AUTHOR=Cai Dongxu , Wang Xianyan , Li Guangwei , Zhu Wenbin , Lu Huayu 

TITLE=Late Cenozoic Denudation and Topographic Evolution History of the Lhasa River Drainage in Southern Tibetan Plateau: Insights From Inverse Thermal History Modeling

JOURNAL=Frontiers in Earth Science

VOLUME=Volume 9 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2021.636459

DOI=10.3389/feart.2021.636459

ISSN=2296-6463

ABSTRACT=The interaction of surface erosion (e.g. fluvial incision) and tectonic uplift shapes the landform in Tibetan Plateau. The Lhasa River flows towards southwest across the central Gangdese Mountains in the southern Tibetan Plateau, characterized by a low-relief and high-elevation landscape. However, the evolution of low-relief topography and the establishment of the Lhasa River remain highly under debate. Here, we collected thermochronological ages reported in the Lhasa River drainage, using a 3D thermokinematic model to invert both late Cenozoic denudation and relief history of the Lhasa River drainage. Our results show that the Lhasa River drainage underwent four-phase denudation history, including two-stage rapid denudation at ~25-16 Ma (with a rate of ~0.42 km/Ma) and ~16-12 Ma (with a rate of ~0.72 km/Ma). In the latest Oligocene-early Miocene, uplift of the Gangdese Mountains triggered the rapid denudation and formation of the current main drainage of the Lhasa River. In the middle Miocene, the second stage of the rapid denudation and high relief were associated with intense incision of the Lhasa River, which is probably due to the enhanced Asian summer monsoon precipitation. This later rapid episode was consistent with records of regional main drainage systems. After ~12 Ma, the denudation rate decreases rapidly, and the relief of topography in the central Gangdese region was gradually subdued. This indicates that the fluvial erosion resulted from Asian monsoon precipatition increase significantly impacts on the topographic evolution in the central Gangdese region.