At Site 1126, in addition to routine monitoring of hydrocarbon gases for safety, analyses were conducted for inorganic carbon, total carbon, nitrogen, and sulfur. The analytical procedures are described in "Organic Geochemistry" in the "Explanatory Notes" chapter.
At Site 1126, concentrations of volatile hydrocarbons were routinely determined from every core using the standard ODP headspace sampling procedure (Table T6). Only low concentrations of methane and ethane are present. From the surface to a depth of 236 mbsf, the concentration of methane varies between 4.6 and 13.6 ppm. Below 253.7 mbsf, methane concentrations are between 2 and 5 ppm and most samples have <3 ppm. Ethane at concentrations from 1.1 to 2.7 ppm was present in five samples between 186.5 and 236 mbsf, but was not detected at greater depths. One gas pocket observed in the core at 97.3 mbsf and sampled by the vacutainer method directly through the core liner had 32 ppm methane and 1 ppm ethane.
Inorganic carbon concentrations were converted to calcium carbonate percentages (see "Organic Geochemistry" in the "Explanatory Notes" chapter). In the upper 116 mbsf the carbonate content is uniformly high at 80 to 91.2 wt% (Table T7; Fig. F14). From 116 to 254.2 mbsf the carbonate values are highly variable, ranging from 30.6 to 93.2 wt%. As a result of poor core recovery, no samples are available in the interval from 254.2 to 348.6 mbsf. Between 348.6 and 389.6 mbsf the carbonate content is again at high levels and falls within a narrow range of 79.5 to 90.0 wt%. Low carbonate values (0.4-0.6 wt%) occur at the base of Hole 1126D from 406.4 to 454.5 mbsf, except for one sample at 409.3 mbsf with a carbonate content of 69.3 wt%.
Organic carbon (Corg) is low throughout the section except for the deepest sample from Hole 1126D, which has 1.3 wt% organic carbon (Table T7; Fig. F14). All other organic carbon values fall within the range of 0 to 0.8 wt% at Site 1126. In the upper 100 mbsf of sediment at Hole 1126B, Corg decreases from 0.8 wt% in near-surface sediments to <0.2 wt% in deeper samples. Corg values for most samples in Holes 1126B and 1126D below 100 mbsf are <0.2 wt%. As a result of low organic carbon contents, no samples were analyzed for Rock-Eval parameters.
Only seven samples have measurable concentrations of nitrogen (0.04-0.10 wt%) (Table T7). Sulfur content varies from 0 to 1.62 wt% (Table T7). From the surface to 54.5 mbsf sulfur ranges from 0.1 to 0.3 wt%. Below 57.5 mbsf in 1126B sulfur is mostly below detection level with a few samples having 0.1 to 0.2 wt% sulfur. In Hole 1126D sulfur is below detection level until the base of the hole where values from 0.1 to 1.6 wt% were measured.