Giant Gas Chimneys and Gas Hydrate Occurrence in the Southwestern Barents Sea

During the past ~2.6 Ma, some 30 glaciations have caused episodic high pressure and low temperature conditions and forced growth and decay of extensive subglacial methane hydrate accumulations globally. Research on Arctic methane release has primarily focused on warm, interglacial episodes when hydrates became unstable across territories either abandoned by former ice sheets or affected by permafrost degradation. Here we present a new mechanism &#8211; the subglacial erosion of gas hydrate-bearing sediments &#8211; that actively mobilizes methane in hydrate and dissolved form and delivers it to the ice sheet margin. We investigate this mechanism using geophysical imaging and ice sheet/gas hydrate modeling focused on a study site in Storfjordrenna, that hosted large ice stream draining the Barents Sea ice sheet. During the last glacial, we find that this ice stream overrode an extensive cluster of conduits that supplied a continuous methane flux from a deep, thermogenic source and delivered it to the subglacial environment. Our analysis reveals that 15,000 to 44,000 m3 of gas hydrates were subglacially eroded from the 17 km2 study site and transported to the shelf-edge. Given the abundance of natural gas reservoirs across the Barents Sea and marine-based glaciated petroleum provinces elsewhere, we propose that this mechanism had the potential to mobilize a substantial flux of subglacial methane throughout multiple Quaternary glacial episodes.

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Multiple episodes of fluid flow in the SW Barents Sea (Loppa High) evidenced by gas flares, pockmarks and gas hydrate accumulation

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2012.03.021 ◽

2012 ◽

Vol 331-332 ◽

pp. 305-314 ◽

Cited By ~ 55

Author(s):

S. Chand ◽

T. Thorsnes ◽

L. Rise ◽

H. Brunstad ◽

D. Stoddart ◽

...

Keyword(s):

Fluid Flow ◽

Gas Hydrate ◽

Barents Sea ◽

Gas Flares ◽

Multiple Episodes

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Dynamics of methane seepage at Leirdjupet Fault Complex (SW Barents Sea) since last deglaciation and possible future scenarios

10.5194/egusphere-egu21-10621 ◽

2021 ◽

Author(s):

Claudio Argentino ◽

Kate Waghorn ◽

Sunil Vadakkepuliyambatta ◽

Stéphane Polteau ◽

Stefan Bünz ◽

...

Keyword(s):

Gas Hydrate ◽

Barents Sea ◽

Ice Sheet ◽

Methane Emissions ◽

Anaerobic Oxidation Of Methane ◽

Last Deglaciation ◽

Methane Seeps ◽

Geochemical Composition ◽

Methane Seepage ◽

The Barents Sea

Methane emissions from Arctic continental margins may increase due to global warming. Present-day ocean fluxes seem to provide a minor contribution to the atmosphere methane pool, but large uncertainties still remain on the magnitude of future emissions from methane seeps and gas hydrate-bearing sediments. The Barents Sea is a natural laboratory to study the evolution of methane seeps in relation to climate change, as it recorded several phases of ice-sheet advance and retreat during the Pleistocene. Glaciations and its concurrent denudation of the Barents Sea influenced the subsurface, causing reservoir expansion and fracturing, thereby driving hydrocarbon (mostly gas) migration which resulted in a sustained regional fluid flow system. New data from this area can shed light on future response of other high-latitude continental shelves worldwide. Here, we present reconstructed methane emission dynamics at Leirdjupet Fault Complex (LFC), SW Barents Sea, since last deglaciation (occurred after ~19 cal Ka BP). The geochemical composition of sediment cores indicate prolonged methane emissions, which started after 14.5 cal Ka BP. Geochemical proxies for anaerobic oxidation of methane in the sediment (barium, calcium and sulfur enrichments, isotopic composition of foraminifera) indicate an overall decrease in seepage intensity over the Holocene toward present-day conditions. Methane-derived authigenic carbonates with aragonite mineralogy and heavy &#948;18O signature recorded an episode of gas hydrate destabilization in this region. Paleo-hydrate stability models suggest that this event was triggered by the influx of warm Atlantic water and isostatic uplift linked to the retreat of the Barents Sea Ice Sheet. Present-day distribution of methane seeps at LFC is strongly linked to underlying faults. Methane hydrates are stable in the southern part of the investigated seepage area and might respond to a future increase in bottom water temperatures.

