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


DEPNO COUNTRY LOCATION ALLNAMES COMMODITIES
40001 Canada (Saskatchewan) 58.11.53 N -- 103.42.41 W Rabbit Lake Uranium Deposit; Rabbit Lake Uranium Mine 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): Rabbit Lake Uranium Deposit (occurrence name); Rabbit Lake Uranium Mine (occurrence name)
Political location(s): Canada; Province or state: Saskatchewan; Nearest community: La Ronge (354 km NNE)
NTS map data: 064L04 (Hidden Bay)
Deposit clan (type): Unconformity-associated
Deposit (sub) types: Unconformity-associated - Proterozoic - fracture-bound; Basement-hosted deposit at the sub-Athabasca Group unconformity; the first discovery that led to the recognition of unconformity-associated deposits as a distinct new uranium deposit-type; Reference: Hoeve, J; Sibbald, T. I. I., 1978: On the Genesis of Rabbit Lake and Other Unconformity-type Uranium Deposits in Northern Saskatchewan; Economic Geology, Volume 73, p. 1450 - 1473
Deposit status: past producer; Size category: large; Status comments: Open pit; ore body mined out during 1975-1984.
Geologic province: Churchill - Hearne Craton
Geologic subprovince: Wollaston Domain (Fold Belt)
Geologic district: Eastern Athabasca Basin
Deposit object located: open pit
Commodities: U
Mineralization styles: fracture-filling (mineralization zone); coating (mineralization zone); disseminated (mineralization zone); fault-controlled (mineralization zone); breccia - matrix (mineralization zone)
Geological ages: Middle Mesoproterozoic (mineralization)
Late Paleoproterozoic (host rocks)
Tectonic setting: continental marginal deformation zone-basement reactivation; transpressive; Formal name: Hudsonian thermotectonic zone (host rocks)
continental transform fault zone-intracratonic; stable; Formal name: Athabasca Basin (mineralization)
continental craton-paleoweathered zone; stable; Formal name: sub-Athabasca regolith (alteration)
Coincident features: fold(s) (deposit on western limb of a syncline in Wollaston Group strata, which trend 065° and dip 65° to SE); Coincident feature name: Rabbit Lake syncline
fault zone (this reverse or thrust fault, variably dipping 30 to 60° to the southeast, defines the footwall of the ore zone); Coincident feature name: Rabbit Lake fault
breccia(s) (the main host unit is dolomitic marble, much of which is solution collapse mega-breccia with magnesian chlorite matrix ); Coincident feature name: Dolomitic mega-breccia
Regional tectonic structure: fold belt (northeast-trending regional tectonic zone between Archean craton to the northwest and juvenile core of the Trans-Hudson orogen tothe southeast) Tectonic structure name: Wollaston fold belt
thrust fault (one of the southeast dipping thrusts in the basement of the eastern Athabasca basin) Tectonic structure name: Rabbit Lake fault
Host rocks: (1) metasomatic-hydrothermal; unclassified metasomatic rocks (plagioclasite; characterized by intense Na-metasomatism; derived from saliferous pelites); Depositional setting: shallow marine; Metamorphic grade: amphibolite - upper; Component: foot wall
External host rock forms:irregular zones
Host rock protoliths:quartz-biotite-feldspar paragneiss (occurs on northwest side of deposit and in footwall of Rabbit Lake fault); Host rock protolith name: Hidden Bay Assemblage
sandstone (feldspathic)
Internal host rock structures:massive
Individual lithologies:arkose (contains irregular patches of biotite-rich paleosome, up to 5 cm in diameter, and calc-silicate stringers and clots)
carbonate (interbedded with feldspathic sandstone)
Host rock stratigraphy:Wollaston Supergroup

(2) metamorphic; metasedimentary schist (in southwestern part of open pit); Depositional setting: shallow marine; Metamorphic grade: amphibolite
External host rock forms:well bedded
Host rock protoliths:dolomitic limestone (massive to finely layered); Host rock protolith name: unit of Wollaston Supergroup
Internal host rock structures:cyclic bedding
Individual lithologies:marble (dolomitic, carbonate dissolution and formation of collapse breccia (fossilized doline))
Host rock stratigraphy:Wollaston Supergroup

