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TitreLate Wisconsinan glacial landsystems on Atlantic Canadian shelves: new evidence from multibeam and single-beam sonar data
AuteurShaw, J; Todd, B J; Brushett, D; Parrott, D R; Bell, T
SourceBoreas vol. 38, no. 1, 2009 p. 146-159, https://doi.org/10.1111/j.1502-3885.2008.00043.x (Accès ouvert)
Année2009
Séries alt.Secteur des sciences de la Terre, Contribution externe 20080068
ÉditeurWiley-Blackwell
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1111/j.1502-3885.2008.00043.x
Mediapapier; en ligne; numérique
Formatshtml; pdf
ProvinceRégion extracotière de l'est
Lat/Long OENS-72.0000 -48.0000 54.0000 41.0000
Sujetsbathymétrie; glace; nappes glaciaires; concentration de glace; caractéristiques sous-marines; dépôts glaciomarins; moraines; elements glaciaires; topographie glaciaire; géologie des dépôts meubles/géomorphologie; géophysique; géologie marine; Cénozoïque; Quaternaire
Illustrationslocation maps; images
ProgrammeLes géosciences à l'appui de la gestion des océans
Résumé(disponible en anglais seulement)
Multibeam sonar surveys in the past decade, augmented by single-beam data from the OLEX charting system, reveal landsystems on Atlantic Canadian shelves that are diagnostic of Late Wisconsinan ice-sheet dynamics. Four landsystems are described. (1) The Bay of Fundy landsystem comprises two contrasting sets of bedforms, and is interpreted as evidence of topographically controlled fast-flowing ice adjacent to slower-moving ice. (2) The German Bank landsystem off southwest Nova Scotia is comprised of glacially fluted terrain overprinted by De Geer moraines and arcuate recessional moraines. We infer that a flow of grounded glacial ice out of the Bay of Fundy was followed by steady retreat, punctuated by at least one major re-advance. (3) The Placentia Bay landsystem consists of a convergent field of streamlined landforms with superimposed De Geer moraines, overprinted in one area by flutings. We infer that this landsystem was formed in the onset zone of fast-flowing ice, and that overprinting was due to a re-advance of ice from offshore. (4) The south coast of Newfoundland landsystem, which includes arcuate, fjord-mouth moraines and a coast-parallel, fluted moraine, indicates strong topographic control on a retreating marine ice margin as it reached a fjord coastline. These submarine glacial landsystems are not inconsistent with a conceptual model showing Late Wisconsinan ice advance to shelf edges, rapid calving retreat along deepwater channels and slower retreat of ice margins grounded in shallow water. The re-advances documented two of the study areas have parallels in the Last British Ice Sheet, confirming that the reorganization of marine-based ice sheets, caused by calving in embayments, led to internally forced re-advances.
GEOSCAN ID225119