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TitleLarge-scale sedimentary bedforms and sediment dynamics on a glaciated tectonic continental shelf: Examples from the Pacific margin of Canada
AuthorBarrie, J V; Conway, K W; Picard, K; Greene, H G
SourceContinental Shelf Research vol. 29, 2009 p. 796-806,
Alt SeriesEarth Sciences Sector, Contribution Series 20080563
PublisherElsevier BV
Mediapaper; on-line; digital
File formatpdf
ProvinceWestern offshore region
AreaPacific Margin; Hecate Strait; Queen Charlotte Sound; Strait of Juan de Fuca
Lat/Long WENS-131.0000 -122.0000 52.0000 47.0000
Lat/Long WENS-134.0000 -127.0000 55.0000 51.0000
Subjectsmarine geology; sedimentology; geophysics; bedforms; bedform movement; sedimentation dynamics; sedimentary rocks; seafloor topography; seabottom topography; bathymetry; dunes; sea level changes; glaciation; sediment transport; submarine transport; transportation
Illustrationslocation maps; profiles; images
ProgramGeoscience for Oceans Management
AbstractThe 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.

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