Late Quaternary deposition and incision sequences of the Golmud River and their environmental implications

摘要

Golmud River is a large river that originates from the Kunlun Mountains and drains into the Qaidam Basin on northern Tibetan Plateau. Well-developed fluvial terraces in the river valley record complex history of tectonic movements and climate changes in this area. The current study investigated fluvial terraces in three cross sections along the river (Xiaogangou. Nachitai and Sanchahe). The ages of the terraces were constrained using optically stimulated luminescence (OSL) and radiocarbon dating methods. The results characterize two stages of fluvial landform evolution since the Late Quaternary: the Sanchahe deposition stage (82-16 ka) and the Golmud incision stage (16 ka until now). During the deposition stage, tectonic movements were relatively stable, which drove the deposition. Meanwhile the enhanced glaciations and precipitation during the Last Glacial promoted the aggradatigns in the river valley as well. During the incision stage, four substages at 16-13 ka, 13-11 ka. 11-5 ka and S ka till now are identified. These substages correspond to the incision of the four terraces. The incision was mainly driven by the tectonic uplift after the Last Glacial Maximum.