Methane hydrate accumulation in “Mound 11” mud volcano, Costa Rica forearc

Schmidt, Mark; Hensen, Christian; Mörz, Tobias; Müller, Christof; Grevemeyer, Ingo; Wallmann, Klaus; Mau, Susan; Kaul, Norbert E

doi:10.1016/j.margeo.2005.01.001

Cited by 78 publications

(78 citation statements)

References 51 publications

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“…Central America, Arctic, and Arabian Sea). Gas hydrates have been previously documented at various cold seeps (Schmidt et al, 2005) and ODP sites along the central American margin . Moderate hydrate concentrations (150-400 kg C m À2 ) occur at $8.5% of total hydrate provinces (western and eastern coasts of North America, Arctic, Sea of Okhotsk, Antarctic, eastern coast of Australia, Africa continental margin, Indian Ocean, Central America, and eastern coast of Greenland).…”

Section: à2mentioning

confidence: 99%

Estimation of the global amount of submarine gas hydrates formed via microbial methane formation based on numerical reaction-transport modeling and a novel parameterization of Holocene sedimentation

Burwicz

Rüpke

Wallmann

2011

Geochimica et Cosmochimica Acta

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151

131

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This study provides new estimates for the global offshore methane hydrate inventory formed due to microbial CH 4 production under Quaternary and Holocene boundary conditions. A multi-1D model for particular organic carbon (POC) degradation, gas hydrate formation and dissolution is presented. The novel reaction-transport model contains an open three-phase system of two solid compounds (organic carbon, gas hydrates), three dissolved species (methane, sulfates, inorganic carbon) and one gaseous phase (free methane). The model computes time-resolved concentration profiles for all compounds by accounting for chemical reactions as well as diffusive and advective transport processes. The reaction module builds upon a new kinetic model of POC degradation which considers a down-core decrease in reactivity of organic matter. Various chemical reactions such as organic carbon decay, anaerobic oxidation of methane, methanogenesis, and sulfate reduction are resolved using appropriate kinetic rate laws and constants. Gas hydrates and free gas form if the concentration of dissolved methane exceeds the pressure, temperature, and salinity-dependent solubility limits of hydrates and/or free gas, with a rate given by kinetic parameters. Global input grids have been compiled from a variety of oceanographic, geological and geophysical data sets including a new parameterization of sedimentation rates in terms of water depth.We find prominent gas hydrate provinces offshore Central America where sediments are rich in organic carbon and in the Arctic Ocean where low bottom water temperatures stabilize methane hydrates. The world's total gas hydrate inventory is estimated at 0:82 Â 10 13 m 3 -2:10 Â 10 15 m 3 CH 4 (at STP conditions) or, equivalently, 4.18-995 Gt of methane carbon. The first value refers to present day conditions estimated using the relatively low Holocene sedimentation rates; the second value corresponds to a scenario of higher Quaternary sedimentation rates along continental margins.Our results clearly show that in-situ POC degradation is at present not an efficient hydrate forming process. Significant hydrate deposits in marine settings are more likely to have formed at times of higher sedimentation during the Quaternary or as a consequence of upward fluid transport at continental margins.

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Section: à2mentioning

confidence: 99%

Estimation of the global amount of submarine gas hydrates formed via microbial methane formation based on numerical reaction-transport modeling and a novel parameterization of Holocene sedimentation

Burwicz

Rüpke

Wallmann

2011

Geochimica et Cosmochimica Acta

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151

131

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“…Therefore, mud volcanoes are situated in active areas of plate boundaries and in zones of young orogenic structures. Thermogenic gas hydrate deposits are abundantly distributed in these active areas in association with faults and mud volcanoes 36 ; for example, the Gulf of Mexico 16,17,39 , the Cascadia margin 12,38 , the Black Sea 42 , the Barbados accretionary prism 34 , the Costa Rica forearc 48 , the Gulf of Cadiz 35 and the Mediterranean Sea 49 . Accordingly, hydrocarbons contained in thermogenic gas hydrates and those contained in chibaite and DOH-type mineral are of the common origin, which is the thermal decomposition of organic matter in deep sediments.…”