(3) metamorphic; paragneiss (graphitic, in southwestern part of open pit); Depositional setting: shallow marine; Metamorphic grade: granulite
Host rock protoliths:feldspathic sandstone, argillaceous (graphite and pyrite associated with argillaceous material); Host rock protolith name: unit of Wollaston Supergroup
Individual lithologies:feldspathic sandstone (argillaceous; underlies dolomitic marble)
Host rock stratigraphy:Wollaston Supergroup

(4) metamorphic; paragneiss (host of high-grade ore); Depositional setting: shallow marine; Metamorphic grade: amphibolite (upper) - granulite; Component: mineralization zone
External host rock forms:massive bed
Host rock protoliths:feldspathic sandstone (dominantly feldspathic but locally quartz up to 50 percent)
Internal host rock structures:indistinct layering
Individual lithologies:arkose (overlain by calc-silicates and meta-arkoses (Upper Gneisses))
Host rock stratigraphy:Upper Wollaston Supergroup

(5) metamorphic; metasedimentary schist (Upper Gneisses sequence); Depositional setting: shallow marine; Metamorphic grade: amphibolite (upper) - granulite; Component: hanging wall
External host rock forms:layered gneiss
Host rock protoliths:feldspathic sandstone and carbonate (compositional layering indicative of bedding; metamorphic segregations of pegmatite-microgranite); Host rock protolith name: unit of Wollaston Supergroup
Internal host rock structures:compositional layering
Individual lithologies:meta-arkose (pink meta-arkose with some biotite and amphibole)
calc-silicate (green cal-silicate with diopside, feldspar and biotite)
Host rock stratigraphy:Upper Wollaston Supergroup

(6) intrusive; granite suite (fine grained dyke; mineralized; on east margin of deposit); Host series: calc-alkaline; Metamorphic grade: unmetamorphosed; Component: basement mineralization
External host rock forms:dyke
Host rock protoliths:granite (plagioclase (70%), anhedral quartz (25%) and biotite altered to chlorite (5%), subhedral apatite is important accessory); Host rock protolith name: Late Paleoproterozoic Granite
Internal host rock structures:massive
Individual lithologies:granite (microgranite dyke vertical, broken up within a breccia zone with blocks of marble; highly altered)
Host rock stratigraphy:Hudson Granite Suite
Country rocks: (1) granitoid gneiss; (basement of the Wollaston Group, reactivated during the Hudsonian orogeny as domes); Country rock name: remobilized Archean basement; Metamorphic grade: amphibolite
Country rock protoliths:granitoid rocks (mainly granitic plutons and granitized supracrustal remnants); Country rock protolith name: Archean Granitoids
Individual lithologies:gneissic granitoids (mostly in the granite-granodiorite-monzonite range)

(2) meta-arkose and calc-silicate; (folded and metamorphosed sediments; deposited in late foreland basin of the Trans-Hudson orogen; Hidden Bay assemblage of earlier literature); Country rock name: Upper Wollaston Supergroup ; Metamorphic grade: amphibolite - upper
Country rock protoliths:sandstone-mudstone-carbonate (deposition in shallow, marine, near-shore environment; includes minor organic debris and saliferous pelites); Country rock protolith name: Upper Wollaston Supergroup
Individual lithologies:metasiltstone, calc-silicate (sequence of calcareous and non-calcareous feldspathic metasediments, massive carbonate, overlain by meta-arkoses, quartzites, and metapelites)

