Regional hydroclimates regulate the Holocene aeolian accumulation processes of the Qinghai Lake basin on the northeastern Tibetan plateau

Aeolian sediments are widely distributed in the Qinghai Lake basin on the northeastern Tibetan Plateau (TP), and have been extensively investigated for the palaeoclimate reconstruction. However, due to the relatively scanty of dating materials and applicable techniques, and also the commonly existed hiatus in aeolian sequences, the details of the Holocene aeolian activities in the Qinghai Lake basin remain unclear. In this study, we applied the optically stimulated luminescence (OSL) dating technique to a 3.6 m thick loess-palaeosol sequence (QH-18) located on the southern bank of the Qinghai Lake to establish a high-resolution chronology of the aeolian accumulation history. The quartz OSL chronology demonstrated that the loess accumulation commenced since the last deglaciation and continued during the Holocene (∼14.6–0.5 ka), characterized with a remarkably low sedimentation rate period from 6 ka to 2 ka. Similar phenomenon has been recorded in previously investigated aeolian sequences not only in the Qinghai Lake basin but also across the northeastern TP, which was likely owing to the optimal environment conditions that have suppressed the dust emission from the source areas in the extensive arid and semiarid areas. The end-member (EM) analysis of grain-size distribution in QH-18 yielded an optimal model with three EMs, i.e., EM1 (6 μm, background dust), EM2 (56 μm, fraction of medium or long-distance transportation) and EM3 (447 μm, fraction from proximal or local source). The EM3 fraction can only be transported with saltation process in short distances that derived from proximal or local sources. In addition to the regional climatic conditions, according to the variation and contribution of the EMs, we consider that the Holocene aeolian activity in the Lake Qinghai basin was also modulated by the lake-level fluctuations of Lake Qinghai, in the way of changing the supply of sandy materials.