东大别地壳上地幔精细横波速度结构研究

秦岭-大别-苏鲁超高压变质带是世界上规模最大的超高压变质带，为扬子板块向华北板块俯冲-碰撞的产物，它的研究对了解洋-陆俯冲转化为陆-陆碰撞的过程、后继的造山运动及造山带垮塌的大陆动力学机制具有重要意义。以地震与大地电磁为主的地球物理调查为大别碰撞造山带的形成与演化提供了重要的基础数据。同时，大别地壳上地幔速度分布的精细特征还需要新的地球物理证据和制约。本项目基于密集流动台阵观测的数据结合台站测网数据，采用背景噪声面波和地震面波双平面波层析成像技术，构建东大别造山带地壳上地幔三维精细横波速度及其各向异性结构，重点研究东大别Moho界面、壳内高速体、中地壳低速层和地壳上地幔横波速度分布特征，以期为大别造山带的构造研究提供地球物理依据。预期研究成果对于揭示造山运动及造山带垮塌的大陆动力学机制等问题具有重要意义。

The Qingling-Dabie-Sulu orogenic belt is the largest ultrahigh pressure (UHP) metamorphic zone in the world, which was formed by continent-continent collision between the Yangtze Craton and the North China Craton. Research on the structure of the orogenic belt is important to understand the process of translation from ocean-to-continent subduction to continent-continent collision and continental dynamic mechanism of following orogeny and collapse of orogen. Geophysical studies, such as Magnetotelluric (MT) sounding and seismic profiling, have provided some basic evidences for research on the Dabie orogeny and evolution. In orde to further constrain fine characteristics of the Dabie crust and upper mantle velocity structure, new geophysical studies are needed. The objective of this project is to construct fine crust and upper mantle velocity and anisotropy structure beneath the east Dabie orogenic belt by applying seismic ambient noise and teleseismic surface wave two-plane wave tomography to a flexible seismic array, which is proposed to be deployed during this project. 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 Dabie belt. This project will provide important constraints on the understanding of continental dynamic mechanism of orogeny and collapse of orogen in the Dabie orogenic belt.