GEOSCAN, résultats de la recherche


TitreMorphology of submarine canyons and channels on the central Scotian Slope
AuteurCampbell, D C; Piper, D J W
SourceGAC-MAC-CSPG-CSSS Halifax 2005, building bridges - across science, through time, around the world: abstracts/AGC-AMC-SCGP-SCSS Halifax 2005, Jeter des ponts entre les disciplines scientifiques, les époques, et unifier le monde : recueil des résumés; AGC-AMC-SCGP-SCSS Reunion conjoint, Receuil des Résumés vol. 30, 2005 p. 24
Séries alt.Secteur des sciences de la Terre, Contribution externe 2004354
ÉditeurSociété géoscientifique de l'Atlantique
RéunionHalifax 2005: GAC/MAC/CSPG/CSSS Joint Annual Meeting; Halifax; CA; mai 15-18, 2005
Documentpublication en série
ProvinceRégion extracotière; Nouvelle-Écosse
Lat/Long OENS -63.0000 -59.0000 44.0000 42.0000
Sujetscanyons sous-marins; plaines abyssales; plate-forme continentale; bathymétrie; topographie du fond océanique; glissements de pentes
ProgrammeLes géosciences à l'appui de la gestion des océans
Résumé(disponible en anglais seulement)
Submarine canyons and channels are important conduits for carrying sediment from the outer shelf to the abyssal plain. The Scotian Slope lies approximately 200 km south of Nova Scotia and trends northeast/southwest, parallel to the modern coastline. South of Western
Bank and Banquereau, the Slope is heavily incised by submarine canyons. In 2000, more than 20 000 square kilometres of multibeam
bathymetry was collected on the central Scotian Slope between Mohican Channel and the Gully, from 150 to 3500 metres water depth.
A series of groundtruth expeditions occurred over subsequent field seasons, which together with the multibeam data provide an excellent
dataset for investigating continental slope processes. This study uses qualitative and quantitative geomorphology techniques to describe and interpret submarine canyons and channels on the Scotian Slope. The morphology of the central Scotian Slope ranges from planar in
cross-section with little relief in the west, to concave-up in crosssection with irregular relief in the east. In the eastern part of the study
area major submarine canyons and intercanyon divides are the dominant features. The canyons are dendritic and form distinct catchments which coalesce into large channels on the continental rise. A few canyons erode into the continental shelf, the Gully being the
most severe example. Most canyon tributaries head on the upper slope in glacial till, however some head in water depths as great as 1000 metres. On some canyons there is less rill and gully development on the canyon walls and there is more evidence of seafloor retrogression. Between Mohican Channel and Verrill Canyon, the seafloor has a unique planar shape which is superimposed with continuous failure escarpments up to 100 metres in height. Previous studies have shown that this area has experienced repeated small-scale seabed failure during the Pleistocene, which may explain the distinctive shape. Evidence of seafloor retrogression is common on the upper slope in the western part of the study area, with failure scarps terminating in more competent outer shelf deposits. Linear channels with low relief are present and are continuous from the upper slope to the continental rise. A model is presented that relates canyon style to the major features of shelf crossing glaciation. We evaluate the relative importance of direct hyperpycnal flow from meltwater, sediment fallout from proglacial plumes, retrogressive slope failure, and sediment character of the upper slope in development of the canyon systems.