| Title | Basement to surface expressions of deep mineralization and refinement of critical factors leading to the formation of unconformity-related uranium deposits |
| Author | Potter, E G |
| Source | International Symposium on Uranium Raw Material for the Nuclear Fuel Cycle: Exploration, Mining, Production, Supply and Demand, Economics and Environmental Issues (URAM 2014), abstracts; 2014. |
| Year | 2014 |
| Alt Series | Earth Sciences Sector, Contribution Series 20130508 |
| Publisher | International Atomic Energy Agency (IAEA) |
| Meeting | International Symposium on Uranium Raw Material for the Nuclear Fuel Cycle: Exploration, Mining, Production, Supply and Demand, Economics and Environmental Issues (URAM 2014); Vienna; AT; June 23-27,
2014 |
| Document | book |
| Lang. | English |
| Media | paper |
| Related | This publication is related to Potter, E G; (2015).
Basement-to-surface expressions and critical factors in the genesis of unconformity-related uranium deposits, Geological Survey of Canada, Open File 7664 |
| File format | pdf |
| Province | Saskatchewan; Northwest Territories; Nunavut; Quebec |
| NTS | 74H; 66A; 32P/09; 32P/16 |
| Area | Key Lake; McArthur River; Thelon River; Camie River |
| Lat/Long WENS | -106.0000 -104.0000 58.0000 57.0000 |
| Lat/Long WENS | -98.0000 -96.0000 65.0000 64.0000 |
| Lat/Long WENS | -72.5000 -72.0000 52.0000 51.5000 |
| Subjects | economic geology; geochemistry; geochemical anomalies; uranium; uranium deposits; mineralization; mineral deposits; geochemical analyses; sedimentary rocks; sandstones; unconformities; unconformity-type
deposit; alteration; basement geology; Athabasca Basin; Phoenix Deposit; Millennium Deposit; McArthur River Deposit; Dufferin Lake zone; Thelon Basin; Bong deposit; Otish Basin; Camie River deposit; Precambrian |
| Program | Uranium Ore Systems, Targeted Geoscience Initiative (TGI-4) |
| Program | Uranium Ore Systems, Targeted Geoscience Initiative (TGI-4) |
| Abstract | Under the Targeted Geoscience Initiative Four (TGI-4) program operated by the Geological Survey of Canada, a collaborative project between government, academia and industry is examining
unconformity-related U ore systems in the Proterozoic Athabasca (Phoenix, Millennium McArthur River and Dufferin Lake zone), Thelon (Bong) and Otish (Camie River) basins in order to refine genetic models and exploration tools for these U deposits.
Examination of basement graphite-depleted zones underlying U-bearing zones at the Dufferin Lake zone has revealed the presence of low-ordered carbon species (carbonaceous matter) that may be interpreted as products of graphite consumption (±
later carbon precipitation) by oxidizing Athabasca Basin fluids that migrated downward into the basement. This may have produced a mobile reductant (gas or fluid), which could then have played a role in deposition of UO2. Alternatively, new
numerical modelling supports a previous hypothesis that fluid overpressures may have caused hydrocarbons generated from oil shale at the top of the Athabasca Group to migrate downwards to the sites of U precipitation. A preliminary Fe and Mg
isotopic study of the basement-hosted Bong deposit revealed that high ?57Fe and ?26Mg values are associated with U-bearing illite+chlorite alteration and a bright red hematitic zone that is often ascribed to 'paleoweathering' in the literature. The
higher isotopic values correlate with depletions in molar Fe2+, indicating that the processes that formed both alteration zones mobilized Fe2+ while enriching the exiting fluids in the lighter isotopes of Fe and Mg.
Petrological, geochemical and
isotopic studies of intense alteration concentrated along the P2 fault hosting the McArthur River deposit reaffirm previous studies that the alteration overprinted earlier paleoweathered and diagenetic altered horizons along the unconformity and that
the fault served as a conduit for basinal fluids to modify basement rocks through fluid-rock interactions. This fault-control is also manifested regionally, with new 3D modeling of the unconformity surface highlighting the influence of
northeast-trending reverse faults in formation of a narrow ridge between the Phoenix and McArthur River deposits. Regional clay anomalies documented in previous studies, associated with the majority of deposits and prospects, are also broadly aligned
with this feature.
Athabasca Group sandstones overlying the Phoenix deposits show relatively high concentrations of U, B, Pb, Ni, Co, Cu, As, Y and REEs above the deposit up to the uppermost sandstones and along the ore-hosting WS shear zone. In
support of previous studies, some of the metals (U, Mo, Co, Ag and W) also occur in elevated concentrations in humus and B-horizon soil overlying the Phoenix and Millennium deposits. However, these new results enhance the sensitivity of these
surficial geochemistry detection methods for deeply buried (ca. 600'750 m) uranium deposits. The locations of these anomalously high metal concentrations coincide with surface projections of the reactivated shear zones, consistent with the fault
conduit model. Elevated concentrations of the U decay product 4He in groundwater overlying the deeply buried Millennium deposit also supports this model. |
| Summary | (Plain Language Summary, not published)
The Targeted Geoscience Initiative (TGI-4) 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 conference presentation summarizes key results of the TGI-4 uranium ore systems project that is focused on
unconformity-related uranium deposits. Using examples from Saskatchewan, Nunavut and Quebec, the results further refine the ore deposit models (defining the role of graphite underlying the deposits, iron plus magnesium isotope signatures and 3D
modelling), enhance existing exploration tools (surficial geochemistry) and outline potential new exploration tools (i.e. helium in groundwater) for these highly prospective deposits. |
| GEOSCAN ID | 293823 |
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