Becker, Lukas

Berndt, Christian

Dahlgreen, Torbjørn

Haflidason, Haflidi

Karstens, Jens

Planke, Sverre

Sejrup, Hans Petter

OceanRep

Geophysical Research AbstractsVol. 18, EGU2016-9489, 2016EGU General Assembly 2016© Author(s) 2016. CC Attribution 3.0 License.The impact of increased sedimentation rates associated with the decay ofthe Fennoscandian ice-sheet on gas hydrate stability and focused fluid flowat the Nyegga pockmark field, offshore mid-NorwayJens Karstens (1), Haflidi Haflidason (1), Lukas Becker (1), Hans Petter Sejrup (1), Christian Berndt (2), SverrePlanke (3), and Torbjørn Dahlgreen (4)(1) Department of Earth Science, University of Bergen, Bergen, Norway (Jens.Karstens@uib.no), (2) GEOMAR HelmholtzCentre for Ocean Research Kiel, Germany, (3) Centre for Earth Evolution and Dynamics (CEED), University of Oslo, Oslo,Norway, (4) Statoil, Harstad, NorwayClimatic changes since the Last Glacial Maximum (LGM) have affected the stability of gas hydrate systems onglaciated margins by sea-level changes, bottom water temperature changes, isostatic uplift or subsidence and vari-ability in sedimentation rates. While subsidence and sea-level rise stabilize gas hydrate deposits, bottom watertemperature warming, uplift and enhanced sedimentation have the opposite effect. The response of gas hydratesystems to post-glaciation warming is therefore a complex phenomenon and highly depends on the timing andmagnitude of each of these processes. While the impact of bottom water warming on the dissociation of gashydrates have been addressed in numerous studies, the potential of methane release due to basal gas hydrate disso-ciation during periods of warming has received less attention. Here, we present results from numerical simulationswhich show that rapid sedimentation associated with the decay of the Fennoscandian ice-sheet was capable of caus-ing significant basal gas hydrate dissociation. The modeling is constrained by a high-resolution three-dimensionalsedimentation rate reconstruction of the Nyegga pockmark field, offshore mid-Norway, obtained by integratingchrono-stratigraphic information derived from sediments cores and a seismo-stratigraphic framework. The modelrun covers the period between 28,000 and 15,000 calendar years before present and predict that the maximumsedimentation rate-related gas hydrate dissociation coincides temporally and spatially with enhanced focused fluidflow activity in the study area. Basal gas hydrate dissociation due to rapid sedimentation may have occurred as wellin other glaciated continental margins after the LGM and may have caused the release of significant amounts ofmethane to the hydrosphere and atmosphere. The major post glaciation deposition centers are the location of someof the largest known submarine slide complexes. The release of free gas due to basal gas hydrate dissociation hasthe potential to destabilize the continental slopes by focused fluid migration and the transfer of overpressure.

The impact of increased sedimentation rates associated with the decay of

the Fennoscandian ice-sheet on gas hydrate stability and focused fluid flow

at the Nyegga pockmark field, offshore mid-Norway

The impact of increased sedimentation rates associated with the decay of the Fennoscandian ice-sheet on gas hydrate stability and focused fluid flow at the Nyegga pockmark field, offshore mid-Norway

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