Glacial Erosion and Weathering Enhance U Isotopic Activity Ratio and Particle Migration in the Muztagh Glacial Watershed, Pamir Plateau

Abstract Glacial watersheds provide an ideal setting for studying chemical weathering, sediment transport and circulation at high altitudes. This study analyzed cryoconite, river sediments, and water samples from the Muztagh glacial watershed in the Pamir Plateau. The results showed that the cryoconite dust in the glacier originated mainly from the Asia arid regions. The ( 234 U/ 238 U) activity ratio of river sediments ranges from 0.998 to 0.976, in which the uranium comminution age indicates that the fine‐particles age from bedrock is approximately 3.3–43.6 ka. Correlation analysis with topographic, climatic, and hydrological parameters reveals that glacial (physical) erosion is the primary factor driving the variability of sediment surface processes between the tributary and mainstream in the glacier watershed. Glacier erosion contributes a mean of 67 ± 25% of the sediment input of the glacier‐fed tributaries of the Muztagh watershed, while down to the main stream in the Gaizi River, the contribution drops to 60 ± 26%. The concentrations of [U] and [Li] in river water increased along the glacier to downstream area, while U‐Li isotope ratios showed high ( 234 U/ 238 U) and δ 7 Li values at the glacier terminus, showing a gradual decrease mode subsequently. These findings suggest that glacial action in the Muztagh Glacier region causes extensive physical comminution of mineral particles, leading to strong α recoil, in which 234 U is preferentially ejected from damaged crystal lattice sites, while limited chemical weathering. In contrast, non‐glacial regions experience reduced recoil effects and enhanced chemical weathering. This study provides new insights into the sediment production and transported process in glacial watersheds.