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TitleA drift isopach model for the southwestern Great Slave Lake region, Northwest Territories, Canada
AuthorSmith, I RORCID logo; Deblonde, C; Hagedorn, G; Paulen, R CORCID logo
SourceJournal of Maps 2022 p. 1-12, 1 sheet, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20220262
PublisherTaylor & Francis Online
MapsPublication contains 1 map
Map Info.geological, Isopach, 1:600,000
ProjectionUniversal Transverse Mercator Projection, UTM zone 11N (NAD83)
Mediapaper; digital; on-line
File formatpdf
ProvinceNorthwest Territories
NTS85A; 85B; 85C; 85D; 85E; 85F; 85G; 85H
AreaGreat Slave Lake
Lat/Long WENS-120.0000 -114.0000 62.0000 60.0000
Subjectsgeneral geology; stratigraphy; drift deposits; glacial deposits; sediments; lithostratigraphy
Illustrationsisopach maps; tables; location maps
ProgramGEM2: Geo-mapping for Energy and Minerals Mackenzie Corridor
Released2022 12 16
AbstractThis study produced a drift thickness model for the southwestern Great Slave Lake area of northern Canada, using 12,692 lithostratigraphic records (seismic shothole drillers' logs, diamond drill holes, petroleum wells), and field observations. Numerous algorithms and modelling parameters were tested using 6122 records of absolute drift thickness, and based on a cross-validation analysis, an empirical Bayesian kriging K-Bessel detrended algorithm was found to produce the best fit. The final model, incorporating selected maximum and minimum thickness estimate data, produced a root mean square error of 4.98 m, with 94.8% of the data points within ±2 m of the modelled drift thicknesses. The model identifies widespread areas of drift >10 m thick, and prominent southeast-northwest aligned bedrock ramps. Karst structures buried by 73 m of drift were identified southwest of Great Slave Lake and appear to be aligned with regional fault systems like ore-associated karst at Pine Point. These may be the source of anomalous glacial sediment-derived base metal indicators collected proximally to the west. The most striking drift anomaly is in Cameron Hills where the eastern and northern margins are comprised of shale and siltstone bedrock overlain by 20-40 m of glacial sediments, but the central and western uplands have petroleum well logs identifying glacial sediments up to 400 m thick. In addition to mineral exploration, results of this study provide baseline data that can be used predictively by the petroleum industry in designing future seismic and drilling (casing depth) operations, and by those modelling groundwater sources and flow.
Summary(Plain Language Summary, not published)
This publication presents a map of drift (glacial sediment) thicknesses in the southern Mackenzie region of Northwest Territories. It is based off 14 541 archival lithostratigraphic records (petroleum wells, diamond drill holes, seismic shothole drillers' logs) and field observations. Constructed in ArcGIS Pro's Geostatistical Analyst, numerous different interpretive models (algorithms) were used to assess the best-fit, and then it was tested against maximum and minimum drift thickness estimate data. The final model produces an excellent fit, with a root mean square error of 4.980 and ~95% of the data points falling within ±2 m of the modelled drift thicknesses. Results demonstrate the existence of buried karst structures, immediately up-glacial flow of where surface sediment samples with enriched base metal indicator concentrations were collected; these are perhaps analogous to the ore-associated karst in the Pine Point mining district. The model also identifies extreme thicknesses of glacial sediments (?400 m) comprising the central and western Cameron Hills uplands, and not bedrock, as was previously believed.

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