Planktonic foraminifera of IODP Site 306-U1314@en

Surface water conditions at the Integrated Ocean Drilling Program (IODP) Site U1314 (Southern Gardar Drift, 56° 21.8' N, 27° 53.3' W, 2820 m depth) were inferred using planktic foraminifer assemblages between Marine Isotope Stage (MIS) 19 and 11 (ca. 800-400 ka). Factor analysis of the planktic foraminifer assemblages suggests that the assemblage was controlled by three factors. The first factor (which explained 49% of the variance) is dominated by transitional and subpolar species and points to warm and salty surface water conditions (Atlantic water). The second factor (37%) is dominated by Neogloboquadrina pachyderma sin and has been associated with the presence of cold and low saline surface waters (Arctic water). Finally, the third factor (9%), linked to a significant presence of Turborotalita quinqueloba, reflects the closeness of the Arctic front (the boundary between Atlantic and Arctic water). The position of the Arctic and Polar fronts has been estimated across the glacial-interglacial cycles studied according to planktic foraminifer abundances from Site U1314 (and their factor analysis) combined with a synthesis of planktic foraminifer and diatom data from other North Atlantic sites. Regarding at the migrations of the Arctic front and the surface water masses distribution across each climatic cycle we determined five phases of development. Furthermore, deep ocean circulation changes observed in glacial-interglacial cycles have been associated with each phase. […]本研究依托综合大洋钻探计划（Integrated Ocean Drilling Program, IODP）U1314站位（南加达漂移区，北纬56°21.8′，西经27°53.3′，水深2820 m）的浮游有孔虫（planktic foraminifer）组合，重建了海洋同位素阶段（Marine Isotope Stage, MIS）19至11（约80万~40万年前）期间的表层海水环境。对浮游有孔虫组合的因子分析（factor analysis）结果表明，该组合受三大主控因子调控：第一因子解释了49%的方差，以过渡型与亚极地带种占主导，指示暖盐型表层水环境（大西洋水团）；第二因子解释37%的方差，以厚新抱球虫左旋型（Neogloboquadrina pachyderma sin）为优势类群，与冷低盐表层水环境（北极水团）的出现相关；第三因子解释9%的方差，与五叶小抱球虫（Turborotalita quinqueloba）的显著富集存在关联，反映了北极锋——大西洋与北极水团的分界——的位置邻近。本研究结合U1314站位的浮游有孔虫丰度数据及其因子分析结果，辅以其他北大西洋站位的浮游有孔虫与硅藻（diatom）数据开展综合分析，估算了所研究冰期-间冰期旋回内北极锋与极锋的位置。针对各气候旋回中北极锋的迁移过程与表层水团分布特征，本研究划分出5个发育阶段。此外，观测到的冰期-间冰期旋回深海环流变化，均与上述各阶段存在关联。[...]