GEOHAZARD INVESTIGATIONS OF PERMAFROST AND GAS HYDRATES IN THE OUTER SHELF AND UPPER SLOPE OF THE CANADIAN BEAUFORT SEA

Scott Dallimore, C.K. Paull, A.E. Taylor, M. Riedel, H.A. MacAulay, M.M. Côté, Y.K. Jin

In the proceedings of: GeoQuébec 2015: 68th Canadian Geotechnical Conference & 7th Canadian Permafrost Conference

Session: John Ross MacKay Symposium - Permafrost II / Symposium John Ross MacKay - Pergélisol II

ABSTRACT: Building on the early work of J. Ross Mackay, this paper reviews the state of knowledge of offshore permafrost and gas hydrates beneath the Beaufort Shelf. A thick and extensive interval of transgressed terrestrial permafrost is present beneath the central shelf, warming seaward and pinching out at 90-100 m water depth near the shelf-slope break. A complex gas hydrate regime is recognised with possible intrapermafrost and subpermafrost gas hydrate beneath the shelf, a zone with no gas hydrates at the shelf-slope transition, and a marine gas hydrate zone where water depths are greater than ~270 m. We believe that changes induced by transgression (formation and thawing of ground ice and gas hydrate) have created unique porous media conditions in this setting that can influence geohazards and active geologic processes. To this end we have undertaken a variety of multidisciplinary field investigations that have included marine geophysics, high resolution sea bed mapping, sediment coring, sea floor moorings and ROV dives.

RÉSUMÉ: Se basant sur les premiers travaux de J. pergélisol sous-marin et sur les hydrates de gaz se situant sous le plateau continental de la mer Beaufort. Une vaste sgression marine est présente sous la région centrale du -100 m, près de la transition plateau-pente continentale. Un régime cos de gaz est de gaz à la transition plateau-sont supérieures à ~270 m. Nous croyons que les changements résultant de la transgression marine (soit la formation et les risques géologiques et les processus géologiques actifs. Nous avons donc entrepris un programme multidisciplinaire de recherche sur le terrain qui inclut la géophysique marine, la cartographie de fonds marins à haute résolution, le carottage de sédiments, -marin téléguidé.

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