A study of the chemistry of pore fluids and authigenic carbonates in methane seep environments: Kodiak Trench, Hydrate Ridge, Monterey Bay, and Eel River Basin

Gieskes, Joris M.; Mahn, Chris; Day, Shelley; Martin, Jonathan B.; Greinert, Jens; Rathburn, Anthony E.; McAdoo, Brian G.

doi:10.1016/j.chemgeo.2005.04.002

Cited by 107 publications

(65 citation statements)

References 34 publications

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“…These concretions appear to form at the interface of the sediment and underlying bedrock, and thus take on the appearance of exposed bedrock. This mode of occurrence is distinct from methane-derived carbonates from other seep environments (Bohrmann et al 1998;Michaelis et al 2002;Gieskes et al 2005;Niemann et al 2006), where sulfate penetration and AOM are limited to the upper sediment column. The occurrence of quartz sand cemented by 13 Fig.…”

Section: Subsurface Gas Pocketsmentioning

confidence: 95%

“…The occurrence and formation of carbonate minerals depleted in 13 C is common among marine methane seeps (Stakes et al 1999;Luff and Wallmann 2003;Gieskes et al 2005;Naehr et al 2007;Paull et al 2007), and is used as an indicator of seepage occurrence in the geologic record (Peckmann et al 1999;Schwartz et al 2003;Campbell 2006;Gontharet et al 2007). Carbonate minerals precipitate because of the high carbonate alkalinity associated with vigorous sulfate reduction common to methane seeps.…”

Section: Introductionmentioning

confidence: 99%

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Gas flux and carbonate occurrence at a shallow seep of thermogenic natural gas

et al. 2010

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The Coal Oil Point seep field located offshore Santa Barbara, CA, consists of dozens of named seeps, including a peripheral ∼200 m 2 area known as Brian Seep, located in 10 m water depth. A single comprehensive survey of gas flux at Brian Seep yielded a methane release rate of ∼450 moles of CH 4 per day, originating from 68 persistent gas vents and 23 intermittent vents, with gas flux among persistent vents displaying a log normal frequency distribution. A subsequent series of 33 repeat surveys conducted over a period of 6 months tracked eight persistent vents, and revealed substantial temporal variability in gas venting, with flux from each individual vent varying by more than a factor of 4. During wintertime surveys sediment was largely absent from the site, and carbonate concretions were exposed at the seafloor. The presence of the carbonates was unexpected, as the thermogenic seep gas contains 6.7% CO 2 , which should act to dissolve carbonates. The average δ 13 C of the carbonates was −29.2±2.8‰ VPDB, compared to a range of −1.0 to +7.8‰ for CO 2 in the seep gas, indicating that CO 2 from the seep gas is quantitatively not as important as 13 Cdepleted bicarbonate derived from methane oxidation. Methane, with a δ 13 C of approximately −43‰, is oxidized and the resulting inorganic carbon precipitates as highmagnesium calcite and other carbonate minerals. This finding is supported by 13 C-depleted biomarkers typically associated with anaerobic methanotrophic archaea and their bacterial syntrophic partners in the carbonates (lipid biomarker δ 13 C ranged from −84 to −25‰). The inconsistency in δ 13 C between the carbonates and the seeping CO 2 was resolved by discovering pockets of gas trapped near the base of the sediment column with δ 13 C-CO 2 values ranging from −26.9 to −11.6‰. A mechanism of carbonate formation is proposed in which carbonates form near the sediment-bedrock interface during times of sufficient sediment coverage, in which anaerobic oxidation of methane is favored. Precipitation occurs at a sufficient distance from active venting for the molecular and isotopic composition of seep gas to be masked by the generation of carbonate alkalinity from anaerobic methane oxidation.

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Section: Subsurface Gas Pocketsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Gas flux and carbonate occurrence at a shallow seep of thermogenic natural gas

et al. 2010

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“…Seep carbonates are known to show complex mineralogical as well as carbon and oxygen isotopic compositions (Campbell, 2006;Gieskes et al, 2005;Mazzini et al, 2005;Naehr et al, 2007;Peckmann et al, 1999Peckmann et al, , 2001aPeckmann and Thiel, 2004;Roberts et al, 2010;Roberts and Aharon, 1994). Carbonate minerals in seep carbonates are primarily high-Mg calcite (HMC), aragonite and dolomite (protodolomite; Greinert et al, 2001;Naehr et al, 2007;Peckmann et al, 2001b;Roberts et al, 2010;Roberts and Aharon, 1994).…”

Section: Introductionmentioning

confidence: 99%

“…C as high as 26&; Gieskes et al, 2005;Naehr et al, 2007;Paull et al, 2007). The stable oxygen isotopic compositions of a specific carbonate mineral phase depend on the formation temperature and isotopic composition of the source water where the precipitation occurred (Friedman and O'Neil, 1977;Naehr et al, 2000Naehr et al, , 2007.…”

mentioning

confidence: 99%

Tracing the evolution of seep fluids from authigenic carbonates: Green Canyon, northern Gulf of Mexico

Bian

Dong

Roberts

et al. 2013

Marine and Petroleum Geology

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“…Regarding the curvatures in the graphs for Cl − and SO 4 2− , the upward curvatures appear to imply upward movement of waters from depth. The occurrence of bacterial mats suggests that some CH 4 escapes to the surface to feed these mats (Gieskes et al 2005). The curvatures of δ 18 O H2O and δD H2O are also apparent, especially in D949 C3, with some 'flyers' in the δD H2O in the deeper part of C3.…”

Section: Methodsmentioning

confidence: 86%

Origin and transport of pore fluids in the Nankai accretionary prism inferred from chemical and isotopic compositions of pore water at cold seep sites off Kumano

et al. 2014

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We used push corers during manned submersible dives to obtain sediment samples of up to 30 cm from the subseafloor at the Oomine Ridge. The concentrations of B in pore water extracted from the sediment samples from cold seep sites were higher than could be explained by organic matter decomposition, suggesting that the seepage fluid at the site was influenced by B derived from smectite-illite alteration, which occurs between 50°C and 160°C. Although the negative δ 18 O H2O and δD H2O values of the pore fluids cannot be explained by freshwater derived from clay mineral dehydration (CMD), we considered the contribution of pore fluids in the shallow sediments of the accretionary prism, which showed negative δ 18 O H2O and δD H2O values according to the results obtained during Integrated Ocean Drilling Program (IODP) Expeditions 315 and 316. We calculated the mixing ratios based on a four-end-member mixing model including freshwater derived from CMD, pore fluids in the shallow (SPF) accretionary prism sediment, seawater (SW), and freshwater derived from methane hydrate (MH) dissociation. However, the Oomine seep fluids were unable to be explained without four end members, suggesting that deep-sourced fluids in the accretionary prism influenced the seeping fluids from this area. This finding presents the first evidence of deep-sourced fluids at cold seep sites in the Oomine Ridge, indicating that a megasplay fault is a potential pathway for the deep-sourced fluids.

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A study of the chemistry of pore fluids and authigenic carbonates in methane seep environments: Kodiak Trench, Hydrate Ridge, Monterey Bay, and Eel River Basin

Cited by 107 publications

References 34 publications

Gas flux and carbonate occurrence at a shallow seep of thermogenic natural gas

Gas flux and carbonate occurrence at a shallow seep of thermogenic natural gas

Tracing the evolution of seep fluids from authigenic carbonates: Green Canyon, northern Gulf of Mexico

Origin and transport of pore fluids in the Nankai accretionary prism inferred from chemical and isotopic compositions of pore water at cold seep sites off Kumano

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