基于双差层析成像研究西秦岭及周边区域的地壳结构  

Study on crustal structure of the West Qinling and its surrounding areas based on double-difference tomography

作　　者：江世宇 孙娅[1,2] 黄基文 柳建新[1,2] 沈平 JIANG Shiyu;SUN Ya;HUANG Jiwen;LIU Jianxin;SHEN Ping(School of Geosciences and Info-Physics,Central South University,Changsha 410083,China;Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University),Ministry of Education,Changsha 410083,China;Hunan Earthquake Agency,Changsha 410004,China)

机构地区：[1]中南大学地球科学与信息物理学院,湖南长沙410083 [2]有色金属成矿预测与地质环境监测教育部重点实验室(中南大学),湖南长沙410083 [3]湖南省地震局,湖南长沙410001

出　　处：《中南大学学报(自然科学版)》2025年第1期111-122,共12页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金面上基金资助项目(42274083,41974049)。

摘　　要：秦岭造山带在南北方向受华南块体和华北块体碰撞挤压,东西向受青藏高原的东向挤压和太平洋板块的西向俯冲,使得该地区地震活动剧烈、深大断裂广泛分布。对地壳结构精细化有利于进一步认识该地区的地壳构造变形和深部动力学过程。本文利用2009-2020年记录的P波(纵波)走时信息,采用双差层析成像方法对区域(30°N-36°N,103°E-113°E)进行研究。研究结果表明:在西秦岭和青藏高原东缘的中下地壳内存在大范围的低速异常,而在西秦岭与青藏高原东缘相连的区域(北纬34°、东经106°)存在明显的柱状高速异常体,由上地幔顶部向上延伸到上地壳。结合地质资料,推断青藏高原的中下地壳流在西秦岭高速异常体的阻挡下并未向东延伸,而在受到四川盆地和鄂尔多斯盆地的阻挡后,沿深大断裂带在龙门山和六盘山发生向上和向下运动。The Qinling Orogenic belt is formed by the collision and compression of the South China block and the North China block in the Cenozoic era.It is subjected to the eastward compression of the northeastern margin of the Tibetan Plateau in the west and the subduction of the Pacific Plate in the east.Deep and large faults are widely distributed and the seismic activity is intense.The refined crustal structure is of great significance for furtherly studying the crustal deformation and deep dynamic processes in the region.In the paper,the direct P-wave arrival time recorded between 2009 and 2020 and the double difference tomography method were used to study the area(30°N-36°N,103°E-113°E).The results show that there are large-scale low-speed anomalies in the middle and lower crust of the western Qinling Mountains and the eastern edge of the Qinghai Tibet Plateau,and there is a obvious columnar high-speed anomaly in the area connecting the western Qinling and the east Tibetan Plateau(34°N and 106°E),extending from the top of the upper mantle to the upper crust.Based on geological data,it is inferred that the lower and middle crustal flow of the Tibetan Plateau does not extend eastward under the obstruction of the high-speed anomaly in the western Qinling Mountains.Instead,after being blocked by the Sichuan Basin and the Ordos Basin,the crustal flow on the eastern edge of the Tibetan Plateau tends to move downwards and upwards in the Longmenshan belt,and upwards in the Liupanshan.

关 键 词：双差层析成像 秦岭造山带 纵波 中下地壳流 

分 类 号：P315[天文地球—地震学]