青藏高原东北缘甘东南地区地壳各向异性特征及构造意义

本文利用径向和切向接收函数确定地壳各向异性的方法，处理了布设在青藏高原东北缘甘东南地区、横跨西秦岭北缘等断裂的24个密集宽频带流动台站远震资料，得到了研究区地壳各向异性特征.结果显示，平均快波方向呈现NW-SE、NWW-SEE及NNW-SSE，平均分裂时间0.56 s.甘东南中部及北部地区快波方向与GPS速度方向、前人利用XKS波分裂获取的快波方向及该地区断层展布方向基本一致，说明该地区壳幔运动可能是耦合的.同时研究区南部少数台站快波方向呈现NNW-SSE，与断裂方向及GPS速度方向有一定夹角，表明台站下方壳幔运动可能是解耦的.全区快波方向自北向南由近E-W逐渐转变为NW-SE，最后变为NNW-SSE.据此推测地壳在该区的变形挤压有顺时针方向旋转的趋势，这与该区块体挤压应力方向一致.

Crustal anisotropy and tectonic implications beneath southeastern Gansu province in northeastern margin of the Tibetan Plateau

We constrained the crustal anisotropy of southeastern Gansu Province in northeastern margin of Tibetan Plateau with teleseismic receiver functions. The observations are from a dense broadband seismic array with 24 seismometers, which across several large scale faults as West Qinling. The result indicated that the dominant fast direction are NW-SE, NWW-SEE and NNW-SSE with~0.56 s average delay time. The direction of fast wave in the central and northern region of southeastern Gansu is consistent with the results from GPS, XKS wave splitting and the distribution direction of faults in this region, which imply the crust-mantle movement in this region may be coupled. Whereas, the NNW-SSE fast wave direction of the individual stations in the southern part of the study area, which is a little deviated from the direction of the fracture and the direction of the GPS speed, indicate that the crust and mantle movement in the area may be decoupled. From north to south study area, the fast direction gradually changes from near E-W to NW-SE and finally to NNW-SSE. Based on the results, we deduced that the compression deformation of crust of the area is rotating clockwise, which is consistent with the compression stress direction of the block in this area.