HU Chuanhui1,2, LIU Yu1,3, WANG Shijie1,3, ZHANG Xinbao4, HU Kaiheng4, DAI Bin1,2, WU Chaohua2,4, LI Yanji2,4, ZHANG Qiyuan2,4
(1.State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;
2.University of Chinese Academy of Sciences, Beijing 100049, China;
3.Puding Karst Ecosystem Research Station, Chinese Academy of Sciences, Puding Guizhou 562100, China;
4.Key Laboratory of Mountain Hazards and Earth Surface Process, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences & Ministry of Water Conservancy, Chengdu 610041, China)
Abstract: Dammed lake deposition is a key for understanding the drainage evolution of the Jinsha River and regional tectonic activities. The elemental geochemistry of fine-grained (<0.063mm) sediment samples from Cenozoic dammed lakes, underlying fluvial facies and modern banks of the Jinsha River between Benzilan and Qiaojia were analyzed to reveal the provenance change of each dammed lake, and to briefly discuss the indicative significance to drainage evolution of the Jinsha River. The three key findings of this study are: 1. The elemental geochemistry of sediments from modern banks and dammed lakes such as Sasaideng, Benzilan, Shigu, Taoyuan and Jintang are the same, indicating they have the same provenanceof the Jinsha River; 2. The elemental geochemistry of the fluvial gravel beds beneath the Xigeda Formation at Geliping and the Xigeda Formation at the downstream Lazha are the same as those of other dammed lakes, indicating the sediment all comes from the Jinsha River; the trace element geochemical characteristics of the Xigeda Formation at Xigeda Village and Bingcaogang are different from those of underlying fluvial facies at Geliping and Lazha and other dammed lake deposits as a result of affection by sediment from the Yalong River; 3. The consistency of the provenance of dammed lakes, underlying fluvial facies and modern banks between Benzilan and Qiaojia indicates that the east-flowing Jinsha River had already been formed before the formation of these dammed lakes, and their provenance has not changed significantly so far.
Key words: Jinsha River; dammed lake; elemental geochemistry; provenance
EARTH AND ENVIRONMENT Vol.49, No.2, Tot No.340, 2021, Page 115-124