As required by safety regulations, headspace gas analyses at Site 1095 were performed immediately upon recovery on one sample from each core, for a total of 60 analyses (Table T29). Inorganic carbon concentrations were measured on one sample per section for a total of 160 samples (Table T30), whereas total carbon was measured on a small subset of only 23 samples because of a limited supply of oxygen for elemental analyses.
Headspace methane concentrations did not exceed background levels in Hole 1095A, except for the slightly elevated value (125 ppm) obtained for the uppermost sample at ~1 mbsf (Table T29). Significant amounts of methane and trace amounts of ethane first appeared at ~170 mbsf in Hole 1095B (Table T29; Fig. F28). No heavier gases (C3+) could be detected by the natural gas analyzer, and the methane/ethane ratio remained stable throughout Hole 1095B (Table T29). The minor amounts of gas detected lie well within the limits for safety and pollution risk. The observed methane and ethane probably originated biogenically (Claypool and Kvenvolden, 1983), as indicated by the absence of heavier hydrocarbon gases and the downhole decrease of interstitial water sulfate concentration through the same interval (see "Inorganic Geochemistry").
Measured inorganic carbon and calculated calcium carbonate concentrations generally remain <0.16 wt% and <1.3 wt%, respectively, at Site 1095 (Table T30). A few thin intervals with carbonate contents of >1.3 wt% appear to correlate with intervals where foraminifers are observed (see "Biostratigraphy"). Total carbon and organic carbon concentrations also remain quite low, at <0.6 wt% and <0.5 wt%, respectively (Table T30). The small variations detected in inorganic and organic carbon at Site 1095 occurred both in laminated and bioturbated intervals and cannot be attributed to any specific sediment type. The generally low values show no obvious downhole trend and reflect low biological productivity of carbonaceous material, postdepositional dissolution of carbonate, and a high input of terrigenous sediment.