Cenozoic thermal evolution of the Quxu batholith in the Gangdese belt: Constraints from (U-Th)/He thermochronology

The uplift history of the Tibetan Plateau remains a pivotal scientific frontier in Earth Science, with broad implications for continental dynamics and environmental change. Along the southern margin of the Lhasa terrane, the Gangdese batholith offers an exceptional natural laboratory for investigating plateau uplift. This study focuses on the Quxu batholith and its surrounding volcanic-sedimentary strata in the Gangdese belt. We systematically collected seven representative rock samples, including diorite, granite, sandstone and andesite. By integrating apatite and zircon (U-Th)/He thermochronology, we have precisely constrained the Cenozoic thermal evolution of the Quxu batholith. Weighted-mean apatite (U-Th)/He ages range from 6.9±1.6Ma to 13.98±0.82Ma. The sample nearest the Yarlung River yields a distinctly younger age (6.9±1.6Ma), plausibly reflecting enhanced fluvial incision, whereas the remaining samples cluster around the mid-Miocene (~13Ma). Zircon (U-Th)/He weighted-mean ages span 17.0±1.6Ma to 39.4±9.2Ma; only the northernmost sample preserves an Eocene age (39.4±9.2Ma), with the others indicating Miocene cooling (~17Ma). Thermal history modeling resolves two episodes of rapid cooling: (1) mid-Eocene to early Oligocene (43~30Ma), likely associated with crustal thickening in the southern Lhasa terrane; and (2) early to mid-Miocene (21~10Ma), probably driven by deep-seated processes such as lithospheric delamination and asthenospheric upwelling. Integrated with existing thermochronological datasets from the Gangdese batholith, these results indicate that its Cenozoic differential exhumation reflects the combined effects of regional tectonics, deep lithospheric dynamics, and fluvial incision. Collectively, these mechanisms place critical constraints on tectonic-geomorphic coupling and uplift along the southern margin of the Tibetan Plateau.