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


DEPNO COUNTRY LOCATION ALLNAMES COMMODITIES
40044 Canada (Nunavut) 64.20.04 N -- 097.53.46 W Andrew Lake Deposit; Southwest Grid 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): Andrew Lake Deposit (occurrence name); Southwest Grid (occurrence name)
Political location(s): Canada; Province or state: Nunavut; Nearest community: Baker Lake settlement (91 km 270°)
NTS map data: 066A05 (Judge Sissons Lake)
Deposit clan (type): Unconformity-associated
Deposit (sub) types: Unconformity-associated - Proterozoic - clay-bound; mineralization in lenses along gently dipping metasiltsone and phyllonite cut by granitic dykes, more than 200 m below sub-Thelon unconformity; accompanied by clay alteration but not restricted to it; Reference: Wallenberg, P., 1994: Update on the Uranium Exploration in the Thelon Basin; In Exploration Overview 1994, Edited by Goff, S. P., Annual Exploration Overview, Department of Indian and Northern Affairs, Canada, Department of Indian and Northern Affairs, Yellowknife, Canada, p. 154 - 155
Deposit status: advanced prospect; Size category: large; Status comments: 3.575 Mt
Geologic province: Churchill - Rae Craton
Geologic subprovince: Amer Fold Belt
Geologic district: Eastern Thelon Basin
Deposit object located: drill hole
Commodities: U
Mineralization styles: vein (mineralization zone); aggregates (mineralization zone); disseminated (mineralization zone)
Geological ages: Late Paleoproterozoic (host rocks)
Middle Mesoproterozoic (mineralization)
Tectonic setting: continental marginal deformation zone-fold belt; transpressive; Formal name: Amer Fold Belt (host rocks)
continental basin-unconformity; stable; Formal name: Thelon Paleosol (host rocks)
continental fault-controlled volcano-sedimentary basins-grabens; divergent; Formal name: Dubawnt Group (country rocks)
continental basin-intracratonic; stable; Formal name: Thelon Formation (country rocks)
Coincident features: strata-bound (the mineralized main and subsidiary lenses are subparallel to the bedding and foliation in the host metasedimentary beds, which dip gently to the east); Coincident feature name: Phyllonite-Metasiltstones
breccia(s) (cataclastic zone; a few metre thick quartz breccia separates the Upper lens in phyllonites and granite from the Lower lens in metasiltstone; it dips g); Coincident feature name: quartz breccia zone
fault(s) (the fault dips 70° to the SE and is located at the north end of New Southern lens; it is regarded as a subsidiary fracture of the Sissons Lake fault); Coincident feature name: northeast-trending cross fault
lithological contact(s) (Thelon Formation is eroded in the deposit area; proximity to the unconformity indicated by effects of lateritic paleoweathering in its basement rocks); Coincident feature name: Sub-Thelon unconformity
paleoregolith (paleoweathered boundary of basement with unconformably overlying siliciclastic strata); Coincident feature name: Thelon Paleosol
Regional tectonic structure: fault (fault-controlled 20 km linear trend hosting 7 uranium deposits, striking NE and gently convex to the NW, between the Thelon and Sissons Lake faults) Tectonic structure name: Kiggavik Trend
fault (NE-trending fault intersecting the major ENE-trending Sissons Lake fault and offsets it sinistrally, and hosts the Andrew Lake and End Grid deposits) Tectonic structure name: Andrew Lake fault
Host rocks: (1) metamorphic; metasedimentary schist (host of the upper lens located at 200 m depth); Depositional setting: platform-shelf; Metamorphic grade: greenschist - upper; Component: mineralization zone
External host rock forms:thin to thick bedded
Host rock protoliths:siltstone-mudstone-shale (probably equivalent of the Early Paleoproterozoic Lower Hurwitz Group to the south deposited on the Rae craton); Host rock protolith name: Phyllonite (mylonite?)
Internal host rock structures:schistose
Individual lithologies:metasiltstone (schistosity suggests a shear zone at low angle to the bedding that dips gently to the ESE; includes a banded cherty iron horizon above the upper lens)

