(Table 2) Chemical composition of basalts from the DSDP Leg 74 Walvis Ridge transect

Five sites were drilled along a transect of the Walvis Ridge. The basement rocks range in age from 69 to 71 m.y., and the deeper sites are slightly younger, in agreement with the sea-floor-spreading magnetic lineations. Geophysical and petrological evidence indicates that the Walvis Ridge was formed at a mid-ocean ridge at anomalously shallow elevations. The basement complex, associated with the relatively smooth acoustic basement in the area, consists of pillowed basalt and massive flows alternating with nannofossil chalk and limestone that contain a significant volcanogenic component. Basalts are quartz tholeiites at the ridge crest and olivine tholeiites downslope. The sediment sections are dominated by carbonate oozes and chalks with volcanogenic material common in the lower parts of the sediment columns. The volcanogenic sediments probably were derived from sources on the Walvis Ridge. […]