Abstract

Over the past decades, paleoenvironmental studies in the Indian summer monsoon region have mainly focused on precipitation change, with few published terrestrial temperature records from the region. We analysed the distribution of isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) in the sediments of Lake Chenghai in southwest China across the Pleistocene-Holocene transition, to extract both regional hydrological and temperature signals for this important transition period. The lake level was reconstructed from the relative abundance of crenarchaeol in isoGDGTs (%cren) and the crenarchaeol'/crenarchaeol ratio. The %cren-inferred lake level identified a single lowstand (15.4-14.4 ka cal BP), while the crenarchaeol'/crenarchaeol ratio suggests a relatively lower lake level between 15.4-14.4 and 12.5-11.7 ka cal BP, corresponding to periods of weakened ISM during the Heinrich 1 and Younger Dryas cold event. A filtered TetraEther indeX consisting of 86 carbon atoms (TEX86 index) revealed that lake surface temperature was similar to present-day values during the last deglacial period and suggests a substantial warming of similar to 4 degrees C from the early Holocene to the mid-Holocene. Our paleotemperature record is generally consistent with other records in southwest China, suggesting that the distribution of isoGDGTs in Lake Cheng-hai sediments has potential for quantitative paleotemperature reconstruction.