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Wallmann K, Riedel M, Hong WL, Patton H, Hubbard A, Pape T, Hsu CW, Schmidt C, Johnson JE, Torres ME, Andreassen K, Berndt C, Bohrmann G. Gas hydrate dissociation off Svalbard induced by isostatic rebound rather than global warming. Nat Commun 2018; 9:83. [PMID: 29311564 PMCID: PMC5758787 DOI: 10.1038/s41467-017-02550-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 12/07/2017] [Indexed: 11/25/2022] Open
Abstract
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. Methane seepage from continental slopes has been attributed to gas hydrate dissociation induced by anthropogenic bottom water warming. Here, the authors show that hydrates dissociated before the Anthropocene when the isostatic rebound induced by deglaciation of the Arctic ice sheet outpaced eustatic sea-level rise.
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Affiliation(s)
- Klaus Wallmann
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstr. 1-3, Kiel, 24148, Germany.
| | - M Riedel
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstr. 1-3, Kiel, 24148, Germany
| | - W L Hong
- Geological Survey of Norway, N-7022, Trondheim, Norway.,CAGE Centre for Arctic Gas Hydrate Research, Environment and Climate, Department of Geosciences, UiT-The Arctic University of Norway, Tromsø, N-9037, Norway
| | - H Patton
- CAGE Centre for Arctic Gas Hydrate Research, Environment and Climate, Department of Geosciences, UiT-The Arctic University of Norway, Tromsø, N-9037, Norway
| | - A Hubbard
- CAGE Centre for Arctic Gas Hydrate Research, Environment and Climate, Department of Geosciences, UiT-The Arctic University of Norway, Tromsø, N-9037, Norway.,Department of Geography & Earth Science, Aberystwyth University, Wales, SY23 3DB, UK
| | - T Pape
- MARUM-Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Klagenfurter Str., Bremen, 28359, Germany
| | - C W Hsu
- MARUM-Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Klagenfurter Str., Bremen, 28359, Germany
| | - C Schmidt
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstr. 1-3, Kiel, 24148, Germany
| | - J E Johnson
- Department of Earth Sciences, University of New Hampshire, 56 College Rd., Durham, NH, 03824-3589, USA
| | - M E Torres
- College of Oceanic and Atmospheric Sciences, Oregon State University, 104 Ocean Admin Building, Corvallis, OR, 97331-5503, USA
| | - K Andreassen
- CAGE Centre for Arctic Gas Hydrate Research, Environment and Climate, Department of Geosciences, UiT-The Arctic University of Norway, Tromsø, N-9037, Norway
| | - C Berndt
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstr. 1-3, Kiel, 24148, Germany
| | - G Bohrmann
- MARUM-Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Klagenfurter Str., Bremen, 28359, Germany
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Mau S, Römer M, Torres ME, Bussmann I, Pape T, Damm E, Geprägs P, Wintersteller P, Hsu CW, Loher M, Bohrmann G. Widespread methane seepage along the continental margin off Svalbard - from Bjørnøya to Kongsfjorden. Sci Rep 2017; 7:42997. [PMID: 28230189 PMCID: PMC5322355 DOI: 10.1038/srep42997] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 01/17/2017] [Indexed: 11/09/2022] Open
Abstract
Numerous articles have recently reported on gas seepage offshore Svalbard, because the gas emission from these Arctic sediments was thought to result from gas hydrate dissociation, possibly triggered by anthropogenic ocean warming. We report on findings of a much broader seepage area, extending from 74° to 79°, where more than a thousand gas discharge sites were imaged as acoustic flares. The gas discharge occurs in water depths at and shallower than the upper edge of the gas hydrate stability zone and generates a dissolved methane plume that is hundreds of kilometer in length. Data collected in the summer of 2015 revealed that 0.02-7.7% of the dissolved methane was aerobically oxidized by microbes and a minor fraction (0.07%) was transferred to the atmosphere during periods of low wind speeds. Most flares were detected in the vicinity of the Hornsund Fracture Zone, leading us to postulate that the gas ascends along this fracture zone. The methane discharges on bathymetric highs characterized by sonic hard grounds, whereas glaciomarine and Holocene sediments in the troughs apparently limit seepage. The large scale seepage reported here is not caused by anthropogenic warming.
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Affiliation(s)
- S Mau
- MARUM - Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Klagenfurter Str., 28359 Bremen, Germany
| | - M Römer
- MARUM - Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Klagenfurter Str., 28359 Bremen, Germany
| | - M E Torres
- College of Oceanic and Atmospheric Sciences, Oregon State University, 104 Ocean Admin Building, Corvallis, Oregon 97331-5503, USA
| | - I Bussmann
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - T Pape
- MARUM - Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Klagenfurter Str., 28359 Bremen, Germany
| | - E Damm
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - P Geprägs
- MARUM - Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Klagenfurter Str., 28359 Bremen, Germany
| | - P Wintersteller
- MARUM - Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Klagenfurter Str., 28359 Bremen, Germany
| | - C-W Hsu
- MARUM - Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Klagenfurter Str., 28359 Bremen, Germany
| | - M Loher
- MARUM - Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Klagenfurter Str., 28359 Bremen, Germany
| | - G Bohrmann
- MARUM - Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Klagenfurter Str., 28359 Bremen, Germany
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Suess E, Torres M, Bohrmann G, Collier R, Rickert D, Goldfinger C, Linke P, Heuser A, Sahling H, Heeschen K, Jung C, Nakamura K, Greinert J, Pfannkuche O, Trehu A, Klinkhammer G, Whiticar M, Eisenhauer A, Teichert B, Elver M. Sea Floor Methane Hydrates at Hydrate Ridge, Cascadia Margin. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/gm124p0087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
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MacDonald IR, Bohrmann G, Escobar E, Abegg F, Blanchon P, Blinova V, Brückmann W, Drews M, Eisenhauer A, Han X, Heeschen K, Meier F, Mortera C, Naehr T, Orcutt B, Bernard B, Brooks J, de Faragó M. Asphalt volcanism and chemosynthetic life in the Campeche Knolls, Gulf of Mexico. Science 2004; 304:999-1002. [PMID: 15143278 DOI: 10.1126/science.1097154] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In the Campeche Knolls, in the southern Gulf of Mexico, lava-like flows of solidified asphalt cover more than 1 square kilometer of the rim of a dissected salt dome at a depth of 3000 meters below sea level. Chemosynthetic tubeworms and bivalves colonize the sea floor near the asphalt, which chilled and contracted after discharge. The site also includes oil seeps, gas hydrate deposits, locally anoxic sediments, and slabs of authigenic carbonate. Asphalt volcanism creates a habitat for chemosynthetic life that may be widespread at great depth in the Gulf of Mexico.
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Affiliation(s)
- I R MacDonald
- Physical and Life Sciences Department, Texas A & M University-Corpus Christi, 6300 Ocean Drive, Corpus Christi, TX 78412, USA.
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