中央造山带地壳上地幔各向异性研究

中国中央造山带（秦岭-大别-苏鲁超高压变质带）是扬子板块向华北板块俯冲-碰撞的产物，是研究洋-陆俯冲转化为陆-陆碰撞及后继的造山运动等大陆动力学过程的天然实验室。深入研究中央造山带地壳上地幔横波速度和各向异性结构是正确理解超高压变质带形成和演化等动力学过程的基础和关键。本项目基于中国地震台网及区域台网和全球地震台网数据，利用背景噪声面波成像结合地震面波双平面波成像技术，对研究区域地震台网联合全球地震台站进行大台站距背景噪声互相关，利用高分辨率Radon变换进行面波模式分离、对重构的基阶面波进行频散测量等最新数据处理技术，研究中央造山带地壳上地幔三维横波速度和各向异性结构。重点研究Moho界面、壳内高速体、中地壳低速层的横波速度和各向异性分布特征，以期为陆壳深俯冲与折返和岩浆作用等构造演化研究提供地球物理依据。预期研究成果对认识块体相互作用的动力学机制具有重要科学意义。

The Central Orogenic Belt of China (Qingling-Dabie-Sulu orogenic belt) was formed by continent-continent collision between the Yangtze Craton and the North China Craton. It is the natural library for continental dynamic study of translation from ocean-to-continent subduction to continent-continent collision and continental dynamic mechanism of following orogeny and collapse of orogen. Research on the crustal and upper mantle shear-wave and anisotropic structure beneath the orogenic belt is the key to better understand the process of ultrahigh pressure (UHP) metamorphic belt. The objective of this project is to construct fine crust and upper mantle velocity and anisotropy structure beneath the Central Orogenic Belt by applying seismic ambient noise and teleseismic surface wave two-plane wave tomography to broadband seismic stations of the Chinese National Seismic Network (CNSN) in the region and Global Seismographic Network (GSN). We will use two newest technique during our study: teleseismic cross-correlation of ambient noise between CNSN stations and GSN stations, and mutimode surface wave mode separation by high-resolution Linear Radon Transform (LRT) and dispersion measurements on surface waves only containing the fundamental mode of surface waves. We will focus our research efforts on crustal high shear wave velocities, low shear wave velocity layer in the middle crust, and crust and upper mantle velocity characteristics, which will provide geophysical evidences for the orogenic structure of the belt. This project will provide important constraints on the understanding of continental dynamic mechanism of orogeny and collapse of orogen in the Central Orogenic Belt.