Abstract: The exhumation history of the Gangdese orogenic belt and its geomorphologic evolution process are key issues to
understand the formation and evolution of the Tibetan Plateau. This region’s unique geological and geomorphological evolution makes it an ideal case study for analyzing the interaction of tectonics, surface processes, and climate in shaping orogenic belts. Despite significant progress in studying the exhumation history of the Gangdese belt, most studies have focused on the eastern part of the belt. The lateral variability in the exhumation of this over 1000-km-long belt remains unclear. In this study, we collected thermochronological ages from the Xigaze area published and applied a 3D thermokinematic model to reconstruct the late Cenozoic exhumation and topographic history of the central Gangdese belt. Our simulation results indicate that since ~30 Ma, the central Gangdese has undergone four exhumation stages. The exhumation rates generally followed a “slow-fast-slow” pattern, while topographic relief showed “low-high-low” changes. Two relatively rapid exhumation phases were identified at ~27-18 Ma (~0.3 km/Myr) and ~18-14 Ma (~0.75 km/Myr), corresponding to periods of sustained high topographic relief（R=1.5-1.7） in the central Gangdese. In the early Oligocene, lower exhumation rates (0.15 km/Myr) were observed, likely due to the tectonic transition of the Tibetan Plateau system to the E-W extension, topographic flattening, and reduced precipitation during this stage. From the mid-late Oligocene to early Miocene, the exhumation rate rose to ~0.3 km/Myr, potentially influenced by intense activity of the Gangdese thrust fault system and the expansion of the Asian monsoon system into the plateau interior. The maximum exhumation rate (0.75 km/Myr) occurred during the middle Miocene, and was closely related to the high topographic relief (R=1.7) in Gangdese and the warm-humid climate of the mid-Miocene Climatic Optimum. From ~14-10 Ma to the present, exhumation rates decreased again (~0.2 km/Myr), associated with enhanced precipitation shielding due to Himalayan terrane uplift, Asian inland drying, and progressive topographic flattening in the Gangdese region.

Key words: Gangdese orogenic belt, Low temperature thermochronology, Thermokinematic model, Exhumation