The biogenic portions of sediments contain rare to frequent diatoms, rare nannofossils, silicoflagellates, siliceous sponge spicules, and phytoliths, and traces of radiolarian and foraminifer fragments. Authigenic components are dominated by the presence of glauconite, dolomite, and iron sulfides. Detailed comparisons between the magnetic susceptibility record generated on the MST and high resolution color reflectance measured with the Minolta spectrophotometer demonstrated complete recovery of the sedimentary sequence down to 183 mcd, with gaps in the continuous record at 25 and 125 mcd. Calcareous microfossil abundance and preservation varies between the different groups and deteriorates with depth. Benthic foraminifers are abundant and well preserved down to 120 mbsf, calcareous nannofossils down to 130 mbsf, and planktonic foraminifers down to 150 mbsf.
Siliceous microfossils are abundant and well preserved throughout the entire section.
Both planktonic and benthic foraminifer assemblages display a major change at 52 mbsf. This change may represent a change in position of water masses at this location. Among these are moderately high levels of methane and carbon dioxide generated by in situ microbial activity. These postdepositional processes are strongly similar to those found at nearby Sites 1075 and 1076 on the Congo Margin. A high resolution study of interstitial water and headspace methane was conducted over the depth range at which a prominent seismic reflector exists to test whether this reflector is caused by methane hydrate.