The impacts of base level and lithology on fluvial geomorphic evolution at the tectonically active Laohu and Hasi Mountains,northeastern Tibetan Plateau  

作　　者：Zhengchen LI Xianyan WANG Yang YU Huiping ZHANG Qi SU Xiaodong MIAO Huayu LU 

机构地区：[1]School of Geography and Ocean Science,Nanjing University,Nanjing,210023,China [2]Institute of Geology,China Earthquake Administration,Beijing,100029,China [3]School of Resource and Environmental Sciences,Linyi University,Linyi,276000,China

出　　处：《Science China Earth Sciences》2021年第6期906-919,共14页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.41971005,41522101);the Second Tibetan Plateau Scientific Expedition Program(Grant No.2019QZKK0205);the National Key Research and Development Program(Grant No.2016YFA0600500)。

摘　　要：Previous researches had emphasized tectonic impacts on the fluvial system at the tectonically active areas,while the effects of lithology and local base level change have received relatively rare attention.Here we investigated fluvial landforms at different spatial scales,focusing on knickpoints and channel network reorganization from an area affected by the Haiyuan Fault in the northeastern Tibetan Plateau.The geomorphic indices,i.e.,drainage pattern andχanomalies,were calculated and investigated.The results show that two regional radial drainages formed around the Laohu and Hasi Mountains.Within the interior of the radial drainage,tributaries from the southeast side of the Laohu Mountain experienced near 180°direction change.We interpret this as the gradual drainage capture originating from the height difference(~190 m)of the local base level between the two catchments.Some tributaries from the Hasi Mountain show alternating gorges and broad valleys controlled by lithology.Besides,tectonic uplift and the lowering of base level(from the incision of the Yellow River)triggered an autogenic positivefeedback transition from parallel to dendritic drainage patterns.These observations suggest that base level change and lithology play a crucial role in landscape evolution,even in a tectonically active region.

关 键 词：River piracy Base level LITHOLOGY Geomorphic index Haiyuan Fault Northeastern Tibetan Plateau 

分 类 号：P931.1[天文地球—自然地理学]