10.1594/PANGAEA.714864
Moore, T S
T S
Moore
Murray, Richard W
Richard W
Murray
Kurtz, A C
A C
Kurtz
Schrag, Daniel P
Daniel P
Schrag
Stable carbon isotope ratios and the formation of dolomite in ODP Leg 175 sites
PANGAEA
2004
Composite Core
Leg175
Joides Resolution
Ocean Drilling Program (ODP)
1997-09-09T00:00:00/1997-09-21T00:00:00
en
Supplementary Publication Series of Datasets
10.1016/j.epsl.2004.10.015
7 datasets
application/zip
Creative Commons Attribution 3.0 Unported
We examine the link between organic matter degradation, anaerobic methane oxidation (AMO), and sulfate depletion and explore how these processes potentially influence dolomitization. We determined rates and depths of AMO and dolomite formation for a variety of organic-rich sites along the west African Margin using data from Ocean Drilling Program (ODP) Leg 175. Rates of AMO are calculated from the diffusive fluxes of CH4 and SO4, and rates of dolomite formation are calculated from the diffusive flux of Mg. We find that the rates of dolomite formation are relatively constant regardless of the depth at which it is forming, indicating that the diffusive fluxes of Mg and Ca are not limiting. Based upon the calculated log IAP values, log K(sp) values for dolomite were found to narrowly range between -16.1 and -16.4. Dolomite formation is controlled in part by competition between AMO and methanogenesis, which controls the speciation of dissolved CO2. AMO increases the concentration of CO3[2-] through sulfate reduction, favoring dolomite formation, while methanogenesis increases the pCO2 of the pore waters, inhibiting dolomite formation. By regulating the pCO2 and alkalinity, methanogenesis and AMO can regulate the formation of dolomite in organic-rich marine sediments. In addition to providing a mechanistic link between AMO and dolomite formation, our findings provide a method by which the stability constant of dolomite can be calculated in modern sediments and allow prediction of regions and depth domains in which dolomite may be forming.
Supplement to: Moore, T S; Murray, Richard W; Kurtz, A C; Schrag, Daniel P (2004): Anaerobic methane oxidation and the formation of dolomite. Earth and Planetary Science Letters, 229(1-2), 141-154
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13.0277777777777
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-19.6199444444444
Benguela Current, South Atlantic Ocean