LATE GLACIAL AND HOLOCENE CLIMATE VARIABILITY OF THE SOUTHERN TIBETAN PLATEAU BASED ON A HIGH-RESOLUTION GRAIN-SIZE RECORD IN LAKE PEIKU CO

Lakes in the Tibetan Region are highly susceptible to climate change. The climate is influenced by the Westerlies, East Asian monsoon, Indian monsoon, and Siberian cold polar airflow. The position of the Intertropical Convergence Zone (ITCZ) over the southern plateau makes it sensitive to climate change and Indian monsoon variations. While the lakes in central Tibetan Plateau have experienced significant expansion and deepening since the late 1990s, the lakes in the southern Tibetan Plateau have decreased in size. These high mountain lakes are pivotal repositories of sediment history, and understanding their responses to climate dynamics is crucial in the context of global warming. However, not many studies have been carried out in the southern regions compared to the north. Peiku Co is an alpine lake located in the southern Tibetan Plateau that has experienced shrinkage since the past few decades. This study addresses the lacustrine sediment archives of Peiku Lake, utilizing a new high-resolution record of grain size analysis, and published geochemical data, and radioactive carbon dating, to reconstruct climate change over the Late-Glacial and Holocene. We conducted grain size distribution analysis for 352 samples of a ~7m core (PCO071B) using a Malvern Mastersizer 3000 laser particle sizer. Grain size analysis can reveal the hydrodynamic history with lake level changes due to evaporation, precipitation, and variations of inflow from melt in case of glacier fed lakes. The initial result of the grain size analysis shows the sediments are mostly comprised of silt and clay with the presence of some coarser grains (>250 mm) in sediments older than 15 ka BP and those dated 11ka BP to 13 ka BP. The presence of coarser sediment in the bottom of the core might indicate variations in the detrital input from glacial runoff. By analyzing the sediment archives of Peiku Co Lake, we aim to contribute valuable insights into the historical climate variations that have shaped the southern Tibetan Plateau. Understanding these variations is essential for predicting and managing the impact of ongoing global climate change on water resources and sensitive ecosystems in the region.