深地震测深揭示的华南地区地壳结构及其动力学意义  

Crustal structure beneath South China revealed by deep seismic soundings and its dynamics implications

作　　者：邓阳凡[1,2] 李守林[2,3] 范蔚茗[1] 刘佳[2,3] 

机构地区：[1]中国科学院广州地球化学研究所,广州510640 [2]中国科学院研究生院,北京100049 [3]中国科学院地质与地球物理研究所,北京100029

出　　处：《地球物理学报》2011年第10期2560-2574,共15页Chinese Journal of Geophysics

基　　金：中国科学院知识创新工程重大项目(KZCX1-YW-15);SinoProbe-03-02(201011047)联合资助

摘　　要：20世纪70年代以来,我国实施与华南地区有关的深地震测深剖面达57条.本文收集该区的深地震测深研究成果,利用保真能力强的三维克里金插值技术构建了100°E～125°E,18°N～34°N区域内的三维地壳速度模型.基于三维地壳结构模型,分别探讨了华南地区不同构造单元地壳厚度空间变化特征、地壳属性、上地幔顶部地震波速变化以及太平洋向欧亚板块的俯冲方向等.研究结果表明:(1)扬子地块平均地壳厚度为40 km左右,地壳平均速度为6.30 km/s;华夏地块平均地壳厚度32 km左右,地壳平均速度6.24 km/s.(2)扬子地块的四川盆地与全球地台区具有相似的地壳速度-深度变化特征,华夏地块与全球伸展区结构相似,台湾造山带具有较典型全球大陆弧的特点.(3)华夏地块上地幔顶部Pn波平均速度为8.02 km/s;台湾造山带Pn波平均速度为7.98 km/s;扬子地块的Pn波速度为7.94 km/s,包含四川盆地(Pn速度达8.02 km/s)和川滇地区(Pn速度最低为7.75 km/s).川滇地区和松潘—甘孜褶皱带东部构造活动性较强,四川盆地和华夏地块相对较稳定.(4)推测太平洋板块向欧亚板块俯冲的方向为Nw-SE方向.Since the 1970s, 57 DSS profiles have been carried out in South China. In this paper we collect all DSS profiles in South China, construct the 3-D crust velocity model in the region （100°E- 125°E and 18°N-34°N） using robust 3 D Kriging interpolation method. We discuss the spatial distribution of Moho depth and Pn velocity in detail; analyze the relationship between average velocity and thickness in tectonic units; investigate the crust character and the subduction direction of Pacific plate to Eurasian plate. The results show that： （1） the average Moho depth of Yangtze block is about 40 km, the average crust velocity is 6.30 km/s, while the Moho depth of Cathaysia block is about 32 kin, the average velocity is 6.24 km/s; （2） Sichuan basin has the same character as continental platforms in the world, Cathaysia block has the character of extended continent, Taiwan has the character of continental arcs; （3） the average Pn velocity is 8.02 km/s in Cathaysia block 7.98 km/s in Taiwan orogen, and 7.94 km/s in Yangtze block, including the fastest 8.02 km/s in Sichuan basin and the slowest 7. 75 km/s in east Songpan- Ganzi. Chuandian area and east Songpan-Ganzi is relatively active, while Sichuan basin and Cathaysia block are steady （4） the subduction direction of Pacific plate to Eurasian plate should be NW-SE.

关 键 词：华南地区 深地震测深 三维速度结构 莫霍面 PN波速度 

分 类 号：P315[天文地球—地震学]