Tectonic transition in the northeastern Tibetan Plateau: Constraints from InSAR and GNSS measurements

Summary The northeastern Tibetan Plateau is bounded by the left-lateral Altyn Tagh and Haiyuan faults. How crustal motion along these fault systems transitions to crustal shortening and uplift is key for deciphering the geodynamic link between the escape tectonics and the growth of the Tibetan Plateau. Here, we use the PS-InSAR observations, combined with GNSS and leveling data, to obtain a high-resolution 3D model of the present-day crustal motion in the northeastern Tibetan Plateau. The resolved deformation field covers the entire northeastern Tibetan Plateau with a spatial resolution of approximately 0.01° × 0.01 °. Our analysis of slip rates and strain partitioning reveals that crustal motion along the Altyn Tagh fault gradually diminishes eastward and is absorbed by thrusting and uplift in the Qilianshan orogenic belt within the plateau. A similar tectonic transition occurs between the Haiyuan fault and the Liupanshan orogen on the eastern margin of the plateau. Some of the eastward crustal motion is accommodated by the younger Xiangshan-Tianjingshan fault system to the north of the Haiyuan fault, indicating the ongoing northward expansion of the Tibetan Plateau. Our results align with geological evidence of crustal deformation in the past few million years, highlighting the continuing tectonic transition from eastward crustal motion along the left-lateral strike-slip faults to the growth of the Tibetan Plateau.