A Shallow-Burial Mineralization Model for the Unconformity-Related Uranium Deposits in the Athabasca Basin

Chi, Guoxiang; Li, Z.; Chu, Hong; Bethune, Kathryn M.; Quirt, David; Ledru, Patrick; Normand, Charles; Card, Colin; Bosman, Sean; Davis, W J; Potter, E G

doi:10.5382/econgeo.2018.4588

Cited by 46 publications

(21 citation statements)

References 53 publications

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“…The presence of a sedimentary cusp and interconnecting structures would likely facilitate deep crustal hydrothermal fluid transport and circulation up to the surface (Fig. 10C, bottom), as suggested by Chi et al (2018). This highlights the importance of the aforementioned structural architecture that is capable of predetermining future regions for uranium mineralisation.…”

Section: Determining the Reference Model For The Wmtz In The Hearne Cmentioning

confidence: 84%

Precambrian deformation belts in compressive tectonic regimes: A numerical perspective

et al. 2020

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Section: Determining the Reference Model For The Wmtz In The Hearne Cmentioning

confidence: 84%

Precambrian deformation belts in compressive tectonic regimes: A numerical perspective

et al. 2020

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“…13–15 . Based on regional geochronology and stratigraphic data, it was proposed that the primary U mineralization in the Athabasca Basin took place at relatively shallow depths (<~3 km) during the deposition of the Carswell Formation 36 , at which time the sediments in the basin had not been significantly compacted and cemented, in contrast to a conventional model suggesting deep burial (>5 km) environment for mineralization 26,37 .…”

Section: Discussionmentioning

confidence: 99%

“…The third mechanism requires a fluid convection system in which basinal brines infiltrated into the upper part of the basement and circulated back into the basin 27 . Such a fluid convection system is theoretically possible based on numerical modeling 41,42 , and may have been further facilitated by elevated geothermal gradients as implied in the shallow-burial model 36 discussed above. However, the efficiency of this mechanism depends on the permeability of the upper part of the basement, which remains poorly constrained.…”

Section: Discussionmentioning

confidence: 99%

“…1720 Ma) and primary U mineralization (ca. 1540 Ma), the sediments probably remained poorly consolidated due to shallow burial 36 , which further facilitated brine migration and fluid-rock reaction. Finally, the high geothermal gradients implicated by the high fluid temperatures of ~200 °C 12,19,26,37 and shallow burial (~3 km) environments as constrained by regional geochronological and stratigraphic data 36 , may have enhanced fluid convection 41,42 , which further facilitated fluid-rock reactions and extraction of U from source rocks including the uppermost part of the basement.…”

Section: Discussionmentioning

confidence: 99%

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Uranium-rich diagenetic fluids provide the key to unconformity-related uranium mineralization in the Athabasca Basin

Chi

Chu

Petts

et al. 2019

Sci Rep

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The Proterozoic Athabasca Basin is well known for its unusually large-tonnage and high-grade ‘unconformity-related’ uranium (U) deposits, however, explanations for the basin-wide U endowment have not been clearly identified. Previous studies indicate that U-rich brines with up to ~600 ppm U and variable Na/Ca ratios (from Na-dominated to Ca-dominated) were present at the sites of U mineralization, but it is unknown whether such fluids were developed solely in the vicinity of the U deposits or at a basinal scale. Our microthermometric and LA-ICP-MS analyses of fluid inclusions in quartz overgrowths from the barren part of the basin indicate that U-rich brines (0.6 to 26.8 ppm U), including Na-dominated and Ca-dominated varieties, were widely developed in the basin. These U concentrations, although not as high as the highest found in the U deposits, are more than two orders of magnitude higher than most naturally occurring geologic fluids. The basin-scale development of U-rich diagenetic fluids is interpreted to be related to several geologic factors, including availability of basinal brines and U-rich lithologies, and a hydrogeologic framework that facilitated fluid circulation and U leaching. The combination of these favorable conditions is responsible for the U fertility of the Athabasca Basin.

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“…1720 and ca. 1267 Ma ( [26] and references therein). The basement below the Athabasca Basin is subdivided into two lithostructural subprovinces of the Western Churchill province: the Rae Subprovince to the west and the Hearne Subprovince to the east, separated by the Virgin River Shear Zone [27], the Southern extension of the Snowbird Tectonic Zone (Figure 1).…”

Section: Regional Geological Setting and Location Of Studied Sitesmentioning

confidence: 99%

Structural Controls of Uranium Mineralization in the Basement of the Athabasca Basin, Saskatchewan, Canada

et al. 2021

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The occurrence of unconformity-related uranium mineralization requires the combination of three components: fluids with the right composition, geochemical traps with the right agents that produce precipitation, and structural traps with the right geometry. In the Athabasca Basin unconformity-related uranium deposits, while basinal brines are commonly accepted as the principal mineralized fluids and graphite and gases (CH4, CO2, and H2S) are well known as the reductants, only few case studies describing structural traps are published. A number of recent works, including numerical modelling, have improved the understanding of the role of inherited shear zones on fluid flow and the development of uranium deposits at a micro- and regional-scale. Nevertheless, there is still a lack of knowledge about the meso- or deposit-scale structural controls that lead to the present (and potentially predictive) localization of uranium deposits along a given shear zone. The present work examines new structural data from drill holes and deals with (i) the identification of mesoscale structural traps that lead to the formation of the Athabasca unconformity-related uranium deposits hosted within the basement and (ii) with the understanding of the role and mode of reactivation of the inherited shear zones. The Sue deposits (McClean Project), the Tri-Island showing (Martin Lake Project) in the Eastern Athabasca, and the Spitfire prospect (Hook Lake Project) in the Western Athabasca have been selected for a detailed analysis of structures and related uranium mineralization. The structural analysis performed brings new insights about the mesoscale structural controls, the role the inherited ductile fabric had on the mode of brittle reactivation and to trap mineralization, and the tectonic regime to which basement-hosted uranium deposits may be associated in the Athabasca Basin.

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A Shallow-Burial Mineralization Model for the Unconformity-Related Uranium Deposits in the Athabasca Basin

Cited by 46 publications

References 53 publications

Precambrian deformation belts in compressive tectonic regimes: A numerical perspective

Precambrian deformation belts in compressive tectonic regimes: A numerical perspective

Uranium-rich diagenetic fluids provide the key to unconformity-related uranium mineralization in the Athabasca Basin

Structural Controls of Uranium Mineralization in the Basement of the Athabasca Basin, Saskatchewan, Canada

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