Hydrothermal and eco-environmental evolution on the southeastern Chinese Loess Plateau since the last deglaciation: evidence from terrestrial mollusk records.

The ongoing global warming is altering hydrothermal patterns and eco-environments. However, it is unclear how they would respond under a natural warming scenario. Terrestrial mollusks in loess-paleosol sequences could serve as natural biological archives to explore this issue. 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 overall biodiversity increased gradually during the last deglaciation (∼19.0–11.5 ka BP), which was accompanied with the shift from cold-dry to warm-humid climate. Moreover, the mollusk communities reacted to Heinrich event 1 (H1) cooling. In the early-middle Holocene (∼11.5–5.5 ka BP), mollusk communities were dominated by the thermo-humidiphilous species, characterized by stable community composition, increased species richness and evenness with warm-humid climate. Thereafter, there was a noticeable decrease in species diversity and increase in the cold-aridiphilous species in the mid-late Holocene (∼5.5–0 ka BP), associated with a gradual shift towards a cold-dry climate. On the whole, it is noteworthy that the count of thermo-humidiphilous species increased remarkably at ∼16 ka BP, which is synchronous with a significant increase in the Northern Hemisphere summer insolation. Interestingly, this change of terrestrial mollusks preceded the formation of the Holocene paleosol at ∼8 ka as indicated by the pronounced increase in magnetic susceptibility and decrease of mean grain size. This suggests that the substantial East Asian summer monsoon (EASM) precipitation 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 last deglaciation. Altogether, this provides crucial geological background evidence for exploring the potential regional hydrothermal and biodiversity responses to global warming in the near future. • Paleoclimate and eco-environment on the southeastern Chinese Loess Plateau since the last deglaciation were reconstructed. • Mollusk biodiversity responded to climate fluctuations by adjusting community stability, richness, and evenness. • The substantial East Asian summer monsoon precipitation lagged the onset of deglacial warming for ∼8 ka. [ABSTRACT FROM AUTHOR]