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TitleUraninite geochemistry in the Central Mineral Belt, Labrador, Canada
AuthorAcosta-Gongora, P; Potter, EORCID logo; Lawley, CORCID logo; Petts, DORCID logo; Sparkes, G
SourceNGF abstracts and proceedings of the Geological Society of Norway: Vinterkonferansen 2021; by Nakrem, H A (ed.); Husås, A M (ed.); 2021 p. 2 Open Access logo Open Access
LinksOnline - En direct (complete volume - volume complet, PDF, 2.52 MB)
Alt SeriesNatural Resources Canada, Contribution Series 20210208
PublisherNorsk Geologisk Forening
MeetingNorsk Geologisk Forening, Vinterkonferansen 2021 - Geological Society of Norway, 34th Geological Winter Meeting; January 6-8, 2021
Mediadigital; on-line
File formatpdf
ProvinceNewfoundland and Labrador
NTS13J; 13K; 13L; 13M; 13N; 13O
AreaLabrador; Jacques Lake; Moran Lake; Anna Lake; Snegamook Lake; Kanairiktok River
Lat/Long WENS -62.7000 -58.9500 55.3833 54.0500
Subjectseconomic geology; geochemistry; Science and Technology; Nature and Environment; mineral deposits; uranium; base metals; precious metals; uraninite; ore mineral genesis; mineralization; host rocks; statistical analyses; trace element geochemistry; thermal analyses; magmatism; hydrothermal systems; metasomatism; alteration; Central Mineral Belt; Dandy Prospect; Near Miss Prospect; Jacques Lake Deposit; Precambrian; Proterozoic
ProgramTargeted Geoscience Initiative (TGI-5) Uranium ore systems - deep metasomatic processes
Released2021 01 01
AbstractThe Central Mineral Belt (CMB) of Labrador in Canada is host to several enigmatic Proterozoic U±base±precious metal showings, prospects and deposits that have disparate features in terms of their mineralization styles (e.g., vein and breccia-hosted, disseminated) and host rocks (metasedimentary, - volcanic and -intrusive). Through multivariate statistical analysis (principal component and cluster analyses), quantitative trace element maps of uraninite grains were used to understand the origins of U mineralization from selected locations across the CMB.
Chemical signatures of uraninite from the felsic intrusion- and intermediate volcanic-hosted Dandy prospect (negative Eu anomaly, U/Th < 1000 and sigma-LREE/sigma-HREE= 3) and Near Miss prospect (Near Miss 1; U/Th > 1000 and sigma-REE > 1 wt.%) and Jacques Lake deposit (U/Th < 1000 and sigma-REE almost equal to 1 wt.%), respectively, support formation under high temperature magmatic-hydrothermal or metasomatic environments. However, post-crystallization alteration caused LREE enrichment and increased U/Th values in uraninite. Lower temperature (<350 °C) hydrothermal vein-type conditions are inferred for uraninite samples from the Two-Time deposit (Two-Time 1 to 3), and Anomaly No. 7 (Anomaly No. 7 1 to 4) and Near Miss (Near Miss 2) prospects based on high U/Th values (>> 1000), elevated sigma-LREE/sigma-HREE ratios (> 14) and variable sigma-REE contents (from < 1 wt.% to >1 wt.%). Trace element mapping of uraninite from the Anomaly No. 7 revealed concentric multi-elemental (e.g., Zr, Bi, V, Hf) zoning representing four uraninite generations that formed under relatively equivalent hydrothermal conditions (analogous sigma-LREE/sigma-HREE and U/Th values). The more ambiguous chemical footprints and complex textural features of the metasedimentary-hosted uraninite from the Moran Lake Upper C Zone, Nash and Anna Lake deposits (U/Th >> 1000), sigma-REE << 1 wt.% and sigma-LREE/sigma-HREE < 5) indicate formation by syn- to post-metamorphic, high salinity and low temperature hydrothermal fluids.
Overall, this study reveals the presence of distinct U mineralizing events and fluid sources, driven by syn- to post-mineralization orogenic and magmatic events.
Summary(Plain Language Summary, not published)
The Targeted Geoscience Initiative (TGI) is a collaborative federal geoscience program that provides industry with the next generation of geoscience knowledge and innovative techniques to better detect buried mineral deposits, thereby reducing some of the risks of exploration. This contribution summarizes the chemical composition of the ore mineral uraninite from several mineral occurrences from the Central Mineral Belt in Labrador. The contrasting chemical signatures of uraninite indicate the deposits formed by several processes and do not represent a single ore-forming event.

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