Saskatchewan-Descriptive-Mineral-Deposit-Models 2011

19 48

Although the Ministry of Energy and Resources has

exercised all reasonable care in the compilation,

interpretation, and production of this report, it is not

possible to ensure total accuracy, and all persons who rely

on the information contained herein do so at their own

risk. The Ministry of Energy and Resources and the

Government of Saskatchewan do not accept liability for

errors, omissions or inaccuracies that may be included in,

or derived from, this report.

Parts of this publication may be quoted if credit is given.

It is recommended that reference to this report be made as

follows:

Rogers, M.C. (2011): Saskatchewan descriptive mineral

deposit models; Sask. Ministry of Energy and

Resources, Open File Rep. 2011-57, URL

, 112p.

Front Cover: Seabee gold mine headframe, northern

Saskatchewan (photograph courtesy of Claude Resources

Inc.).

Sask. Ministry of Energy and Resources ii Open File Report 2011-57

Table of Contents iii Introduction 1 Acknowledgements 1

A. Metallic Mineral and Gem Deposit Types

1.Athabasca Basin Unconformity-associated Uranium ± Polymetallic 2

2.Beaverlodge-type Uranium ± Polymetallic 5

3.Unconformity-associated Copper-Silver ± Polymetallic 7

4.Sedimentary-hosted Copper ± Polymetallic 9

5.Sandstone-hosted Uranium 12

6.Sandstone-hosted Lead-Zinc-(Silver) 14

7.Placer and Paleoplacer 16

8.Structurally-controlled Mesothermal Lode Gold 18

9.Stratabound Gold 21

10.Epithermal Gold ± (Silver–Base Metals) – Low-Sulphidation Subtype23

11.Calc-Alkaline Porphyry Copper-Molybdenum-Gold-Tungsten 26

12.Volcanic-associated Massive Sulphide 29

13.Banded Iron Formation 32

14.Sedimentary-hosted Manganese 34

15.Sedimentary-Exhalative Massive Sulphide Zinc-Lead-(Silver) 36

16.Mississippi Valley–type Lead-Zinc 39

17.Volcanic-hosted Copper 42

18.Mafic-Ultramafic Intrusion-hosted Magmatic Nickel-Copper-(Platinum Group Element) 44

19.Peter Lake Domain Mafic-(Ultramafic) Intrusion-hosted Magmatic Platinum Group Element 47

20.Komatiite-hosted Nickel-(Copper-Platinum Group Element) 49

21.Gabbro-Anorthosite–hosted Iron-Titanium-(Vanadium-Chromium-Phosphorus) 51

22.Hoidas Lake–type Rare Earth Element 53

23.Fort à la Corne Kimberlite-hosted Diamond 55

24.Pegmatite-hosted Beryl-(Rare Metal) 57

25.Pegmatite-hosted Uranium-(Thorium-Molybdenum-Rare Earth Element) 59

B. Industrial Mineral Deposit Types

1.Saskatchewan Potash 61

2.Saskatchewan Halite (Salt) 63

3.Sodium (and Magnesium) Sulphate 65

4.Saskatchewan Magnesium 67

5.Sedimentary-hosted Phosphate 69

6.High-purity Limestone 71

7.Saskatchewan Coal 73

8.Whitemud Formation Kaolinite 75

9.Saskatchewan Bentonite 77 Sask. Ministry of Energy and Resources iii Open File Report 2011-57

10.Silica Sand 79

11.Sand and Gravel Aggregates 81

12.Sedimentary-hosted Flake Graphite 83

13.Nepheline Syenite 85

14.Building Stone 87

15.Saskatchewan Peat 89

C. Petroleum Deposit Types

1.Saskatchewan Oil Shale 91

2.Saskatchewan Oil Sand 93 Tables

1.Summary of the Interpreted Mineral Deposit Types in the Precambrian Rocks of Northern 95

Saskatchewan

2.Interpreted Precambrian Metallogenic Relationships in Northern Saskatchewan 98

3.Summary of the Interpreted Mineral Deposit Types in the Phanerozoic Rocks of Southern 106

