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Emeis, Kay-Christian; Morse, John W; Mays, Linda L (1991): Organic carbon, reduced sulfur, and iron in Miocene to Holocene sediments from the Oman and Beguela upwelling systems [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.757160, Supplement to: Emeis, K-C et al. (1991): Organic carbon, reduced sulfur, and iron in Miocene to Holocene upwelling sediments from the Oman and Benguela upwelling systems. In: Prell, WL; Niitsuma, N; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 117, 517-527, https://doi.org/10.2973/odp.proc.sr.117.155.1991

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Abstract:
We examined sediments from Neogene and Quaternary sections of the Benguela and Oman upwelling systems (DSDP Site 532, ODP Sites 723 and 722) to determine environmental and geochemical factors which control and limit pyrite formation in organic-carbon-rich marine sediments.
Those samples from the upwelling sites, which contained low to moderate concentrations of total organic carbon (0.7%-3%), had C/S ratios typical of normal marine sediments, i.e., around 2.8. In these sediments, TOC availability probably limited pyrite formation. Results that do not conform with accepted models were found for the sediments high in TOC (3^0-12.4%). The organic matter was of marine origin and contained considerable pyrolytic hydrocarbons, a fact that we take as a sign of low degradation, yet significant concentrations of dissolved sulfate coexisted with it (> 5 mmol/L in the case of Sites 532 and 723). Detrital iron was probably not limiting in either case, because the degree of pyritization was always less than 0.65. Therefore, controls on sulfate reduction and pyrite formation in the organic matter-rich sediments do not appear to conform simply to generally accepted diagenetic models. The data from these thermally immature, old, and organic-rich marine sediments imply that (1) the total reduced sulfur content of organic-rich marine upwelling sediments rarely exceeds an approximate boundary of 1.5% by weight, (2) the C/S ratio of these sediments is not constant and usually much higher than the empirical values proposed for marine sediments. We conclude that sedimentary pyrite formation in upwelling sediments is limited by an as yet unknown factor, and that caution is advised in using C/S ratios and C vs. S diagrams in paleoenvironmental reconstructions for organic-rich sediments.
Project(s):
Deep Sea Drilling Project (DSDP)
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: 4.976433 * Median Longitude: 42.641033 * South-bound Latitude: -19.744300 * West-bound Longitude: 10.518800 * North-bound Latitude: 18.051800 * East-bound Longitude: 59.795300
Date/Time Start: 1980-08-20T00:00:00 * Date/Time End: 1987-09-17T04:30:00
Event(s):
75-532B * Latitude: -19.744300 * Longitude: 10.518800 * Date/Time: 1980-08-20T00:00:00 * Elevation: -1331.0 m * Penetration: 291.3 m * Recovery: 264.9 m * Location: South Atlantic * Campaign: Leg75 * Basis: Glomar Challenger * Method/Device: Drilling/drill rig (DRILL) * Comment: 72 cores; 284.3 m cored; 7 m drilled; 93.2 % recovery
117-722A * Latitude: 16.621800 * Longitude: 59.795300 * Date/Time Start: 1987-09-07T02:30:00 * Date/Time End: 1987-09-08T12:00:00 * Elevation: -2034.0 m * Penetration: 280 m * Recovery: 225.98 m * Location: Arabian Sea * Campaign: Leg117 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 29 cores; 280 m cored; 0 m drilled; 80.7 % recovery
117-723A * Latitude: 18.051800 * Longitude: 57.609000 * Date/Time Start: 1987-09-15T11:45:00 * Date/Time End: 1987-09-17T04:30:00 * Elevation: -806.0 m * Penetration: 432.3 m * Recovery: 298.29 m * Location: Arabian Sea * Campaign: Leg117 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 46 cores; 432.3 m cored; 0 m drilled; 69 % recovery
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
3 datasets

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Datasets listed in this publication series

  1. Emeis, K-C; Morse, JW; Mays, LL (1991): (Table 1) Organic carbon, reduced sulfur and iron in sediments of DSDP Hole 75-532B. https://doi.org/10.1594/PANGAEA.757157
  2. Emeis, K-C; Morse, JW; Mays, LL (1991): (Table 3) Organic carbon and reduced sulfur in sediments of DSDP Hole 117-722A. https://doi.org/10.1594/PANGAEA.757159
  3. Emeis, K-C; Morse, JW; Mays, LL (1991): (Table 2) Organic carbon, reduced sulfur and iron in sediments of DSDP Hole 117-723A. https://doi.org/10.1594/PANGAEA.757158