Site 1084 is located off Lüderitz, near the currently most active coastal upwelling cell of the Benguela region. This cell maintains a central position within the system and is believed to have remained active throughout the late Neogene, irrespective of latitudinal shifts of the South Atlantic high-pressure cell and associated southeasterly winds. Sediments retrieved from Site 1084 contained record contributions of organic carbon and biogenic opal. The high-resolution biostratigraphic framework developed at this site is therefore based on a combination of siliceous and calcareous microfossil datum events. Drilling at Site 1084 recovered a continuous sequence extending into the lower Pliocene (bottom age: ~4.7 Ma), with sediments accumulating at a mean rate of 13 cm/k.y. (Fig. 3A, Fig. 3B). Pleistocene sediments accumulated at a high rate of 18 cm/k.y., with peaks of 27 cm/k.y. between 0.8 and 1 Ma. The uppermost Pliocene was also characterized by high accumulation rates close to 17 cm/k.y. These two episodes of increased sedimentation rates at the Pleistocene revolution and during the latest Pliocene occur in association with two distinct depositional peaks of diatom skeletons: a Chaetoceros-rich interval in the Pleistocene part of the section and Thalassiotrix mat-like structures in upper Pliocene sediments.
Sites 1085, 1086, and 1087 were cored in the SCB, an area affected by highly seasonal and less intense upwelling conditions. Mean average sedimentation rates estimated from the calcareous microfossil-based biostratigraphy are close to 4 cm/k.y. for the three sites. Drilling at Site 1085 recovered a continuous sedimentary record from the present down to 16 Ma in the middle Miocene. The shallow-water Site 1086 penetrated late Miocene sediments but did not recover sediments younger than 1.6 Ma. Finally, Site 1087, the last site cored during Leg 175, was the only one to contain evidence of major stratigraphic discontinuities. These stratigraphic anomalies affected the lowermost 70 m of sediment; the overlying 530-m-long section maintained nearly continuous sedimentation from ~9 Ma to the present.
Common features of the three SCB sites are (1) an episode of increased sedimentation rate across the Miocene/Pliocene boundary between ~5 and 6 Ma, (2) the rare presence or absence of siliceous microfossils in sediments older than 3 Ma, and (3) the distinct presence of dinoflagellate cysts in the late Miocene.