The investigated interval from Sample 162-986D-28R-1, 30-36 cm (647.72 mbsf), through 45R-7, 29-36 cm (820.02 mbsf), belongs to lithologic Unit III (Fig. 3, Fig. 4, Fig. 5, Fig. 6). This unit is characterized by a relatively high sand content and the absence of dropstones. The primary lithologies are very dark gray to dark greenish gray silty clay with sand, clayey silt with sand, silty clay, and sandy silty clay. Biogenic calcareous sediment is present in trace to minor amounts throughout the unit. The biocarbonate consists largely of calcareous nannofossils in amounts up to 20% (by volume) and shows a slight increase downcore. Authigenic iron sulfides, primarily in the form of disseminated pyrite, are commonly present in minor amounts (Jansen, Raymo, Blum, et al., 1996).
The section from Sample 162-986D-46R-1, 29-36 cm (820.59 mbsf), to the base (60R-1, 29-36 cm, 955.32 mbsf) belongs to lithologic Unit IV (Fig. 3, Fig. 4, Fig. 5, Fig. 6). The transition from Unit III to Unit IV is marked by a decrease in sand- and silt-sized components. Subunit IVA (820.0-895.42 mbsf) is distinguished from the underlying sediments by increased magnetic susceptibility values and higher sand content. The sediments are predominantly composed of dark gray to black silty clay, with minor amounts of dark gray to black silty sand. Biocarbonate is present in minor amounts within this subunit (average 2.8%). Subunit IVB (897.62-955.32 mbsf) is distinguished from the overlying sediments by very low magnetic susceptibility values, a further decrease in sand content, and by the absence of biocarbonates. Subunit IVB is entirely composed of very dark to black silty clay. Silt- and sand-sized mineral components are less abundant than in Subunit IVA (Jansen, Raymo, Blum, et al., 1996).