Database name: |
Uranium Deposits, Athabasca Basin |
Custodial agency: |
Geological Survey of Canada |
Compilers: |
Sunil S. Gandhi |
Release date: |
2007-03-02 |
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Deposit name(s): |
Middle Lake Uranium Showings (occurrence name); Dee Showing (occurrence name) |
Political location(s): |
Canada; Province or state: Saskatchewan; Nearest community: Stony Rapids settlement (13 km East) |
NTS map data: |
074P04 (Elizabeth Falls) |
Deposit clan (type): |
Unconformity-associated |
Deposit (sub) types: |
Unconformity-associated - Proterozoic - clay-bound; disseminated secondary yellow uranium minerals autunite and phosphuranylite in the Athabasca sandstone at basal unconformity and regolith below; first example of the clan recognized by Kermeen (1955); Reference: Homeniuk, L. A.; Clark, R. J. M., 1986: North Rim Deposits, Athabasca Basin; Chapter 4, Section Saskatchewan Unconformity-associated and Sedimentary-hosted Deposits of Helikian Age, In Uranium Deposits of Canada, Edited by Evans, E. L., Special Volume, The Canadian Institute of Mining and Metallurgy, The Canadian Institute of Mining and Metallurgy, 33, 323 p., p. 230 - 240 |
Deposit status: |
drilled showing; Size category: unknown |
Geologic province: |
Churchill - Rae Craton |
Geologic subprovince: |
Tantato Domain |
Geologic district: |
Athabasca Basin (North Rim) |
Deposit object located: |
outcrop |
Commodities: |
U |
Mineralization styles: |
disseminated (mineralization zone); coatings (mineralization zone) |
Geological ages: |
Middle Proterozoic (host rocks) Late Proterozoic (mineralization) |
Tectonic setting: |
continental basin-intracratonic; stable; Formal name: Athabasca Basin (host rocks) |
Coincident features: |
unconformity (uranium minerals occur in the matrix of Athabasca sandstone above the unconformity surface and as disseminated grains in clay-like regolith below it); Coincident feature name: Sub-Athabasca unconformity fault(s) (five uranium showings close to a north-south fault in basement along Middle Lake; possibly a reactivated subsidiary fault of the Black Lake fault zone); Coincident feature name: Middle Lake Fault paleoregolith |
Regional tectonic structure: |
fault zone (northeast-trending Black Lake fault zone in the basement 7.5 km east of the showing, a segment of the Snowbird Tectonic Zone, hosts pitchblende veins) Tectonic structure name: Black Lake Fault fault zone (Middle Lake area is between the Snowbird and Platt Creek shear zones to the east and west, respectively, and is highly deformed part of Tantato domain) Tectonic structure name: Platt Creek-Patterson Creek Shear Zone |
Host rocks: |
(1) surficial; laterite (weathered basement); Host series: paleoregolith; Depositional setting: subaerial; Metamorphic grade: unmetamorphosed; Component: mineralization zoneExternal host rock forms: | lateritic profile paleoregolith | Host rock protoliths: | mafic and felsic gneisses and mylonites (amphibolite, biotite-rich metapelites, amphibole-biotite gneiss and feldspar-quartz gneiss; all garnetiferous; granulite facies; variably mylonitized); Host rock protolith name: Archean gneiss complex | Internal host rock structures: | lateritic zonation | Individual lithologies: | laterite (clay-hematite rich assemblage is a few m thick with a bleached zone at the top grading below into red hematitic then green chloritic zones) |
(2) sedimentary; sandstone (10 to 15 m thick in exposures and drill holes; flat-lying; overburden up to 4 m thick; minor faults); Depositional setting: fluviatile; Metamorphic grade: unmetamorphosed; Component: mineralization zoneExternal host rock forms: | thick bedded | Host rock protoliths: | sandstone-pebbly sandstone-conglomerate (coarse lag conglomerate 1.5 m thick with vein quartz boulders; overlain by 10 m of sandstone; then a 1 m thick conglomerate horizon in the sandstone); Host rock protolith name: basal unit of Athabasca Group | Internal host rock structures: | fine to very coarse grained | Individual lithologies: | quartz arenite (basal unit with tourmaline-bearing quartz boulders, and lenses of specularite, and monazite-bearing quartz pebble conglomerate; sandstone well-sorted) |
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Country rocks: |
(1) mafic and felsic gneisses; (Tantato domain contains metapelite, amphibolite, and 3.4 and 2.63-2.58 Ga old granites; all metamorphosed to granulite facies and variably mylonitized); Country rock name: Archean Basement Complex; Metamorphic grade: granuliteCountry rock protoliths: | sedimentary, volcanic and granitic rocks (pelitic sediments, mafic volcanic rocks and granitic intrusives of late Archean age); Country rock protolith name: Archean Basement Complex | Individual lithologies: | garnetiferous gneisses (quartzo-feldspathic gneisses predominant; biotite-hornblende gneisses and amphibolites as remnants of the supracrustals; which occur at Middle Lake) |
