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TitleGeological and uranium metallogenic comparisons of the Thelon and Athabasca basins
AuthorJefferson, C W; Potter, E GORCID logo; Rainbird, R HORCID logo; Davis, WORCID logo; Card, C; Bosman, S; Ramaekers, P
SourceGAC-MAC 2021; Geological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Abstracts Volume vol. 44, 2021 p. 151
LinksOnline - En ligne
Alt SeriesNatural Resources Canada, Contribution Series 20210215
PublisherGeological Association of Canada
MeetingGAC-MAC 2021; London, Ontario; CA; November 1-5, 2021
Mediapaper; on-line; digital
File formatpdf
Subjectsgeneral geology; mineralogy; Science and Technology; Nature and Environment; uranium metallogenesis; uranium; Thelon Basin; Athabasca Basin
ProgramGEM2: Geo-mapping for Energy and Minerals
ProgramGEM: Geo-mapping for Energy and Minerals
Released2021 11 21
AbstractNew and compiled data in the Thelon and Athabasca basin regions enhance comparisons of their respective uranium metallogenies. The Athabasca Supergroup overlaps the Rae and Hearne cratons of the western Churchill Province, whereas the Dubawnt Supergroup of Nunavut and the eastern NWT rests entirely within the Rae craton, west of the Snowbird Tectonic Zone cratonic boundary. The Athabasca Supergroup fills the Martin and Athabasca basins whereas the Dubawnt Supergroup fills the Baker Lake and Thelon basins. The Athabasca Supergroup comprises five, unconformity-bounded, second-order clastic sequences in the Martin, Jackfish, Cree and Mirror basins. The Martin and Jackfish sequences roughly correspond to the lower (Baker) and middle (Whart) sequences of the Dubawnt Supergroup. Three more sequences filled the Cree and Mirror basins while two more of the Barrensland Group filled the upper Baker Lake and most of the Thelon basins, completing the Dubawnt Supergroup. The Thelon Formation (lower Barrensland Group) comprises three, third-order, upward-fining, siliciclastic sequences. Limited facies and paleocurrent data suggest a single, "big river" system axial to the Thelon Basin. The upper Barrensland Group comprises Kuungmi Formation ultrapotassic mafic tuff and flows (1.54 Ga) in contrast to 1.54 Ga black shale of the Douglas Formation, and the Lookout Point Formation carbonate, much like the Carswell Formation atop the Athabasca Supergroup. The two supergroups have similar but distinct crustal settings, paleocurrents, facies changes, provenance, igneous components, geochronology and tectonic histories. Beneath the Athabasca Basin, granulite- to amphibolite-facies, conductive-graphitic-pyritic deformation zones are spatially associated with known major deposits. Conductive temporal analogues below the Thelon Basin are barren, impermeable, albeit sheared, black pyritic phyllite of anchizone to epizone facies. Instead, hosts of the smaller Thelon uranium deposits are Neoarchean pyritic greywacke and epiclastic rocks that range in metamorphic grade from lower to upper amphibolite, including partially melted paragneiss. The basins developed independently but broadly contemporaneously, possibly bridged at times by since-eroded, more extensive upper units. Pre-ore fluorapatite cements of the Athabasca and Thelon basins are 1.64 vs. 1.69-1.67 Ga respectively. The Thelon Formation and deposits lack hydrothermal tourmaline. Similarities include uranium sources in surrounding terranes and the basin fills, sodic brine transport, diagenetic and hydrothermal alteration of basement and basin-fill (hematite, clay and chlorite minerals, aluminum phosphate sulphate minerals, fluid inclusion data, silicification [before, during and after mineralization] and dequartzification), and reactivated faults that focused alteration and mineralization. Such cumulative knowledge supports adaptive exploration strategies between these prospective regions.
Summary(Plain Language Summary, not published)
This contribution outlines key geological features in common and unique to the Thelon and Athabasca basins; the latter of which hosts the highest-grade uranium deposits in the world. New geological knowledge acquired under the Geomapping for Energy and Minerals program highlights that the two regions have different crustal settings, paleocurrents, facies changes, provenances, igneous components, geochronologic and tectonic histories. However, similar basin materials, fluid composition, diagenetic to hydrothermal alteration and association with reactivated faults indicates that uranium exploration strategies can be adapted between these prospective regions.

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