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  • 1
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    IODP Expedition 337, Shimokita Deep Coalbed Biosphere (2015)
    PANGAEA
    In:  Supplement to: Inagaki, F; Hinrichs, Kai-Uwe; Kubo, Y; Bowles, Marshall W; Heuer, Verena B; Hong, W-L; Hoshino, Tatsuhiko; Ijiri, Akira; Imachi, H; Ito, M; Kaneko, Masanori; Lever, Mark A; Lin, Yu-Shih; Methe, B A; Morita, S; Morono, Yuki; Tanikawa, Wataru; Bihan, M; Bowden, Stephen A; Elvert, Marcus; Glombitza, Clemens; Gross, D; Harrington, G J; Hori, T; Li, K; Limmer, D; Liu, Chiung-Hui; Murayama, M; Ohkouchi, Naohiko; Ono, Shuhei; Park, Young-Soo; Phillips, S C; Prieto-Mollar, Xavier; Purkey, M; Riedinger, Natascha; Sanada, Yoshinori; Sauvage, J; Snyder, Glen T; Susilawati, R; Takano, Yoshinori; Tasumi, E; Terada, Takeshi; Tomaru, Hitoshi; Trembath-Reichert, E; Wang, D T; Yamada, Y (2015): Exploring deep microbial life in coal-bearing sediment down to ~2.5 km below the ocean floor. Science, 439 (6246), 420-424, https://doi.org/10.1126/science.aaa6882
    Details
    Publication Date: 2023-04-29
    Description: Microbial life inhabits deeply buried marine sediments, but the extent of this vast ecosystem remains poorly constrained. Here we provide evidence for the existence of microbial communities in ~40° to 60°C sediment associated with lignite coal beds at ~1.5 to 2.5 km below the seafloor in the Pacific Ocean off Japan. Microbial methanogenesis was indicated by the isotopic compositions of methane and carbon dioxide, biomarkers, cultivation data, and gas compositions. Concentrations of indigenous microbial cells below 1.5 km ranged from 〈10 to ~10**4 cells cm**-3. Peak concentrations occurred in lignite layers, where communities differed markedly from shallower subseafloor communities and instead resembled organotrophic communities in forest soils. This suggests that terrigenous sediments retain indigenous community members tens of millions of years after burial in the seabed.
    Keywords: Integrated Ocean Drilling Program / International Ocean Discovery Program; IODP
    Type: Dataset
    Format: application/zip, 2 datasets
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    DATA PANGAEA
  • 2
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    Stable carbon isotopic composition of dissolved inorganic carbon (δ¹³C-DIC) in sediment core GeoB21637-1 (2019)
    PANGAEA
    Details
    Publication Date: 2024-02-02
    Keywords: Center for Marine Environmental Sciences; Core; DEPTH, sediment/rock; DIC; Dissolved inorganic carbon; GeoB21637-1; Lunde pockmark; Maria S. Merian; MARUM; MeBo; MeBo (Meeresboden-Bohrgerät); MSM57; MSM57/2; MSM57/2_649-1; Optional event label; Sample ID; stable carbon isotopic composition; Vestnesa Ridge; δ13C, dissolved inorganic carbon
    Type: Dataset
    Format: text/tab-separated-values, 51 data points
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    DATA PANGAEA
  • 3
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    Methane flux from miniseepage in mud volcanoes of SW Taiwan: Comparison with the data from Italy, Romania, and Azerbaijan (2013)
    Elsevier Science Limited
    Details
    Publication Date: 2017-04-04
    Description: Mud volcanoes (MVs) are considered important methane (CH4) sources for the atmosphere; gas is not only released from macro-seepage, i.e., from craters and visible gas bubbling manifestations, but also from invisible and pervasive exhalation from the ground, named miniseepage. CH4 flux related to miniseepage was measured only in a few MVs, in Azerbaijan, Italy, Japan, Romania and Taiwan. This study examines in detail the flux data acquired in 5 MVs and 1 ‘‘dry’’ seep in SW Taiwan, and further compares with other 23 MVs in Italy, Romania and Azerbaijan. Miniseepage from the six manifestations in SW Taiwan MVs and seeps annually contribute at least 110 tons of methane directly to the atmosphere, and represents about 80% of total degassing during a quiescent period. Combining miniseepage flux and geo-electrical data from the Wu-shan-ding MV revealed a possible link between gas flux and electrical resistivity of the vadose zone. This suggests that unsaturated subsoil is a preferential zone for shallow gas accumulation and seepage to the atmosphere. Besides, miniseepage flux in Chu-huo everlasting fire decreases by increasing the distance from the main gas channeling zone and molecular fractionation (methane/ethane ratio) is higher for lower flux seepage, consistently with what observed in other MVs worldwide. Measurements from Azerbaijan, Italy, Romania, and Taiwan converge to indicate that miniseepage is directly proportional to the vent output and it is a significant component of the total methane budget of a MV. A miniseepage vs. macro-seepage flux equation has been statistically assessed and it can be used to estimate theoretically at least the order of magnitude of the flux of miniseepage for MVs of which only the flux from vents was evaluated, or will be evaluated in future. This will allow a more complete and objective quantification of gas emission in MVs, thus also refining the estimate of the global methane emission from geological sources.
