Late Neogene to Quaternary paleoproductivity of the western Indian Ocean and the eastern South Atlantic from coccolithophore assemblage and coccolith geochemistry

Abstract

Recent productivity reconstructions off South Africa have demonstrated the link between climate perturbations and coccolithophore productivity, especially over the glacial/interglacial cycles. These studies suggested enhanced productivity during glacial periods reaching maxima during terminations, and fluctuating in concert with orbital periodicities, suggesting that long-termed climatic variability have controlled the productivity patterns in this region. However most of these studies have focused on the highly productive regions of the northern and eastern Indian Ocean, and the Benguela upwelling area of the South Atlantic, whereas productivity reconstructions outside of these high-nutrient environments remain relatively scarce. Thus this research fills this gap by investigating sediment cores collected off Tanzania, the Natal Valley, the Mozambique Channel, and the Walvis Ridge. The strategic positions of the selected study sites allowed inter-basin and latitudinal comparisons, and accordingly a comprehensive productivity reconstruction of the western Indian Ocean and the eastern South Atlantic over the past 500 kyr, and across the Plio-Pleistocene transition. The coccolithophore assemblage composition and species distributions, preservation, and coccolith fraction geochemistry provided the groundwork for this reconstruction.