Late Holocene coccolith assemblage data of sediment core GeoB8323-2 from the Benguela Upwelling System

Coccolith occurrences in sediment core GeoB 8323-2, from the Benguela Upwelling System off south-western Africa, were analysed to reconstruct the temporal changes in surface water conditions, upwelling intensity and associated productivity during the late Holocene (last 2.25ka BP). Absolute numbers of total coccolithophores are low throughout the core, reaching a maximum of 320 x 10^6 coccoliths/gram sediment around 770 years BP. Despite the low abundance of coccoliths, coherent patterns of a changing assemblage composition can be identified. These suggest a consistent paleoceanographic development of highly variable Late Holocene environmental change during the last three millennia. Phases of decreased upwelling in the Benguela Upwelling System are indicated by elevated abundances of Florisphaera profunda alongside reduced occurrence of Coccolithus pelagicus and C. braarudii from 2.25-2.00ka BP, ~ 1.00ka BP and during the last 200 years, also accompanied by a reduced species diversity. Sea surface temperatures estimated with a Gephyrocapsa-based transfer function are in the order of 18-20°C. These phases are intersected by periods of colder sea surface temperatures of 16-17°C and increased productivity, as indicated by an opposing trend for the aforementioned species. Given the climatological and oceanographical complexity of the area, deciphering a single driving mechanism for these changes proves difficult. Synchronous changes in the Antarctic sea ice extent, however, give credit to the conceptual model of latitudinal migration of the westerly wind belt and its interaction with the south-easterly trade winds as an important driver for oceanographic changes in the area.