Show simple item record

dc.contributor.authorRiedel, M.
dc.contributor.authorVillinger, H.
dc.contributor.authorFreudenthal, T.
dc.contributor.authorPape, T.
dc.contributor.authorBünz, Stefan
dc.contributor.authorBohrmann, G.
dc.date.accessioned2021-02-11T22:15:54Z
dc.date.available2021-02-11T22:15:54Z
dc.date.issued2020-11-10
dc.description.abstractThe Svalbard margin represents one of the northernmost gas hydrate provinces worldwide. Vestnesa Ridge (VR) and Svyatogor Ridge (SR) west of Svalbard are two prominent sediment drifts showing abundant pockmarks and sites of seismic chimney structures. Some of these sites at VR are associated with active gas venting and were the focus of drilling and coring with the seafloor‐deployed MARUM‐MeBo70 rig. Understanding the nature of fluid migration and gas hydrate distribution requires (among other parameters) knowledge of the thermal regime and in situ gas and pore fluid composition. In situ temperature data were obtained downhole at a reference site at VR defining a geothermal gradient of ~78 mK m<sup>−1</sup> (heat flow ~95 mW m<sup>−2</sup>). Additional heat probe data were obtained to describe the thermal regime of the pockmarks. The highest heat flow values were systematically seen within pockmark depressions and were uncorrelated to gas venting occurrences. Heat flow within pockmarks is typically ~20 mW m<sup>−2</sup> higher than outside pockmarks. Using the downhole temperature data and gas compositions from drilling we model the regional base of the gas hydrate stability zone (BGHSZ). Thermal modeling including topographic effects suggest a BGHSZ up to 40 m deeper than estimated from seismic data. Uncertainties in sediment properties (velocity and thermal conductivity) are only partially explaining the mismatch. Capillary effects due to small sediment grain sizes may shift the free gas occurrence above the equilibrium BGHSZ. Changes in gas composition or pore fluid salinity at greater depth may also explain the discrepancy in observed and modeled BGHSZ.en_US
dc.identifier.citationRiedel M, Villinger, Freudenthal T, Pape T, Bünz S, Bohrmann G. Thermal Characterization of Pockmarks Across Vestnesa and Svyatogor Ridges, Offshore Svalbard. Journal of Geophysical Research (JGR): Solid Earth. 2020;125(12)en_US
dc.identifier.cristinIDFRIDAID 1867558
dc.identifier.doi10.1029/2020JB019468
dc.identifier.issn2169-9313
dc.identifier.issn2169-9356
dc.identifier.urihttps://hdl.handle.net/10037/20565
dc.language.isoengen_US
dc.publisherAmerican Geophysical Unionen_US
dc.relation.journalJournal of Geophysical Research (JGR): Solid Earth
dc.relation.projectIDinfo:eu-repo/grantAgreement/RCN/SFF/223259/Norway/Centre for Arctic Gas Hydrate, Environment and Climate/CAGE/en_US
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2020 The Author(s)en_US
dc.subjectVDP::Mathematics and natural science: 400::Geosciences: 450::Marine geology: 466en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Marin geologi: 466en_US
dc.titleThermal Characterization of Pockmarks Across Vestnesa and Svyatogor Ridges, Offshore Svalbarden_US
dc.type.versionpublishedVersionen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US


File(s) in this item

Thumbnail

This item appears in the following collection(s)

Show simple item record