| Title | Uranium enrichment processes in metasomatic iron oxide and alkali-calcic systems as revealed by uraninite trace element chemistry |
| |
| Author | Potter, E G ;
Acosta-Góngora, P; Corriveau, L; Montreuil, J -F; Yang,
Z |
| Source | Mineral systems with iron oxide copper-gold (IOCG) and affiliated deposits; by Corriveau, L (ed.); Potter, E G (ed.); Mumin, A H (ed.); Geological Association of Canada, Special Paper 42, 2022 p. 325-345 |
| Image |  |
| Year | 2022 |
| Alt Series | Natural Resources Canada, Contribution Series 20210044 |
| Publisher | Geological Association of Canada |
| Document | serial |
| Lang. | English |
| Media | digital; on-line |
| Related | This publication is related to Uranium enrichment processes
in metasomatic iron oxide and alkali-calcic systems as revealed by uraninite trace element chemistry - supplementary data |
| File format | pdf |
| Province | Northwest Territories |
| NTS | 85M; 85N; 85O; 86A; 86B; 86C; 86D; 86E; 86F; 86G; 86J; 86K; 86L |
| Area | Lou Lake; Cole Lake; Fab Lake; Hottah Lake; Great Bear Lake; Gameti |
| Lat/Long WENS | -120.0000 -114.0000 67.0000 63.0000 |
| Subjects | economic geology; geochemistry; Science and Technology; Nature and Environment; mineral deposits; metasomatic deposits; uranium; iron oxides; copper; gold; ore mineral genesis; mineralization; mineral
enrichment; uraninite; provenance; geochemical analyses; trace element geochemistry; electron probe analyses; mass spectrometer analysis; Great Bear Magmatic Zone |
| Illustrations | location maps; tables; diagrams; photographs; charts |
| Program | Targeted Geoscience Initiative (TGI-5) Uranium ore systems - deep metasomatic processes |
| Released | 2022 07 01 |
| Abstract | Uranium enrichment is relatively common in metasomatic iron oxide and alkali-calcic systems that can host iron oxide- apatite (IOA), magnetite-, magnetite-hematite and hematite-group iron
oxide-copper-gold (IOCG) and albitite-hosted uranium and Au-Co-U deposits. In Canada, the best exposed and studied IOCG and affiliated occurrences are those of the Great Bear magmatic zone in the Northwest Territories. Trace element concentrations in
uraninite from these occurrences produce relatively flat chondrite-normalized rare earth element (REE) patterns with negative europium anomalies, lanthanum depletion and mild heavy-REE depletion. In one of the occurrences, mild light-REE (LREE)
depletion is linked to co-precipitation of LREE-bearing allanite (Nori showing). The high REE and thorium concentrations and negative europium anomalies are interpreted to reflect precipitation from high-temperature, reduced fluids that evolved and
equilibrated through extensive Na alteration (albite), then Ca-Fe (amphibole+magnetite±apatite) and ultimately K-Fe (K-feldspar/biotite+iron-oxides) metasomatic facies. In most systems, field observations, petrography, and geochemistry indicate
precipitation of primary uraninite during the transition from high temperature Ca-Fe to K-Fe facies in magnetite-dominant (reduced) assemblages. Unlike models proposed for hematite-group deposits, primary uranium enrichment in magnetite-dominant
systems was likely sourced and transported as chloride complexes in high-temperature, reducing fluids rather than oxidized brines. Uranium precipitation was likely triggered by cooling of the fluids and/or changes in fluid chemistry induced by
extensive fluid-rock interactions. Alteration of primary uraninite caused significant changes in major element chemistry (e.g. Pb, Ca, Fe, Si, etc.) but the chondrite-normalized REE patterns only deviate slightly, primarily through changes to LREE
abundances. As observed in both magnetite- and hematite-group deposits globally, the remobilization of uranium indicates that although IOCG systems may have primary magmatic-hydrothermal origins, multiple generations of uranium mineralization occur
through alteration, dissolution and re-precipitation as the hydrothermal cells collapse and surface-derived waters interact with the ores. |
| 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 uses the trace element composition of an ore mineral (uraninite) to unravel the metal sourcing,
transport and precipitation in uranium-bearing iron oxide-copper-gold (IOCG) deposits. The results support a revised genetic model that can be applied to exploration programs. |
| GEOSCAN ID | 328303 |
|
|