GEOSCAN, résultats de la recherche


TitreLarge-scale sedimentary bedforms and sediment dynamics on a glaciated tectonic continental shelf: Examples from the Pacific margin of Canada
AuteurBarrie, J V; Conway, K W; Picard, K; Greene, H G
SourceContinental Shelf Research vol. 29, 2009 p. 796-806,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20080563
ÉditeurElsevier BV
Documentpublication en série
Mediapapier; en ligne; numérique
ProvinceRégion extracotière de l'ouest
Lat/Long OENS-131.0000 -122.0000 52.0000 47.0000
Lat/Long OENS-134.0000 -127.0000 55.0000 51.0000
Sujetsconfigurations lit; déplacement de la configuration lit; dynamique sédimentaire; roches sédimentaires; topographie du fond océanique; topographie du fond océanique; bathymétrie; dunes; changements du niveau de la mer; glaciation; transport des sediments; transport sous-marin; moyens de transport; géologie marine; sédimentologie; géophysique
Illustrationslocation maps; profiles; images
ProgrammeLes géosciences à l'appui de la gestion des océans
Résumé(disponible en anglais seulement)
The Pacific margin of Canada has been subjected to tectonism, dramatic sea level change and vigorous storm and tidal energy since glacial times resulting in a complex seafloor. Extensive multibeam mapping of this shelf has provided an opportunity to understand how these processes have impacted sedimentology and morphology. Bathymetric restriction of the tidally dominated flow between the inland seas and the open Pacific has resulted in the development of very large subaqueous dune fields and terrace moats. For example, in the southern Strait of Georgia nearly symmetrical dunes with wavelengths between 100 and 300m, dune heights up to 28m, cover the seafloor in 170 - 210m water depth. In northern Hecate Strait a 72 km2 area of large 2D dunes occurs at the transition with Dixon Entrance which opens to the Pacific Ocean and steep (4101) wave-cut terraces and drowned spits, a result of sea level changes during the Holocene, are now being undercut to generate moats 7m deep, in a narrowing shelf trough. Currents, with velocities ranging between 0.2 and 2.2ms-1, are dominated by semi-diurnal tidal streams that are continually modified by wind and estuarine circulation. There appears to be a clear association of grain size, water depth and flow velocity controlling the size of the subaqueous dunes.