Paleoclimatic and eco-environmental changes on the southeastern Chinese Loess Plateau since the last deglaciation: evidence from terrestrial mollusk records 

ABSTRACT  Terrestrial mollusks in loess-paleosol sequences serve as natural biological archives that document the evolution of paleoclimate and paleoenvironment. In this study, terrestrial mollusk records from two loess-paleosol profiles on the southeastern Chinese Loess Plateau (CLP) were analyzed. Our results show that the cold-aridiphilous species decreased and the mollusk communities expanded gradually during the last deglaciation (~19.0-11.5 ka BP), which was accompanied with the shift from cold-dry to warm-humid climate. In the early-middle Holocene (~11.5-6.5 ka BP), mollusk communities were dominated by the thermo-humidiphilous and warmth-loving species, characterized with stable community composition, increased species richness and evenness. Thereafter, there was a noticeable decrease in species diversity and increase in the cold-aridiphilous species in the late Holocene (~6.5-0 ka BP), associated with a gradual shift towards cold-dry climate. Notably, the count of thermo-humidiphilous and warmth-loving species increased remarkably at ~16 ka BP, which is synchronously with significant increase in the Northern Hemisphere summer insolation. Interestingly, this change of terrestrial mollusks preceded the rise in magnetic susceptibility and decrease of mean grain size for ~6.5 ka, suggesting that the East Asian summer monsoon (EASM) precipitation intensification lagged the onset of deglacial warming on the southeastern CLP. Furthermore, this delay may be attributed to the negative feedback of North Atlantic meltwater, which caused a decline in the intensity of Atlantic Meridional Overturning Circulation (AMOC) and inhibited the rapid enhancement of EASM precipitation during the initial of last deglaciation. Altogether, this provides crucial geological background evidence for exploring the regional hydrothermal responses to global climate change. Key words: Terrestrial mollusk; Loess-paleosol; Species diversity; Paleoclimate; Deglacial warming