Synergistic trade-off between desertification and lake evolution in the eastern Qinghai Lake region since the late Last Glacial Interstadial: Evidence from aeolian sediments

Aeolian sediments in the eastern Qinghai Lake region, China serve as sensitive paleoclimate archives, offering an ideal window into past environmental conditions. This study investigated the Dashuitang (QDST) profile in the eastern Qinghai Lake region by integrating sediment grain size, chroma, and magnetic susceptibility (MS) proxies to reconstruct the regional environmental evolution since the Last Glacial Interstadial and to investigate its relationship with the water level fluctuations of Qinghai Lake. Grain size end-member modeling analysis (EMMA) identified three end-members: end-member 1 (EM1) represented fine-grained material transported over longer distances through mixing processes, which could reveal the regional moisture conditions; end-member 2 (EM2) primarily consisted of coarse-grained material from nearby sources transported via saltation or creep, indicating the intensity of the winter monsoon; and end-member 3 (EM3) mainly reflected deposition from dust storm events controlled by regional low-altitude wind systems. In addition, the regional environmental sequence demonstrated coherence with other records, collectively elucidating the sub-orbital-scale dynamics of the Asian monsoon. The environmental sequence was divided into four principal phases on the basis of sedimentary characteristics and climatic responses: the late Last Glacial Interstadial, Last Glacial Maximum, Last Deglaciation, and Holocene phases. Additionally, the results of this study revealed that there is a close linkage between desertification and lake evolution in the eastern Qinghai Lake region. Since the Last Glacial Interstadial, desertification and lake evolution processes have generally exhibited a trade-off relationship, wherein lake level decline and desert expansion exhibited a direct positive feedback. However, during the early period of the Late Holocene (approximately 2.80–1.50 ka BP), a synergistic response pattern emerged, characterized by relatively high lake levels alongside moderate desert expansion, reflecting an asymmetric decoupling mechanism between the hydrological processes and aeolian dynamics during climatic transition periods. This study provides important insights for predicting the future evolution trends of lake-desert systems under climate change.