Crustal Deformation and Uplift Mechanisms in the Central‐Eastern Tien Shan Constrained by Seismic Ambient Noise Tomography

Abstract The Tien Shan orogenic belt, located in the intracontinental region of Central Asia, exhibits complex tectonic deformation resulting from the long‐term convergence between the Indian and Eurasian plates. However, the deformation and uplift mechanisms in this region is still in debate. Using data from 224 broadband seismic stations, we constructed a 3‐D model of shear wave velocity (Vs) and azimuthal anisotropy via ambient noise tomography. Our model reveal a vertically decoupled deformation regime: the upper crust (0–30 km) displays strong azimuthal anisotropy aligned with major faults, reflecting a combination of shape‐ and lattice‐preferred orientations. In contrast, the mid‐to‐lower crust (30–60 km) exhibits weaker anisotropy with fast polarization directions rotating toward a N‐S orientation, consistent with regional compressional stress. Notably, the mid‐lower crustal low‐Vs anomalies (3.57–3.94 km/s) exhibit pronounced spatial heterogeneity. In the eastern Tien Shan, a moderate inverse correlation between Vs and surface elevation is observed, primarily driven by bidirectional compression from the adjacent basins. Conversely, this correlation is negligible within the central Tien Shan and the central‐to‐eastern transition zone. In this region, the structural strike NE‐SW orientation, leading to oblique convergence characterized by the intense northward indentation and rotation of the Tarim Craton. Such complex kinematics, potentially coupled with lithospheric subduction and deep thermal perturbations, effectively decouple the crustal velocity structure from surface topography. The lateral discontinuity of these low‐Vs zones further supports a segmented orogenic model. These findings suggest that Tien Shan uplift is driven by the interaction between heterogeneous basin‐mountain compressional regimes and deep rheological weakening, providing new constraints on intracontinental geodynamic processes.