EXTECH IV ATHABASCA URANIUM DEPOSIT DATABASE
Geological Survey of Canada, Saskatchewan Industry and Resources, and Alberta Geological Survey


DEPNO COUNTRY LOCATION ALLNAMES COMMODITIES
40024 Canada (Saskatchewan) 59.13.14 N -- 105.32.38 W Middle Lake Uranium Showings; Dee Showing U

Database name: Uranium Deposits, Athabasca Basin
Custodial agency: Geological Survey of Canada
Compilers: Sunil S. Gandhi
Release date: 2007-03-02
   
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 zone
External 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 zone
External 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)
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: granulite
Country 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: unmetamorphosed
Country 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: unmetamorphosed
Country 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)
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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