DEPNO | COUNTRY | LOCATION | ALLNAMES | COMMODITIES |
40023 | Canada (Saskatchewan) | 57.37.30 N -- 105.37.32 W | Millennium Deposit; Millennium Prospect; Millennium Zone; Cree Lake Extension Project | 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): | Millennium Deposit (occurrence name); Millennium Prospect (occurrence name); Millennium Zone (occurrence name); Cree Lake Extension Project (claim name) | ||||||||||||||||||
Political location(s): | Canada; Province or state: Saskatchewan; Nearest community: McArthur River mine-mill complex (35 km SW) | ||||||||||||||||||
NTS map data: | 074H12 (Friesen Lake) | ||||||||||||||||||
Deposit clan (type): | Unconformity-associated | ||||||||||||||||||
Deposit (sub) types: | Unconformity-associated - Proterozoic - strata-bound; Mineralized lenses occur in paraneisses 150 m depth below the Athabasca unconformity, in the hanging wall of a thrust of the paragneisses over granitoid gneisses, and below a graphitic marker unit.; Reference: Roy, C.; Halaburda, J.; Thomas, D.; Hirsekorn, D., 2005: Millennium Deposit - Basement-hosted Derivative of the Unconformity Uranium Model; Topic: Uranium Geology & Deposits, In Symposium on Uranium Production and Raw Materials for Nuclear Fuel Cycle - Supply and Demand, Economics, the Environment and Energy Security (IAEA-CN-128): Extended Synopses, Edited by Anonymous, International Atomic Energy Agency Conference (International Symposium), IAEA in co-operation with OECD/NEA, WNA, NEI and UN-ECE, International Atomic Energy Agency, CN-128, 344 p., p. 42 - 45 | ||||||||||||||||||
Deposit status: | advanced prospect; Size category: large | ||||||||||||||||||
Geologic province: | Churchill - Hearne Craton | ||||||||||||||||||
Geologic subprovince: | Mudjatik Domain | ||||||||||||||||||
Geologic district: | Southeastern Athabasca Basin | ||||||||||||||||||
Deposit object located: | drill hole | ||||||||||||||||||
Commodities: | U | ||||||||||||||||||
Mineralization styles: | massive (mineralization zone); breccia - matrix (mineralization zone); fracture fill (mineralization zone); aggregates (mineralization zone); veinlets (mineralization zone) | ||||||||||||||||||
Geological ages: | Middle Mesoproterozoic - Late Mesoproterozoic (mineralization) Late Paleoproterozoic (host rocks) Late Paleoproterozoic - Middle Mesoproterozoic (country rocks) | ||||||||||||||||||
Tectonic setting: | continental marginal platform-fold belt; convergent; Formal name: Wollaston Fold Belt (host rocks) | ||||||||||||||||||
Coincident features: | strata-bound (a highly graphitic, east-dipping marker unit appears to control high grade mineralized zone on the footwall side, and a lower grade zone farther below); Coincident feature name: Pelitic gneiss fault zone (a post-Athabasca Group reverse fault dipping about 60° to the east at the base of metasedimentary belt acted as channel way for mineralizing solutions); Coincident feature name: Millennium Fault (?) | ||||||||||||||||||
Regional tectonic structure: | thrust fault (post-Athabasca Group reverse fault at the base of the east-dipping host metasedimentary belt beneath the mineralized zones is concordant to the belt) Tectonic structure name: Millennium Fault (?) fault (a major brecciated zone along the fault shows kinematic indicators for the reverse movement; it provided ingress of the mineralizing basinal fluids) Tectonic structure name: fault breccia zone | ||||||||||||||||||
Host rocks: | (1) metamorphic; metasedimentary schist (mineralization in two distinctive pelitic to semipelitic assembalges separated by a calc-silicate unit); Depositional setting: epizonal; Metamorphic grade: amphibolite; Component: basement mineralization
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Country rocks: | (1) metasediments; (200 m thick zone of calc-silicates and metapelites with graphitic beds); Country rock name: Wollaston Group; Metamorphic grade: amphibolite
(2) granite; (granitic assemblage on both sides of metasedimentary rocks); Country rock name: reactivated Archean granitic complex; Metamorphic grade: amphibolite
(3) granitoid; (pegmatite); Country rock name: Hudsonian Granites; Metamorphic grade: unknown
(4) sandstone; (600 m thick, flat-lying strata unconformably overlying crystalline basement); Country rock name: Athabasca Group; Metamorphic grade: unmetamorphosed
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Metallogenic signatures: | U | ||||||||||||||||||
Alteration signatures: | argillic alteration: illite, dominant in and around high grade ore; What was altered: host metapeltic strata; Component: alteration halo tourmalinization: dravitization in and around high grade ore; What was altered: host metapeltic strata; Component: alteration halo chlorite alteration: chloritization in the proximal zone; What was altered: host metapeltic strata; Component: alteration halo saussuritization: feldspar alteration in distal zone; What was altered: host metapelitic rocks; Component: alteration halo | ||||||||||||||||||
