| Title | Formation of the high-grade Triple R uranium deposit revealed by Fe and S isotopes in pyrite |
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| Author | Mount, S M; Potter, E G ; Yang, Z; Fayek, M; Powell, J W; Chi, G; Rizo, H
G |
| Source | Geochemistry: Exploration, Environment, Analysis 22, 3, 2022 p. 1-25, https://doi.org/10.1144/geochem2021-023  Open Access |
| Image |  |
| Year | 2022 |
| Alt Series | Natural Resources Canada, Contribution Series 20210457 |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Alberta; Saskatchewan |
| NTS | 74E; 74F; 74G; 74H; 74I; 74J; 74K; 74L; 74M; 74N; 74O; 74P |
| Lat/Long WENS | -112.0000 -104.0000 60.0000 57.0000 |
| Subjects | geochemistry; mineralogy; uranium; iron; isotopes; stable isotope studies; Athabasca Basin; Patterson Lake Formation |
| Illustrations | location maps; photographs; cross-sections; images; figures; geochemical charts; tables |
| Program | Targeted Geoscience Initiative (TGI-5) Uranium ore systems - fluid pathways |
| Released | 2022 06 22 |
| Abstract | The Patterson Lake corridor (PLC), located on the southwestern margin of the Athabasca Basin, contains several basement-hosted uranium deposits that formed via protracted, structurally controlled
fluid-rock interactions. Using multiple generations of pyrite grains (pre-, syn- and post-mineralization) from the Triple R deposit, in-situ iron isotopic analyses revealed large intra-sample and -grain variations (d56Fe values ranging from -2.21 to
+1.67 per mil) whereas sulfur isotopes yielded minor variations (d34S values ranging from -4.44 to + 5.3 per mil) relative to natural isotopic variations for both elements. The wide range in d56Fe values supports textural and chemical evidence that
fluctuating oxidation states and chemistry in the fault zone fluids caused multiple generations of pyrite oxidation and precipitation. Sulfur isotope data from shallower mineralized zones show a slight enrichment in heavier isotopes consistent with
limited Rayleigh fractionation. However, when coupled with iron isotope data, the overall dataset supports a sulfur-rich, open system wherein heat from intrusions at depth and fault movements drove sulfur-rich fluids upwards, causing precipitation of
pre-mineralization pyrite and graphite. During fault reactivation, fluid pressure fluctuations between hydrostatic and sub-hydrostatic regimes drew oxidizing, uranium-bearing, basinal brines down into the basement to react with sulfides in the host
rocks and deeply sourced, H2S-bearing reducing fluids. These redox reactions and fluid mixing resulted in precipitation of uraninite and syn-mineralization pyrite. These results further support the importance of structural control, repeated faulting
and thermal anomalies in the basement for mineralization, necessitating re-examination of the current exploration model for unconformity-related uranium deposits. |
| 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 proposes how variations in the chemistry and isotopic composition of the mineral pyrite associated with
the deposits provides insights on critical components required to form the deposits. These results suggest modification of the exploration model to expand beyond traditional metapelite host rocks, focusing instead on faults in the basement associated
with elevated paleothermal anomalies. |
| GEOSCAN ID | 329307 |
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