华南大陆东部地壳物质组成的地震学研究  

Crustal composition of the eastern South China Block based on the seismological study

作　　者：檀玉娟[1] 段永红[1] 林吉焱[1,2,3] 李玮 王高春 李学民 王国法[1] 邹长桥[4] 赵延娜 周铭[1] TAN YuJuan;DUAN YongHong;LIN JiYan;LI Wei;WANG GaoChun;LI XueMin;WANG GuoFa;ZOU ChangQiao;ZHAO YanNa;ZHOU Ming(Geophysical Exploration Center,China Earthquake Administration,Zhengzhou 450002,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Science,Beijing 100049,China;Southern University of Science and Technology,Department of Ocean Science and Engineering,Shenzhen Guangdong 518055,China)

机构地区：[1]中国地震局地球物理勘探中心,郑州450002 [2]中国科学院地质与地球物理研究所,北京100029 [3]中国科学院大学,北京100049 [4]南方科技大学海洋科学与工程系,深圳广东518055

出　　处：《地球物理学报》2021年第9期3150-3163,共14页Chinese Journal of Geophysics

基　　金：国家自然科学基金(41174052,41604048和42004080)联合资助.

摘　　要：中生代晚期华南大陆东部发生了大规模的火成岩活动,对地壳物质组成属性有显著影响,地壳中SiO 2的平均含量是判别其属性的重要参数.基于华南大陆东部布设的宽频带地震台阵和固定台站数据,利用噪声成像获取高分辨率的面波频散,联合利用接收函数反演地壳的S波速度结构.由地壳的平均波速比和速度信息,通过与岩石物理实验数据对比,估测了华南大陆地壳平均的SiO 2含量的空间分布特征.结果发现,政和—大埔断裂以东的浙闽沿海碱性火成岩带具有相对高速的下地壳(V S>3.9 km·s^(-1)),相对高的地壳平均波速比(V P/V S>1.77),估测地壳平均SiO 2含量相对较低(60~65wt%);政和—大埔断裂以西的武夷带和江南造山带具有相对低速的下地壳(V S<3.8 km·s^(-1)),相对低的地壳平均波速比(V P/V S<1.75),估测地壳平均SiO 2含量相对较高(65~75wt%).政和—大埔断裂以东的地壳整体略偏基性,以西的地壳则偏长英质.推测古太平洋板块消减作用对华南大陆东部的影响主要为热扰动的形式,壳-幔物质交代作用仅限于政和—大埔断裂以东的区域.In the late Mesozoic,extensive igneous activities occurred in the eastern South China Block(ESCB),which might change the crustal composition.The SiO 2 contents of the crust is an essential feature of its properties.Based on the data from the broadband seismic array and permanent stations deployed in the ESCB,we use ambient noise tomography to obtain high-resolution surface wave dispersions,and then we apply joint inversion of surface wave dispersions and receiver functions to construct the crustal S-wave velocity structure.Finally,based on the crustal average S-wave velocity and V P/V S ratio,we further estimate the spatial distribution of crustal SiO 2 contents referring to the petrophysical experiment data.The results show high lower crustal S-wave velocity(greater than 3.9 km·s^(-1)),relatively high V P/V S ratio(greater than 1.77),and intermediate composition with SiO 2 contents of 60~65 wt%in the southeast coastal region at where extensive alkaline igneous rocks emplaced.In contrast,the Wuyi orogenic belt and Jiangnan orogenic belt have relatively low S-wave velocity(lower than 3.8 km·s^(-1)),relatively high V P/V S ratio(lower than 1.75),and contains relatively felsic composition with SiO 2 contents of 65~70 wt%.The diverse crustal components across the Zhenghe-Dapu fault,as intermediate-mafic to the east while felsic to the west,indicate that the subduction of the paleo-Pacific plate has caused thermal erosion process beneath the ESCB,and the crust-mantle metasomatism is mainly limited to the east of the Zhenghe-Dapu fault.

关 键 词：华南大陆东部 地壳成份 SiO 2含量 联合成像 

分 类 号：P315[天文地球—地震学]