(2) metamorphic; metasedimentary schist (host of the lower lens located at 250 m depth); Depositional setting: platform-shelf; Metamorphic grade: greenschist - upper; Component: mineralization zone
External host rock forms:thin to thick bedded
Host rock protoliths:sandstone-siltstone-shale (probably equivalent of the Early Paleoproterozoic Lower Hurwitz Group to the south deposited on the Rae craton); Host rock protolith name: Drab Grey Gneiss
Internal host rock structures:medium to coarse grained; bedding well preserved
Individual lithologies:metasiltstone (somewhat coarser and more siliceous with better bedded character than the metasiltstone above, separated by a thin zone of granite and quartz breccia)

(3) metamorphic; metasedimentary schist (up to 100 m thick; hosts top part of the upper lens); Depositional setting: platform-shelf; Metamorphic grade: greenschist - upper; Component: mineralization zone
External host rock forms:thick bedded
Host rock protoliths:sandstone wacke and arkose (gentle dip toward the End Grid 2 km to the NE where the metasiltstones are more than 500 m thick and correlate with those beneath the greywacke-arkose); Host rock protolith name: Metagreywacke and meta-arkose
Individual lithologies:metagreywacke (interlayered mafic and felsic quartzo-feldspathic gneisses)
meta-arkose

(4) intrusive; granite suite (dykes of granite and syenite; affected by clay alteration); Depositional setting: hypabyssal; Metamorphic grade: unmetamorphosed; Component: mineralization zone
External host rock forms:dyke
Host rock protoliths:granitic and syenitic dykes (offshoots of a differentiating granitic pluton related to the end stage of Husdsonian orogeny to the south); Host rock protolith name: Late Paleoproterozoic Granite
Internal host rock structures:medium grained, massive
Individual lithologies:granite (the dykes are apparently different phases of the same granitic magmatism and predate uranium mineralization)
syenite

(5) surficial; laterite (clay alteration at the upper mineralized zone); Host series: paleoregolith; Depositional setting: subaerial; Metamorphic grade: unmetamorphosed; Component: regional alteration
External host rock forms:lateritic profile
paleoregolith
Host rock protoliths:metasedimentary and granitic rocks (the sub-Thelon weathered zone is eorded at the deposit, but its extension deeper along fault zones may be represented by hematitic and clay alteration); Host rock protolith name: Thelon Paleosol
Internal host rock structures:weathered fragile mass
Individual lithologies:laterite (the clay alteration and hematization are not seen in the lower lens; hence their genetic relation with the uranium mineralization is ambiguous)
Country rocks: (1) paragneiss-orthogneiss; (older paragneisses SW of the deposit); Country rock name: Archean Basement Complex; Metamorphic grade: amphibolite
Country rock protoliths:platform-shelf sediments (highly deformed and metamorphosed Archean supracrustal sequence of the Rae craton, associated with mafic and felsic orthogneisses); Country rock protolith name: Archean Basement Complex
Individual lithologies:quartzofeldspathic and mafic gneiss (foliated and schistose biotite and/or hornblende bearing felsic gneisses, may include metavolanic rocks; in part migmatized)

(2) meta-arkose & metapelite; (Paleoproterozoic sedimentary sequence; informal name); Country rock name: Judge Sissons Lake sequence; Metamorphic grade: amphibolite - lower
Country rock protoliths:feldspathic wackes, pelites (probably equivalent of the Lower Hurwitz Group to the south deposited on the Rae craton before intrusion of gabbro sills at 2110 Ma ); Country rock protolith name: Judge Sissons Lake sequence
Individual lithologies:meta-arkoses and metapelites (mainly drab green sulphide-bearing biotite-muscovite feldspathic wackes; metapelites and metasemipelites with minor lean oxide facies iron formation)

(3) orthoquartzite; (overlies the feldspathic wacke strata); Country rock name: Amer Group equivalent; Metamorphic grade: greenschist - upper
Country rock protoliths:supermature sandstone (similar to the basal orthoquartzite of the late Paleoproterozoic Amer Group to the north and northeast; possible unconformity with feldspathic wackes ); Country rock protolith name: Amer Group equivalent
Individual lithologies:orthoquartzite (scattered outcrops in the area 10 km to the NNE and NE of the deposit; comformable with the meta-pelite and meta-arkose; affected by paleoweathering)

