Headspace gas analysis was conducted as part of the standard protocols required for shipboard safety and pollution prevention monitoring. A total of 17 cores from Hole 1210A were evaluated (Table T10). The concentrations of CH4 were at background levels (range = 1.7-2.2 µL/L [ppmv]); no hydrocarbon gases higher than C1 were detected.
Carbonate determinations by coulometry were made for a total of 106 samples from Hole 1210A and 25 samples from Hole 1210B (Table T11). Samples were selected to provide a measure of the carbonate content within different units and to assess the influence of carbonate content on color reflectance. In addition, parts of Cores 198-1210A-14H and 20H within Unit II were sampled at 20-cm intervals to calibrate reflectance profiles with carbonate contents. The carbonate content ranges from 24 to 92 wt% (Table T11; Fig. F23) in Unit I. The low values in Unit I come from condensed intervals enriched in clay, notably in Core 198-1210A-13H at the base of the unit. There also is a general trend toward increasing carbonate with increasing depth in this unit (Fig. F23). A similar trend is discernible in Unit II, where the median value for the carbonate contents of the nannofossil ooze is 95.1 wt%. Again the low values, including the minimum of 1.3 wt% for Sample 198-1210A-23H-6, 71 cm, correspond to clay-rich condensed intervals. The nannofossil ooze in Unit III possesses uniformly high carbonate contents (mean = 96.7 wt%).
Elemental concentrations of C, H, N, and S were measured for a few samples in Unit I (Table T12). The contents of organic carbon were low in all samples and decreased with depth. Their C/N ratios, when organic carbon was measured, were indicative of algal material. Sample 198-1210A-26H-CC, 1 cm, consists of brown-black blebs containing 27.7 wt% carbonate (Table T11) that are associated with pyritized burrows. However, it contains no organic carbon or sulfur (Table T12); XRD analysis of a decalcified sample indicates that the blebs are hydrated Ba/Mn oxide (romanechite: Ba0.65Mn5O10 · 1.3H2O).