(2) paleo-regolith; (up to 50 m thick lateritic profile); Country rock name: sub-Athabasca regolith; Metamorphic grade: unmetamorphosedCountry rock protoliths: | mafic and felsic gneisses and mylonites (various orthogneisses and paragneisses; variably mylonitized, sheared and faulted; deeper paleo-weathering along faults; amphibolite-granulite facies); Country rock protolith name: Archean Basement Complex | Individual lithologies: | Lateritic (lateritic profile up to 50 m thick; characterized by lower chloritic green zone grading to red hematitic zone above; thin bleached clayey zone at top) |
(3) conglomerate-sandstone; (the basal strata and the gneissic basement exposed at the northern erosional margin of the little deformed siliciclastic group); Country rock name: Manitou Falls Fm. / Athabasca Group; Metamorphic grade: unmetamorphosedCountry rock protoliths: | sandstone-pebbly sandstone-conglomerate (southern half of the region around Middle Lake is underlain by the fluvial, siliciclastic strata of the Manitou Falls Formation of the Athabasca Group); Country rock protolith name: Manitou Falls Formation | Individual lithologies: | conglomerate-sandstone-siltstone (upward fining cycles; bouldery lag conglomerate common at the base; sandstones predominate; commonly cross-bedded; include pebbly and mudstones beds) |
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Metallogenic signatures: |
U |
Alteration signatures: |
reprecipitation by ground water: uranium leaching and redeposition in sandstone; What was altered: pitchblende veins and uraniferous pegmatites; Component: alteration halo |
Mineralogy: |
(disseminated mineralization / alteration halo): autunite, phosphuranylite |
Deposit shape: |
irregular |
Qualified comments: |
(Applies to: discovery and development) This showing is located at the base of a 15 m high escarpment of Athabasca sandstone. The first exploration in 1952 included surface work and drilling of 26 holes totalling 381.3 m, and showed low grade mineralization. Kermeen (1955) stated that "Regardless of the origin, the unconformity at the base of the Athabasca appears to have had major effect on localization of uranium". This was the first example of unconformity-associated clan, which itself was fully recognized in Canada 13 years later with the discovery of Rabbit Lake deposit. Exploration was undertaken again at Middle Lake in 1966 with an airborne survey, which was follow-up by surface work and 185.9 m of diamond drilling. Further surface exploration and drilling of 1672 m in 27 holes showed high uranium concentration at or near the surface. More extensive geophysical and geochemical surveys in the area around the showing were undertaken during 1976-1980, including drilling of 6 holes in 1980. No significant uranium values were intersected. |
Links to other databases: |
SMDI; Key value: 1762 SMDI; Key value: 1763 SMDI; Key value: 1764 GSC U-Th File (Prasad); Key value: 2891 |
References: |
Beck, L. S., 1969 |
Uranium Deposits of the Athabasca Region, Saskatchewan |
Report, Department of Mineral Resources, Province of Saskatchewan, Department of Mineral Resources, Province of Saskatchewan, Publication code 126, 140 p., 4 maps. |
Hanmer, S., 1997 |
Geology of the Striding -Athabasca Mylonite Zone, Northern Saskatchewan and Southeastern District of Mackenzie |
Bulletin, Geological Survey of Canada, Publication code 501, 92 p.. |
Homeniuk, L. A.; Clark, R. J. M., 1986 |
North Rim Deposits, Athabasca Basin |
Chapter 4, Section Saskatchewan Unconformity-associated and Sedimentary-hosted Deposits of Helikian Age, In Uranium Deposits of Canada, Edited by Evans, E. L., Special Volume, The Canadian Institute of Mining and Metallurgy, The Canadian Institute of Mining and Metallurgy, 33, 323 p., p. 230 - 240 |
Kermeen, J. S., 1955 |
A Study of Some Uranium Mineralization in Athabasca Sandstone near Stony Rapids, Northern Saskatchewan, Canada |
M. Sc. Thesis, University of Saskatchewan, 36 p.. |
Robinson, S. C., 1952 |
Autoradiographs as a Means of Studying Distribution of Radioactive Minerals in Thin Section |
American Mineralogist, Volume 37, p. 544 - 547 |
Saskatchewan Industry and Resources, 2001 |
Saskatchewan Mineral Deposits Index |
Government of Saskatchewan, Geological Atlas of Saskatchewan, Internet |
Thomas, D. J.; Jefferson, C. W.; Card, C.; Yeo, G.; Sopuck, V., 2002 |
Introduction: the Eastern Athabasca Basin and its Uranium Deposits |
Chapter 1, In Field Trip A1: the Eastern Athabasca Basin and its Uranium Deposits, May 24-26, 2002, GAC-MAC Saskatoon 2002, Edited by Andrade, N; Breton, G.; Jefferson, C. W.; Thomas, D. J.; Tourigny, G.; Wilson, S.; Yeo, G. M., Field Guide Book, Geological Association of Canada - Mineralogical Associationof Canada, Geological Association of Canada, 102 p., p. 1 - 22 |
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