A Simple Scenario for Explaining Asymmetric Deformation Across the Altyn Tagh Fault in the Northern Tibetan Plateau: Contributions from Multiple Faults

Asymmetric deformation has been observed along the Altyn Tagh Fault (ATF), the northern boundary of the Tibetan Plateau. Several mechanisms have been proposed to explain this asymmetry, including contrasts in crustal strength, lower crust/upper mantle rheology, deep fault dislocation shifts, and dipping fault geometry; however, the real scenario remains debated. This study utilizes a time series Interferometric Synthetic Aperture Radar (InSAR) technique to investigate spatially variable asymmetries across the western section of the ATF (83–89°E). We generated a high-resolution three-dimensional (3D) crustal velocity field from Sentinel-1 data for the northwestern Tibetan Plateau (~82–92°E; 33–40°N). Our results confirm that pronounced greater deformations within the Tibetan Plateau occur only along the westernmost section of the ATF (83–85.5°E). We propose this asymmetry is primarily driven by a splay fault system within a transition zone, bounded by the ATF in the north and the Margai Caka Fault (MCF)–Kunlun Fault (KLF) in the south, which accommodates an east–west extension in the central Tibetan Plateau while transferring sinistral shear to the KLF. The concentrated strain observed along the ATF and MCF–KLF lends more support to a block-style eastward extrusion model, rather than a continuously deforming model, for Tibetan crustal kinematics.