Slide structure and role of gas hydrate at the northern boundary of the Storegga Slide, offshore Norway

Brown, H. E.; Holbrook, W. Steven; Hornbach, Matthew J.; Nealon, J. W.

doi:10.1016/j.margeo.2006.03.011

Cited by 122 publications

(44 citation statements)

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“…has been correlated with rising sea levels, and peaks in atmospheric methane levels due to disintegration of gas hydrates in the North Atlantic sector, including the Nordic seas and the Mediterranean Sea (Maslin et al 2004). Similar slide scarps have been reported in offshore regions of Norway (Brown et al 2006). Therefore, we suggest that sea-level fluctuations can be considered as an alternative explanation for the slumping/slides observed in the present study.…”

Section: Discussionsupporting

confidence: 89%

Multidisciplinary investigations exploring indicators of gas hydrate occurrence in the Krishna–Godavari Basin offshore, east coast of India

et al. 2008

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We report some main results of multidisciplinary investigations carried out within the framework of the Indian National Gas Hydrate Program in [2002][2003] in the Krishna-Godavari Basin offshore sector, east coast of India, to explore indicators of likely gas hydrate occurrence suggested by preliminary multi-channel seismic reflection data and estimates of gas hydrate stability zone thickness. Swath bathymetry data reveal new evidence of three distinct geomorphic units representing (1) a delta front incised by several narrow valleys and mass flows, (2) a deep fan in the east and (3) a WNW-ESE-trending sedimentary ridge in the south.Deep-tow digital side-scan sonar, multi-frequency chirp sonar, and sub-bottom profiler records indicate several surface and subsurface gas-escape features with a highly resolved stratification within the upper 50 m sedimentary strata. Multi-channel seismic reflection data show the presence of bottom simulating reflections of continuous to discrete character. Textural analyses of 76 gravity cores indicate that the sediments are mostly silty clay. Geochemical analyses reveal decreasing downcore pore water sulphate (SO 4 2− ) concentrations (28.7 to <4 mM), increasing downcore methane (CH 4 ) concentrations (0-20 nM) and relatively high total organic carbon contents (1-2.5%), and microbial analyses a high abundance of microbes in top core sediments and a low abundance of sulphate-reducing bacteria in bottom core sediments.Methane-derived authigenic carbonates were identified in some cores. Combined with evidence of gasescape features in association with bottom simulating reflections, the findings strongly suggest that the physicochemical conditions prevailing in the study area are highly conducive to methane generation and gas hydrate occurrence. Deep drilling from aboard the JOIDES Resolution during 2006 has indeed confirmed the presence of gas hydrate in the KrishnaGodavari Basin offshore.

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Section: Discussionsupporting

confidence: 89%

Multidisciplinary investigations exploring indicators of gas hydrate occurrence in the Krishna–Godavari Basin offshore, east coast of India

et al. 2008

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“…Hydrate dissociation has long been suspected to be a possible cause of slope failure (e.g., Sultan et al 2004;Brown et al 2006). Gas hydrates have been sampled at the seafloor in the South Caspian Basin at water depths (475 and 660 m; Ginsburg and Soloviev 1994) similar to those of the present study.…”

Section: The Hydrate Issuesupporting

confidence: 59%

How to evacuate 10 km3 of mud: saturate with gas and decrease the pressure!

2014

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The crest of the Absheron anticline in the South Caspian Basin at a few hundred meters below the present seafloor shows a subcircular depression about 8 km in diameter and 200 m deep, bounded by steep edges dipping 15°to 45°into it. The depression and the surrounding series are respectively filled and overlain by a regional mass-transport deposit (MTD) 150 m thick outside the depression and 300 m thick inside, composed mostly of extensional blocks. Geometric and stratigraphic analyses indicate that 150 m of initially deposited sediment were removed from a closed area after burial. Seismic evidence of shallow gas accumulations below the crater-like feature suggests that gas likely played a significant role in its development. The model proposed for the emplacement of the crater is that the gas-bearing cover of a shallow gas reservoir underwent exsolution when its overburden thinned during an episode of extensional slope failure. This resulted in loss of resistance to shear and evacuation of the gas-bearing sediment, likely at the shearing base of the failed mass. This evacuation feature is considered an example where the presence of gas locally governs the morphology of an MTD. The interpreted process shows a positive feedback between slope failure and loss of strength at the base of the resulting MTD.

