用接收函数方法研究青藏高原中部地壳结构.doc
用接收函数方法研究青藏高原中部地壳结构摘要：青藏高原是地球上唯一正在进行的“陆陆碰撞”的巨大天然实验场，研究高原的形成和演化有可能对“洋陆碰撞”主宰的经典板块构造学形成重要补充和创新。探测青藏高原壳幔结构及深浅速度界面关系，对研究深浅部动力学和深部物质运移如何影响成矿作用具有理论意义。本文以P波接收函数为手段，对青藏高原樟木双湖宽频带数字台站探测剖面数据进行处理，得出以下认识：1. 在透彻理解接收函数原理的基础上，以FORTRAN和MATLAB语言编写了整套处理程序，并对接收函数方法应用有所发展，使得接收函数处理方便，可视化强。2. 用H-K方法和偏移成像得出了剖面下莫霍面深度的变化特征。证明了莫霍面存在叠瓦状错断并有多处间断点存在。3. 用接收函数方法详细描述了地壳内特征：地壳分层和南北差异性明显。高原内部地壳结构横向变化大，缺少像莫霍面那样稳定可连续追踪的近水平的分层界面。MHT界面在南段从50公里深向北顷至60公里深，而在雅鲁藏布缝合带附近表现为穹隆状构造，说明在缝合带附近地壳内塑性增强。STD界面也表现为穹隆构造，其连续性不如MHT界面。从班公怒江缝合带附近和以北有三个南倾的界面，和印度地壳内的STD、MHT界面相交，汇聚在不同位置。表明陆陆碰撞壳内俯冲主要发生在莫霍面以上。4. 接收函数是利用远震研究壳幔结构的有效手段。随着地震台阵观测密度的增加，数据的积累，接收函数研究向高分辨率的偏移成像方向发展，将以前所未有的高分辨率揭示出地壳上地幔的横向非均一性结构。Abstract：Tibetan Plateau is not only a enormous natural experiment lab of continent-to-continent subduction ,but also a key to supplement and develop the Plate Tectonics Theory. Exploring the crust-mantle structure and seismic wave velocity interface is important to research geodynamics and how to affect mineralization by the deep media exchanging or flowing. The thesis achieves new apperception by using teleseismic receiver function as main method with the Zhangmu-Nielamu seismic profile data. 1. On the base of fully understanding the theory of receiver function anslysis, programming the convenient and visual receiver function processing with Fortran and Matlab PC language and developing the method.2. Moho depth averages 68±5km using the H-K stack method. The Moho depth is shallower in south with 60km than north with 74km and is sunken on the middle nearby the north latitude 31°. The Moho is disconnected under the IYS and BNS.3. The crust has the characters of vertical layeres and difference between south and north. Tibetan Plateau crust varies seriously in horizontal orientation, and has no the stable and continue interface traced as the Moho. The fold interface under IYS from 50km to 60km depth shows the strong converted wave. There are two series of interfaces with intersection or convergence. Inter crust subduction happens mainly above the Moho.Receiver function method is one of the most efficient way to study the crust-mantle structure. With the increasing of seismic observation stations and available data, the receiver function method is improving in complex migration with high space resolution , and clearly shows the structure of curst and mantle.
