2. Study the productivity history of upwelling off Angola and Namibia: Different types of upwellingdomal (Angola Basin), estuarine-influenced (off the Congo River), and coastal (off Lüderitz) were identified. These have different dynamics and histories. The outstanding feature regarding coastal upwelling is the late Pliocene diatom acme, seen between Walvis Ridge and Southern Cape Basin.
3. Determination of oceanographic changes that occur simultaneously in the Atlantic Ocean with the shifting of the Benguela Current: The mid-Pliocene productivity step from low to high diatom production off South Africa is, in essence, synchronous with the building of Northern Hemisphere ice masses. NADW production is affected, as seen in the carbonate record. Details will emerge from comparison of Leg 175 records with those from the Ceara Rise.
4. Determine if changes in the surface-current and upwelling patterns of the Benguela Current cause, or are related to, changes in climates of western South Africa: Clues to aridity history in Namibia and South Africa are contained in windblown dust within sediments recovered from Walvis Ridge and from the Northern Cape Basin. Upwelling history and aridity history will be matched in detail in these sites.
5. Examination of the effect, if any, of sea-level changes on sedimentation below the Benguela Current: Sea-level changes are recorded, in part, in a number of sediment properties, including gamma-ray activity, magnetic susceptibility, and color. Analysis of clay mineral content will be necessary to tie down the details.
6. Study early diagenetic processes in environments with very high organic carbon and opal contents: Chemical activity from the degradation of organic matter is extremely strong in most of the sediments recovered. Some of the most extreme values for ammonia and alkalinity ever measured were found at Site 1084. High methane and carbon dioxide values were ubiquitous. Authigenic mineral formation includes dolomite, which forms lithified beds regionally, affecting acoustic properties of sediments and seismic reflectivity.
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