Detrital zircon geochronology of river sands from the Salween River: Implications for sedimentary provenance and erosion pattern

Abstract

Erosion patterns are generally controlled by the interaction of internal tectonic forces and external surface process, including active tectonic processes, precipitation, hillslope steepness and human activities. Studying sediments in river systems helps us understand watershed erosion, contributing to our comprehension of landform evolution, climate change, and biodiversity. The Salween River is a significant international river in Asia, less disturbed by human activities than other large rivers such as the Yangtze River. In this study, we use zircon U-Pb dating and Hf isotopes of bedrocks and mainstream river sediment to reveal the relative sediment contribution of bedrock in the Salween River. The detrital zircon U-Pb ages and combined Hf isotopic data from the Salween River suggest that bedrocks from the middle section of the river contribute a large amount of sediments to the Salween River. This indicates that the middle section of the Salween River has been experiencing intense erosion. Potential impact factors such as human activities, climate, slope, lithology, and tectonism that may control distribution of erosion are considered. We suggest that the most important factor controlling intense erosion in the middle section of the Salween River is likely to be the hillslope steepness. We also suggest that the characteristic zircon U-Pb age distributions of the Salween River could be used to reconstruct paleo-drainage patterns in the southeastern Tibetan Plateau.