Saskatchewan

4.Stratigraphic Relationships of the Interpreted Mineral Deposit Types in the Phanerozoic Rocks 109

of Southern Saskatchewan

Figures

1.Mineral Resource Map of Saskatchewan 111

2.Stratigraphic Correlation Chart 112

Sask. Ministry of Energy and Resources iv Open File Report 2011-57

Sask. Ministry of Energy and Resources 1 Open File Report 2011-57 Introduction

Synoptic descriptive mineral deposit models for the metallic, industrial, and gem mineral deposit types, and two of the petroleum deposit types, that occur in Saskatchewan are presented. The purpose of the models is to document the key characteristics of each deposit type as an initial reference. They are not meant to be an exhaustive description of each deposit type. Selected bibliographies are included with each model as additional information sources. Summary tables are also included as a quick reference source. The general format follows that used in Cox and Singer (1986) 1These models are intended as an initial reference source on mineral deposit types primarily as an aid to mineral exploration in the province. The models will provide a standard framework for use by the Saskatchewan Geological Survey in its publications. They will also be used by Survey personnel when conducting mineral resource assessments that are used in regional land use planning. The general public may also find the models of interest, however they were written at a technical level for geoscience professionals.

by the United States Geological Survey, but with more extensive descriptions and some additional topics, as the purposes for the models differs. The models are oriented towards the geological environment of Saskatchewan, and in many cases are based entirely on Saskatchewan mineral deposits and settings. They are viewed as a “work-in-progress” and will be revised as new information becomes available.

Files from the Saskatchewan Mineral Deposit Index (SMDI) are referenced extensively in these models. The files can be accessed at d0e4fe06f524ccbff0218498.sk.ca/SMDI . Stated reserve, resource, and production figures in the models are current to the end of April, 2011.

Acknowledgements

The many reviewers of one or more of the models are thanked for their time, insightful comments, and information. These include three external reviewers, Charles Jefferson (Geological Survey of Canada), Shawn Harvey (Shore Gold Inc.) and Lynn Kelley (Whitemud Resources Inc.). Survey geologists who did reviews include Ken Ashton, Jason Berenyi, Sean Bosman, Janet Campbell, Colin Card, Charles Harper, Dan Kohlruss, Dave MacDougall, Ralf Maxeiner, Ryan Morelli, and Melinda Yurkowski.

1 Cox, D.P. and Singer, D.A. (1986): Mineral deposit models; United States Geological Survey, Bulletin 1693, 379p

A. Metallic Mineral and Gem Deposit Types

Model Number A-1: Athabasca Basin Unconformity-associated Uranium ± Polymetallic

Synonyms: Unconformity-type; unconformity-related.

Concise Description: Structurally-controlled uraninite ± polymetallic minerals spatially located at, above, and/or below the unconformity between Archean to Paleoproterozoic basement rocks and Late Paleoproterozoic to Mesoproterozoic sedimentary rocks of the Athabasca Basin.

Geological Environment

Host Rock Types: Flat-lying, oxidized, permeable, fluviatile siliciclastic conglomerate, sandstone, and minor lacustrine mudstone in the two basal sequences of the Athabasca Group, which rest unconformably on basement rocks comprising metamorphosed Archean felsic gneiss, Archean to Paleoproterozoic supracrustal rocks, and Paleoproterozoic intrusive rocks. Uranium deposits are spatially associated with the metasedimentary rocks of the Wollaston Domain and the transition between the Wollaston-Mudjatik domains in the eastern Athabasca Basin, especially graphitic metapelitic gneiss. In the western part of the Athabasca Basin similar metasedimentary rocks are structurally intercalated with granitoid gneiss of the Taltson magmatic zone. Metres to tens of metres of paleoweathered regolith characterize the unconformity assemblage. Basement rocks enriched in uranium such as granite, pegmatite, and leucosomes of paragneiss are common.

Rock Textures: Strongly foliated to gneissic basement rocks commonly transected by shear zones. Primary sedimentary features in the Athabasca Group are overprinted by dissolution and collapse breccia and/or silicification and brecciation by episodic, brittle faults in reactivated basement shear zones.