(4) granite; (intrusions in the metasedimentary strata); Country rock name: Hudsonian Granites; Metamorphic grade: unmetamorphosed
Country rock protoliths:granite-granodiorite (intrusive into metasediments; probably equivalent of Hudsonian granites emplaced during 1860-1760 Ma: includes a fluorite granite stock at the deposit); Country rock protolith name: Hudsonian Granites
Individual lithologies:granite-granodiorite-monzonite (massive to gneissic; includes some diorite, syenite and porphyries of uncertain age)

(5) clastic sediments and potassic volcanics; (sedimentary-volcanic sequence deposited in the post-Hudsonian fault-controlled Baker Lake basin); Country rock name: Dubawnt Group; Metamorphic grade: unmetamorphosed
Country rock protoliths:clastic red beds & K-rich volcanics (basal red conglomerate-arkose-siltstone beds; subaerial potassic mafic-intermediate flows; upper dacite-rhyolite flows; related subvolcanic intrusions); Country rock protolith name: Dubawnt Group
Individual lithologies:clastic red beds & K-rich volcanics (deposited 1.84-1.75 Ga; alluvial fan-braided stream sediments; extensive subaerial trachytic basalt and andesite, trachyte; rhyolite with minor dacite)

(6) paleo-regolith; (lateritic weathering); Country rock name: Thelon Paleosol; Metamorphic grade: unmetamorphosed
Country rock protoliths:gneisses, granites and supracrustal strata (profile up to 50 m thick; deeper along faults; weathering effects vary on different rock types); Country rock protolith name: sub-Athabasca basement
Individual lithologies:Lateritic (hematization in the upper part of weathered zone; locally bleached; kaolinite is abundant in the zone and occurs as clay-clasts in the sandstone above)

(7) conglomerate-sandstone; (siliciclastic sediments; undeformed; present area 85000 sq km and thickness 1.3 km); Country rock name: Thelon Formation; Metamorphic grade: unmetamorphosed
Country rock protoliths:conglomerate-pebbly sandstone-siltstone (basal conglomerate unit with pebbly sandstone and siltstone beds; succeeded by mature sandstone, quartz arenite and lithic subarenite-siltstone units); Country rock protolith name: Thelon Formation
Individual lithologies:conglomerate-sandstone-siltstone

(8) diabase dyke; (northwest-trending, vertical or very steep dykes); Country rock name: Mackenzie diabase dyke swarm; Metamorphic grade: unmetamorphosed
Country rock protoliths:gabbroic magma (part of the largest dyke swarm in the world, related to the 1.27 Ga Mackenzie magmatic events); Country rock protolith name: Mackenzie diabase dyke swarm
Individual lithologies:diabase (medium to coarse grained gabbro-quartz gabbro; chilled at dyke margins; unaltered or little altered)
Metallogenic signatures: U
Alteration signatures: sericite/muscovite alteration: sericite-illite plus kaolinite; 'white' alteration; What was altered: feldspars and mica in host rocks; Component: alteration halo
oxidation: hematitic; red colouration; local development of r; What was altered: mafic silicates and iron oxides in host rocks; Component: alteration halo
silicification: deposition of secondary quartz; What was altered: quartz breccia; Component: alteration halo
oxidation: secondary yellow uranium minerals; What was altered: high grade zones; Component: mineralization zone
Mineralogy: (alteration / mineralization zone): hematite, clay minerals, chlorite
(mineralization / mineralization zone): boltwoodite
(mineralization - disseminated / mineralization zone): pitchblende
(mineralization - vein / mineralization zone): pitchblende
Deposit shape: stacked lenses
Deposit dimensions:length: 450 metre
width: 180 metre
height: 100 metre
Qualified comments: (Applies to: discovery and development) The deposit was discovered in 1988 by Urangesseschaft Canada Ltd. during exploratory drilling on a gravity anomaly and related geophysical anomalies. Further drilling over the next two years confirmed it as a deposit. By 1991 drilling done at 50 m spacing had revealed two lenses and a high grade intersection to the south. In 1992 Cogema Resources Inc., now Areva Resources Canada Inc., acquired 70 % interest in, and became operator of the properties held by Urangesellschaft Canada Ltd. By 1993 drill holes 25 m apart defined three gently dipping lenses that comprise the deposit: the Upper and New Southern lenses at 200 m depth and the Lower lens at 250 m depth. The Upper lens is the most northerly, and its outline overlaps partially the projection of the lower lens in plan view. All lenses dip gently to the northeast.

