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dc.contributor.authorPape, Thomas
dc.contributor.authorBuenz, Stefan
dc.contributor.authorHong, Wei-Li
dc.contributor.authorTorres, Marta E.
dc.contributor.authorRiedel, Matthias
dc.contributor.authorPanieri, Giuliana
dc.contributor.authorLepland, Aivo
dc.contributor.authorHsu, Chieh Wei
dc.contributor.authorWintersteller, Paul
dc.contributor.authorWallmann, Klaus
dc.contributor.authorSchmidt, Christopher
dc.contributor.authorYao, Haoyi
dc.contributor.authorBohrmann, Gerhard
dc.date.accessioned2020-03-11T12:58:22Z
dc.date.available2020-03-11T12:58:22Z
dc.date.issued2019-10-25
dc.description.abstractWe report on the geochemistry of hydrocarbons and pore waters down to 62.5 mbsf, collected by drilling with the MARUM‐MeBo70 and by gravity coring at the Lunde pockmark in the Vestnesa Ridge. Our data document the origin and transformations of volatiles feeding gas emissions previously documented in this region. Gas hydrates are present where a fracture network beneath the pockmark focusses migration of thermogenic hydrocarbons characterized by their C<sub>1</sub>/C<sub>2</sub>+ and stable isotopic compositions (δ<sup>2</sup>H‐CH<sub>4</sub>, δ<sup>13</sup>C‐CH<sub>4</sub>). Measured geothermal gradients (~80°C km‐1) and known formation temperatures (>70°C) suggest that those hydrocarbons are formed at depths >800 mbsf. A combined analytical/modeling approach, including concentration and isotopic mass balances, reveals that pockmark sediments experience diffuse migration of thermogenic hydrocarbons. However, at sites without channeled flow this appears to be limited to depths > ~50 mbsf. At all sites we document a contribution of microbial methanogenesis to the overall carbon cycle that includes a component of secondary carbonate reduction (CR) – i.e. reduction of dissolved inorganic carbon (DIC) generated by anaerobic oxidation of methane (AOM) in the uppermost methanogenic zone. AOM and CR rates are spatially variable within the pockmark and are highest at high‐flux sites. These reactions are revealed by <sup>13</sup>C‐DIC depletions at the sulfate‐methane interface at all sites. However, <sup>13</sup>C‐CH<sub>4</sub> depletions are only observed at the low methane flux sites because changes in the isotopic composition of the overall methane pool are masked at high‐flux sites. <sup>13</sup>C‐depletions of TOC suggest that at seeps sites, methane‐derived carbon is incorporated into de novo synthesized biomass.en_US
dc.identifier.citationPape, Buenz, Hong, Torres, Riedel, Panieri, Lepland, Hsu, Wintersteller, Wallmann, Schmidt, Yao, Bohrmann. Origin and transformation of light hydrocarbons ascending at an active pockmark on Vestnesa Ridge, Arctic Ocean. Journal of Geophysical Research (JGR): Solid Earth. 2019en_US
dc.identifier.cristinIDFRIDAID 1741633
dc.identifier.doi10.1029/2018JB016679
dc.identifier.issn2169-9313
dc.identifier.issn2169-9356
dc.identifier.urihttps://hdl.handle.net/10037/17716
dc.language.isoengen_US
dc.publisherAmerican Geophysical Union (AGU)en_US
dc.relation.journalJournal of Geophysical Research (JGR): Solid Earth
dc.relation.projectIDNorges forskningsråd: 223259en_US
dc.relation.projectIDNorges forskningsråd: 255150en_US
dc.relation.projectIDinfo:eu-repo/grantAgreement/RCN/SFF/223259/Norway/Centre for Arctic Gas Hydrate, Environment and Climate/CAGE/en_US
dc.relation.projectIDinfo:eu-repo/grantAgreement/RCN/PETROMAKS2/255150/Norway/Norwegian margin fluid systems and methane- derived carbonate crusts - Recent scientific advances in service of petroleum exploration//en_US
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2019 The Author(s)en_US
dc.subjectVDP::Mathematics and natural science: 400::Geosciences: 450en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Geofag: 450en_US
dc.titleOrigin and transformation of light hydrocarbons ascending at an active pockmark on Vestnesa Ridge, Arctic Oceanen_US
dc.type.versionpublishedVersionen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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