基于横波分裂、GPS和断裂第四纪滑动速率数据研究青藏高原东缘岩石圈/软流圈动力学特征

项目名称： 基于横波分裂、GPS和断裂第四纪滑动速率数据研究青藏高原东缘岩石圈/软流圈动力学特征

项目编号： No.41474088

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 天文学、地球科学

项目作者： 常利军

作者单位： 中国地震局地球物理研究所

项目金额： 90万元

中文摘要： 青藏高原东缘岩石圈/软流圈的变形模式可以通过联合分析地表变形场和地幔变形场来确定。本项目拟收集位于青藏高原东缘的宽频带固定和流动地震台（共1810个台）记录的SKS波形资料，采用最小切向能量的网格搜索和叠加分析方法求取表征地幔变形场特征的横波分裂参数；并利用发表的GPS和断裂第四纪滑动速率数据，采用连续样条函数方法求取地表连续变形场。根据应变率分布和岩石圈构造特征，按照高应变率和厚岩石圈区域采取岩石圈变形模式分析，定量求取和确定各个观测点的变形类型（左旋简单剪切、右旋简单剪切或纯剪切变形），通过预测的各向异性参数与实测参数的对比来确定岩石圈壳幔力学耦合的程度并讨论其动力学含义；在低应变率和薄岩石圈区域采用简单软流圈变形模式分析，依据预测的各向异性参数与实测参数的对比来确定由迭代反演求取的地幔流并分析其动力学含义。

中文关键词： 地震各向异性；全球定位系统；断裂第四纪滑动速率；岩石圈变形；地幔流

英文摘要： The extent of crust-mantle coupling in lithosphere and mantle flow in asthenosphere beneath the eastern margin of Tibetan Plateau can be determined through the joint analysis of surface and mantle deformation fields. In order to infer the mantle deformation field, we will determine the SKS fast polarization directions and delay time for 1810 permanent and temporary broadband seismic stations where the fast polarization and delay time for each arrival were determined following the method of Silver and Chan (1991) and stacking procedure. A continuous surface deformation field will be determined using continuous spline functions to interpolate between observed surface strain rate data inferred from both GPS observations and Quaternary fault slip rates. According to the magnitude of strain rate and lithosphere thickness, we divide the study area into two parts, one is high strain rates and thick lithosphere, and another is low strain rates and thin lithosphere. In high strain rates and thick lithosphere area, we will measure the deformation pattern (left-lateral simple shear, right-lateral simple shear or pure shear) at each station based on lithosphere deformation model. We can constrain the extent of crust-mantle coupling through comparing the predicted anisotropy orientations with the observed anisotropy. In low strain rates and thin lithosphere area, we can assume the anisotropy is generated by the differential flow between the lithosphere and asthenosphere. The mantle flow is determined in an iterative inversion by comparing the predicted anisotropy, based differential velocities between predicted mantle flow and the velocity field at the surface, with orientations with the observed anisotropy.

英文关键词： Seismic anisotropy;globle positioning system;Quaternary fault slip rates;lithosphere deformation;mantle flow