Hydroclimate Variations in Southeastern China During the Last Glacial Period: Insights from Multi-Proxy Stalagmite Records

During the Last Glacial Period, millennial-scale abrupt climate events were closely linked to the weakening of the Atlantic Meridional Overturning Circulation (AMOC). This weakening is also significantly associated with the increasing frequency of modern extreme climate events in the context of global warming. However, geological records detailing regional climate responses in southeastern China during these events, particularly the Heinrich cold events, remain limited. In this study, we analyze climate characteristics during the Heinrich Stadials (HS1-HS4) using multiple proxies from the stalagmite YXG01, which was collected from Yindi Cave in Huangshi City, Hubei Province (located in the lower reaches of the Yangtze River). The proxies include δ¹³C, δ¹⁸O, Mg/Ca, Sr/Ca, and Ba/Ca, and the dating spans from 47.47 to 11.92 ka BP. Our results show that during HS1-HS4, δ¹⁸O values in the stalagmite exhibit significant positive excursions, indicating a weakening of the East Asian summer monsoon (EASM). In contrast, δ¹³C, Mg/Ca, Sr/Ca, and Ba/Ca ratios show negative excursions. Furthermore, stalagmite growth rates significantly increased during these stadials, reflecting more favorable hydroclimatic conditions. On the orbital timescale, our δ¹⁸O variations also show inverse relationships with δ¹³C, Mg/Ca, Sr/Ca, and Ba/Ca ratios, suggesting that the stalagmite δ¹⁸O variations are anticorrelated with changes in rainfall in southeastern China. These findings support the hypothesis of a "tripole precipitation pattern" in monsoonal China, where stronger EASM periods correspond to more precipitation in North and South China and less in Central-East China, while weaker EASM periods show the opposite pattern. Nevertheless, during the Last Glacial Period, both on the orbital timescale and during Heinrich Stadials (HSs), the robustness of the tripole precipitation pattern in monsoonal China still needs to be further validated through the use of well-dated and reliable precipitation proxies.