    Description: Published
    Description: 3–12
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: restricted
    Keywords: Mud volcano ; Miniseepage ; Macro-seepage ; Global methane emission ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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    PAPER (OA)
  • 4
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    Bottom-simulating reflector dynamics at Arctic thermogenic gas provinces: An example from Vestnesa Ridge, offshore west Svalbard (2017)
    AGU (American Geophysical Union) | Wiley
    In:  Journal of Geophysical Research: Solid Earth, 122 (6). pp. 4089-4105.
    Details
    Publication Date: 2020-02-06
    Description: The Vestnesa Ridge comprises a 〉100 km long sediment drift located between the western continental slope of Svalbard and the Arctic mid-ocean ridges. It hosts a deep water (〉1000 m) gas hydrate and associated seafloor seepage system. Near-seafloor headspace gas compositions and its methane carbon isotopic signature along the ridge indicate a predominance of thermogenic gas sources feeding the system. Prediction of the base of the gas hydrate stability zone for theoretical pressure and temperature conditions and measured gas compositions results in an unusual underestimation of the observed bottom-simulating reflector (BSR) depth. The BSR is up to 60 m deeper than predicted for pure methane and measured gas compositions with 〉99% methane. Models for measured gas compositions with 〉4% higher-order hydrocarbons result in a better BSR approximation. However, the BSR remains 〉20 m deeper than predicted in a region without active seepage. A BSR deeper than predicted is primarily explained by unaccounted spatial variations in the geothermal gradient and by larger amounts of thermogenic gas at the base of the gas hydrate stability zone. Hydrates containing higher-order hydrocarbons form at greater depths and higher temperatures and contribute with larger amounts of carbons than pure methane hydrates. In thermogenic provinces, this may imply a significant upward revision (up to 50% in the case of Vestnesa Ridge) of the amount of carbon in gas hydrates.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1002/2016JB013761
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Gas hydrate dissociation off Svalbard induced by isostatic rebound rather than global warming (2018)
    Nature Research
    In:  Nature Communications, 9 (Article number: 83 ).
    Details
    Publication Date: 2021-03-19
    Description: Methane seepage from the upper continental slopes of Western Svalbard has previously been attributed to gas hydrate dissociation induced by anthropogenic warming of ambient bottom waters. Here we show that sediment cores drilled off Prins Karls Foreland contain freshwater from dissociating hydrates. However, our modeling indicates that the observed pore water freshening began around 8 ka BP when the rate of isostatic uplift outpaced eustatic sea-level rise. The resultant local shallowing and lowering of hydrostatic pressure forced gas hydrate dissociation and dissolved chloride depletions consistent with our geochemical analysis. Hence, we propose that hydrate dissociation was triggered by postglacial isostatic rebound rather than anthropogenic warming. Furthermore, we show that methane fluxes from dissociating hydrates were considerably smaller than present methane seepage rates implying that gas hydrates were not a major source of methane to the oceans, but rather acted as a dynamic seal, regulating methane release from deep geological reservoirs.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    DOI: 10.1038/s41467-017-02550-9
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    R/V MARIA S. MERIAN Cruise Report MSM57, Gas Hydrate Dynamics at the Continental Margin of Svalbard, Reykjavik – Longyearbyen – Reykjavik, 29 July – 07 September 2016 (2017)
    In:  Berichte, MARUM – Zentrum für Marine Umweltwissenschaften, Fachbereich Geowissenschaften, Universität Bremen, 314 . UNSPECIFIED, Bremen, 204 pp.
    Details
    Publication Date: 2018-07-17
    Type: Report , NonPeerReviewed
    Format: text
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    OceanRep: Report - Cruise Report
  • 7
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    Quantifying long-term methane flux change by coupling authigenic mineral distribution and kinetic modelling at southern Hydrate Ridge, Oregon. (2010)
    In:  [Talk] In: AGU Fall Meeting 2010, 13.12.--17.12.2010, San Francisco, California, USA .