(3) sandstone-conglomerate; (continental siliciclastic sediments ); Country rock name: Athabasca Group; Metamorphic grade: unmetamorphosed
Country rock protoliths:siliceous sediments (basal conglomerate and sandstone units; deposited on lateritic paleosol); Country rock protolith name: Manitou Falls Formation
Individual lithologies:conglomerate-sandstone (basal conglomerate, overlain by massive conglomerate with sandy layers and shale partings)
Metallogenic signatures: U
Alteration signatures: phyllosilicate alteration: light green flakes resembling mica; What was altered: dolomitic marble, graphitic granulite; Component: mineralization
phyllosilicate alteration: light green flakes resembling mica (phlogopitic in; What was altered: upper gneisses, microgranite breccia; Component: mineralization zone
carbonate reprecipitation: extensive dissolution and crystallization; What was altered: dolomitic marble; Component: mineralization zone
hematization: disseminated fine hematite; red colouration; What was altered: host metasediments; Component: mineralization zone
chlorite alteration: dark green aggregates; What was altered: mafic silicates in host metasediments; Component: mineralization zone
silicification: introduction of silica in fractures and cavities; What was altered: host rocks; Component: mineralization zone
tourmalinization: tourmaline; What was altered: host rocks; Component: alteration halo
anatase alteration: ananatase; What was altered: titanite and Fe-Ti oxides in host rocks; Component: alteration halo
Mineralogy: (alteration / mineralization zone): kasolite, massuyite, triuranium-lead heptaoxide, vandendriesscheite, wölsendorfite, alpha uranophane, beta uranophane, boltwoodite, carbon buttons
(alteration / host rocks): phyllosilicates, dolomite
(alteration - undifferentiated / host rocks): dravite, adularia
(fracture fillings, coatings, disseminations / mineralization zone): pitchblende - massive, pitchblende - colloform, coffinite, pyrite, arsenopyrite, marcasite, chalcopyrite, bornite, chalcocite, covellite, copper, galena, clausthalite, sphalerite, niccolite, quartz, calcite, dolomite, siderite
(fracture fillings, coatings, disseminations / wall rock): hematite, chlorite - Mg-rich
Radiometric ages: Object dated: Mineralogy(1); Age - Ma: 1,281; +11; -11; Dating method: U-Pb; Concentrate: pitchblende; Source rock: mineralization; Event dated: mineralization; Interpretive comment: minimum age of initial uranium deposition from 5 discordant points; lower intercept at 494 ± 19 Ma; Reference: Cumming, G. L.; Rimsaite, J., 1979: Isotopic Studies of Lead-depleted Pitchblende, Secondary Radioactive Minerals, and Sulphides from the Rabbit Lake Uranium Deposit, Saskatchewan; Canadian Journal of Earth Sciences, Volume 16, p. 1702 - 1715
Deposit shape: elongate pod
Deposit dimensions:length: 550 metre
width: 250 metre
thickness: 200 metre
Qualified comments: (Applies to: discovery and development) An airborne radiometric survey was conducted over the region by New Continental Oil Company of Canada Limited in 1967. Encouraging results led to acquisition of exploration permits, which were optioned to British American Oil Company that was absorbed shortly thereafter by Gulf Minerals Canada Limited. In 1968 the company carried out follow-up ground geophysical and geological work on selected aiborne survey anomalies. This work located a radioactive boulder train, a gravity low and a zone of low seismic velocity at a small rabbit-shaped lake. Drilling in 1968 and 1969 confirmed the discovery of Rabbit Lake deposit. It was subsequently delineated by more than 36 km of drilling. It was mined during 1975-1984 from an open pit about 600 m in diameter at the surface and 200 m deep. The open pit was utilized later as a tailings disposal reservoir, and the mill processed uranium ore from the mines in its vicinity.

(Applies to: regional geology) The Rabbit Lake deposit is located at the present east margin of the Mesoproteroszoic Athabasca basin. The crystalline basement here comprises Archean granitoid rocks and Paleoproterozoic Wollaston Supergroup. These were deformed and highly metamorphosed during the late Paleoproterozoic Trans-Hudson orogeny, in a foreland fold and thrust belt viz., the Wollaston Domain, which trends northeast. Its structural evolution involved the initial basement-cover intercalation during thrusting, followed by multiple fold phases, resulting in dome and basin structures. Thrusts or reverse faults, which developed during the early stage, commonly dip moderately to the southeast. Majority of them are located along graphitic metapelite horizons of the supergroup, but others like the Rabbit Lake fault are in other units. These are dispaced by cross-cutting faults. During the long interval before deposition of the Athabasca sediments, all the faults were repeatedly reactivated, the terrain was peneplaned and subjected to intense lateritic paleoweathering to a depth of 50 m. The Athabasca Group dips regionally very gently to the west, but in the Rabbit Lake area, local gentl southeast dips are a result of differential offsets along the various reactivated faults. Subsequent erosion over the millennia exposed this deposit and partly mantled it by glacial till with drumlins. This surface position resulted in its discovery as a radiometric anomaly in 1968. It precipitated the first staking rush over the Athabasca Basin, and played a major role in development of the unconformity-associated uranium deposit model.

