Planktonic foraminiferal geochemistry and assemblage data from sediment core CDH-89 (western equatorial Atlantic) during the penultimate deglaciation@en

We apply a multi-proxy approach to marine sediment core CDH-89 (western equatorial Atlantic, WEA) to investigate ITCZ variability during the penultimate deglaciation. Planktonic foraminiferal assemblages were used to calculate the RN/Gg ratio, defined as %Neogloboquadrina / (%Neogloboquadrina + %Globigerina glutinata), providing insights into upper-ocean structure. We further reconstructed surface hydrography using a suite of oxygen-isotope–based proxies, including Neogloboquadrina dutertrei δ¹⁸O, Globigerinoides ruber (white, sensu stricto) δ¹⁸O, and the interspecies gradient Δδ¹⁸O (N. dutertrei – G. ruber). In addition, we estimated seawater isotopic composition (δ¹⁸O_SW) for both species (N. dutertrei δ¹⁸O_SW and G. ruber δ¹⁸O_SW), as well as the interspecies difference Δδ¹⁸O_SW (N. dutertrei – G. ruber), to infer past salinity variations. Sea-surface temperature was reconstructed using N. dutertrei Mg/Ca-derived calcification temperatures, and we calculated the interspecies temperature gradient ΔTemperature (N. dutertrei – G. ruber) to provide additional constraints on upper-ocean thermal structure.本研究以大西洋西部赤道海域（western equatorial Atlantic, WEA）CDH-89深海沉积岩芯为研究对象，采用多代用指标法探究倒数第二次冰消期的热带辐合带（Intertropical Convergence Zone, ITCZ）变化。研究通过浮游有孔虫组合计算得到RN/Gg比值，该比值定义为新拟抱球虫属百分比与（新拟抱球虫属百分比+胶粘抱球虫（Globigerina glutinata）百分比）的比值，以此揭示上层海洋结构特征。本研究进一步基于一系列氧同位素代用指标重建表层水文状况，涵盖杜氏新拟抱球虫（Neogloboquadrina dutertrei）δ¹⁸O、狭义白色型红拟抱球虫（Globigerinoides ruber (white, sensu stricto)）δ¹⁸O，以及二者的属间氧同位素梯度Δδ¹⁸O（杜氏新拟抱球虫-红拟抱球虫）。此外，本研究还估算了两种有孔虫对应的海水同位素组成（δ¹⁸O_SW），即杜氏新拟抱球虫海水氧同位素δ¹⁸O_SW与红拟抱球虫海水氧同位素δ¹⁸O_SW，并计算二者的属间差值Δδ¹⁸O_SW（杜氏新拟抱球虫-红拟抱球虫），以此反演过去的盐度变化。本研究利用杜氏新拟抱球虫的Mg/Ca比值所指示的钙化温度重建海表温度，同时计算杜氏新拟抱球虫与红拟抱球虫的属间温度差ΔTemperature（杜氏新拟抱球虫-红拟抱球虫），为上层海洋热结构特征提供额外约束。