Crustal Deformation Modes in the Pamir‐Tianshan Inferred From Crustal Anisotropy: Compressional Shortening Versus Gravitational Collapse

Abstract The Pamir Plateau stands out at the westernmost Tibetan Plateau as a north‐facing convex promontory, bordering the tectonically rejuvenated Tianshan orogen. To understand the mode of crustal deformation, we analyze crustal anisotropy in the Pamir‐Tianshan using shear wave splitting of the Moho‐converted phases. Our results reveal an orogen‐parallel anisotropy from the northeastern Pamir to the Tianshan, suggesting crustal compressional shortening. In contrast, gravitational collapse in the western Pamir toward the Tajik Basin, is inferred from the anisotropy pattern, which reflects basal shear. Moreover, along‐strike anisotropy near the intermediate‐depth seismic zone delineates a C‐shaped front of the cratonic Indian slab. Its northward indentation into the Asian lithosphere drives regional crustal deformation as orthogonal collision facilitates compressional shortening in the eastern Pamir and Tianshan, whereas oblique convergence promotes gravitational collapse of the western Pamir crust.