Weathering and pedogenesis of the late Pleistocene and Holocene aeolian loess-paleosol sections in the Yellow River source area, NE Tibetan Plateau

The aeolian loess-paleosol sections on the northeast Tibetan Plateau (NETP) are a valuable source of paleoclimatic information because of their geographical location. In this study, two late Pleistocene-Holocene aeolian loess-paleosol sections were identified based on detailed field investigations in the Maqu reach in the Yellow River source area on the NETP. A robust chronostratigraphic framework for these two sections was established using AMS C-14 dating, optically stimulated luminescence (OSL) dating, Bacon age-depth modelling and strati graphic correlation. Measurements of magnetic susceptibility, hygroscopic water, loss-on-ignition, grain-size, micromorphology, and chemical element analysis suggest that most stratigraphic units in these aeolian loesspaleosol sections are in weak weathering and pedogenesis, whereas the mid-Holocene paleosol approaches to the moderate weathering and pedogenesis, and the sediments are in initial weathering stage of Na+ and Ca2+ leaching is dominated by plagioclase weathering. The main pedogenesis in the mid-Holocene paleosol is calcification process. In terms of intensity of weathering and pedogenesis, the stratigraphic units can be ordered as follows: paleosol > modern soil > transitional loess > aeolian loess. Multi-index comparison shows that the local climatic evolution during the late Pleistocene-Holocene was closely related to the evolution of the East Asian summer monsoon (EASM) and the Westerlies. Overall, the results provide a foundation for further exploration of the pedogenic and paleoclimatic evolution on the NETP.

Automated summary

This study investigates aeolian loess-paleosol sections on the northeast Tibetan Plateau to establish a chronostratigraphic framework and understand the weathering and pedogenesis of the soil. The results show a close relationship between the local climatic evolution during the late Pleistocene-Holocene and the evolution of the East Asian summer monsoon and the Westerlies.