利用接收函数方法约束西沙碳酸盐岩台地沉积厚度与速度结构  

Thickness and velocity structures of the carbonate platform sediments in the Xisha Islands constrained by receiver function method

作　　者：黄海波[1,2] 丘学林 龙根元[4,5] 矫东风 韩孝辉 HUANG Haibo;QIU Xuelin;LONG Genyuan;JIAO Dongfeng;HAN Xiaohui(Key Laboratory of Ocean and Marginal Sea Geology(South China Sea Institute of Oceanology,Chinese Academy of Sciences),Guangzhou 511458,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China;University of Chinese Academy of Sciences,Beijing 100049,China;Hainan Key Laboratory of Marine Geological Resources and Environment,Haikou 570206,China;Marine Geological Institute of Hainan Province,Haikou 570206,China)

机构地区：[1]中国科学院边缘海与大洋地质重点实验室(中国科学院南海海洋研究所),广东广州511458 [2]南方海洋科学与工程广东省实验室(广州),广东广州511458 [3]中国科学院大学,北京100049 [4]海南省海洋地质资源与环境重点实验室,海南海口570206 [5]海南省海洋地质调查研究院,海南海口570206

出　　处：《热带海洋学报》2023年第1期135-144,共10页Journal of Tropical Oceanography

基　　金：国家自然科学基金项目(42176081、42174110);南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项(GML2019ZD0204);海南省海洋地质资源与环境重点实验室开放课题(HNHYDZZYHJKF003)。

摘　　要：碳酸盐岩台地的沉积厚度和弹性波速度是评估珊瑚礁发育规模以及结构稳定性的重要参数。本文根据西沙地区琛航岛和永兴岛流动地震台站所记录的远震接收函数波形,通过识别沉积底部产生的转换横波及其多次波震相,精确拾取震相走时信息。同时参考岛屿钻井资料和人工地震探测结果,计算获得了台站下方碳酸盐岩台地的沉积厚度、平均纵波速度和波速比。结果显示:永兴岛和琛航岛下方沉积体的平均纵波速度约为3.5km·s^(-1),波速比约为2.42,平均厚度分别约为1.35km和1.55km。计算获得的平均厚度与西沙钻至基底的测井结果较为一致(约1.257km)。琛航岛沉积厚度略大于永兴岛(约200m),表明碳酸盐岩台地沉积基底的起伏或与生物礁沉积相的差异有关。Thickness and elastic wave velocity are important parameters for evaluating the size and structural stability of coral reef.This study collected the receiver functions from two portable seismic stations on the Chenhang Island and Yongxing Island in the Xisha area,South China Sea.Travel times of the P-to-S converted waves and their multiple phases generated at the base of the carbonate platform are accurately picked up.At the same time,the thickness,average P-wave velocity,and velocity ratio of the carbonate platform sediments were calculated based on the drilling data and artificial seismic exploration results.The results show that the average P-wave velocity of the platform sediments on the Yongxing Island and Chenhang Island is about 3.5 km·s^(-1),the V_(p)/V_(s)ratio is 2.42,and the average thicknesses are about 1.35 km and 1.55 km,respectively.The calculated thicknesses are consistent with that of the well on the Yongxing Island which reaches the reef bottom at about 1.257 km.The sediment thickness of the Chenhang Island is slightly larger than that of the Yongxing Island(about 200m),which reflects the fluctuation of the basement beneath the island or is related to the reef growth faces.

关 键 词：碳酸盐岩台地 速度结构 波速比 接收函数 西沙群岛 

分 类 号：P738.4[天文地球—海洋地质]