Planktonic foraminifera faunal data and sea-surface temperatures for the Marine Isotope Stage (MIS) 18 to MIS 28 interval of IODP Site 339-U1387, Gulf of Cadiz@en

In this study we focus on IODP Site U1387 on the southern Portuguese margin to reconstruct surface water circulation and related plankton foraminifera ecosystem changes during the interval of Marine Isotope Stage (MIS) 28 to MIS 18 (1006-750 ka). Our planktonic foraminifera assemblages and SST reconstructions (foraminifera assemblages and UK'37 alkenone index) demonstrate warm, stable SST conditions during much of the interval due to persistent influence of subtropical gyre waters as indicated by the tropical-subtropical and Azores Current related foraminifera species and the periods with dominant sinistral coiling direction of the species Globorotalia truncatulinoides. Maximum interglacial SSTs were up to 2ºC warmer than at present in both summer and winter, with the exception of interglacial MIS 23 with SSTs ~1.5°C colder than in the other interglacials. The relative warm conditions were periodically interrupted by millennial-scale extreme cold events when polar species Neogloboquadrina pachyderma became abundant (>30%) and the SSTs, reconstructed from the foraminifera assemblage data, dropped below 10°C in summer and 5 °C in winter.本研究聚焦葡萄牙陆缘南部的国际大洋发现计划（Integrated Ocean Drilling Program, IODP）U1387站位，旨在重建海洋同位素阶段（Marine Isotope Stage, MIS）28至MIS 18（距今1006~750 ka）期间的表层水循环及其相关的浮游有孔虫（planktonic foraminifera）生态系统变化。本研究通过浮游有孔虫组合与海表温度（Sea Surface Temperature, SST）重建结果——涵盖浮游有孔虫组合与UK'37烯酮指数（UK'37 alkenone index）——发现，该时段多数时期的海表温度呈现温暖且稳定的状态，这一特征与亚热带环流圈水体的持续影响高度契合：热带-亚热带类群及与亚速尔海流相关的有孔虫物种，以及截锥圆辐虫（Globorotalia truncatulinoides）以左旋壳旋向占优势的时期均为此提供了佐证。除MIS 23间冰期的海表温度较其余间冰期低约1.5℃外，其余间冰期的最高海表温度在夏季和冬季均较现代高出可达2℃。相对温暖的环境会周期性被千年尺度极端冷事件打断，此时极地类群厚壳新方抱球虫（Neogloboquadrina pachyderma）丰度超过30%，基于浮游有孔虫组合数据重建的海表温度在夏季降至10℃以下、冬季降至5℃以下。