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“…As suas dimensões são gigantescas: volume, 5 600km 3 ; espessura, 450m; comprimento da cicatriz, 290km; distância percorrida pelos sedimentos, 800km. Abalos sís-micos e gaseificação dos hidratos são apontados como as causas mais próximas do colapso do talude continental em três momentos principais, entre 30 000 BP e 50 000 BP para o primeiro e entre 6 000 e 8 000 BP para os dois últimos, em período de deglaciação (Bugge et al, 1987;Brown et al, 2006). O megatsunami que o episódio 8 000 BP provocou no Mar da Noruega encontra-se bem documentado, tendo deixado vestí-gios sedimentológicos de uma onda gigantesca de mais de 20m nas costas das ilhas Shetland e da Escócia (Bondevik et al, 2003).…”

Section: Os Hidratos De Metano E a Instabilidade Dos Taludes Contunclassified

Passado e presente dos recursos hídricos no Brasil

Ferreira¹

2012

FIT

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Resumo -Os hidratos de metano constituem uma fonte interessante de energia cujas reservas oceânicas recenseadas em 2001 foram estimadas em duas vezes as reservas conhecidas de gás natural, petróleo e carvão reunidas. Encontram-se nos sedimentos marinhos das margens continentais, e a fraca profundidade, no permafrost. Tendo em conta a necessidade crescente da sociedade em energia e o preço cada vez mais elevado do petróleo, a exploração desta nova fonte de energia é tentadora, mas também arriscada, acarretando problemas ambientais difíceis de resolver. A desestabilização e rejeição na atmosfera do metano imobilizado nos hidratos são vistas como uma ameaça tanto para a estabilidade dos taludes continentais como para o futuro do clima do planeta.Palavras-chave: Hidratos de metano, recursos energéticos, gases com efeito de estufa, aquecimento global, movimentos de massa, margem continental, permafrost. Abstract -METHANE HYDRATES: ENERGY RESOURCE OR SOURCE OF ENVI-RONMENTAL HAZARD?Methane hydrates are a very interesting source of energy. Worldwide estimated resources of methane hydrates in oceans in 2001 are twice the amount of carbon contained in all fossil fuels on Earth. They occur in marine sediments along the continental margins and in polar continental environment, in permafrost. Both the increasing energy needs of the society and the high prices of petroleum challenge the research on gas hydrates recovery and on the possibility of using in the near future this huge resource of energy. The major environmental issues related to the exploitation of gas hydrates are rapid climate warming through emissions of methane from marine sediments and permafrost into the atmosphere and extensive mass failure in the sediments of the continental slopes.Key words: Methane hydrates, energy resources, greenhouse gas, global warming, landslides, continental margin, permafrost. celle qui compose tous les combustibles fossiles de la planète. Ils se logent dans les sédiments marins des plateformes continentales et dans le permafrost des régions polaires continentales. Les besoins croissants en énergie des sociétés humaines et les prix en hausse du pétrole défient la recherche sur les modes d´extraction des hydrates et sur la possibilité de les inclure, dans un futur proche, dans l´assiette énergétique mondiale. Les risques majeurs associés à l´exploitation des hydrates concernent surtout une accélération du réchauffement de la planète due à un échappement incontrôlable vers l´atmosphère du méthane contenu dans les sédiments marins et dans le permafrost, et l´occurrence de collapses généralisés des sédiments des talus continentaux. Mots-clés:Hydrates de méthane, ressources énergétiques, gaz à effet de serre, réchauffement global, mouvements de masse, marge continental, permafrost.

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Slide structure and role of gas hydrate at the northern boundary of the Storegga Slide, offshore Norway

Cited by 122 publications

References 18 publications

Multidisciplinary investigations exploring indicators of gas hydrate occurrence in the Krishna–Godavari Basin offshore, east coast of India

Multidisciplinary investigations exploring indicators of gas hydrate occurrence in the Krishna–Godavari Basin offshore, east coast of India

How to evacuate 10 km3 of mud: saturate with gas and decrease the pressure!

Passado e presente dos recursos hídricos no Brasil

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