Biogenic methane from abyssal brine seeps at the base of the Florida escarpment

Journal Article · Thu Aug 01 04:00:00 EDT 1991 · Geology; (United States)

DOI:https://doi.org/10.1130/0091-7613(1991)019<0851:BMFABS>2.3.CO;2· OSTI ID:5920342

Martens, C S; Chanton, J P; Paull, C K ^[1]

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1. Univ. of North Carolina, Chapel Hill (United States)

Dissolved methane is present at concentrations exceeding 10mM in the pore waters of sulfidic, salt-brine-enriched sediments underlying chemosynthetic communities at the base of the Florida escarpment. Light hydrocarbon samples were obtained from brine seep sediments by means of an in situ probe and push cores deployed by the deep submersible Alvin. Pore-water methane had a {delta}{sup 13}C value of {minus}83.3 {plus minus}7.0 (Peedee belemnite, N = 17), contained < 1.3% modern carbon, and was enriched over ethane concentrations by 10{sup 3} to 10{sup 5}; these results all indicate a fossil, biogenic carbon source within the Florida platform. Methane-rich brine fluids arriving at seep sites are depleted in dissolved sulfate, although they have been diluted twenty-fold with sulfate-rich seawater during transit. It appears that sulfate reduction and methano-genesis are important processes within the platform.

• OSTI ID: 5920342
• Journal Information: Geology; (United States), Journal Name: Geology; (United States) Vol. 19:8; ISSN GLGYB; ISSN 0091-7613
• Country of Publication: United States
• Language: English

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03 NATURAL GAS
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58 GEOSCIENCES
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ALKANES
BRINES
CARBON 13
CARBON ISOTOPES
CHEMICAL REACTIONS
CONTINENTAL MARGIN
DEVELOPED COUNTRIES
DISSOLUTION
ECOLOGICAL CONCENTRATION
ENERGY SOURCES
ETHANE
EVEN-ODD NUCLEI
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FOSSIL FUELS
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GAS FUELS
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GEOLOGIC DEPOSITS
GROUND WATER
HYDROCARBONS
HYDROGEN COMPOUNDS
INTERSTITIAL WATER
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
METHANE
MINERAL RESOURCES
NATURAL GAS
NATURAL GAS DEPOSITS
NORTH AMERICA
NUCLEI
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
REDUCTION
RESOURCES
SEAWATER
SEDIMENTS
SEEPS
STABLE ISOTOPES
SULFATES
SULFUR COMPOUNDS
USA
WATER