GEOSCAN, résultats de la recherche


TitreEvolution of a nearshore and coastal macrotidal sand transport system, Queen Charlotte Islands, Canada
AuteurBarrie, J V; Conway, K W
SourceGeology of siliciclastic shelf seas; par De Batist, M (éd.); Jacobs, P (éd.); Geological Society, Special Publication no. 117, 1996 p. 233-247,
Séries alt.Commission géologique du Canada, Contributions aux publications extérieures 31295
ÉditeurGeological Society of London
Documentpublication en série
Mediapapier; en ligne; numérique
ProvinceRégion extracotière de l'ouest; Colombie-Britannique
Lat/Long OENS-132.0000 -131.0000 54.1667 53.8333
Sujetsmilieu côtièr; transport des sediments; bathymétrie; dépôts de marée; milieux de marée; soulèvement de la croûte; cordons littoraux sableux; géologie des dépôts meubles/géomorphologie
Illustrationslocation maps; photographs; graphs
Diffusé1996 01 01
Résumé(disponible en anglais seulement)
An extensive (40 km) coastal plain is prograding on the north coast of the Queen Charlotte Islands off the Pacific margin of Canada while the entire 120 km eastern coast of Graham Island is actively eroding. At the junction of these two systems is Rose Spit, which extends northeastward at a point of sediment transport convergence. Historical bathymetrical data and aerial photographs indicate that a spit platform extends 10 km to the northeast and at least four portions (up to 4 km in length) of the platform bank have become emergent since 1911. The area is seismically active and subject to storm-related sediment transport events superimposed on strong semi-diurnal tidal flows. The rapid emergence of the offshore banks and the net coastal changes are primarily controlled by: (1) convergence of sediment transport between the waters of Hecate Strait to the south and Dixon Entrance to the north, particularly during winter storms; and (2) localized tectonic uplift.
Sediment is transported north from the shallow waters of Hecate Strait by southeasterly winter storms and east, by longshore transport, along the accreting northern coast of the Queen Charlotte Islands to converge at Rose Spit. A 'hydraulic fence' has formed resulting in the creation of the elongate spit platform with emergent sand bars, east of the spit. Transpressional folding has occurred in this area east of the Queen Charlotte Fault, which separates the North American and Pacific Plates. This has resulted in localized uplift since Pliocene time, complementing the accretion process.