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TitleSedimentary architecture of a deeply karsted Precambrian - Cambrian unconformity, Victoria Island, Northwest Territories
AuthorMathieu, J; Turner, E C; Rainbird, R H
SourceGeological Survey of Canada, Current Research (Online) no. 2013-1, 2013, 18 pages, (Open Access)
PublisherNatural Resources Canada
Mediaon-line; digital
RelatedNRCan photo(s) in this publication
File formatpdf
ProvinceNorthwest Territories
AreaVictoria Island; Minlo Inlet
Lat/Long WENS-116.0000 -115.0000 71.5000 71.2500
Subjectssedimentology; stratigraphy; unconformities; sedimentary rocks; carbonates; sandstones; karst topography; sedimentary structures; dolomites; hydrothermal alteration; Wynniatt Formation; Precambrian; Cambrian; Paleozoic
Illustrationslocation maps; photographs; tables; stratigraphic columns; diagrams
ProgramPGE/Base Metals - Victoria Island (NWT and Nunavut), GEM: Geo-mapping for Energy and Minerals
Released2013 03 04
AbstractA deeply karsted unconformity separates Proterozoic carbonate rocks of the Wynniatt Formation from overlying Cambrian sandstone near the head of Minto Inlet on Victoria Island, Arctic Canada. Sandstone-filled paleocaverns, hundreds of metres wide and tens of metres high, are present approximately 10 to 15 m stratigraphically below the nominal stratigraphic contact between Proterozoic and Cambrian rocks; the position of the paleocaves relative to the main unconformity surface suggests development along a paleointerface possibly associated with the water table. Gryke networks and karstic towers are present in the Wynniatt Formation at the unconformity. Crossbedded sandstone that overlies the unconformity contains unusual, vertical columnar sandstone structures, decimetres to metres in diameter, which cut sharply across bedding and contain weak concentric layering. These pillar-like structures are attributed to water escape through submarine springs, where groundwater flowing through the karst network emerged onto the Cambrian seafloor. The pillars are most densely clustered in the most northern exposure of the sandstone, and diminish in abundance southward, suggesting that the coastline and the source of hydraulic head were to the north of the study area.