郯庐断裂带上地幔小尺度对流研究

The Tan-Lu fault zone is a major tectonic boundary throughout the east margin of China continent, and also one of the most important active earthquake belts in China. A large number of geophysical and geochemical observations show that there may be a relatively active upper mantle convection system beneath the Tan-Lu fault zone and to control the regional tectonics. In this project, we propose to constrain the density and rheology structures of upper mantle using seismic tomography, gravity anomaly, surface topography and heat flow observations, calculate the convectional velocity, stress and strain fields in the upper mantle using the finite element method, and study the influence of the small-scale upper mantle convection on the tectonic activity in the Tan-Lu fault zone. This project is significant to deeply understand the geodynamic process and its deep background of the Tan-Lu fault zone.

郯庐断裂带是纵贯中国东部大陆边缘的一条深大构造变型带，也是中国大陆最为重要的地震活动带之一。大量的地球物理及地球化学观测证据显示，郯庐断裂带下可能存在比较活跃的上地幔小尺度对流系统，并对区域构造动力学过程有一定的控制作用。本申请项目拟利用地震层析成像、重力异常、地表地形和大地热流观测资料，对上地幔的密度和流变结构作出有效约束。在此基础上，采用有限元方法，研究由密度驱动的郯庐断裂带上地幔对流速度场和上地幔应力应变场，定量分析郯庐断裂带上地幔小尺度对流对区域构造活动的作用和贡献。本项目对深入理解郯庐断裂带构造动力学过程及其深部动力学背景具有重要的科学意义。