Mineralogy: | (alteration - undifferentiated / mineralization zone): sericite, chlorite, dravite, hematite (alteration - undifferentiated / alteration halo): illite (alteration - undifferentiated / regional alteration): kaolinite (mineralization / mineralization zone): pitchblende, coffinite, uraninite | ||||||||||||||||||
Deposit shape: | multiple lenses; Component: mineralization zone
lensoid; Component: main zone
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Qualified comments: | (Applies to: location and access) The Millenium Uranium Zone is located 0.48 km) immediately east of a small northeast trending lake that is located immediately west of Moon Lake. (Applies to: discovery and development) The Millennium deposit, discovered in 2000 by Cameco Corporation, represents a significant discovery of basement-hosted variant of the Unconformity-associated deposits, in which the mineralization is localized on the footwall side of a graphitic structure at 600 m depth. It currently ranks as second in size to the Eagle Point deposit among the conventionally mine-able basement-hosted deposits of the Athabasca basin. Discovery hole CX-40 was drilled in 2000 and targeted at hydrothermal alteration in adjacent hole; it intersected weak to moderate mineralization over 150 m at 608-761 m depth, including 3.63 % U over 30.3 m. (Applies to: mineralization) Strata-bound mineralization is restricted to the metapelitic and metasemipelitic beds of the Wollaston Group that were thrusted over granitic gneiss along a fault with a well developed breccia zone. Rotated bedding in the overlying Athabasca Group is more pronounced near the unconformity and is interpreted to be the result of structural dragging of the flat-lying beds in the hanging wall adjacent to the reverse or thrust fault. The fault is interpreted to have allowed penetration of oxidized uranium-bearing basinal fluids into the relatively reduced basement rocks, and consequent deposition of uranium. Association of mineralization with graphitic horizons in the basement is common among the Unconformity-associated deposits. The monometallic character of the Millennium deposit, however, contrasts with polymetallic character of most of these deposits, which generally contain significant amounts of Ni, Co and As. Localization of the main zone of the deposit on the footwall side of a highly graphitic marker unit is also unusual. Weaker persistent mineralization occurs in the lower pelitic-semipelitic strata referred to as the 'Bracketed Assemblage'. The deposit as whole has a gentle plunge to the south. Hydrothermal alteration associated with the deposit is strongly developed on the hanging wall side of the reverse or thrust fault, and is poorly developed on the footwall side of the fault. (Applies to: geophysical surveys) Discovery of the basement-hosted Millennium deposit at 600 m depth in a region of mature exploration provides impetus for further exploration. It resulted from progressive drill step-outs westward from a north-south segment of the main B1 conductor defined by early (1985-'95) Fixed Loop TDEM EM survey. Difficulty in intersecting the conductor resulted from significant unconformity relief, presence of unresolved conductors in the survey and granite structurally above the thin metasedimentary belt. However, favourable data on sandstone geochemistry and structure, and ultimately good basement alteration in the drill hole CX38 led to drilling of hole CX40 nearby that led to intersection of weak to moderate uranium mineralization over core length of 150 m from 608-761 m vertical depth. Recent geophysical work in the area has included an airborne triaxial magnetic gradiometer survey and MEGATEM test, as well as ground Moving Loop and sounding TDEM, AMT. 2D/3D resistivity and gravity surveys with objective of contributing to the additional discoveries. They represent application of innovative geophysical techniques in the Athabasca basin. (Applies to: regional stratigraphy) Mineralized lenses are hosted by a 75 m thick stratigraphic zone of two pelitic-semipelitic assemblages separated by a thin calc-silicate unit, over 250 m strike and 150 m depth below the Athabassca unconformity. A highly graphitic pelitic gneiss is a marker unit along the upper margin of the host stratigraphic zone, and the high grade mineralization of the main zone is localized along the footwall of this marker unit. (Applies to: reserve/resource descriptions) Drill indicated resources as of Dec. 2004: 547000 tonnes ore at 2.43 % U; plus 293000 t at 2.07 % U classified as inferred resources; total of 840000 t ore averaging 2.306 % U and containing 19370 t U. | ||||||||||||||||||
Links to other databases: | SMDI; Key value: 2742 | ||||||||||||||||||
Geophysical-chemical signature: | Signature type: Ground EM; Response type: positive (moderate) Signature type: Airborne Magnetometer; Response type: positive (moderate) Signature type: Ground Gravity; Response type: positive (weak) Signature type: Ground IP Resistivity; Response type: positive (moderate) | ||||||||||||||||||
References: |
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Resource data: |
Percent weights allocated to deposit: 100.0% Generated 2007-03-02 2:36:35 PM with GQuery -- 3.7 ADO (3.19/3.20/3.21 -- 2006-02-24) |