GEOSCAN Search Results: Fastlink


TitleNeoproterozoic-Cambrian stratigraphy of the Mackenzie Mountains, northwestern Canada, part IV: a stratigraphic reference section for the Ediacaran-Cambrian transition in NTS 95-M (Wrigley Lake map area)
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorMacNaughton, R BORCID logo; Fallas, K MORCID logo
SourceGeological Survey of Canada, Open File 8839, 2021, 56 pages, Open Access logo Open Access
Alt SeriesNorthwest Territories Geological Survey Contribution 0416
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
RelatedNRCan photo(s) in this publication
RelatedThis publication is related to the following publications
File formatpdf
ProvinceNorthwest Territories
NTS95M/05; 95M/06
AreaMackenzie Mountains; Wrigley Lake; Moose Horn River
Lat/Long WENS-127.5833 -127.2000 63.4667 63.2667
Subjectsregional geology; stratigraphy; paleontology; sedimentology; Science and Technology; Nature and Environment; Lower Cambrian; systematic stratigraphy; stratigraphic analyses; stratigraphic nomenclature; stratigraphic correlations; lithostratigraphy; bedrock geology; lithology; sedimentary rocks; carbonates; limestones; dolostones; shales; siltstones; clastics; sandstones; arenites; mudstones; unconformities; sedimentary structures; fossils; Canadian Cordillera; Neoproterozoic; Ediacaran; Sheepbed Formation; Backbone Ranges Formation; Sekwi Formation; Rockslide Formation; Risky Formation; Windermere Supergroup; Terreneuvian; Miaolingian; Phanerozoic; Paleozoic; Cambrian; Precambrian; Proterozoic
Illustrationslocation maps; geoscientific sketch maps; stratigraphic charts; photographs; lithologic sections; correlation sections; stratigraphic sections
ProgramGEM-GeoNorth: Geo-mapping for Energy and Minerals GEM Program Coordination
Released2021 12 02
AbstractA composite reference section for the upper Ediacaran and lower Cambrian is documented for a location near Moose Horn River in Wrigley Lake map area (NTS 95-M), Mackenzie Mountains, Northwest Territories. Four measured stratigraphic sections cover, in ascending order: the uppermost Sheepbed Formation; the informal Sheepbed carbonate; the lower, middle, and upper members of the Backbone Ranges Formation; the Sekwi Formation; and the lowermost beds of the Rockslide Formation. The uppermost Sheepbed Formation is dominated by dark-weathering shale and siltstone. The Sheepbed carbonate (440 m) lies conformably on the Sheepbed Formation and consists of limestone, dolostone, and dolomitic siltstone, including several horizons of rudstone with clasts up to boulder size. The upper surface of the Sheepbed carbonate has been eroded and the unit thins to a zero edge to the east. The lower member of the Backbone Ranges Formation (253 m) is heterolithic, including interbedded quartzose siltstone and quartzose sandstone, quartz arenite (locally with horizons of quartz pebbles), and dolostone to dolomitic sandstone. The middle member of the Backbone Ranges Formation (93 m) consists mainly of pink to grey-weathering limestone with red mudstone partings. The upper member (501.5 m) is dominated by quartz arenite, but also contains intervals of siltstone. Partway through the upper member there is a marker unit of dolostone to dolomitic sandstone that previous work suggests is a tongue of the Ediacaran Risky Formation. Based on regional correlations, the top of this marker may approximate the Ediacaran-Cambrian boundary in this section. The Sekwi Formation lies abruptly upon the Backbone Ranges Formation. The contact is unconformable at this locality and mapping in the area indicates eastward erosional removal of the upper member of the Backbone Ranges Formation beneath the Sekwi Formation. The Sekwi Formation here consists of variegated siltstone with lesser dolostone, limestone, and quartz sandstone. An abrupt contact with nodular limestone and grey shale of the overlying Rockslide Formation approximates the base of Cambrian Series 3.
Summary(Plain Language Summary, not published)
This report provides detailed stratigraphic documentation of a new reference locality for late Ediacaran and early Cambrian sedimentary strata in the Mackenzie Mountains (Wrigley Lake map area). Previously, detailed information on rocks of this age from this map area has been limited. The locality described will be an important point of comparison for these rocks throughout the Mackenzie Mountains and more widely in northwestern Canada. Detailed descriptions are included for the following units: the Sheepbed carbonate; the Backbone Ranges Formation (lower, middle, upper members); and the Sekwi Formation. These units are likely to span the time from about 560 million to about 485 million years ago.

Date modified: