新疆和周边地区地壳厚度和V_p/V_s比值变化的接收函数约束  

Crustal thickness and V_p/V_s ratio variations of Xinjiang and surrounding regions constrained by receiver function stacking

作　　者：刘文学[1,2] 刘贵忠[1] 周刚[2] 李欣[2] 张慧民[2] 徐恒垒[2] 

机构地区：[1]西安交通大学,西安710049 [2]西北核技术研究所,西安710024

出　　处：《地球物理学报》2011年第8期2034-2041,共8页Chinese Journal of Geophysics

基　　金：军控核查技术项目(513310101)资助

摘　　要：我们用修订后的接收函数H-κ叠加算法估计了新疆和周边地区90个地震台站下的地壳厚度和波速比V_P/V_S.该地区平均地壳厚度约为52 km,变化范围约为33～79 km.最厚地壳位于西昆仑山的TAG台站,最薄地壳在塔拉斯Κ费尔干那断层附近的NRN台站.对每个台站的点地壳厚度估计结果进行了线性各向同性变差模型的标准克里金空间插值,得到了新疆和周边地区0.1°×0.1°分辨率的地壳厚度横向变化图像.该图像显示研究区域地壳厚度变化和地表地形有很强的相关性,即盆地比周围造山带地壳厚度薄,显示该地区莫霍面由盆地向两侧造山带倾斜的特征.波速比估计的结果范围为1.61～1.89,平均值为1.76.波速比复杂的变化说明地壳内物质成分构成的复杂性,这种复杂性可能由于地幔物质随着构造活动上涌侵入地壳内部所致,同时地幔物质的底侵可能对该地区地壳增厚有贡献.We have estimated crustal thicknesses and Vp/Vs ratios under 90 seismic stations in Xinjiang and its surrounding regions. The technique we used is the modified H-k stacking method. The average crustal thickness in this region is about 52 km. The crustal thicknesses range from about 33 km to 79 km. The thickest crust is under TAG station, which is situated in the West Kunlun mountains. On the other hand, the thinnest crust is under NRN station, which is near the Talas-Fergana fault. In order to get the map of the crustal thickness variations, the crustal thicknesses under all stations were gridded with standard Kriging technique for a linear isotropic variogram model. The resolution of the gridded map is 0. 1°× 0.1°, and the map shows strong correlations to the surface topography. The crustal thicknesses under the basin regions arethinner than that under orogenic regions. This implies that the Moho under the basins dip into the orogenic belt. The Vp/Vs ratios range from 1.61 to 1.89, with the average value of 1.76. The complex variation of Vp/Vs ratios characterizes the complex crustal composition of this region. The complex composition of the crust is probably caused by the mantle upwelling. This complexity also implies that underplating may be one of the reasons of the crustal thickening in the study area.

关 键 词：新疆和周边地区 接收函数 地壳厚度 波速比 Hk叠加 

分 类 号：P315[天文地球—地震学]