Marine pore-water sulfate profiles indicate in situ methane flux from underlying gas hydrate

Borowski, Walter S; Paull, C. K.; Ussler, William

doi:10.1130/0091-7613(1996)024<0655:mpwspi>2.3.co;2

Cited by 525 publications

(412 citation statements)

References 0 publications

Supporting

Mentioning

384

Contrasting

Unclassified

Order By: Relevance

“…The presence of abundant hydrotroilite at the base of the core (i.e., 380-470 cmbsf ) is indicative of the consumption of methane by microbial SR and release of sulfide to pore waters (Eq. 1) (Borowski et al 1996(Borowski et al , 1997. In this interval, the sulfide ions have reacted with available iron to form iron sulfide.…”

Section: Discussionmentioning

confidence: 99%

“…Methane hydrate formation near the seafloor typically occurs below the SMI and immediately above this interface, as the SR process consumes dissolved methane and inhibits hydrate formation. The depth to which hydrate is formed is constrained by a balance between downward diffusing sulfate and the upward flux of methane towards the seafloor (Borowski et al 1996).…”

Section: Discussionmentioning

confidence: 99%

“…This difference might be attributed to different upward flux of methane (Berner 1980). According to Borowski et al (1996), rate of sulfate consumption and steepness of sulfate gradients are controlled by methane flux from below. Therefore, the low angle profile of lower part (below 250 cmbsf ) is attributed to higher flux than the upper part (until 250 cmbsf ).…”

Section: Discussionmentioning

confidence: 99%

“…AOM occurs at or close to the boundary between SR zone and the methanogenic zone, where methane diffuses upward. The boundary between these two zones is called sulfate/ methane interface (SMI).Upward fluxes of methane may affect the depth of SMI below the seafloor (Borowski et al 1996).…”

Section: Introductionmentioning

confidence: 99%

“…The occurrence of AOM primarily at the SMI is indicated by a linear sulfate profile in areas with large amounts of methane diffusing upwards (Borowski et al 1996, Niewöhner et al 1998, Hinrichset al 1999. AOM can be represented by the reaction ahead (Eq.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

The influence of methane fluxes on the sulfate/methane interface in sediments from the Rio Grande Cone Gas Hydrate Province, southern Brazil

et al. 2017

View full text Add to dashboard Cite

Much research has been published regarding the relation between major gas hydrate accumulations and the global carbon cycle. In this context, the determination of the sulfate/methane interface (SMI) depth is of primary importance in order to understand the dynamics of methane flux in the shallow section. This paper identifies the depth of the SMI in sediments based on sulfate and methane concentration profiles in cores recovered in the Rio Grande Cone Gas Hydrate Province, Pelotas Basin, southern Brazil. The shape of methane and sulfate concentration profiles in the sediments can be linked to the local methane flux rate as follows: (i) near linear, high upward-diffusing methane flux coupled with high sulfate diffusion from seawater; (ii) irregular, variable methane flux rates; and (iii) kink-type profile, which is indicative of variable rather than strictly high upward methane flux. The areas in which a high methane flux was identified are spatially associated with gas chimneys in sediments within pockmarks, whereas profiles with low methane flux are present in adjacent areas. These chimneys appear as acoustic blankings in seismic records and can therefore be mapped in subsurface. The wavy-like seismic reflection following the SMI coincides with the occurrence of authigenic carbonate nodules and concretions. In addition, high methane fluxes and the occurrence of concretions and nodules carbonates were correlated by stratigraphic position of the concretions bearing intervals and sulfate profiles. KEYWORDS: gas hydrate; methane flux; Rio Grande Cone; Brazil. RESUMO: Muitas pesquisas têm sido publicadas relacionando elevadas acumulações de hidrato de gás e o ciclo global do carbono. Nesse contexto, a determinação da profundidade da interface sulfato/metano (SMI) é importante para entender a dinâmica do fluxo de metano em locais rasos. Este artigo científico identifica a profundidade da SMI em sedimentos com base em perfis de concentração de sulfato e metano em testemunhos recuperados na Província do Hidrato de Gás do

