Carbon and Carbonate Analyses, Leg 17

Abstract

Leg 17 sediments were analyzed for total carbon and acid-insoluble (organic) carbon using a LECO 70 Second Analyzer. The 3-cc sediment samples were first dried at 105° to 110°C and then ground to a homogeneous powder. The ground sediment was redried and two samples, a 0.1-g and a 0.5-g sample, were than weighed into LECO clay crucibles. The 0.5-g sample was acidified with dilute hydrochloric acid and washed with distilled water. The sample was then dried and analyzed for acid-insoluble carbon which is labeled in the table as "organic" carbon. The 0.1-g sample was analyzed for total carbon without further treatment. If the result showed less than 10% CaCθ3, an additional 0.5-g sample was analyzed for greater accuracy. The calcium carbonate percentages were calculated as follows: (% total C-% organic C) × 8.33 = % CaCθ3 Although other carbonates may be present, all acid-soluble carbon was calculated as calcium carbonate. All results are given in weight percent (Table 1). Precisions for the analyses are as follows: Total Carbon: (1.2 to 12%): ±0.2% (absolute variation) (0to 1.2%): ±0.04% (absolute variation) Organic Carbon: ±0.04% (absolute variation) Calcium Carbonate: (10 to 100%): ±2% (absolute variation) (0 to 10%): ±0.6% (absolute variation) Detailed descriptions of the technique and theory may be found in Bader, Gerard, et al. (1970) and Boyce and Bode (1972).

Jurassic through Early Cretaceous Sedimentation History of the Central Equatorial Pacific and of Sites 800 and 801

“…There is approximately 2% FeMn-oxide present as coarse-silt-sized particles and stain. Carbonate analyses indicate about 85%-95% CaCO 3 in the chalks and 25%-50% CaCO 3 in the porcellanites (Bode, 1975;Keene, 1975). We estimate the bulk composition as 15% biogenic silica, 75% carbonate, and 8% clay.…”

“…The recovery indicates a general upward increase in carbonate from Cores 11R to 7R. A carbonate analysis of a typical siliceous limestone (Sample 307-9R-1,148 cm) yielded 26% CaCO 3 (Bode, 1975). Thin-sections indicate that even the limestone intervals contained up to 40% radiolarians, now largely replaced by micrite or infilled by microcrystalline quartz or chalcedony (Sample 7R-1,59-61 cm).…”

“…The light-tan siliceous limestones are bioturbation-homogenized with faint banding and gray chert or porcellanite nodules. Carbonate analyses average from 20% (Site 305) to 45% (Site 306) (Bode, 1975), and the calcareous-rich porcellanites are about 50% CaCO 3 (Keene, 1975). About a third of the radiolarians are silica-or calcitefilled molds; the rest are partially replaced ghosts.…”

“…Carbonate contents for the Valanginian through Barremian range from 95%-31%, averaging about 90% for the light grayish limestone and about 50% for clay-rich intervals (Bode, 1973). Incorporating the thin-section and core observations, bulk composition of the Site 167 sediments is estimated as 80% CaCO 3 , 15% clay, and 5% biogenic silica.…”

Data Report: Carbon and Carbonate Contents of the Cenomanian-Turonian Sediments from Hole 869B (Leg 143): Comparison with Other Deep Basins from Central and Northwestern Pacific Ocean

“…At Sites 166 and 170 in the Central Pacific Basin, drilling recovered early Hauterivian-to-Turonian calcareous zeolitic mudstone and chert (Winterer, Ewing, et al, 1973). These sediments are devoid of organic matter (Bode, 1973).…”