Coupled U-Pb dating and Hf isotopic analysis of detrital zircon of modern river sand from the Yalu River (Yarlung Tsangpo) drainage system in southern Tibet: Constraints on the transport processes and evolution of Himalayan rivers

摘要: We conducted coupled U-Pb dating and Hf isotope analysis of detrital zircon in modern sand the Yalu River southern Tibet. Our work indicates that presence or absence distinctive populations main stream depends critically on geometric configuration tributary rivers. The proportion upper-stream decreases systematically downstream direction, which is caused mainly by addition from new source areas region. In some extreme cases, upstream signals can completely be lost region due to this dilution effect. Analysis modal composition reveals a increase lithic fragments along River, ∼40% ∼60% over distance ∼600 km. This may attributed combined effect an eastward topographic relief annual precipitation across drainage basin. Quantitative comparison detrital-zircon ages between Neogene sediments eastern Himalayan foreland supports previous proposal once flowed directly Himalaya, without going around Himalaya through its syntaxis. shortcut appears have been transient, as it only recorded specific stratigraphic horizons sediments. inferred diversion past advances glaciers emplacements giant landslides temporarily dammed River.