Biogenic opal in Late Pleistocene sediments of ODP Leg 177 holes

Sediments in the southeast Atlantic sector of the Southern Ocean were cored during Ocean Drilling Program (ODP) Leg 177 to study the paleoceanographic history of the Antarctic region on short (millennial) to long (Cenozoic) timescales. Seven sites were drilled along a north-south transect across the Antarctic Circumpolar Current (ACC) from 41° to 53°S. The general goals of Leg 177 were twofold: (1) to document the biostratigraphic, biogeographic, and paleoceanographic history of the Paleogene and early Neogene, a period marked by the establishment of the Antarctic cryosphere and the ACC, and (2) to target expanded sections of late Neogene sediments, which can be used to resolve the timing of Southern Hemisphere climatic events on orbital and suborbital time scales (Gersonde, Hodell, Blum, et al., 1999, doi:10.2973/odp.proc.ir.177.1999). Closely spaced measurements of sedimentary physical properties were obtained from all cores recovered during Leg 177 using the ODP whole-round multisensor track. In addition, high-resolution diffuse color reflectance and resistivity measurements were collected on the Oregon State University Split Core Analysis Track. These whole-core and split-core measurements provide high-resolution proxy data sets for the estimation of biogenic and terrigenous mineralogy and mass flux. To assist investigators in calibrating these proxy data sets from sites located within the circum-Antarctic opal belt, samples from Sites 1093 (50°S) and 1094 (53°S) were analyzed for biogenic opal content.