青藏高原岩石层三维和二维结构与大陆动力学  

THE 2D and 3D LITHOSPHERE STRUCTURE AND CONTINENTAL DYNAMICS OF QINGHAI-XIZANG PLATEAU

作　　者：滕吉文[1] 尹周勋[1] 刘宏兵[1] 张中杰[1] 胡家富[1] 孙克忠[1] 魏计春[1] 

机构地区：[1]中国科学院地球物理研究所,云南大学

出　　处：《地球物理学报》1994年第A02期117-130,共14页Chinese Journal of Geophysics

基　　金：中国科学院岩石圈构造演化实验室资助

摘　　要：本文基于在西藏高原地区所进行的人工地震探测、天然地震长周期面波与分格三维反演，并结合大地电磁测深资料，对该区岩石层结构、断裂纵向延伸与横向展布及其性质进行了综合研究．发现西藏地区巨厚的层状地壳存在着两个低速层，且西藏高原地壳的速度比相邻地区低；地幔低速层埋藏较浅，仅为９０－１００ｋｍ，形成了该区特异的巨厚地壳与相对较薄的岩石层格局．地壳到地幔速度结构的纵向结构变化，横向分区和走时残差随深度的显著变化，板块边界的地球物理异常场效应，垂直向差异显著的地壳结构与深大断裂体系，低速层的变异、分布、尖灭与缺失，以及近代火山活动地区典型的地热活动特征等，不仅说明构造异常，而且也说明了青藏高原地壳与上地幔在纵向与横向上都不均匀．最后提出了该区深大断裂展布及属性，地幔物质上涌，印度板块向北“楔入”，深部物质侧向流展，巨厚地壳和薄岩石层模式。In this paper,a combined study was curried out for interpreting structure,distribution and tension of fault, wave field effect, heat state and nonelastic medium by explosion seismic Sounding, ZD and 3D long period surface waves of earthquake,magnetotelluric deep sounding,heat flow survey,the mechanism of tectonic movement and deep internal processes in Qinghai-Xizang Plateau.Some characteristics indicate an image of deep matter uplifting and recent tectonic movements,e.g.lithosphere structure, constitute and nature of Qinghai-Xizang Plateau, strong absorptivity for seismic wave of crust-mantle media and strong attenuation of lg wave,intense geothermal activities and velocity disturbances of plate margins,high heat flow,anisotropy of electric ProPerty of Yarlung Zangbo River and the distribution of ophiolite suite.Qinghsi-Xizang Plateau lies in the position of collision and compression between Indian and Eurasian plates. From the characteristics of geophysical fields, lithosphere structure and deformation, the 300-500 km-wide zone from Yarlung-Zangbo River to the northern margin of Ganges River plain is a transitional zone of collision and compression of the two pleates.The upper mantle matter of Indian plate was wedged into lower crust of Xizang Plateau towards north,resulting in huge shear nappe structure in Himalayan zone. The cooperation of wedging,deep thermal matter uplifting, gravity isostatic adjustment and northward movement of Indian Plate lead to crust shortening,crust bottom of middle Plateau sinking and entire Plateau swellin In the collision and compression process between two large plates,amalgamated matter of Xizang crust flow towards Qinghai-Sichuan-Yunnan lithosphere along cracking crustal bottom and at the same time,some of them migrated westward to the Hindu Kush region.Within this process,large-scale EW strike-slip faults occurred in Xizang Plateau,but in Qinghai-Sichuan-Yunnan and Hindu Kush regions,matter migration caused intensive seismic activites that complicated tectonic setting.

关 键 词：青藏高原 岩石层 板块运移 大陆动力学 

分 类 号：P541[天文地球—构造地质学] P548.244[天文地球—地质学]