Section: Discussionmentioning

confidence: 99%

New silica clathrate minerals that are isostructural with natural gas hydrates

Momma

Ikeda

Nishikubo³

et al. 2011

Nat Commun

131

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silica clathrate compounds (clathrasils) and clathrate hydrates are structurally analogous because both materials have framework structures with cage-like voids occupied by guest species. The following three structural types of clathrate hydrates are recognized in nature: cubic structure I (sI); cubic structure II (sII); and hexagonal structure H (sH). In contrast, only one naturally occurring silica clathrate mineral, melanophlogite (sI-type framework), has been found to date. Here, we report the discovery of two new silica clathrate minerals that are isostructural with sII and sH hydrates and contain hydrocarbon gases. Geological and mineralogical observations show that these silica clathrate minerals are traces of lowtemperature hydrothermal systems at convergent plate margins, which are the sources of thermogenic natural gas hydrates. Given the widespread occurrence of submarine hydrocarbon seeps, silica clathrate minerals are likely to be found in a wide range of marine sediments.

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“…Both mounds are located at the same fault zone, although they differ in fluid flow advection intensity (Hensen et al, 2004;Linke et al, 2005;Karaca et al, 2010;Krause et al, 2014), fluid origin (Hensen et al, 2004;Han et al, 2004;Schmidt et al, 2005), and microbial activity (Krause et al, 2014). In the last 50 kyr both mounds have displayed individual active phases interrupted by phases of inactivity (Kutterolf et al, 2008).…”

Section: Geological Settingmentioning

confidence: 99%

“…Organic carbon accumulation at continental margins can lead to the formation of large methane reservoirs through its biological or thermogenic breakdown (Judd et al, 2002;Schmidt et al, 2005;Hensen and Wallmann, 2005;Crutchley et al, 2014). Produced methane gas may be transported upwards in solution by molecular diffusion or by ascending fluids, mobilized by, for example, sediment compaction or clay mineral dehydration (Hensen et al, 2004;Tryon et al, 2010;Crutchley et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Efficiency and adaptability of the benthic methane filter at Quepos Slide cold seeps, offshore of Costa Rica

et al. 2015

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Abstract. Large amounts of methane are delivered by fluids through the erosive forearc of the convergent margin offshore of Costa Rica and lead to the formation of cold seeps at the sediment surface. Besides mud extrusion, numerous cold seeps are created by landslides induced by seamount subduction or fluid migration along major faults. Most of the dissolved methane migrating through the sediments of cold seeps is oxidized within the benthic microbial methane filter by anaerobic oxidation of methane (AOM). Measurements of AOM and sulfate reduction as well as numerical modeling of porewater profiles revealed a highly active and efficient benthic methane filter at the Quepos Slide site, a landslide on the continental slope between the Nicoya and Osa Peninsula. Integrated areal rates of AOM ranged from 12.9 ± 6.0 to 45.2 ± 11.5 mmol m −2 d −1 , with only 1 to 2.5 % of the upward methane flux being released into the water column.Additionally, two parallel sediment cores from Quepos Slide were used for in vitro experiments in a recently developed sediment-flow-through (SLOT) system to simulate an increased fluid and methane flux from the bottom of the sediment core. The benthic methane filter revealed a high adaptability whereby the methane oxidation efficiency responded to the increased fluid flow within ca. 170 d. To our knowledge, this study provides the first estimation of the natural biogeochemical response of seep sediments to changes in fluid flow.

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Methane hydrate accumulation in “Mound 11” mud volcano, Costa Rica forearc

Cited by 78 publications

References 51 publications

Estimation of the global amount of submarine gas hydrates formed via microbial methane formation based on numerical reaction-transport modeling and a novel parameterization of Holocene sedimentation

Estimation of the global amount of submarine gas hydrates formed via microbial methane formation based on numerical reaction-transport modeling and a novel parameterization of Holocene sedimentation

New silica clathrate minerals that are isostructural with natural gas hydrates

Efficiency and adaptability of the benthic methane filter at Quepos Slide cold seeps, offshore of Costa Rica

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