    Details
    Publication Date: 2012-02-23
    Type: Conference or Workshop Item , NonPeerReviewed
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    OceanRep: Talk
  • 8
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    Towards a global quantification of volcanogenic aluminosilicate alteration rates through the mass balance of strontium in marine sediments (2020)
    Elsevier
    Details
    Publication Date: 2023-02-08
    Description: Despite the important role that volcanogenic aluminosilicate (VA) alteration has on elemental cycles in marine sediments, there is no mechanism to arrive at a global assessment of this process. To quantify the VA alteration rates from Japan, New Zealand (NZ), and Costa Rica, we developed a mass balance approach that is constrained by the strontium concentration and 87Sr/86Sr ratios in pore fluid, authigenic carbonates, and VA. We derived VA alteration rates ranging from 101 to 103 nmole Sr/m3 bulk sediment/yr with the highest rate obtained for Tuaheni, NZ (Site GeoB80202), which has the youngest sediment. We showed that 87Sr/86Sr ratios of VA derived from this mass balance approach are significantly higher than the reported ratios from volcanic glass samples, indicating a concomitant role of volcanogenic feldspar dissolution and/or authigenic clay formation. Most of the strontium released during VA alteration is precipitated as authigenic carbonate, with important implications for carbon inventories. The VA alteration rates derived from this approach can also be used to quantify the release of other critical elements, such as release of iron that can stimulate formation of Fe‑carbonates and/or fuel microbial activity at depth.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 9
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    Origin and transformation of light hydrocarbons ascending at an active pockmark on Vestnesa Ridge, Arctic Ocean (2020)
    AGU | Wiley
    Details
    Publication Date: 2023-02-08
    Description: We 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 C1/C2+ and stable isotopic compositions (δ2H‐CH4, δ13C‐CH4). 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 δ13C‐DIC depletions at the sulfate‐methane interface at all sites. However, δ13C‐CH4 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. 13C‐depletions of TOC suggest that at seeps sites, methane‐derived carbon is incorporated into de novo synthesized biomass.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
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    Interactions between deep formation fluid and gas hydrate dynamics inferred from pore fluid geochemistry at active pockmarks of the Vestnesa Ridge, west Svalbard margin (2021)
    Elsevier
    Details
    Publication Date: 2024-02-07
    Description: Highlights • A saline formation fluid originated from great depths was documented. • Gas hydrates are currently at a dynamic equilibrium due to the low methane flux. • Fluids were diverted by the buried seep carbonates in Lunde pockmark. Abstract Seafloor seepage sites along the Vestnesa Ridge off west-Svalbard have been, for decades, a natural laboratory for the studies of fluid flow and gas hydrate dynamics at passive continental margins. The lack of ground truth evidence for fluid composition and gas hydrate abundance deep in the sediment sequence however prohibits us from further assessing the current model of pockmark evolution from the region. A MARUM-MeBo 70 drilling cruise in 2016 aims to advance our understanding of the system by recovering sediments tens of meters below seafloor from two active pockmarks along Vestnesa Ridge. We report pore fluid composition data focusing on dissolved chloride, stable isotopes of water (δ18O and δD), and the isotopic composition of dissolved boron (δ11B). We detect a saline formation water around two layers where gas hydrates were recovered from one of the seepage sites. This saline formation pore fluid is characterized by elevated chloride concentrations (up to 616 mM), high B/Cl ratios (9×10-4 mol/mol), high δ18O and δD isotopic signatures (+0.6 ‰ and +3.8 ‰, respectively) and low δ11B signatures (+35.0 ‰), which collectively hint to a high temperature modification at great depths. Based on the dissolved chloride concentration profiles, we estimated up to 47 % of pore space occupied by gas hydrate in the sediments shallower than 11.5 mbsf. The observation of bubble fabric in the recovered gas hydrates suggests formation during past periods of intensive gaseous methane seepage. The presence of these gas hydrates without associated positive anomalies in dissolved chloride concentrations however suggests that the decomposition of gas hydrate is as fast as its formation. Such a state of gas hydrates can be attributed to a relatively low methane supply transported by the saline formation water at present. Our findings based on pore fluid composition corroborate previous inferences along Vestnesa Ridge that fluids sustaining seepage have migrated from great depths and that the variable gaseous and aqueous phases through the gas hydrate stability zone controls the distributions of authigenic carbonates and gas hydrates.
    Type: Article , PeerReviewed
    Format: text
    Format: archive
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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