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TitleThe eastern extent of the Risky Formation (Ediacaran), Mackenzie Mountains, Northwest Territories
AuthorMacNaughton, R B; Fallas, K M
SourceGeological Survey of Canada, Current Research (Online) 2019-2, 2019, 15 pages, (Open Access)
PublisherNatural Resources Canada
Mediaon-line; digital
File formatpdf (Adobe® Reader®)
ProvinceNorthwest Territories
AreaMackenzie Mountains; Wrigley Lake
Lat/Long WENS-128.0000 -127.8917 63.1958 63.1542
Subjectsstratigraphy; economic geology; systematic stratigraphy; stratigraphic correlations; stratigraphic analyses; stratigraphic nomenclature; bedrock geology; lithology; sedimentary rocks; dolostones; arenites; siltstones; sandstones; breccias, collapse; structural features; faults; faults, normal; faults, thrust; mineral deposits; mineral potential; base metals; sulphide deposits; mineral occurrences; sedimentary structures; depositional environment; marine environments; Risky Formation; Neoproterozoic; Ediacaran; Backbone Ranges Formation; Plateau Fault; Natla Fault; Windermere Supergroup; Sekwi Formation; mississippi valley type deposits; Phanerozoic; Paleozoic; Cambrian; Precambrian; Proterozoic
Illustrationsgeoscientific sketch maps; stratigraphic charts; photographs; correlation charts; stratigraphic sections; tables
ProgramGEM2: Geo-mapping for Energy and Minerals, Mackenzie Corridor, Shield-to-Selwyn geo-transect, Mackenzie-Selwyn sub-activity
Released2019 07 05
AbstractNewly documented exposures of dolostone, sandy dolostone, and quartz arenite in the Natla structural panel, western Wrigley Lake map area (NTS 95-M; Mackenzie Mountains, Northwest Territories) are assigned to the Ediacaran Risky Formation. Similarities in lithology and stratigraphic succession with the type area of the formation (Sekwi Brook structural panel, Mackenzie Mountains) support the assignment. The newly recognized occurrence of Risky Formation is within an interval previously mapped as Backbone Ranges Formation and implies that the base of the Cambrian is much higher within that unit than is suggested by previous correlations. The Risky Formation forms an eastward-thinning tongue within the Backbone Ranges Formation and may extend as far east as the hanging wall of the Plateau Fault. Karst breccia within the Risky Formation hosts base-metal mineralization in the type area of the unit and in the Wernecke Mountains. Thus, there may be limited exploration potential in the eastward extension of the Risky Formation.
Summary(Plain Language Summary, not published)
The Risky Formation is a unit of carbonate rock that is of late Ediacaran age (i.e., slight more than 541 million years old). It is found in the Mackenzie Mountains (NWT) and Wernecke Mountains (Yukon). This report documents that the Risky Formation extends further east in the Mackenzie Mountains than previously was recognized. This is significant for three reasons. First, it will help to produce more accurate bedrock geology maps of the region. Second, the new occurrences of the Risky Formation are found to lie within another unit, the Backbone Ranges Formation, pointing out the need for restudy of that unit. Third, the Risky Formation is known to contain base-metal mineralization (mainly lead and zinc) in other locations. Increasing its known extent may open up new potential for mineral exploration in the Mackenzie Mountains, although caution is needed on this point at present.