Downwind aeolian sediment accumulations associated with lake-level variations of the Qinghai Lake during the Holocene, Northeastern Qinghai–Tibetan Plateau

Abstract

Many lakes in the Qinghai–Tibetan Plateau (QTP) have aeolian sands distributed in their downwind shores. However, it has been rarely systemically investigated on whether the downwind dune sand and lake evolved in association with each other or they evolved independently. Here we take the well known Qinghai Lake and its downwind sand area as a case study to investigate the issue of water–sand interaction. Grain size, magnetic susceptibility and geochemical data along with optically stimulated luminescence (OSL) ages suggest that the downwind eastern shore sandy lands co-varied with the lake level fluctuations (or lake extension changes) of the Qinghai Lake during the Holocene epoch. During the early Holocene lake lowstands (11–9 ka, ka is 1000 years), vast areas of exposed lacustrine sediments were eroded by prevailing westerly winds, therefore, causing sand to accumulate at the eastern shore bajada areas along the west piedmonts of the Riyue Mount, and to expand along the Daotang River valley. In contrast, during the mid to late Holocene lake highstands (7–1.2 ka), eastern shore dune sands were largely stabilized, and loess accumulated and even paleosol developed, leading to substantial shrinkage of the eastern shore sandy lands. In addition, using GIS tool, we reconstructed the spatial extensions of the lake during highstand (Mid-Holocene) and lowstand (Early Holocene), and eastern shore desert range of early Holocene. As a result, this study indicates a close connection between the lakes in QTP and the aeolian sands downwind.