桂林理工大学学报2023，Vol.43Issue(4)：570-580,11.DOI:10.3969/j.issn.1674-9057.2023.04.004
华南块体西南缘地壳结构特征及其地质意义
Characteristics of crustal structure and its geological significance of the southwestern margin in South China
摘要
Abstract
The Yangtze and Cathaysian blocks began to collide and form the South China block in the Neoprot-erozoic Era.The South China block underwent multiple complex tectonic magmatic activities.The study of crust thickness and stratification structure of South China block is helpful to further understand the history of the colli-sion of South China plate.It is instructive to the related large-scale diagenesis and mineralization in Mesozoic.This paper is based on 16 months continuous waveform data of vertical component recorded by 162 broadband fixed stations on the southwest edge of the South China,and empirical Green functions are extracted by ambient noise cross-correlation technology.Surface wave tomography is carried out.Rayleigh wave phase velocity maps of 3-45 s and S-wave velocity(VS)structures of crust and uppermost mantle above 50 km are obtained.VS slices at different depths show that the crustal thickness of the Yangtze block is generally greater than that of the Cathay-sian block.There is a significant velocity difference between the middle-lower crust and the uppermost mantle at a depth of more than 20 km.The boundary between high and low velocity anomalies is roughly located to the west of the Chenzhou-Linwu fault(CLF).The three VS profiles across the CLF further show that the upper crus-tal thrust faults represented by the CLF and the NWW trending faults of the middle-lower crust all converge in the brittle-ductile transition zone with low velocity of the middle crust.It is speculated that these structures may be the thrust structures formed by the collision of the Yangtze and Cathaysian blocks.Under the Yanshanian ex-tensional setting,they were further reactivated into crustal or supracrustal scale detachment faults.Geological and geophysical data indicate that the CLF is the tectonic boundary of the Yangtze and Cathaysian blocks in southwestern margin of South China,and the upper and lower crust of the latter might have been decoupled dur-ing the collision period between the Yangtze and Cathaysian blocks.关键词
华南块体/扬子-华夏块体/背景噪声层析成像/地壳结构/郴州-临武断裂Key words
South China block/Yangtze-Cathaysian blocks/ambient noise tomography/crustal structure/Chenzhou-Linwu fault分类
地球科学引用本文复制引用
李鹏宇,张智,张晓青,刘锋,徐涛,俞贵平,王敏玲,侯爵,李奇..华南块体西南缘地壳结构特征及其地质意义[J].桂林理工大学学报,2023,43(4):570-580,11.基金项目
国家自然科学基金项目(41974048 （）
42374059 （）
42104042) （）
广西自然科学基金项目(2023GXNSFDA026055) （2023GXNSFDA026055）
