34S of dissolved sulfate in Holes 1165A-1165C are shown in Figure F1. The 13C vs. depth of dissolved inorganic carbon and calcite nodules in Holes 1165A-1165C is shown in Figure F2.
Concentrations and stable isotope ratios of selected pore water constituents in Holes 1165A-1165C are given in Table T1. A plot of the concentrations vs. depth of dissolved sulfate, methane, alkalinity, and the 34S of dissolved sulfate in Holes 1165A-1165C are shown in Figure F1. The 13C vs. depth of dissolved inorganic carbon and calcite nodules in Holes 1165A-1165C is shown in Figure F2.
Analyses of pore water samples from Site 1165 (Shipboard Scientific Party, 2001) showed that dissolved sulfate concentrations in Hole 1165B decreases linearly, approaching zero at a depth of ~150 mbsf. Alkalinities are low and reach a maximum of 7.4 mM at a depth of 150 mbsf. The alkalinity maximum is matched by a minimum in calcium concentrations, also at 150 mbsf, with a steep calcium gradient (0.05 mM/m) continuing to greater depths. In the depth interval from 30 to 150 mbsf, methane concentrations are low but above background levels (10-400 ppmv in headspace or 2-90 µM in pore water). At depths greater than 150 mbsf, the residual methane content of the pore water increases rapidly, reaching residual (after core outgassing) values of 6-7 mM at a depth of ~300 mbsf.
The 34S of sulfate increases from 21
to 26 over the 0- to 150-mbsf interval. The dissolved inorganic carbon (DIC) in Holes 1165A-1165C is characterized by extreme negative 13C values, reaching a minimum of -56 at a depth of 150 mbsf. Below 150 mbsf, 13C of DIC rapidly shifts to more positive values, reaching a maximum of about -7 at ~550 mbsf (D. Schrag and K. Kryc, pers. comm., 2001).
The carbon and oxygen isotopic and mineralogical compositions of carbonate nodules are given in Table T2. Photographs of the nodules and layers are shown in core photographs in the Leg 188 Initial Reports volume (see "Core Descriptions" in O'Brien, Cooper, Richter, et al., 2001). The sampled calcite nodules or layers in Holes 1165B and 1165C occur over the depth range of 273 to 961 mbsf and have 13C values ranging from -48.1 to -8.2, generally subparallel with the DIC 13C curve. The 18O values of the authigenic carbonates in Holes 1165B and 1165C ranged from -1.5 to +4.6. Siderite nodules collected from Hole 1166A span a 1-m interval (296.5-297.6 mbsf) in Upper Cretaceous (Turonian) carbonaceous shales (organic carbon contents up to 5 wt%) near the base of the cored section on the Antarctic continental shelf in Prydz Bay. The nodules have 13C values ranging from -7.6 to -15.3 and 18O values of -0.7 to 3.2. There are no data on Cretaceous pore water to use to evaluate these nodules.
