GEOSCAN, résultats de la recherche


TitreAnatomy of the tidal scour system at Minas Passage, Bay of Fundy, Canada
AuteurShaw, J; Todd, B J; Li, M Z; Wu, Y
SourceWorkshop on Geoscience Characterization of the Seabed for Environmental Assessment of Marine Renewable Energy Activities; 2012.
Séries alt.Secteur des sciences de la Terre, Contribution externe 20120162
RéunionGEOHAB 2012; Orcas Island WA; US; mai 2012
ProvinceRégion extracotière de l'est; Nouvelle-Écosse; Nouveau-Brunswick
SNRC21H/01; 21H/02; 21H/07; 21H/08; 11E/04; 11E/05
Lat/Long OENS -65.0000 -64.0000 45.3333 45.0000
Sujetscaractéristiques sous-marines; milieux de marée; marques d'affouillement; milieux marins; sédiments marins; dépôts glaciaires; dunes; transport des sediments; distribution des sédiments; déplacement des sédiments
Illustrationslocation maps; digital elevation models; photographs; seismic reflection profiles; schematic diagrams
ProgrammeGestionnaire de programme, Géosciences environnementales
Résumé(disponible en anglais seulement)
Strong currents have eroded thick Quaternary sediments to create a scour trough at Minas Passage, in the Bay of Fundy, Canada, site of Earth's largest tides. We describe this trough in the context of a larger system that comprises a range of elements, viz: 1) Scour troughs extending 170 m below mean sea level are incised into thick glaciomarine sediments and have exhumed bedrock over wide areas. The flanking uneroded terrain has low relief and a winnowed surface. 2) Sets of sand banner banks off Cape D'Or and Cape Chignecto. 3) The atypical set of banner banks at Cape Split, consisting of the Scots Bay dune field and its counterpart, a large gravel bank trapped in the Minas Passage scour trough. 4) Low-relief banks with sand ribbons and barchan dunes alongside some banner banks, and termed 'shadow banks'. 5) A large (0.8 km3) sediment drift at the entrance to Minas Channel (without large bedforms). The location of troughs and banks can be correlated with tidal-current patterns: trenches are located in regions of very strong bi-directional currents; banner banks near headland-sited tidal gyres; shadow banks in areas of maximum mean bottom stress asymmetry; and the sediment drift at the entrance to Minas Channel in an area of weak bottom stress at all stages of the tides. Previous work has argued that the scour system formed after 3400 14C yrs BP (radiocarbon years before present) following collapse of a barrier system across Minas Passage. We speculate that formation of the scour trough system may have released vast quantities of sediment that have not been accounted for in previous sediment budgets, and that much of this released sediment has been sequestered in the late-Holocene salt marshes at the head of the Bay of Fundy.