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Gas Hydrate Stability Zone of the Barents Sea and Kara Sea Region

Energy Procedia ◽

10.1016/j.egypro.2016.10.005 ◽

2016 ◽

Vol 97 ◽

pp. 302-309 ◽

Cited By ~ 6

Author(s):

Peter Klitzke ◽

Manja Luzi-Helbing ◽

Judith M. Schicks ◽

Mauro Cacace ◽

Antoine B. Jacquey ◽

...

Keyword(s):

Gas Hydrate ◽

Barents Sea ◽

Kara Sea ◽

Stability Zone ◽

The Barents Sea ◽

Hydrate Stability

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Gas hydrate and free gas indications within the Cenozoic succession of the Bjørnøya Basin, western Barents Sea

Marine and Petroleum Geology ◽

10.1016/s0264-8172(96)00038-4 ◽

1996 ◽

Vol 13 (8) ◽

pp. 921-940 ◽

Cited By ~ 25

Author(s):

Jan Sverre Laberg ◽

Karin Andreassen

Keyword(s):

Gas Hydrate ◽

Barents Sea ◽

Free Gas

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Geological Controls on Fluid Flow and Gas Hydrate Pingo Development on the Barents Sea Margin

Geochemistry Geophysics Geosystems ◽

10.1029/2018gc007930 ◽

2019 ◽

Vol 20 (2) ◽

pp. 630-650 ◽

Cited By ~ 7

Author(s):

M. Waage ◽

A. Portnov ◽

P. Serov ◽

S. Bünz ◽

K. A. Waghorn ◽

...

Keyword(s):

Fluid Flow ◽

Gas Hydrate ◽

Barents Sea ◽

The Barents Sea

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The influence of methane fluxes on the sulfate/methane interface in sediments from the Rio Grande Cone Gas Hydrate Province, southern Brazil

Brazilian Journal of Geology ◽

10.1590/2317-4889201720170027 ◽

2017 ◽

Vol 47 (3) ◽

pp. 369-381 ◽

Cited By ~ 7

Author(s):

Luiz Frederico Rodrigues ◽

João Marcelo Ketzer ◽

Rogerio Véscia Lourega ◽

Adolpho Herbert Augustin ◽

Gesiane Sbrissa ◽

...

Keyword(s):

Gas Hydrate ◽

Rio Grande ◽

Methane Flux ◽

Concentration Profiles ◽

Southern Brazil ◽

Methane Fluxes ◽

Stratigraphic Position ◽

Seismic Records ◽

Pelotas Basin ◽

Gas Chimneys

ABSTRACT: Much research has been published regarding the relation between major gas hydrate accumulations and the global carbon cycle. In this context, the determination of the sulfate/methane interface (SMI) depth is of primary importance in order to understand the dynamics of methane flux in the shallow section. This paper identifies the depth of the SMI in sediments based on sulfate and methane concentration profiles in cores recovered in the Rio Grande Cone Gas Hydrate Province, Pelotas Basin, southern Brazil. The shape of methane and sulfate concentration profiles in the sediments can be linked to the local methane flux rate as follows: (i) near linear, high upward-diffusing methane flux coupled with high sulfate diffusion from seawater; (ii) irregular, variable methane flux rates; and (iii) kink-type profile, which is indicative of variable rather than strictly high upward methane flux. The areas in which a high methane flux was identified are spatially associated with gas chimneys in sediments within pockmarks, whereas profiles with low methane flux are present in adjacent areas. These chimneys appear as acoustic blankings in seismic records and can therefore be mapped in subsurface. The wavy-like seismic reflection following the SMI coincides with the occurrence of authigenic carbonate nodules and concretions. In addition, high methane fluxes and the occurrence of concretions and nodules carbonates were correlated by stratigraphic position of the concretions bearing intervals and sulfate profiles.

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