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Geological controls on the Storegga gas-hydrate system of the mid-Norwegian continental margin

Geological controls on the Storegga gas-hydrate system of the mid-Norwegian continental margin
Geological controls on the Storegga gas-hydrate system of the mid-Norwegian continental margin
The geologic setting of the formerly glaciated mid-Norwegian continental margin exerts specific controls on the formation of a bottom-simulating reflector (BSR) and the inferred distribution of gas hydrates. On the continental slope the lithology of glacigenic debris flow deposits and pre-glacial basin deposits of the Kai Formation prevent gas-hydrate formation, because of reduced pore size, reduced water content and fine-grained sediment composition. Towards the continental shelf, the shoaling and pinch-out of the gas-hydrate stability zone terminates the area of gas-hydrate growth. These geological controls confine the occurrence of gas hydrates and ensuing formation of a BSR to a small zone along the northern flank of the Storegga submarine slide and the slide area itself. A BSR inside the slide area indicates a dynamically adjusting gas-hydrate system to post-slide pressure–temperature equilibrium conditions. These observations, together with widespread evidence for fluid flow and deep-seated hydrocarbon reservoirs, suggest that the formation of BSR and gas hydrates on the mid-Norwegian continental margin is dominated by an advection of gas from the strata distinctly beneath the gas-hydrate stability zone. Fluids migrate upward within the Naust Formation and are deflected laterally by hydrated sediments and less permeable layers. Gases continually accumulate at the top of the slope, where overpressure eventually results in the formation of blow-out pipes and consequent pockmark development on the seabed.
gas hydrate, bottom-simulating reflector, fluid flow, pipes, pockmark, polygonal faults, reflection seismic, hydrocarbon, norwegian margin, storegga slide, møre basin, vøring basin
0012-821X
291-307
Bunz, S.
3969591c-f8ea-4035-a0ac-b8a4990bf362
Mienert, J.
90ba1f28-5249-4663-ad09-b6abc8b46068
Berndt, C.
231544d4-f681-44a2-ae6e-74385e588bf6
Bunz, S.
3969591c-f8ea-4035-a0ac-b8a4990bf362
Mienert, J.
90ba1f28-5249-4663-ad09-b6abc8b46068
Berndt, C.
231544d4-f681-44a2-ae6e-74385e588bf6

Bunz, S., Mienert, J. and Berndt, C. (2003) Geological controls on the Storegga gas-hydrate system of the mid-Norwegian continental margin. Earth and Planetary Science Letters, 209 (3-4), 291-307. (doi:10.1016/S0012-821X(03)00097-9).

Record type: Article

Abstract

The geologic setting of the formerly glaciated mid-Norwegian continental margin exerts specific controls on the formation of a bottom-simulating reflector (BSR) and the inferred distribution of gas hydrates. On the continental slope the lithology of glacigenic debris flow deposits and pre-glacial basin deposits of the Kai Formation prevent gas-hydrate formation, because of reduced pore size, reduced water content and fine-grained sediment composition. Towards the continental shelf, the shoaling and pinch-out of the gas-hydrate stability zone terminates the area of gas-hydrate growth. These geological controls confine the occurrence of gas hydrates and ensuing formation of a BSR to a small zone along the northern flank of the Storegga submarine slide and the slide area itself. A BSR inside the slide area indicates a dynamically adjusting gas-hydrate system to post-slide pressure–temperature equilibrium conditions. These observations, together with widespread evidence for fluid flow and deep-seated hydrocarbon reservoirs, suggest that the formation of BSR and gas hydrates on the mid-Norwegian continental margin is dominated by an advection of gas from the strata distinctly beneath the gas-hydrate stability zone. Fluids migrate upward within the Naust Formation and are deflected laterally by hydrated sediments and less permeable layers. Gases continually accumulate at the top of the slope, where overpressure eventually results in the formation of blow-out pipes and consequent pockmark development on the seabed.

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More information

Published date: 2003
Keywords: gas hydrate, bottom-simulating reflector, fluid flow, pipes, pockmark, polygonal faults, reflection seismic, hydrocarbon, norwegian margin, storegga slide, møre basin, vøring basin

Identifiers

Local EPrints ID: 2058
URI: http://eprints.soton.ac.uk/id/eprint/2058
ISSN: 0012-821X
PURE UUID: 26f5b45f-a9de-4a2f-8f1e-febafe4f1986

Catalogue record

Date deposited: 12 May 2004
Last modified: 15 Mar 2024 04:44

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Contributors

Author: S. Bunz
Author: J. Mienert
Author: C. Berndt

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