Hydroclimatic evolution of the southwestern Tibetan Plateau since the last glacial maximum inferred from multi-proxy data in Lake Zabuye

Abstract

Hydroclimatic variations on the Tibetan Plateau since the Last Glacial Maximum (LGM) are still debated. Here, we reconstructed climatic and hydrological variability in the southwestern Tibetan Plateau since the LGM using climate proxies based on molecular distributions of n-alkanes, hydrogen (δD) and carbon (δ¹³C) isotopic compositions of terrestrial n-alkanes from sediments, and oxygen isotopic composition (δ¹⁸O) of authigenic carbonate at Lake Zabuye. The impact of climatic and environmental factors on these multiple proxies was discussed, and the TraCE-21 ka simulation was employed to facilitate a comprehensive model-data comparison. Our findings indicate that the δD of nC₃₁ alkane in this lake was primarily influenced by temperature from the LGM to early deglaciation period, shifting to a predominance of precipitation influence from the Heinrich event 1 (H1) to the Holocene period. In contrast, the carbonate δ¹⁸O was found to be primarily governed by evaporative processes. Through comprehensive analysis of all proxies, we suggest that Lake Zabuye was dominated by the mid-latitude westerlies with cold and moist conditions from the LGM to early deglaciation. The H1 and Younger Dryas events were characterized by low temperatures and reduced precipitation due to the influence of the moderately intensified westerlies. The Indian summer monsoon (ISM) intensified during the Bølling/Allerød period, and its strength was comparable to that of the westerlies, resulting in plentiful rainfall and high evaporation. The ISM was dominant during the Holocene, characterized by abundant rainfall and high evaporation.