Coccolith species abundances in ODP Site 1082 of the past 750 ka in the region of the Benguela Current (BC) system

Late Pleistocene coccolith data of ODP Site 1082 from the eastern South Atlantic off Namibia were analysed to document spatial and temporal changes in surface–ocean circulation, upwelling intensity, and associated productivity. The studied site is located on the continental slope close to prominent oceanographic features such as the coastal upwelling mixing area, the open oceanic realm, and the warm-water regime of the Angola Current. Highest numbers of total coccoliths up to >30x10⁹ coccoliths g⁻¹ sediment were observed during relatively warm periods characterised by decreased upwelling intensity. These elevated numbers of coccoliths are due to higher surface water temperatures and document a domain probably influenced by lower nutrient concentrations in an area where oceanic and filamentous water mix. In contrast, low numbers of coccoliths during glacial periods probably characterise time intervals of enhanced upwelling accompanied by a broad filamentous mixing area. Coccoliths of the genus Gephyrocapsa are the most abundant taxa in samples of Site 1082. Their occurrences are characterised by abrupt changes in the investigated time interval. In addition, Calcidiscus leptoporus, Pseudoemilinia lacunosa, and Reticulofenestra asanoi contribute a common part of the assemblage.对纳米比亚周边南大西洋东部海域的大洋钻探计划（Ocean Drilling Program, ODP）1082站位的晚更新世颗石（coccolith）数据开展分析，以揭示表层大洋环流、上升流强度及相关海洋生产力的时空变化特征。该研究站位位于大陆坡，邻近多处显著的海洋学特征：近岸上升流混合区、开阔大洋域以及安哥拉海流的暖水团体系。在上升流强度减弱的相对暖期，观测到总颗石丰度最高可达每克沉积物>30×10^9颗。此类颗石丰度升高的成因是表层水温升高，其指示的区域大概率受较低营养盐浓度影响，处于大洋水与丝状水团的混合地带。与之相反，冰期阶段的颗石丰度较低，这大概率对应上升流增强且伴随大范围丝状水团混合的时段。桥石藻属（Gephyrocapsa）颗石是1082站位样品中丰度最高的分类群，其产出在研究时段内呈现出显著的突变特征。此外，细孔盘星石（Calcidiscus leptoporus）、粒面假埃米利亚藻（Pseudoemilinia lacunosa）以及浅井网盾颗石（Reticulofenestra asanoi）均为该颗石组合中的常见组分。