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TitreSurficial geology and features of the inner shelf of eastern shore, offshore Nova Scotia
TéléchargerTéléchargements
AuteurKing, E L
SourceCommission géologique du Canada, Dossier public 8375, 2018, 41 pages (1 feuille), https://doi.org/10.4095/308454
Année2018
ÉditeurRessources naturelles Canada
Documentdossier public
Lang.anglais
DOIhttps://doi.org/10.4095/308454
CartesCette publication contient 1 carte
Info. cartedépôts meubles, 1/160,000
ProjectionProjection transverse universelle de Mercator, zone TUM 20 (NAD83)
Mediaen ligne; numérique
Formatspdf
ProvinceRégion extracotière de l'est; Nouvelle-Écosse
SNRC11D/06; 11D/07; 11D/08; 11D/09; 11D/10; 11D/11; 11D/14; 11D/15; 11D/16
Lat/Long OENS -63.0833 -62.2333 45.0000 44.4000
Sujetsmarges continentales; plate-forme continentale; topographie du fond océanique; bathymétrie; structures sédimentaires; levés géophysiques; levés acoustiques marins; sonar latéral; levés sismiques marins; levés de reflexion sismiques; géologie du substratum rocheux; lithologie; roches métamorphiques; roches sédimentaires métamorphosées; ardoises; caractéristiques sous-marines; dorsales sous-marines; fosses abyssales; bassins; sédiments marins; dépôts postglaciaires; boues; antecedents glaciaires; glaciation; déglaciation; changements du niveau de la mer; trangressions; dépôts glaciaires; elements glaciaires; topographie glaciaire; erosion glaciaire; chenaux; écoulement glaciaire; stries glaciaires; drumlins; moraines; moraine frontale; moraine, de geer; moraine côtelée; tills; dépôts glaciomarins; dépôts résiduels; sables; graviers; blocs; milieux marins; estuaires; échantillons prélevés au hasard; échantillons carrotés; photographie; analyses granulométriques; milieu sédimentaire; discordances; corrélations stratigraphiques; trous; icebergs; marques d'affouillement; gisements minéraux; potentiel minier; gisements alluvionaires, marins; or; aggrégats; organismes marins; benthos; caractéristiques structurales; failles; diaclases; plis; anticlinaux; synclinaux; Plate-Forme de Néo-écossaise; Moraine d'Eastern Shore ; Supergroupe de Meguma ; Enregistrement vidéo; directions d'écoulement glaciaire; Infrastructure; géologie marine; géologie des dépôts meubles/géomorphologie; géophysique; stratigraphie; sédimentologie; géologie de l'ingénieur; géologie économique; géologie de l'environnement; Phanérozoïque; Cénozoïque; Quaternaire; Paléozoïque
Illustrationslocation maps; geoscientific sketch maps; tables; seismic profiles; profiles; stratigraphic correlations; bar graphs; photographs
Consultation
Endroit
 
Bibliothèque de Ressources naturelles Canada - Ottawa (Sciences de la Terre)
 
ProgrammeLes géosciences pour les nouvelles sources d'énergie - la coordination du programme, Les géosciences pour les nouvelles sources d'énergie
Image
Diffusé2018 08 09
Résumé(disponible en anglais seulement)
The report describes the Quaternary geology across the inner continental shelf of the Eastern Shore of Nova Scotia, stretching about 70 km from Clam Bay to Moosehead and from the coast to about 40 km offshore. A surficial geology map was constructed from a mosaic of seabed topography images from water depth soundings gridded at spatial resolutions ranging from high (5 m) to low (500 m), supplemented with a sparse network of acoustic geophysical transects and limited sample data. The coast and inner shelf morphology, to about 120 m water depth, is primarily governed by bedrock and has a far more rugged topography than the offshore. Hard meta-sedimentary rocks comprising slates and meta-sandstones of the Lower Paleozoic age Meguma Supergroup present bedding and cleavage at the seabed which impart a rough ridge and trough morphology trending parallel to the coast. The glacial depositional and erosional imprint is strong in the area; numerous broad fjord-like channels oriented normal to the coastline cut deep into bedrock and were largely mud-filled during deglaciation. Different ice flow phases are recognized from striae, drumlins and moraines. Bedrock is locally covered by ground moraine, drumlins and moraines or their erosional remnants. Outcrops with little sediment cover dominate the seabed from 70 m water depth to the headlands except where the broad channels and shallow basins developed a sand and gravel lag during the sea-level transgression. The precise low-stand of sea-level on this part of the inner shelf is not clear but has been reported as >-50 m (Forbes et al. 1991) immediately east of Halifax, and -65 to -70 m (Stea et.al. 1992b, 1994, 1995). Based on near-complete littoral washing of sediments from the bedrock surface as represented in the multibeam bathymetric images, a -70 m elevation is suggested but the shallower low-stand allows for greater sub-littoral wave-erosion action and is likely no less valid. Post-glacial marine mud, largely derived from the reworking of glacigenic sediments during transgression, dominates the offshore, below about 120 m and in harbours and near-shore basins that are relatively sheltered from storm action.
Glacial reconstruction was largely established before this mapping exercise but the improved characterization of features and spatial patterns contributes further detail. Regional ice flow phases established are successfully correlated to the offshore. All but the latest (Chignecto) phase are represented by one or several glacial elements including deep mud-filled bedrock channels, drumlin, moraine and striae. There is no clear pattern as to which flow phases preferentially create or preserve glacial features. The last offshore imprint was during the Scotian Phase, nearly normal to the coastline. If a later glacial phase extended into the offshore, its margin was likely farther east.
Résumé(Résumé en langage clair et simple, non publié)
Le plateau continental intérieur de la côte est de la Nouvelle-Écosse est présentement à l'étude pour le statut de zone de protection marine. Ce rapport contribue aux exigences d'évaluation scientifique de Pêches et Océans Canada.
GEOSCAN ID308454