摘要
根据天山及其邻近区域88个宽频带地震台站的接收函数和欧亚大陆的基阶瑞利波群速度图像,联合反演了这些台站下的地壳上地幔一维S波速度结构.在这些速度模型的基础上,利用线性各向同性变差克里金空间插值技术得到了该区域的地壳上地幔三维S波速度模型.通过在垂向不同深度上的切片和横向上剖面投影的方式,显示和分析了天山及其邻区地壳上地幔的剪切波速度特性与构造特性之间的关系.结果表明,天山及其邻区的地壳结构垂向上分为上、中、下3层,每层的界面大致位于20,40和50km,并且这些界面的起伏随不同块体的构造差异而变化.天山地区和塔里木盆地隆起区的上地壳表现为高速特征,而沉积盆地大部分地区和山前坳陷区的上地壳则表现为低速特征.东、西天山之间下地壳存在的近南北向低速带以及上地幔高速盖层在深度上的差异均说明东、西天山在构造活动和形变上有明显的差别,这种差别可能是由于印度板块与欧亚大陆的碰撞对它们产生的不同影响而造成的.
The crust and upper mantle S-wave velocity structure beneath 88 seis- mic stations were established by joint inversion of surface wave dispersion and teleseismic receiver functions, and the 3D S-wave velocity structure for Tian- shan and its adjacent regions were constructed based on 1D models beneath 88 stations at each depth by linear isotropic variogram Kriging technique. The 3D velocity model was illustrated by images of depth slices and cross section pro- files, and relations between the velocity structures and tectonic activities were discussed. The crust of Tianshan and its adjacent regions consists of upper, middle and lower layers. The boundaries of these layers are located at about 20, 40 and 50 km, respectively, and the topography of these boundaries varies with different tectonic terrains. The upper crust of Tianshan and the uplift of Tarim basin are characterized by relative high velocities, whereas the upper crust of most part of basins and depressions in front of mountains show relative low ve- locities. The approximately NS-trending low velocity zone of lower crust and the high velocity lid of upper mantle vary with depths between east and west parts of Tianshan, implying the differences in tectonic activities and deforma- tions for eastern and western Tianshan. The differences may be caused by the different responses of western and eastern Tianshan to the India-Eurasia colli- sion.
出处
《地震学报》
CSCD
北大核心
2014年第1期20-31,158,共12页
Acta Seismologica Sinica
基金
军控预研项目(513310101)资助
关键词
天山地区
接收函数
面波频散
联合反演
Tianshan region
receiver function
sur{ace wave dispersion
jointinversion
