Late Pleistocene Climate–Weathering Dynamics in Bohai Bay: High-Resolution Sedimentary Proxies and Their Global Paleoclimatic Synchronicity

Understanding the climate&ndash:weathering coupling mechanisms remains pivotal for interpreting global glacial&ndash:interglacial cycles, yet advancements have been constrained by the limited high-resolution sedimentary archives. The newly acquired BXZK2017-2 borehole (30.5 m core) from Bohai Bay provides an exceptional sedimentary sequence to investigate the Late Quaternary climate&ndash:weathering interactions. Through an integrated high-resolution chronostratigraphic framework (AMS 14C and OSL dating) coupled with multi-proxy sedimentological analyses (major element geochemistry and granulometric parameters), we reconstructed the chemical&ndash:weathering dynamics in the Bohai coastal region since the Late Pleistocene. Our findings revealed four distinct climate-weathering phases that correlate with the regional paleoenvironmental evolution and global climate perturbations: (1) enhanced weathering during mid-MIS3 to ~37.5 cal kyr BP (Chemical Index of Alteration (CIA): 55.9&ndash:62.2), corresponding to regional warming and strengthened summer monsoon circulation: (2) weathering minimum in late MIS3 through early&ndash:mid-MIS2 (37.5&ndash:14.8 cal kyr BP, CIA &lt: 55), marking the peak aridity before the Last Glacial Maximum: (3) maximum weathering intensity from mid-MIS2 to early MIS1 (14.8&ndash:3.34 cal kyr BP, CIA: 65&ndash:68), documenting the postglacial humidification driven by the intensified East Asian Summer Monsoon: (4) renewed weathering decline during the Neoglacial (3.34 cal kyr BP-present, CIA: 59&ndash:63), coinciding with the late Holocene cooling events. Remarkably, this study identifies a striking synchronicity between the CIA in marine drill cores and &delta:18O records derived from Greenland ice cores. Our results indicate that chemical weathering proxies from marginal sea sediments can serve as robust recorders of post-Late Pleistocene climate variability, establishing a new proxy framework for global paleoclimate comparative research.