| Title | Neoproterozoic-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) |
| Download | Downloads |
| |
| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | MacNaughton, R B ;
Fallas, K M |
| Source | Geological Survey of Canada, Open File 8839, 2021, 56 pages, https://doi.org/10.4095/329217  Open Access |
| Image |  |
| Year | 2021 |
| Alt Series | Northwest Territories Geological Survey Contribution 0416 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | on-line; digital |
| Related | NRCan photo(s) in this
publication |
| Related | This publication is related to the following
publications |
| File format | pdf |
| Province | Northwest Territories |
| NTS | 95M/05; 95M/06 |
| Area | Mackenzie Mountains; Wrigley Lake; Moose Horn River |
| Lat/Long WENS | -127.5833 -127.2000 63.4667 63.2667 |
| Subjects | regional 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 |
| Illustrations | location maps; geoscientific sketch maps; stratigraphic charts; photographs; lithologic sections; correlation sections; stratigraphic sections |
| Program | GEM-GeoNorth: Geo-mapping for Energy and Minerals GEM Program Coordination |
| Released | 2021 12 02 |
| Abstract | A 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. |
| GEOSCAN ID | 329217 |
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