Leg 208

Walvis Ridge

The Walvis Ridge, located in the southern Atlantic Ocean, is an ideal location for obtaining sediments suitable for reconstructing early Cenozoic variations in the thermal and chemical characteristics of S. Atlantic deep and surface waters. Paleogene and Neogene pelagic sediments with well-preserved microfossils were sampled from several locations on Walvis Ridge during DSDP Leg 74. However, because of poor recovery and drilling disturbance, many of the cores are unsuitable for high resolution studies.

The primary objective of Leg 208 is to APC/XCB core six sites in a depth transect targeting the upper Cretaceous and early Cenozoic pelagic chalks and oozes on Walvis Ridge. The proposed sites will be used to reconstruct in detail the paleoceanographic variations associated with several prominent episodes of early Cenozoic extreme climate change, including the late Paleocene Thermal Maximum, the early Eocene Climate Optimum,, and the early Oligocene Glacial Maximum. A fundamental objective is to characterize variations in water mass chemistry and circulation at different depths on orbital time scales in transition across these extreme climate states. The primary sites have a maximum penetration of 300 to 400 m in sediments with a water depth of 2500 to 4200 m. Chert is a possible drilling problem in lower Paleocene sediments. All sites will be logged.