Paleoprecipitation variations from LGM to early-middle Holocene on the southeastern Chinese Loess Plateau: evidence from land snail shells δ13C

Abstract

Here, we present stable carbon isotope of high-resolution fossil snail shell (δ¹³C_s) and soil organic matter (δ¹³C_org) from the Lingbao area on the southeastern Chinese Loess Plateau (CLP). Our results show that land snails have a dietary preference for C₃ plants which have dominated the studied area since 19 ka. Thus, their shell δ¹³C_s could be used to investigate the δ¹³C variations of C₃ plants and precipitation changes. The highest δ¹³C_s values with the smallest standard deviation (SD) reflect the intense water stress experienced by C₃ plants during the Last Glacial Maximum (LGM). In the last deglaciation, the δ¹³C_s values decreased gradually, indicating increased East Asian summer monsoon (EASM) precipitation. The lowest δ¹³C_s values occurred in the early-middle Holocene, suggesting that abundant precipitation enhanced favorable conditions for C₃ plants. Thereafter, the δ¹³C_s values increased again, which may be linked to elevated water stress for C₃ plants in the mid-late Holocene. Altogether, our study implied that there is a ∼300 mm mean increase of precipitation from the LGM to the early-middle Holocene on the southern CLP. Notably, the deglacial warming preceded the onset of EASM precipitation increase by ∼2 ka, as indicated by the fossil snail count and their δ¹³C_s values, and this decoupled phenomenon is more robust and convincing compared with previous work, because it is derived from the exact same geological archive.