Shear wave splitting in Xinjiang region

Shear wave splitting analysis has been carried out using teleseismic data from broadband digital seismic stations permanently deployed in Xinjiang region. We determined fast polarization direction (phi;) and delay time (delta;t) between fast and slow waves using both the minimum energy method and rotation-correlation method. Our measurements show that fast directions of teleseismic shear wave beneath the northern Tarim basin, Tien Shan orogenic belt and Altai orogenic belt are generally parallel to the strike of structure beneath the stations. The delay times vary from 0.8 s to 1.8 s. All of these are related to shortening of lithosphere caused by the collision between India and Eurasia continent. In contrast, weak anisotropy beneath Tarim basin and Junggar basin implies that these basins have not experienced strong deformation since Cambrian. The fast polarization directions near the Altyn fault show remarkable correspondence with the fault strike, indicating that the fault may cut the whole lithosphere.