Shear-wave velocity structures of the shallow crust beneath the Ordos and Sichuan Basins from multi-frequency direct P-wave amplitudes in receiver functions  

作　　者：Chenxiao TANG Ling CHEN Xu WANG 

机构地区：[1]State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [2]Deep Earth Science Excellence and Innovation Center,Chinese Academy of Sciences,Guangzhou 510640,China [3]College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Science China Earth Sciences》2022年第5期810-823,共14页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 41688103 and 42004041)

摘　　要：As the two largest cratonic basins in China,the Ordos Basin and the Sichuan Basin are of key importance for understanding the evolutionary history of the Chinese continent.In this study,the shear-wave velocity(V_(S))structures of the shallow crust(depth up to 10 km)beneath the two basins are imaged based on the frequency-dependence of direct P-wave amplitudes in receiver functions.The teleseismic data used in the study came from 160 broadband seismic stations,including permanent and temporary stations.The results show that the V_(S) and the thickness of the sediments in the Ordos Basin and the Sichuan Basin are respectively lower and thicker in the west than in the east.In the Ordos Basin,the shallow crustal V_(S) increases gradually from 2.10 km s^(−1)in the northwest to 2.65 km s^(−1)in the southeast and the thickest sediments are 7–8 km in the northwest and 5 km in the east.In the Sichuan Basin,the shallow crustal V_(S) increases from 2.4 km s^(−1) in the west to 2.7 km s^(−1)in the east and the thickness of the sediments decreases from>7 km in the west to 6 km in the east.The east-west difference of the shallow crustal structures of the two basins may have been controlled by the Cenozoic India-Eurasia collision.The western parts of the basins near the collision have a higher deposition rate,while in the parts inside the basins far from the collision,the V_(S) slowly increases with depth,indicating that these areas have experienced a more uniform deposition process.In addition,both basins are characterized by velocity structures that are higher along the edges and lower inside of the basins.The edges of the basins suffered strong denudation due to the uplifting and deformation influenced by tectonic evolution.The downward gradient of the shear-wave velocity beneath the Ordos Basin is twice that of the Sichuan Basin,which may be caused by the different deposition and denudation rates of the two basins resulting from differences in structural evolution and thermal events.In addition,the northern Ordos

关 键 词：Shallow crustal velocity structures Receiver function Frequency dependence Ordos Basin Sichuan Basin Tectonic evolution 

分 类 号：P542[天文地球—构造地质学]