Longitudinal profile of the Upper Weihe River: Evidence for the late Cenozoic uplift of the northeastern Tibetan Plateau

Abstract

The Upper Weihe River (UP‐WHR) basin is located along the northeastern Tibetan Plateau. With the northeastward expansion of the Tibetan Plateau since the late Cenozoic, it has involved foreland propagation and undergone obvious surface uplift. In order to determine the latest differential rock uplift and river incision, longitudinal profiles for 12 major tributaries of the UP‐WHR were extracted. Among them, 11 tributaries display uneven profiles with “slope‐break” knickpoints, suggesting that they are in a transient state and that the change in base level caused by tectonic forces may respond to the channel evolution. In addition, channel steepness index (ksn) was calculated to detect the spatial variations of the rock uplift rate. The results show that the north margin of West Qinling (WQL) and the south Liupan Shan (LPS) areas have a high uplift rate. Reconstruction of the paleochannel indicates that the Weihe River has an average incision of 354 ± 130 m since it formed, and the south tributaries have a higher incision of 144 ± 25 m than the north. An average river erosion rate of 0.25–0.3 m/ka was estimated, the WQL has a higher erosion rate of 0.1–0.12 m/ka than Longzhong Basin and the south LPS. This uplift and river incision can be correlated to the northeastward growth of the Tibetan Plateau since the late Cenozoic.