柴达木盆地, 苏干湖盆地, 中更新世, 构造隆升, 沉积环境, 古地理演化

Based on sedimentary and tectonic geomorphological analysis, this study found that the paleogeographic environment of the Qaidam and Suganhu basins underwent significant changes during the middle Pleistocene. In the early Pleistocene (2.54–0.78 Ma), the Qaidam and Suganhu basins shared a widespread lacustrine environment. Paleo-currents indicate a drainage connection between the two basins. However, since the mid-Pleistocene (0.78 Ma to present), continuous tectonic activities, evidenced by soft sediment deformation structures, in the North Qaidam structural belt resulted in the uplift of Xiaosaishiteng range, which separated the Qaidam and Suganhu basins. The lacustrine environment became alluvial fans and braided river environments near the ranges, while isolated small saline lakes dominated the distal areas. We attribute the rapid evolution of paleogeographic environment and drainage system in the Qaidam and Suganhu basins to the mid-Pleistocene uplift of the North Qaidam structural belt. The uplifted North Qaidam structural belt blocked the runoff from the South Qilian Shan into the Qaidam Basin, causing the lakes within the Qaidam Basin to shrink and dry out since the middle Pleistocene.

Qaidam Basin, Suganhu Basin, mid-Pleistocene, tectonic uplift, sedimentary environment, paleogeographic evolution