Holocene incisions and flood activities of the Keriya River, NW margin of the Tibetan plateau

Fluvial terraces are common in the tectonically active western Kunlun Mountains (WKLM) region, northwestern margin of the Tibetan Plateau, and incision of rivers since 5 ka was attributed to the accelerated uplift of the WKLM. However, it is difficult to evaluate their tectonic or climatic origin without detailed chronology. In this study, Optically Stimulated Luminescence (OSL) dating was applied to fluvial/flood and aeolian sediments on five lowest fluvial terraces (49 m in total) along the Keriya River, and the 21 OSL ages (from 11 samples) revealed the incision processes since the mid-Holocene, especially the fast incision (3.5-0 ka, 10.9 mm/a) during the late Holocene. This was supported by the climatic background, i.e., increased precipitation from the westerlies and meltwater from frequent glacial advance-retreat events. As a response to the climatic changes, largescale floods were frequent as well, e.g., at 3.5, 2.6, 0.87, and 0.25 ka, which were crucial for the fast incisions on the filling gravels. Additionally, the flood also caused the river's further extension into the Talclamakan Desert and controlled the evolution of oases in the desert, including ancient cities and cultures. Consequently, we suggest that climatic change was important for the incision and formation of cut-in-fill terraces along the Keriya River during the Holocene, and influences from other factors, including surface uplift, should not be ignored, but were difficult to be evaluated.