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Samples for headspace analyses were taken from 12 depths in Hole U1394A; none were taken from cores that consisted largely of coarse-grained material. One sample (from Section 340-U1394A-9X-1) had a methane concentration of 4.7 ppm, but all other samples had levels between 1.9 and 3.3 ppm. No higher hydrocarbons were detected.

Twenty-nine samples were taken for X-ray diffraction (XRD) and carbonate analysis. XRD results fall into three groups. Samples from pelagic sediment intervals predominantly contain calcite and high-Mg calcite ± aragonite, together with minor volcanic phases (mostly plagioclase with lesser orthopyroxene and hornblende) and clay minerals that cannot be readily identified on the XRD pattern (Fig. F4A). Samples from volcanic-rich horizons contain dominant plagioclase and lesser amounts of orthopyroxene and hornblende, along with minor sedimentary carbonate (Fig. F4B). One tephra layer contains abundant smectite in addition to the volcanic minerals and background pelagic phases noted above (Fig. F4C; Table T2).

CaCO3 weight percent is much higher in the largely pelagic sections than in the largely volcanic turbidites, but the presence of 3.5–7.5 wt% CaCO3 in some of the latter indicates a significant biogenic component (Fig. F5A). Organic carbon concentrations in the pelagic sections are similar to those expected in this area (up to or exceeding ~1 wt%) and lower in the turbidite sections (<0.2 wt%) (Fig. F5B; Table T2).

It is not possible to collect meaningful pore water data from permeable turbidite and turbidite horizons, so pore fluid samples were largely taken from intervals dominated by pelagic carbonate. Alkalinity values increased from 3.3 mM in the uppermost section (340-U1394A-1H-3; 4.4 mbsf) to a consistent value of 11.5 mM at 132.8 mbsf before decreasing to 7.5 mM at the base of the hole (Fig. F6A). pH values remain relatively constant at 7.4–7.5 throughout the hole. Ammonia concentrations increase from ~0.1 mM in the uppermost sample to ~2.1 mM at 127.6 mbsf before decreasing to ~1.7 mM in the deepest sample at 175.6 mbsf (Fig. F6B). Of the major cations, calcium decreases from values close to bottom water in the uppermost sample to reach a minimum at 120 mbsf before increasing toward the bottommost sample (Fig. F6C), whereas magnesium shows a monotonic decrease in concentration with depth (Fig. F6D). Sodium and potassium concentrations exhibit a weak increase (Na) and decrease (K) with depth (Table T3). ΣS concentrations show a pattern similar to that of calcium (Fig. F6E). Chloride concentrations fluctuate within the normal range (540–580 mM) expected for pore water obtained from squeezing carbonate sediment. Overall, pore water data are consistent with diagenesis of carbonate-rich sediment with organic carbon concentrations that are typical of an open marine setting. The slight change in pore water concentrations in the deepest sediment may reflect nonsteady-state diagenetic conditions that may be due to waters advecting through the relatively permeable volcanic-rich turbidite that lies at the base of the hole; however, not all dissolved constituents necessarily support this idea, and such an assertion would require further analysis (Table T3).

Microbiological Sample 340-U1394A-17H-3, 140–150 cm, was taken after the piston core had been preloaded with a microsphere bag to assess potential surface contamination. A total of 20 g of sediment was taken for shore-based microbiological activity measurements and was stored at 0°C. A total of 4 g of sediment was taken for shore-based RNA analysis and stored at –80°C.