OSL chronology and palaeoclimatic implications of aeolian sediments in the eastern Qaidam Basin of the northeastern Qinghai-Tibetan Plateau

Abstract

Aeolian sediments are widely distributed in the hyper-arid Qaidam Basin and are good palaeoclimatic records. Due to limited age control, aeolian processes and their relevance to palaeoclimatic change are poorly understood. In this study, we present 28 optically stimulated luminescence (OSL) ages for both loess (14 samples) and aeolian sand (14 samples) from 8 profiles in eastern Qaidam Basin (EQB) in order to provide a detailed chronology for understanding the timing of aeolian processes and associated environmental conditions. We reconstructed the history of aeolian activity in the EQB since deglaciation by combining OSL chronologies, lithologic stratigraphy and grain-size analysis. The results indicate that (1) aeolian sand underlying the loess accumulated at ca. 12.4–11.5ka and 10–8ka, but not during the Last Glacial Maximum, (2) loess accumulation started at 10ka and lasted to 0.45ka at least, while most of the loess was deposited during 8–4.5ka, (3) palaeoclimates in the EQB are inferred to be arid during 12.4–11.5ka, (relatively) humid during 10–8ka, humid during 8–4.5ka and relatively arid during 4.5–0.45ka, and (4) evolution of aeolian sediments were mainly controlled by effective moisture, and also affected by local topography.