青藏高原三维地壳结构的重力正演模拟  

The forward simulation of gravity for 3D crustal structures in the Tibetan plateau

作　　者：柯小平[1] 王勇[1] 许厚泽[1] 

机构地区：[1]中国科学院测量与地球物理研究所动力大地测量重点实验室,武汉430077

出　　处：《地球物理学进展》2009年第4期1225-1234,共10页Progress in Geophysics

基　　金：国家自然科学基金项目(40874036;40574033;40774011);国家科技重大专项(2008ZX05008-006 006-02);地球空间环境与大地测量教育部重点实验室测绘基础研究基金项目(06-04)资助

摘　　要：青藏高原地壳结构的重力学研究主要集中于莫霍面深度反演及单个剖面的重力正演,但是,在亚东-格尔木与下察隅-共和之间没有地震测线的区域,地壳结构的研究受到限制.为了探讨从青藏高原中部到东部的地壳结构特征,本文采用三维重力正演的方法,对青藏高原三维地壳结构进行了重力正演模拟.研究结果显示,地壳各层界面起伏较大,表明高原地壳变形强烈.研究区域中,藏南喜马拉雅地体界面相对较浅,处于界面陡变带,往北进入拉萨地体,界面相对变深.正演剖面中,大的界面起伏与大的断裂构造有关,莫霍面的陡变也暗示着莫霍面存在错断现象.东构造结莫霍面有抬升现象,在玛多附近莫霍面有下凹现象.地壳分层正演显示,32 km以下地壳产生的重力异常占总异常的80%以上,低速层及高速体产生的重力异常最大可占到总异常的10%左右.The studies of crustal structures with gravity in Tibetan plateau are concentrated mainly in Moho depth inversion and gravity forward of single profile, but the research of crustal structures is restricted by data in the area without seismic lines, especially between Yadong-Golmud and Xiachayu-Gonghe. In order to investigate the characteristics of crustal structures from the central to eastern Tibetan plateau, the three-dimensional crustal structures are simulated with gravity data in the Tibetan plateau. The results of three-dimensional gravity forward modeling show that the undulation of interface is large in each layer of crust, and this demonstrates that the crust of the plateau highly deformed. In the research area, the interface is shallow in the Himalayan terrane of southern Tibet, and located in the steep belt of interface. The interface is deep relatively in the Lhasa terrane. In the forward profiles, the large interface undulation is associated with large faults. The steep Moho interface implies that the Moho had been ruptured. The Moho interface uplifts in the ＇ Himalayas east structural knot~ , and depresses in Maduo. The forward calculation of the crustal layered model indicates that the gravity anomaly produced by the crust under 32 km is 80 percent of the total anomalies, the gravity anomalies from the low velocity layers and the high velocity bodies can reach about 10% of the total anomalies.

关 键 词：地壳结构 重力 正演模拟 青藏高原 

分 类 号：P312[天文地球—固体地球物理学]