GEOSCAN, résultats de la recherche


TitrePalaeoceanographic information derived from acoustic surveys of glaciated continental margins: examples from eastern Canada
AuteurSyvitski, J P M; Lewis, C F M; Piper, D J W
SourceLate Quaternary palaeoceanography of the North Atlantic margins; par Andrews, J T (éd.); Austin, W E N (éd.); Bergsten, H (éd.); Jennings, A E (éd.); Geological Society, Special Publication no. 111, 1996 p. 51-76,
Séries alt.Commission géologique du Canada, Contributions aux publications extérieures 24495
ÉditeurGeological Society of London
Documentpublication en série
Mediapapier; en ligne; numérique
ProvinceRégion extracotière de l'est
Lat/Long OENS -76.0000 -36.0000 60.0000 40.0000
Sujetsinterpretations sismiques; profils sismiques marins; levés sismiques marins; levés de reflexion sismiques; isopaques; débit de sedimentation; déglaciation; dépôts glaciomarins; marges glaciaires; plate-forme continentale; talus continental; gougeage de la glace; dispersion des sédiments; profils de dispersion; courants de marée; géologie marine; sédimentologie; géologie des dépôts meubles/géomorphologie; Quaternaire
Illustrationslocation maps; seismic reflection profiles; schematic cross-sections; graphs
Diffusé1996 01 01
Résumé(disponible en anglais seulement)
Much palaeoceanographic information can be gleaned from seismic, sidescan and bathymetric data on glaciated continental shelves. High-resolution seismic reflection surveys of regional ice terminus features define palaeo-ice margins, datable using interfingering ice-proximal glacimarine deposits. Isopach maps show differences in regional accumulation rates of sediments during deglaciation phases and help locate positions of former glacifluvial discharge outlets. Maps of ice-distal glacimarine muds suggest that surface currents carrying buoyant plumes of glacial flour may extend >100 km from an ice margin. Transport and melt of icebergs controlled by circulation of deeper outer shelf and slope currents and episodic storms can result in a glacial influence >1000 km from the ice margin, but most iceberg-rafted sedimentation occurs within a few hundred kilometres of calving. The direction of these palaeo-mid-depth currents may be obtained from statistical analysis of relict iceberg scour patterns and from sediment dispersal patterns. The geometry of glacimarine deposits commonly suggests that there was water column stratification with associated weak near-seafloor currents. Comparison of the shape of glacimarine and post-glacial sediment packages shows that in many places the tidal current intensity has increased through the Holocene, reflecting sea-level change on the shelf.