Controls on the preservation of buried organic matter in an anoxic coastal marine sediment

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:6135683

Haddad, R I ^[1]; Martens, C S ^[2]

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1. UNOCAL, Brea, CA (United States)
2. Univ. of North Carolina, Chapel Hill, NC (United States)

Previous work detailing the carbon budget for the upper meter of sediments at Station A-1, Cap Lookout Bight, N.C., indicates that of the 165 [+-] 20 mol C/m[sup 2]y buried below the sediment-water interface, 71 [+-] 14% survives remineralization on a ten-year time scale. Whether this high degree of preservation is due to the nature of the system or to the nature of the organic matter (OM) itself is of considerable interest to geochemists interested in either the dynamics of global element cycling or the prediction of ancient deposition of hydrocarbon-prone organic facies. Organic geochemical measurements have been made to evaluate and compare the carbon budget in terms of the biochemically recognizable carbon fraction (BRC). Results from this study show that the BRC fraction accounts for < 30% of the TOC in the 0--5cm surface interval and that this decreases to 18 [+-] 8% by a depth of 100cm. In terms of carbon preservation, it appears that approximately 50% of the buried BRC fraction survives early diagenesis. Evaluation of the CHS fraction indicates that aside from some possible incorporation of labile biochemicals within the fulvic acids, elemental analysis and CP/MAS 13C-NMR results support a marine/algal/bacterial source for the bulk of the humic organic matter. Comparative microbial sulfate reduction studies employing independent manipulation of both the organic matter and sulfate oxidant concentrations were performed in order to evaluate the effect of inorganic oxidant availability on organic matter preservation. The authors conclude that while the buried organic matter is predominantly derived from microbially-reactive algal/bacterial sources, pre-depositional diagenetic processes effectively transform it into a microbial unreactive form.

• OSTI ID: 6135683
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

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02 PETROLEUM
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58 GEOSCIENCES
580000* -- Geosciences
CARBON CYCLE
CHEMICAL COMPOSITION
CHEMISTRY
COASTAL WATERS
DEPTH
DEVELOPED COUNTRIES
DIAGENESIS
DIMENSIONS
GEOCHEMISTRY
GEOLOGIC HISTORY
HYDROCARBONS
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NORTH AMERICA
NORTH CAROLINA
ORGANIC COMPOUNDS
ORGANIC MATTER
SEDIMENTS
SURFACE WATERS
USA