Holocene paleoclimate variations and East Asian monsoonal dynamics revealed by high-resolution OSL dating of aeolian sediments in the Qinghai Lake Basin

The Holocene paleoenvironmental evolution at the sub-orbital scale on northeast Tibetan Plateau based on aeolian records remains unclear due to ubiquitous depositional hiatuses and erosional events. Here, the Heike (HK) aeolian sand section in the Qinghai Lake Basin (QLB) was dated using high-resolution optically stimulated luminescence (OSL) dating, revealing a continuous HK aeolian sand-palaeosol sequence spaning millennial timescales since the Last Deglaciation (~13.5 ka). Climatic variations since the Last Deglaciation (~13.5 ka) were reconstructed using OSL dating, radiocarbon dating, elemental geochemical characteristics, grain size, total organic carbon and magnetic susceptibility. During the Last Deglaciation (13.5–11.7 ka), the climate appeared cold and dry, dominated by strong aeolian activity. During the Early to the beginning of the mid-Holocene (11.7–7 ka), the climate experienced frequent oscillations between cold-dry and warm-humid conditions, two remarkable cold events occurring around 8.9 and 8.2 ka. During the Holocene Climatic Optimum (7–4 ka), the climate was warm and humid. During the Late Holocene (4–0 ka), the climate began a gradual shift toward colder and drier conditions between 4 and 2 ka, but it was still overall warmer and more humid than the Early Holocene baseline. Since ~2 ka, the cold-dry trend further strengthened, accompanied by a resurgence of aeolian activity in the QLB. Climate changes along the East Asian monsoon margin in the QLB were controlled by the interplay between the East Asian summer monsoon and the East Asian winter monsoon.