Organic carbon, reduced sulfur, and iron in Miocene to Holocene sediments from the Oman and Beguela upwelling systems

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.

Ley 117 de 1913 (6 de diciembre) sobre tarifa de aduanas. Tarifa alfabetica, arreglada por el Ministerio de hacienda y aprobada por el Jurado de aduanas.

At head of title: Républica de Colombia.

1er. Congrès international de le̕nseignement du dessin, tenu à Paris en lH̕ôtel du cercle de la librairie, 117, Boulevard Saint-Germain, du 29 août au 1er septembre 1900.

At head of title: Exposition universelle internationale de 1900.

S. Res. 117 and S. Res. 124, prohibition of the Olympic Games in Beijing : hearing before the Committee on Commerce, Science, and Transportation, United States Senate, One Hundred Third Congress, first session, July 15, 1993.

Shipping list no.: 95-0082-P.

Overture to König Stephan, op. 117 /

Mode of access: Internet.

Benedictus sit Deus : für 4 Singstimmen, 2 Violinen, 2 Violen, Bass, 2 Flöten, 2 Hörner, 2 Trompeten, Pauken und Orgel ; K.117.

Ser.3, no.20 of Mozarts Sämtliche Werke. Reprint of Leipzig: Breitkopf & Härtel, 1876-1905.

2e sonate pour piano et violoncelle, op. 117

Mode of access: Internet.

Geschichte der Landschaft Samaria, von 722 vor Chr. bis 67 nach Chr.; eine historisch-critische Untersuchung.

Bibliography: p. [vii]-viii.

Physics 117 and 118; laboratory instructions and supplementary problems.

Mode of access: Internet.

Organizational maintenance repair parts and special tools lists for maintenance kit, electronic equipment, MK-722/URC (NSN 6625-00-082-4275).

"August 1978."

General support maintenance repair parts and special tools lists for maintenance kit, electronic equipment, MK-722/URC (NSN 6625-00-082-4275).

"July 1978."

Operator's, organizational, direct support, and general support maintenance repair parts and special tools lists (including depot maintenance repair parts and special tools) for shelters, electrical equipment S-280A/G, (NSN 5410-00-999-6022) and S-280B/G, (NSN 5410-00-117-2868).

"April 1978."

Operator's and organizational maintenance manual for teletypewriter sets AN/PGC-1 and AN/PGC-3 and teletypewriters TT-4A/TG, TT-4B/TG, TT-4C/TG, TT-335/TG, TT-537/G, TT-698/TG, TT-698A/TG, TT-698B/TG, TT-722/TG, and TT-722A/TG.

Includes index.