Multiscale Analysis of Fault Systems in the Hengduan Mountains: Implications for Block Rotation Processes in Southeastern Tibet

The Hengduan Mountains in the southeastern Tibetan Plateau develop one of the most complex active fault systems on Earth. GPS measurements and seismic data reveal that these fault systems drive present-day eastward crustal transport and clockwise rotation around the Eastern Himalayan Syntaxis. In this study, we investigate regional block rotation kinematics based on fault slip displacement, spacing, and the orientations of block-bounding strike-slip faults in the Hengduan Mountains. The results of block rotation rates, angles, and rotation radius are then comprehensively analyzed, combined with existing paleomagnetic, geodetic, and multi-timescale slip rate data. Our findings highlight the influence of the development of block-bounding faults and associated sub-blocks on regional block rotation deformation during the southeastward growth of the Tibetan Plateau. The Late Cenozoic block rotation of the Chuandian Block in the Hengduan Mountains exemplifies the transition from a single to a multi-block system, which has critically influenced the spatiotemporal distribution and rates of strike-slip faulting processes along block boundaries. Our study reveals the possible evolution processes of block rotation in regions dominated by large-scale strike-slip fault systems, such as the Hengduan Mountains in southeastern Tibet.