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TitleSekwi Project: Revision maps for the central Mackenzie Mountains, NWT
AuthorGordey, S; Roots, C; Martel, E; Fallas, K; Fischer, B; MacNaughton, R; Thomson, D; Borkovic, B
Source36th Yellowknife Geoscience Forum, abstracts of talks and posters; by Jackson, V; Irwin, D; Northwest Territories Geoscience Office, Yellowknife Geoscience Forum Abstracts Volume vol. 2008, 2008 p. 67-68
Year2008
Alt SeriesEarth Sciences Sector, Contribution Series 20080427
Meeting36th Annual Yellowknife Geoscience Forum; Yellowknife; CA; November 18-20, 2008
Documentserial
Lang.English
Mediapaper
ProvinceNorthwest Territories
NTS95M; 105P; 106A
AreaMackenzie Mountains; Sekwi Mountain
Lat/Long WENS-130.0000 -126.0000 65.0000 63.0000
Subjectsstratigraphy; structural geology; bedrock geology; structural features; lithofacies mapping; Windermere Supergroup; Backbone Ranges Formation; Mackenzie Mountain Supergroup; Earn Group; Selwyn Basin; Coates Lake Group; Plateau Thrust
LinksOnline - En ligne
AbstractA three-year bedrock mapping project initiated by the Northwest Territories Geoscience Office will provide new maps (NTS 105P, 106A and northwestern part of 95M) and an integrated synthesis of stratigraphic and structural information of the Cordilleran fold-thrust belt between 63°N and 65°N. Regional mapping by foot-traverses, spot-checks and measured sections is augmented by improved paleontologic age control, graduate theses and previous stream sediments and water geochemistry, aeromagnetic and radiometric survey data.
The 2008 field season filled in gaps and resolved issues from previous mapping. We measured stratigraphic thicknesses in preparation for drawing restored cross sections.
The unmetamorphosed sedimentary strata range from Late Proterozoic to Cretaceous. The low-angle sub-Cambrian unconformity is a first-order division of the exposed strata, and has allowed greater preservation of Neoproterozoic Sequence C strata to the southwest. In the northern half of the study area (NTS 106A) we documented the telescoped platform and basin assemblages of the Lower Little Dal Group, as well as the great lithologic variation and thickness changes in the Thundercloud Formation of the overlying Coates Lake Group. The Coppercap Formation dolostone (Coates Lake Group) was resolved from lithogically similar strata of the Little Dal Group. A subtle unconformity beneath the Neoproterozoic Keele Formation carbonate cuts out glaciomarine strata of the Rapitan Group, and the Twitya Formation in southwestern 106A. In the northwest, some occurrences of shale previously assigned to the Neoproterozoic Sheepbed Formation have been re-interpreted as a Devono-Mississippian inlier. New mapping in northwestern 95M has updated the stratigraphic nomenclature of Neoproterozoic and Lower Cambrian units in the hanging wall of the Plateau Fault.
Lower Paleozoic units undergo lateral facies transition from Mackenzie Platform in the northeast to Selwyn Basin in the southwest. In the northeastern part of the southern half of the study area (NTS 105P) the Gametrail Formation and lower, middle and upper members of the Backbone Ranges Formation were delineated within a previously undivided map unit. In the Sayunei Ranges the overlying carbonate succession is divided into nine formations. These are flanked to the southwest by the Backbone Ranges Formation where the lower Cambrian clastic Vampire and carbonate Sekwi formations are prominent, overlain by a heterogenous map unit which we resolve into the Hess River, Rabbitkettle and Duo Lakes formations of the Selwyn Basin. The northwestern part of 105P lies in the axis of the Misty Creek embayment, where Ordovician-Silurian Cloudy Formation is the facies equivalent of Mount Kindle Formation.
Middle Devonian to Carboniferous units in the western half of 105P include the brown, shale-dominated Misfortune Formation, equivalent to the blue-black Canol Formation further east, overlain by the shale-conglomerate Thor Hills Formation, which is time correlative with the sandstone-dominated Imperial Formation. The Carboniferous Tsichu Group contains quartz sandstone, shale and carbonate divided in four formations. An inlier of Cretaceous shale, sandstone and conglomerate with coal seams unconformably overlies Permian strata south of the Ekwi River in central 105P.
The region hosts stratabound Cu occurrences within the Coates Lake Group, carbonate-hosted Zn-Pb prospects in several formations, barite occurrences, and a newly discovered beryl occurrence.
GEOSCAN ID225958