Counter-flow of Qiaojia river section and get-through of Chuanjiang-Jinshajiang water system

• 1、School of Geographic and Oceanographic Sciences, Nanjing University
• 2、School of Urban and Environmental Sciences, Xuzhou Normal University
• 3、Tianjin Institute of Geology and Mineral Resources, China Geological Survey

Abstract：According to the analysis of geomorphology and drainage structure, paleo-drainage of Qiaojia river section should once flowed south along Xiaojiang Fault, while its north-flow direction today could be the result of counter-flow triggered by several river capture events. Heavy mineral assemblage analysis of Yibin-Qiaojia river section show us that, during the time of “High-Terrace” formation, paleo-Chuanjiang water system and paleo-Qiaojia water system didn’t get-through yet, and the modern Jinsha River didn’t exist at that time. The counter-flow of Qiaojia river section at least figures out the formation of Menggu-Yibin section of modern Jinsha River, and suggests the get-through of Jinshajiang-Chuanjiang water system. ESR dating of terraces show that the counter-flow of Qiaojia river section and the get-through of Yibin-Qiaojia section occurred at around 1.02 ~ 0.96 Ma. Late Cenozoic uplifts of Tibetan Plateau and Chuanxi Plateau made high relief around the southeast margin of Tibetan Plateau and led upstream erosion of paleo-Chuanjiang and Qiaojia paleo-river, in the direction of southwest and north respectively. Furthermore, uplift of Yunnan Plateau blocked the Qiaojia paleo-river flowing south, and finally caused the capture of Qiaojia paleo-river by paleo-Chuanjiang. Consequently, Qiaojia river section flowed in an opposite direction to north, and connected with Yibin river section. As a result, Chuanjing-Jinshajiang water system got-through and went east to the sea.

Keywords： Jinsha River Qiaojia Section Counter-flow Chuanjiang River Terrace Heavy Mineral