(Applies to: mineralization) Mineralized lenses are parallel to or at low angle to the bedding and foliation; the upper lens is entirely in clay-altered and hematized phyllonite and granite. The lower lens is well below the sub-Thelon unconformity, and lacks characteristic alteration of Unconformity-associated deposits. This suggests either a special case or an earlier distinct mineralization. The deposit is comparable with the End Grid deposit 1 km to the NE in terms of the tonnage and grade, and also in the feature that the deeper part lacks the clay alteration and hematization seen in the shallower part.

(Applies to: reserve/resource descriptions) Drill indicated resources in the Upper, Lower and New Southern lenses: 1.361, 1.281 and 0.932 Mt averaging 0.648, 0.439 and 0.516 % U, respectively; combined grade: 0.539 % U at 0.20 % U cut-off grade.
Links to other databases: NUMIN; Key value: 066ASW0022
Geophysical-chemical signature: Signature type: Ground Gravity; Response type: positive (moderate)
References:
Bundrock, G., 1981
From Armchair Geology to a Deposit in a New Uranium Province
In Uranium Exploration Case Histories: Proceedings of an Advisory Group Meeting, Vienna, 26-29 November 1979, Edited by Anonymous, Proceedings Series (STI/PUB), International Atomic Energy Agency, Vienna, International Atomic Energy Agency, Vienna, 584, 407 p., p. 243 - 277

Cecile, M. P., 1973
Lithofacies Analysis of the Proterozoic Thelon Formation, Northwest Territories (including Computer Analysis of
M. Sc. Thesis, M. Sc. Thesis (unpublished), Carleton University, Ottawa, 119 p..

Fraser, J. A.; Donaldson, J. A.; Fahrig, W. A.; Tremblay, L. P., 1970
Helikian Basins and Geosynclines of the Northwestern Canadian Shield
In Symposium on the Basins and Geosynclines of the Canadian Shield, Edited by Baer, A. J., Paper, Geological Survey of Canada, 70-40, 265 p., p. 213 - 238

Fuchs, H.; Hilger, W.; Prosser, E., 1986
Geology and Exploration History of the Lone Gull Property
5, Section Other Helikian Unconformity-associated and Sedimentary-hosted Deposits, 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. 286 - 292

Fuchs, H. D.; Hilger, W., 1989
Kiggavik (Lone Gull): An Unconformity Related Uranium Deposit in the Thelon Basin, Northwest Territories, Canada
In Uranium Resources and Geology of North America, Edited by Anonymous, TECDOC, International Atomic Energy Agency, Vienna, International Atomic Energy Agency, Vienna, Austria, 500, 529 p., p. 429 - 454

Gall, Q., 1994
The Proterozoic Thelon Paleosol, Northwest Territories, Canada
Precambrian Research, Volume 68, p. 115 - 137

Gandhi, S. S., 1989
Geology and Uranium Potential of the Thelon Basin and Adjacent Basement in Comparison with the Athabasca Basin Region
In Uranium Resources and Geology of North America, Edited by Anonymous, TECDOC, International Atomic Energy Agency, Vienna, International Atomic Energy Agency, Vienna, Austria, 500, 529 p., p. 411 - 428

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

Goff, S. P. Editor(s)), 1994
Exploration Overview 1994
Annual Exploration Overview, Department of Indian and Northern Affairs, Canada, Department of Indian and Northern Affairs, Yellowknife, Canada

Hasegawa, K.; Davidson, G. I.; Wallenberg, P.; Iida, Y., 1990
Geophysical Exploration for Unconformity-related Uranium Deposits in the Northeastern Part of Thelon Basin, Northwest Territories, Canada
Mining Geology, Volume 40, p. 83 - 95

