40ka以来苏拉威西海沉积粒度记录OA北大核心CSCDCSTPCD

The Indo-Pacific Warm Pool is among the most active regions for ocean-atmosphere and ocean-land interactions globally,serving as a crucial site for global material and energy exchange.The Indonesian throughflow(ITF)serves as the primary low-altitude pathway connecting the Pacific and Indian Oceans,playing a significant role in regulating global climate change.Previous studies have used various proxies,including stable oxygen and carbon isotope ratios(δ18O and δ13C)of marine authigenic carbonates and elemental ratios of terrigenous compo-nents,to reconstruct ITF strength and water-mass properties,yielding substantial results.However,the current un-derstanding of the ITF remains largely confined to the upper ocean layer,with limited knowledge of intermediate-and deep-ocean currents.To bridge this gap,this study analyzed the grain size compositions of 446 sediment sam-ples from core MD98-2178,located off the northeastern coast of Borneo,spanning the last 40 ka.End-member(EM)modeling algorithms were applied to the grain size data to decompose the sedimentary components.The results show that a two-EM model accounts for 90%of grain size variability.Over the past 40 ka,the fine EM(EM1)to coarse EM(EM2)ratio(EM1/EM2)has exhibited consistent variation with the sortable silt(SS)record,reflecting fluctuations in deep bottom current velocity.Further comparison of the EM2 and SS grain size records with δ18O data from the Greenland and Antarctic(Maud)ice cores,alongside local precipitation and sea-level changes,sug-gests that the grain size EM variations in the study area are mainly driven by changes in the local current intensity and not by precipitation-driven weathering and denudation in the source region.