Abstract
The southeastern Tibetan Plateau undergoes clockwise rotation and left-lateral shear around the Eastern Himalayan syntaxis. While determining when the modern tectonic architecture and clockwise rotation were established carries important implications for the geodynamics of plateau growth, the exhumation history and mechanisms of the Shan Plateau, which occupies nearly half of SE Tibet, remain subjects of active debate. Here, we utilize apatite and zircon (U-Th)/He thermochronology from three bedrock elevation transects along NE-trending left-lateral faults to refine the Miocene exhumation of the Shan Plateau. Age-elevation relationships and thermal history modeling indicate that a phase of rapid exhumation began at ca. 10 Ma. We attribute this acceleration to left-lateral faulting based on a comparison of regional deformation patterns and timing. By integrating continuous upper-crustal clockwise rotation with tomographic observations, we propose that restricted (~60 km) lithospheric extrusion around the Eastern Himalayan syntaxis in SE Tibet has occurred, within the modern tectonic architecture, since the late Miocene.