Interstitial water (IW) samples from Hole 1133B were taken at a rate of one per core for the first five cores. As a result of poor recovery, further sampling was restricted to Cores 182-1133B-8X and 17X. No samples were taken from Hole 1133A. Samples were analyzed according to the procedures outlined in "Inorganic Geochemistry" in the "Explanatory Notes" chapter. The data are presented in Table T7 and Figures F13 and F14.
Salinity and chlorinity values increase with depth, reaching a maximum concentration of 41 and 662 mM, respectively, at 123.4 mbsf (Fig. F13). This increase of both values suggests that, as at the previous sites, a brine may exist below the cored interval.
As a result of the increasing salinity, the concentrations of Ca2+, Mg2+, K+, and Sr2+ generally increase with depth (Fig. F13). Calculation of the excess concentration normalized to chlorinity, however, shows that as much as 8.9 mM of Mg2+ are lost from the pore fluids at 123.4 mbsf. This depletion most likely results from recrystallization processes involving the uptake of Mg2+. As a result of opal-A dissolution, silica values increase with depth and reach a maximum of 702 µM at 123.4 mbsf. Iron occurs only in minor amounts; the highest concentration, 6.6 µM, was measured from 25.8 mbsf.
As a result of the increasing salinity with depth, sulfate concentration increases from 27.4 mM to a maximum concentration of 29.3 mM at 123.4 mbsf (Fig. F14). Normalization of the SO42- concentration to Cl- shows that as much as 4.8 mM of sulfate has been removed by a depth of 123.4 mbsf. The relatively small increases in alkalinity suggest that most of the 9.6 mM of alkalinity, which should have been produced by sulfate reduction, was precipitated as calcite or dolomite.
As with the IW samples, only the first five cores and Cores 182-1133B-8X and 13X were sampled. The recovered samples show a considerable change in the ratio of low-Mg calcite (LMC) to high-Mg calcite (HMC) ratio (Table T8, also in ASCII format), which is possibly a result of facies changes. However, because of the slow sedimentation rate, even slow diagenetic changes may cause a considerable change in the LMC/HMC ratio (Table T8).