GEOSCAN, résultats de la recherche


TitrePaleoclimate driven evolution of the shelf and upper slope region of the Beaufort Sea
AuteurBlasco, S; Bennett, R; Davies, E; Hughes-Clarke, J; MacKillop, K; Blasco, K
SourceASM2009 Conference Programme and Abstracts; 2009 p. 27
Séries alt.Secteur des sciences de la Terre, Contribution externe 20100301
RéunionArcticnet ASM 2009; Victoria, BC; CA; décembre 8-11, 2009
ProvinceRégion extracotière du nord
Lat/Long OENS-140.0000 -132.0000 72.0000 69.0000
Sujetspaléoclimats; plate-forme continentale; talus continental; antecedents glaciaires; changements du niveau de la mer; variations du niveau de la mer; milieu sédimentaire; géologie des dépôts meubles/géomorphologie; Nature et environnement
ProgrammeGéoscience en mer, Géoscience marine pour le développement économique de l'Arctique
Résumé(disponible en anglais seulement)
Beaufort Sea seabed research is being conducted in response to the recent federal government release of deep water leases for hydrocarbon exploration drilling over the next 5 years. Under the ArcticNet seabed mapping project Coast Guard research vessels Amundsen and Nahidik have continued to acquire multibeam, subbottom profile and sediment sample data to define the geological framework for geohazards assessment. Interpretation of legacy and new data indicate the geological history of the Beaufort Shelf and upper slope region was driven by climate change.
During the late glacial maximum the Beaufort Shelf was dominated by a cold arid climate. Sea level was a maximum of 120m lower than present day ¿ leaving the shelf subaerially exposed to the aggradation of permafrost. The shelf was a refugium for fauna and flora. Under ameliorating climate conditions, melting of the Laurentide ice sheet lead to the rapid deposition of a massive distal outwash plain that extended across the shelf and down slope. Continued ablation of the Late Wisconsinan ice sheet was accompanied by meltwater discharge across the shelf and upper slope resulting in the erosion and incision of glaciofluvial channels into the outwash plain. As the climate continued to warm and the ice sheet disappeared, sea level rose and drowned the shelf. These events probably took place between 21,000 to 8,000 years ago.
For the upper slope region beyond the 100m isobath (very limited exposure during sea level lowstand), the rapid deposition of distal glacial outwash over soft marine clays may have resulted in clay diapirism and slope failures. Over time the peculation of gas/fluids from depth further destabilized the shelf edge and upper slope through mud volcanism. The submarine slumps of the outer shelf/upper slope are draped with a thin veneer of undisturbed recent sediments suggesting deformation may be relict. The surficial sediments thicken down slope. Over the last few thousand years the region has been relatively stable except for the growth of mud volcanoes. The transition from a cold, arid glacial to warm, wet interglacial climate regime was the driving force behind the current structure and stratigraphy of the Beaufort Shelf and upper slope seabed environment.