利用剪切波分裂研究辽宁南部地区上地幔各向异性

Study on Anisotropy of Upper Mantle in Southern Liaoning Province by Shear-wave Splitting

利用辽南地区地震观测台站观测的SKS远震波形数据,采用SpitLab软件来计算分析上地幔各向异性的参数特征,分别得到快波偏振平均方向为NWW向,快、慢波延迟时间为0.65~36 s。综合地质构造等依据分析发现:辽南地区自北向南的上地幔变形因素不仅仅是单一的垂直连贯变形或地幔流动,而是二者共存。同时,通过计算得到辽南地区各向异性厚度大致在74~156km,平均厚度在115km。综合分析,认为该地区的各向异性主要成因是来自上地幔的影响。

There are complex geological structures in the southern liaoning region.In this paper,the ani⁃sotropy of the upper mantle is carefully inverted by using far-seismic wave data,and then the deformation mechanism of the lithosphere and the mantle flow are explored.Splitlab software was used to invert the SKS s-wave splitting results of 10 fixed stations in this area.The average polarization direction of fast wave was NWW direction,and the delay time of fast and slow wave was 0.65~1.36.The upper mantle anisotropy map of Liaoning is obtained.Based on the analysis of geological structure,it is found that the deformation of the upper mantle from north to south is not only a single vertical coherent deformation or mantle flow,but the coexistence of both.At the same time,the calculated anisotropic thickness in southern liaoning is approxi⁃mately 74~156 km,and the average thickness is 115 km.In general,the crust does not contribute much to the anisotropy,and the main cause of anisotropy in southern Liaoning is from the upper mantle.