(Applies to: structure) The Rabbit Lake deposit is typical of the basement-hosted, fracture-controlled and breccia-hosted replacement variant of the unconformity-associated uranium deposit type. It has simple, uraninite-dominated mineralogy. It is located on the hanging wall side of the reverse Rabbit Lake Fault, which strikes 065° and dips 30° to 60° to the southeast. Basal Athabasca Group conglomeratic sandstone and its underlying weathered unmineralized regolith occur on the footwall side of this fault. Vertical displacement along the reverse fault is at least 75 m. The fault partly controls the site of the deposit, which lies entirely above the thrust in the northwesterly limb of of a major syncline and is hosted by massive dolomite and graphitic granulite. In plan, the Rabbit Lake Fault varies in width from 1 to 2 m at the northeast edge of the pit to 35 m at the southwest edge of the pit. The southwest side of the orebody is bounded by a steeply dipping, northeast-side-down, northwest-trending normal fault. On the southeast side the orebody is bounded by the north-south trending, subvertical Dragon Lake fault, east of which are the hanging wall gneisses ('Upper Gneiss'). All of these faults are interpreted as having originated before deposition of the Athabasca Group, and reactivated during and after its deposition. The intersections of these active faults are thought to have favoured hydrothermal fluid flow at a time when the area was more deeply buried beneath the Athabasca Group. The deposit is associated with hydrothermal alteration along the fault zones, including bleaching with illite, chlorite and local redox boundaries.

(Applies to: mineralization) The orebody resembles a laterally flattened pipe, elongated in northeast direction for 550 metres, and is 250 metres wide and up to 200 metres thick. It is characterized by a high grade core surrounded by an envelope of lower grade ore. Uranium mineralization involved multi-phase deposition and remobilization of pitchblende, coffinite, and sklodowskite. It was accompanied by deposition of minor amounts of pyrite, marcasite, galena, clausthalite, sphalerite, chalcocite, native copper and niccolite, plus euhedral quartz, calcite, dolomite, siderite, hematite, Mg-chlorite, dravite, adularia, and carbon buttons. The chloritic alteration halo, increasing in intensity with clay, silica and dravite proximal to the orebody, is typical of the basement-hosted unconformity-associated deposits. Secondary uranium mineralization includes kasolite, massuyite, wölsendorfite, boltwoodite, and uranophane. Geochemically the mineralization is essentially monometallic; despite the occasional presence of ore mineral of other metals, there are only very minor concentrations of these metals, such as Ni, As, Co, and Se.
Links to other databases: SMDI; Key value: 1713
GSC U-Th File (Prasad); Key value: 2657
References:
Babcock, M. R.; Ward, D.; Clark, G. W.; Milde, W. W.; Phillips, R. L. J.; Anderchek, D. S., 1988
The Rabbit Lake Story: Eldorado Resources Limited (a Wholly Owned Subsidiary of Eldorado Nuclear Limited)
Report, Presented at the 90th Annual General Meeting, Canadian Institute of Mining and Metallurgy, Edmonton, Alberta, May 1988, 48 p..

Bennett, R. W., 2002
Geological Atlas of Saskatchewan, Version 5 (2002)
Government of Saskatchewan, CD-ROM

Clark, L. A.; Burrill, G. H. R., 1981
Unconformity-related Uranium deposits, Athabasca Area, Saskatchewan and East Alligator Rivers area, Northern Territory, Australia
Bulletin of the Canadian Institute of Mining and Metallurgy, Volume 74, p. 63 - 72

Cumming, G. L.; Rimsaite, J., 1979
Isotopic Studies of Lead-depleted Pitchblende, Secondary Radioactive Minerals, and Sulphides from the Rabbit Lake Uranium Deposit, Saskatchewan
Canadian Journal of Earth Sciences, Volume 16, p. 1702 - 1715

Cumming, G. L.; Krstic, D., 1992
The Age of Unconformity-Related Uranium Mineralization in the Athabasca Basin, Northern Saskatchewan
Canadian Journal of Earth Sciences, Volume 29, p. 1623 - 1639

Gandhi, S. S., 1995
An Overview of the Exploration History and Genesis of Proterozoic Uranium Deposits in the Canadian Shield
Exploration and Research for Atomic Minerals, Department of Atomic Energy, India, Volume 8, p. 1 - 48

Heine, T. H., 1986
The Geology of the Rabbit Lake Uranium Deposit, Saskatchewan
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. 134 - 143

Hoeve, J; Sibbald, T. I. I., 1978
On the Genesis of Rabbit Lake and Other Unconformity-type Uranium Deposits in Northern Saskatchewan
Economic Geology, Volume 73, p. 1450 - 1473

Hoeve, J.; Quirt, D., 1987
A Stationary Redox Front as a Critical Factor in the Formation of High-Grade, Unconformity Type Uranium Ores in the Athabasca Basin, Saskatchewan, Canada
Bulletin de Mineralogie, Volume 110, p. 157 - 171