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The influence of methane fluxes on the sulfate/methane interface in sediments from the Rio Grande Cone Gas Hydrate Province, southern Brazil

et al. 2017

View full text Add to dashboard Cite

show abstract

Subsurface methane sources and migration pathways within a gas hydrate mound system, Gulf of Mexico

Wilson

Macelloni

Simonetti

et al. 2014

Geochem Geophys Geosyst

View full text Add to dashboard Cite

[1] Geochemical profiles were coupled with seismic information to examine subsurface hydrocarbon source, migration, and fate at a Gulf of Mexico carbonate-gas hydrate mound (Woolsey Mound). Three seafloor features were investigated in detail: (1) major faults resulting from a rising salt body, (2) an acoustic backscatter anomaly, and (3) a pockmark associated with a major fault. We analyzed sulfate, chloride, dissolved inorganic carbon, and hydrocarbon concentrations, and carbon isotopes in pore water extracted from 20 m piston cores to characterize gas source and calculate methane flux. Dissolved biogenic methane dominated the off-fault sites, while the contribution of thermogenic methane increased near a major fault where thermogenic gas hydrates were recovered. Within the pockmark, methane concentrations were low and isotopes indicated a biogenic source. Since pockmarks are typically formed from expulsive fluid flow, this suggests that either the pockmark is the legacy of a conduit that has become plugged or that the expulsed fluid is confined within the fault walls. At the acoustic anomaly,

show abstract

Hydrocarbon seepage and its sources at mud volcanoes of the Kumano forearc basin, Nankai Trough subduction zone

Pape

Geprägs

Hammerschmidt

et al. 2014

Geochem Geophys Geosyst

View full text Add to dashboard Cite

Twelve submarine mud volcanoes (MV) in the Kumano forearc basin within the Nankai Trough subduction zone were investigated for hydrocarbon origins and fluid dynamics. Gas hydrates diagnostic for methane concentrations exceeding solubilities were recovered from MVs 2, 4, 5, and 10. Molecular ratios (C 1 /C 2 < 250) and stable carbon isotopic compositions (d 13 C-CH 4 >240& V-PDB) indicate that hydratebound hydrocarbons (HCs) at MVs 2, 4, and 10 are derived from thermal cracking of organic matter. Considering thermal gradients at the nearby IODP Sites C0009 and C0002, the likely formation depth of such HCs ranges between 2300 and 4300 m below seafloor (mbsf). With respect to basin sediment thickness and the minimum distance to the top of the plate boundary thrust we propose that the majority of HCs fueling the MVs is derived from sediments of the Cretaceous to Tertiary Shimanto belt below Pliocene/Pleistocene to recent basin sediments. Considering their sizes and appearances hydrates are suggested to be relicts of higher MV activity in the past, although the sporadic presence of vesicomyid clams at MV 2 showed that fluid migration is sufficient to nourish chemosynthesis-based organisms in places. Distributions of dissolved methane at MVs 3, 4, 5, and 8 pointed at fluid supply through one or few MV conduits and effective methane oxidation in the immediate subsurface. The aged nature of the hydrates suggests that the major portion of methane immediately below the top of the methane-containing sediment interval is fueled by current hydrate dissolution rather than active migration from greater depth.

show abstract

Marine pore-water sulfate profiles indicate in situ methane flux from underlying gas hydrate

Cited by 525 publications

References 0 publications

The influence of methane fluxes on the sulfate/methane interface in sediments from the Rio Grande Cone Gas Hydrate Province, southern Brazil

The influence of methane fluxes on the sulfate/methane interface in sediments from the Rio Grande Cone Gas Hydrate Province, southern Brazil

Subsurface methane sources and migration pathways within a gas hydrate mound system, Gulf of Mexico

Hydrocarbon seepage and its sources at mud volcanoes of the Kumano forearc basin, Nankai Trough subduction zone

Contact Info

Product

Resources

About