The paleolake hydrology and climate change since the ~40 ka in the Hetao Basin, Inner Mongolia, China

A 8.4-m-long sediment core was collected from the southwestern part of the Hetao Basin. In this study, we reconstructed the hydrological and climate changes of the paleolake since ~40 ka based on multiple organic matter geochemical (total organic carbon, total nitrogen, C/N ratios, and δ13C) and grain size proxies. The results show that in the Hetao Basin, the lake level was relatively high with a high aquatic productivity and a flourishing aquatic ecosystem between ~40 ka and 27 ka. The climate was warm and humid during the late MIS 3 period. The abrupt decrease in the productivity of the aquatic plants after 27 ka indicates that the lake level dropped or the lake dried up as the climatic conditions deteriorated and the passage of the Yellow River together. The deteriorating climatic conditions after 27 ka were caused by the weakness of the Asian summer monsoon, which was caused by the low summer insolation in the Northern Hemisphere in the Hetao Basin since the late MIS 3.