Kyser, K.; Hiatt, E.; Renac, C.; Durocher, K.; Holk, G; Deckart, K., 2000
Diagenetic Fluids in Paleo- and Meso-Proterozoic Sedimentary Basins and Their Implications for Long Protracted Fluid Histories
10, In Fluids and Basin Evolution, Edited by Kyser, K., Short Course Series Volume, The Mineralogical Association of Canada, The Mineralogical Association of Canada, 28, 262 p., p. 225 - 262

LeCheminant, A. N.; Heaman, L. M., 1989
Mackenzie Igneous Events, Canada: Middle Proterozoic Hotspot Magmatism Associated with Ocean Opening
Earth and Planetary Science Letters, Volume 96, p. 38

Miller, A. R.; LeCheminant, A. N., 1985
Geology and Uranium Metallogeny of Proterozoic Supracrustal Successions, Central District of Keewatin, N.W. T. with Comparisons to Northern Saskatchewan
Chapter 3, Section Other Canadian Deposits, In Geology of Uranium Deposits, Edited by Sibbald, T. I. I.; Petruk, W., Special Volume, The Canadian Institute of Mining and Metallurgy, The Canadian Institute of Mining and Metallurgy, 32, 268 p., p. 167 - 185

Miller, A. R.; Cumming, G. L.; Krstic, D., 1989
U-Pb, Pb-Pb, and K-Ar Isotopic Study and Petrography of Uraniferous Phosphate-bearing Rocks in the Thelon Formation, Dubawnt Group, Northwest Territories, Canada
Canadian Journal of Earth Sciences, Volume 26, p. 867 - 880

Patterson, J. G., 1986
The Amer Belt: Remnant of an Aphebian Foreland Fold and Thrust Belt
Canadian Journal of Earth Sciences, Volume 23, p. 2012 - 2023

Ross, G. M., 2000
Proterozoic Stratigraphy of Western Canada: A Short Review
9, In Fluids and Basin Evolution, Edited by Kyser, K., Short Course Series Volume, The Mineralogical Association of Canada, The Mineralogical Association of Canada, 28, 262 p., p. 211 - 224

Wallenberg, P., 1994
Update on the Uranium Exploration in the Thelon Basin
In Exploration Overview 1994, Edited by Goff, S. P., Annual Exploration Overview, Department of Indian and Northern Affairs, Canada, Department of Indian and Northern Affairs, Yellowknife, Canada, p. 154 - 155

Wright, G. M., 1967
Geology of the Southeastern Barren Grounds (350)
Memoir, Geological Survey of Canada, Geological Survey of Canada, Publication code 350, 91 p., 1 maps.

Resource data:
Disclaimer - Reserves/Resource Data

Her Majesty the Queen in Right of Canada, represented by the Minister of Natural Resources (NRCan) does not warrant or guarantee the accuracy, completeness or fitness for any purpose of Reserve and Resource information (Data) contained in this database, including whether the Data is compliant with any securities regulations or standards, and NRCan does not assume any liability with respect to any damage or loss incurred as a result of the use made of the Data.

Resource and reserve figures are historical in nature. The Data source provided with each set of figures should be cited if the Data are re-reported.

Estimate date: 1994; 3.575 million metric tons ore; Combined with production?: no; Provisional entry?: no; Resource category: inferred
Grade-commodity information:U: 0.539 percent
weight-commodity information:U: 19,269 metric ton
Reference: Wallenberg, P., 1994: Update on the Uranium Exploration in the Thelon Basin; In Exploration Overview 1994, Edited by Goff, S. P., Annual Exploration Overview, Department of Indian and Northern Affairs, Canada, Department of Indian and Northern Affairs, Yellowknife, Canada, p. 154 - 155
Percent weights allocated to deposit: 100.0%

Generated 2007-03-02 2:35:34 PM with GQuery -- 3.7 ADO (3.19/3.20/3.21 -- 2006-02-24)
GlobalDB System, Geological Survey of Canada, Natural Resources Canada