Research progress on seismic anisotropy in the Tarim Basin and Tianshan region

The Tarim Basin and the Tianshan region are the key interaction zones between the Central Asian Orogenic Belt and stable blocks, and are natural laboratories for studying the tectonic deformation of the continent, the coupling effect of basin-mountain and the seismic breeding mechanism of the continent. As an “indicator” of lithospheric deformation, seismic anisotropy can effectively reflect the regional tectonic stress field and deep material migration characteristics, which is of great scientific significance for revealing the coupling dynamics mechanism of basin-mountain in this region. In recent years, domestic and international scholars have systematically studied the seismic anisotropy characteristics from the crust to the upper mantle using seismological methods such as receiver functions, shear wave splitting, and surface wave tomography. Research shows that there are significant spatial differences in crustal seismic anisotropy. Generally, the fast wave polarization directions in the Tarim Basin and the Tianshan region are consistent with the regional tectonic stress field and the strike of the Tianshan orogenic belt, which is mainly affected by the long-range effect of the Indian plate collision, the uplift of the Qinghai-Tibet Plateau, and the NS pushing action with the Tianshan Mountains. However, the fast wave polarization directions are dispersed in local areas, and the anisotropic characteristics in regions such as Atushi, Wushi and Keping exhibit a certain degree of complexity, which may be related to stress disturbances caused by local faults. The anisotropic features of the upper mantle are not entirely consistent with those of the crust, and the vertical coherence of lithospheric deformation requires further investigation. Although scholars at home and abroad have made the above progress in the field of seismic anisotropy, the spatial distribution characteristics and dynamic mechanism of seismic anisotropy have not yet reached a unified discussion, and a large number of geophysical observations are still needed to deepen the relationship between seismic anisotropy and tectonic deformation and seismic activity, so as to provide more reliable deep dynamic constraints for regional seismic risk assessment.