deeper than that in the west,and the sediment density is lower than that in the west.The small and medium earthquakes in the area are basically 4-12 km underground.Conclusions:The north-south and north-east ancient water flows in the northern edge of the Zigui Basin successively provide sources for the sedimentation and filling of the basin,forming a structure with lower material density and deeper deposits in the eastern part of the basin;low-density materials in the east are transported and accumulated to the west in the basin.At the same time,it is squeezed by the eastward extension of the Sichuan Basin,and it is speculated that there is a tendency of east-west movement and compression in the basin.

关 键 词：秭归盆地 重力反演 密度结构 构造特征 

分 类 号：P237[天文地球—摄影测量与遥感]