CONCLUSIONS

Each of the four regions investigated during Leg 175 records distinct sedimentological and paleoceanographic regimes. The Congo Basin is a river-influenced hemipelagic environment, the Angola Basin is dominated by hemipelagic sedimentation, the Walvis Ridge and Basin record hemipelagic sedimentation with a strong upwelling signal, and the Cape Basin contains pelagic sediment that has a significant portion of shelf-derived sediment that predates the middle Miocene. Although much has been learned from studying the sediments along the southwest African margin during Leg 175, the following questions remain unanswered:

1. What is the stratigraphic significance of glauconite in the Lower Congo and Angola Basins? Glauconites have long been regarded as one of the best indicators of low sedimentation rates in marine settings (Odin and Matter, 1981; Amorosi, 1995). However, sedimentation rates within these regions range between 10 and 30 cm/k.y., which is higher than those at the Walvis Ridge and Cape Basin (see Giraudeau et al., Chap. 19, this volume).
2. How do the dolomites from the Angola Basin, Walvis Ridge, and Walvis Basin compare with other dolomites recovered during DSDP Leg 64 (Guaymas Basin; Curray, Moore, et al., 1982) and ODP Leg 112 (Peruvian margin; Suess, von Huene, et al., 1988)?
3. What is the stratigraphic and paleoceanographic significance of the laminated sediments in the Angola Basin?
4. What climatic signals do the "black" layers from the Walvis Ridge and Basin record?
5. Do the disconformities at Site 1087 represent major changes in paleoceanography?

Future work will address these questions by integrating the descriptive sedimentology and stratigraphy outlined in this report with geochemical, paleontological, and geophysical data acquired on board and by developing high-resolution stratigraphies to obtain a more detailed picture of the Benguela Current region since the middle Miocene.