These silty units are composed of quartz, feldspar, mica, clay, and chlorite with trace amounts of calcite, hornblende, pyroxene, epidote, and pyrite. Subunit IB is distinguished from Subunit IA by the presence of authigenic carbonate. The core from Hole 1036A contains just a few dolomite nodules. In the core from Hole 1036B, numerous dolomite and calcite nodules are found in the interval from 10.20 to 32.20 mbsf. Hydrothermal alteration also affected the preservation of microfossils in the cores.
Siliceous microfossils disappear at even shallower burial depths in all holes.
Subunit IC contains authigenic anhydrite as disseminated crystals, nodules, and cement, and is a distinctive alteration facies of the hydrothermal system. Lithologic Unit II is characterized by hemipelagic silty clays interbedded with silt to fine sand turbidites. It is subdivided into Subunit IIB , characterized by the occurrence of diagenetic carbonates, and Subunit IIC distinguished by the presence of anhydrite nodules and cement. For example, Hole 1036C contains abundant calcite cement above 40.9 mbsf and contains anhydrite, but no calcite, below 42.0 mbsf. Lithologic Unit IV .