Concentrations of volatile hydrocarbon gases were not measured at Site 1196 because of the generally porous nature of the strata.
Poor core recovery and the dolomitized and highly indurated lithologies encountered during drilling at Site 1196 prevented pore water sampling.
Ninety-three sediment samples were analyzed for carbonate mineralogy from Site 1196 (Fig. F43; Table T9). Carbonate mineralogy in the recovered lithologies varies greatly from pure dolostones to pure limestones. Lithologic Unit IA, the upper 180 m of section, is predominantly dolomite with two relatively thin limestone units between 30 and 50 mbsf and 65 and 75 mbsf. In contrast, lithologic Unit II, from 180 to 350 mbsf, is a nearly pure limestone unit. Lithologic Subunit IIIA is also primarily calcite (Fig. F43; Table T9). Only one sample over the depth interval from 350 to 400 mbsf was found to contain significant dolomite (>40 wt%). Lithologic Subunits IIIB, IIIC, and IIID and Unit IV are all heavily to completely dolomitized. Only at the base in the lowermost sample is calcite again present.
Calcium carbonate (CaCO3) contents at Site 1196 range from ~0.5 to 108 wt%. Measurements are calibrated for calcite; thus, the presence of dolomite can generate values >100 wt%. Total organic carbon (TOC) content is mostly near zero at Site 1196 except between ~185 and 260 mbsf (up to >0.3 wt%) and from ~640 mbsf to total depth (up to >0.8 wt%). These relative TOC enrichments coincide with reduced carbonate contents, particularly in the lower horizon. Note that TOC content values from Rock-Eval pyrolysis and carbon-nitrogen-sulfur analyses provide similar profiles but with different values (Fig. F44; Tables T10, T11).
Hydrogen index (HI) values at Site 1196 range from 0 to 300 mg HC/g TOC (Fig. F44; Table T11), but the low TOC content of some intervals limits the reliability of these values. We performed duplicate and triplicate analyses on low TOC samples with a resulting error of <10%. Oxygen index (OI) values vary from 0 to 65,200 mg CO2/g TOC (Table T11). The high OI values are attributed to the thermal degradation of carbonate minerals during pyrolysis and are not considered in this interpretation. Tmax values range from 311° to 439°C (Table T11), although the most reliable values cluster between 400° and 420°C.
Total sulfur (S) content in Site 1196 sediments ranges from 0.0 to ~5.38 wt% (Fig. F44; Table T10), and its distribution is similar to that of TOC. C/N and C/S ratios (Fig. F44; Table T10) are compatible with interpretations of a marine-dominated environment of formation, although C/N ratios indicative of terrigenous organic matter input were observed in the basal lithologic unit.
Variations in the generally high CaCO3 content of sediments at Site 1196 mostly reflect variations in carbonate mineralogy (i.e., calcite or dolomite) and the ratio of biogenic carbonate to terrigenous sedimentation through time. Little to no organic matter was detected in Unit I. However, slightly higher TOC (up to >0.3 wt%) was measured between ~180 and 260 mbsf associated with an interval containing seagrass (see "Biostratigraphy and Paleoenvironments"). This organic matter is associated with slightly reduced CaCO3 contents, which may have resulted from dilution by detritus associated with the elevated TOC. On the other hand, the lack of organic matter in the overlying and underlying dolostone intervals may be a function of organic matter destruction during dolomitization.
The slightly elevated HI (average = ~171) and low C/N ratios through this interval are compatible with a marine origin for the organic matter, although the HI values are close to the boundary region between marine (Type II) and terrestrial (Type III) organic matter. Brackish and marine coastal plants and grasses are known to have a carbon isotope chemistry intermediate between more open marine plants and land plants (Hunt, 1996), which may explain the HI values in the boundary region between Types II and III organic matter. Of further interest are the two C/S values within this "seagrass" interval, which approach and fall within the slightly brackish water field (Fig. F44).
CaCO3 content (>105 wt%) indicative of dolostones was measured from ~413 to 628 mbsf, an interval that coincides with lithologic Subunits IIIB-IIID and the upper half of Unit IV (see "Lithostratigraphy and Sedimentology"). With this interval, TOC content is effectively zero (see "Biostratigraphy and Paleoenvironments"). From 628 mbsf, CaCO3 content displays a gradual decrease to a depth of ~640 mbsf (roughly lithologic Unit IV), with some variation. CaCO3 content variations exist within a section containing meter-scale cycles of dolostone with quartz overlain by dolostone with glauconite, rudstone, and iron-stained crusts (see "Lithostratigraphy and Sedimentology").
Below the interval of CaCO3 variations, CaCO3 content drops to near zero at ~663 mbsf and then gradually increases to ~40 wt%, corresponding to the quartz sandstones and claystones of lithologic Unit V. TOC content in Unit V is as high as 0.9 wt% and covaries with carbonate content. Hydrogen index values and C/N ratios are indicative of terrigenous organic matter input to the seafloor during this time, and C/S values suggest the deposition occurred in seawater. The highest S (5.38%) value thus far during Leg 194 was measured in this interval.
Concentrations of volatile hydrocarbon gases were not measured at Site 1199 because of the generally porous nature of the strata.
The dolomitized and highly indurated lithologies encountered during drilling on Site 1199 prevented pore water sampling.
Forty-six sediment samples were analyzed for carbonate mineralogy from Site 1199 (Fig. F45; Table T10). In lithologic Unit I from 0 to 152.2 mbsf, the only carbonate mineral present is dolomite. At the transition from lithologic Unit I to Unit II, the carbonate mineralogy changes to 100 wt% calcite. Dolomite remains low, between 0 and 20 wt%, through lithologic Unit IIA, although poor core recovery caused the samples to be widely spaced. For example, only three samples cover the interval from 169 to 265 mbsf. In lithologic Unit II, the mineralogy varies greatly. In general, dolomite is the most common mineral in the upper half of Subunit IIB, whereas calcite is dominant in the lower half.
Calcium carbonate (CaCO3) content at Site 1199 ranges from ~93 to 110 wt% (Fig. F46; Table T12). Measurements are calibrated for calcite; thus, the presence of dolomite can generate values >100 wt% (Fig. F46; Table T13).