Anaerobic diagenesis within Recent, Pleistocene, and Eocene marine carbonate frameworks

Authors

  • FRANCIS J. SANSONE,

    1. Department of Oceanography, University of Hawaii at Manoa, 1000 Pope Road, Honolulu, Hawaii 96822, USA
    2. Hawaii Institute of Geophysics, University of Hawaii at Manoa, 1000 Pope Road, Honolulu, Hawaii 96822, USA
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  • GORDON W. TRIBBLE,

    1. Department of Oceanography, University of Hawaii at Manoa, 1000 Pope Road, Honolulu, Hawaii 96822, USA
    2. Hawaii Institute of Marine Biology, University of Hawaii at Manoa, 1000 Pope Road, Honolulu, Hawaii 96822, USA
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    • 1

      US Geological Survey, 677 Ala Moana Blvd, Suite 415, Honolulu, Hawaii 96813, USA.

  • CHRISTINE C. ANDREWS,

    1. Hawaii Institute of Marine Biology, University of Hawaii at Manoa, 1000 Pope Road, Honolulu, Hawaii 96822, USA
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  • JEFFREY P. CHANTON

    1. Department of Oceanography, Florida State University, Tallahassee, Florida 32306–3048, USA
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ABSTRACT

Porewaters from a variety of Recent, Pleistocene, and Eocene lithified marine carbonate frameworks displayed similar chemical characteristics: highly depleted concentrations of dissolved oxygen (>20 μM), elevated levels of dissolved methane (25-5000 nM), and near-seawater sulphate levels. These porewaters also had low pH values (7·5-7·9), and contained elevated concentrations of sulphide (4–10 μM), dissolved inorganic carbon (2·05–2·46 mM), and inorganic nutrients. Hydrocarbon composition data indicate that the methane is biogenic, whereas the methane δ13C values (–47·4 ± 2·7%0) suggest that it has been subject to oxidation. The porewater dissolved inorganic carbon δ13C values varied from –0·6 to –39%0, suggesting input of carbon dioxide from organic matter oxidation. We conclude that anaerobic diagenesis involving bacterial degradation of organic matter is a common process in lithified marine carbonates and hypothesize that it may be an important factor controlling their carbonate geochemistry.

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