Hoeve, J.; Quirt, D., 1989
A Common Diagenetic-Hydrothermal Origin for Unconformity-type Uranium and Stratiform Copper Deposits
In Sediment-Hosted Stratiform Copper Deposits, Edited by Boyle, R. W.; Brown, A. C.; Jefferson, C. W.; Jowett, E. C.; Kirkham, R. V., Special Paper, Geological Association of Canada, Geological Association of Canada, 36, p. 151 - 172

Knipping, H. D., 1974
The Concepts of Supergene versus Hypogene Emplacement of Uranium at Rabbit Lake, Saskatchewan, Canada
In Formation of Uranium Deposits: Proceedings of a Symposium, Athens, 6-10 May, 1974, Edited by Anonymous, Proceedings, International Atomic Energy Agency, Vienna, International Atomic Energy Agency, Vienna, p. 531 - 548

Langford, F. F., 1978
Origin of Unconformity-type Pitchblende Deposits in the Athabasca Basin of Saskatchewan
Chapter 21, Section E. Deposits in Northern Saskatchewan, In Short Course in Uranium Deposits: Their Mineralogy and Origin, Edited by Kimberley, M. M., Short Course Handbook, Mineralogical Association of Canada, University of Toronto Press, Volume 3, 521 p., p. 485 - 499

Rimsaite, J., 1978
Application of Mineralogy to the Study of Multistage Uranium Mineralization in Remobilized Uranium Deposits, Saskatchewan
Chapter 17, Section E. Deposits in Northern Saskatchewan, In Short Course in Uranium Deposits: Their Mineralogy and Origin, Edited by Kimberley, M. M., Short Course Handbook, Mineralogical Association of Canada, University of Toronto Press, Volume 3, 521 p., p. 403 - 430

Ruzicka, V., 1986
Uranium Deposits in the Rabbit Lake - Collins Bay Area, Saskatchewan
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. 144 - 154

Saskatchewan Geological Survey, 2003
Geology, and Mineral and Petroleum Resources of Saskatchewan
Miscellaneous Report, Saskatchewan Industry and Resources, Publication code 2003-7, 173 p., 4 maps.

Saskatchewan Industry and Resources, 2001
Saskatchewan Mineral Deposits Index
Government of Saskatchewan, Geological Atlas of Saskatchewan, Internet

Thomas, D. J.; Mathews, R. B.; Sopuck, V., 2000
Athabasca Basin (Canada) - Unconformity-type Uranium Deposits: Exploration Model, Current Mine Development and Exploration Directions
In Geology and Ore Deposits 2000: the Great Basin and Beyond; May 15 - 18, 2000 Symposium Proceedings (CD-ROM), Edited by Cluer, J. K.; Price, J. G.; Struhsacker, E. M.; Hardyman, R. F.; Morris, C. L., Symposium Proceedings, Geological Society of Nevada, Geological Society of Nevada, Reno, Nevada, 647 p., p. 103 - 126

Tremblay, L. P., 1978
Geologic Setting of the Beaverlodge-type of Vein-Uranium Deposit and its Comparison to that of the Unconformity-type
Chapter 18, Section E, Section Deposits in Northern Saskatchewan, In Short Course in Uranium Deposits: Their Mineralogy and Origin, Edited by Kimberley, M. M., Short Course Handbook, Mineralogical Association of Canada, University of Toronto Press, Volume 3, 521 p., p. 351 - 456

Tremblay, L. P., 1982
Geology of the Uranium Deposits Related to the Sub-Athabasca Unconformity
Paper, Geological Survey of Canada, Publication code 81-20, 56 p..

Ward, D. M., 1989
Rabbit Lake Project - History of Exploration and General Geology
Bulletin of the Canadian Institute of Mining and Metallurgy, Volume 82, p. 40 - 48

Production data: Report period: from 1975-06-10 until 1984-05; 5.84 million metric tons ore; Provisional entry?: yes; Yearly or summary?: S
Grade-commodity information:U: 0.27 percent
weight-commodity information:U: 15,769 metric ton
Reference: Ward, D. M., 1989: Rabbit Lake Project - History of Exploration and General Geology; Bulletin of the Canadian Institute of Mining and Metallurgy, Volume 82, p. 40 - 48
Percent weights allocated to deposit: 0.0%
Associated mine(s): Rabbit Lake Uranium Mine (40001)

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