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TitleMineralogy, geochronology, and genesis of the Andrew Lake uranium deposit, Thelon Basin, Nunavut, Canada
AuthorShabaga, B M; Fayek, M; Quirt, D; Jefferson, C W; Camacho, A
SourceCanadian Journal of Earth Sciences vol. 54, no. 8, 2017.,
Alt SeriesEarth Sciences Sector, Contribution Series 20170300
PublisherNRC Research Press
Mediapaper; on-line; digital
File formatpdf
NTS66C; 66D
Lat/Long WENS-100.0000 -98.0000 66.0000 64.0000
Subjectsradioactive minerals; uranium deposits; mineralization; quartz; models; uraninite; illite; hematite; iron oxides; coffinite; boltwoodite; uranium lead dates; uranium lead dating; formation fluids; Thelon Basin; Andrew Lake deposit
Illustrationslocation maps; geological sketch maps; tables; lithologic sections; photographs; Concordia diagrams
ProgramSouth Rae Province Bedrock/Surficial geology, GEM2: Geo-mapping for Energy and Minerals
AbstractThe Thelon Basin located in Nunavut, Canada, shares many similarities with the U-producing Athabasca Basin in Saskatchewan. The Kiggavik project area, located near the northeastern edge of the Thelon Basin, contains U deposits and showings along the -30 km long NE-W Kiggavik - Andrew Lake structural trend. The Andrew Lake deposit is near the southern end of this trend. Pre-mineralization is characterized by quartz ± carbonate veins that occupy fault systems later reactivated as conduits for U-mineralizing fluids. A four-phase genetic model is proposed for the Andrew Lake deposit. Phase 1 comprises vein-style uraninite (U1; 1031 ± 23 Ma) that is associated with illite and hematite, and contains variable PbO contents (0.2-9.5 wt.%). Phase 2 is characterized by altered uraninite (U2; -530 Ma) that is associated with coffinite. Altered uraninite (U3; <1 Ma) characterizes phase 3 and occurs as centimetre-scale "roll-fronts". In phase 4, all three uraninite stages, and coffinite, are altered to boltwoodite. Although the oldest uraninite U-Pb age is -1030 Ma, illite associated with the U mineralization gives 40Ar/39Ar ages of 941 ± 31 and 1330 ± 36 Ma. The younger age is similar to the age for U1, suggesting that there was a fluid event that either precipitated U1 or reset the U-Pb isotopic system at -1000 Ma. While the older age for illite (1330 Ma) does not correlate with Andrew Lake U-Pb uraninite ages, it does correlate with ages previously reported for uraninite and clay alteration minerals in the Kiggavik area.