Ages of Host Rocks and Mineralization: Host rocks include both the ≤1.74 to ≤1.5 Ga Athabasca Group and the Paleoproterozoic to Archean basement rocks. Two main, protracted, hydrothermal ore-forming events were at 1600 to 1500 Ma and 1460 to 1350 Ma, with further remobilization at about 1176, 900, and 300 Ma.

Depositional Environment: Uranium-rich, “fertile”, granitic basement is considered a favourable original source of the uranium. Uranium and other elements were mobilized by paleoweathering before deposition of the Athabasca Gp. sedimentary rocks, and during diagenesis/epigenesis within the host rocks by oxidized, basinal, hydrothermal fluids. Deposition of the uranium was at the coincidence of the unconformity and structural and reduction traps. Local factors determined the main foci at, or generally within tens of metres above, and/or below the unconformity. Repeated structural reactivation over long time periods remobilized and further concentrated uranium at favourable sites.

Two main deposit compositions are: 1) monometallic: hosted by brittle faults in basement rocks; ore consists of uraninite in veins, breccia zones, and as replacement bodies; and 2) polymetallic: at or just above the unconformity; as semi-massive, sub-horizontal replacement bodies; with variable U, Ni, Co, and As, with trace to minor REE, Cu, Fe, PGE, Ag, Au, Mo, Pb. Zn, Mn, V, S, and Se. This includes the “perched” subtype.

Tectonic Setting: Intracratonic Late Paleoproterozoic to Mesoproterozoic sedimentary basin deposited on deformed and metamorphosed, peneplaned Archean to Paleoproterozoic basement rocks. Deposits are located in the vicinity of the unconformity. Faults have an important role in localizing mineralization, especially episodic, brittle reactivation (tens to hundreds of metres of displacement) of early ductile structures in the basement. Faults are commonly localized by graphitic metapelite units. Subsidiary splays to major structures are favourable. Cross faults, breccia zones, fracture zones and dilatant features are important. Paleotopographic features that predate and are synchronous with the Athabasca Group include paleovalleys and fault scarps. The paleovalleys are preferentially developed in recessive metapelites and are spatially related to shear zones/faults and deposits.

Associated Deposit Types: Beaverlodge-type epigenetic vein uranium ± polymetallic deposits predate the Athabasca Basin unconformity-associated deposits, but probably developed through similar processes at or near to the basal unconformity of the Martin group.

Deposit Description

Mineralogy: Principal ore minerals are uraninite and pitchblende; minor secondary uranium minerals that include coffinite; generally trace to minor pyrite, chalcopyrite, galena, sphalerite, arsenopyrite, pentlandite, nickeline, millerite, molybdenite, gersdorffite, brannerite, other Ni and Co-bearing sulphides and arsenides, native gold, silver, and selenium, selenides and Au, Bi, Ni, Pb and Pd tellurides. Nickel is a significant and potentially economic commodity in some deposits (e.g., Midwest, Key Lake). Monometallic (simple) and polymetallic (complex) end members.

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Textures and Styles of Mineralization: Usually medium to coarse-grained, crystalline uraninite and crystalline, botryoidal, spherulitic, radial and colloform pitchblende. Multiple stages of mineral development formed veins, semi-massive to massive breccia fillings, and disseminations; and orebodies that are tabular, cylindrical, irregular and pod like in form. Two end-member types: 1) dominantly basement-hosted, linear, fracture-controlled and breccia-hosted, disseminated to massive mineralization within brittle, moderately to steeply-dipping structural features (e.g., Key Lake); and 2) developed along the unconformity or immediately above it as clay-encased, semi-massive to massive, flattened, elongate pods and linear bodies with high-grade cores and lower-grade halos (e.g., Cigar Lake). Perched subset in overlying sedimentary rocks, usually as disseminated uraninite in sandstone adjacent to and within fracture and breccia zones, is a good indicator of an unconformity deposit at depth.

Alteration: 1) district scale: a) regional quartz cementation (Q1) and b) regional diagenetic dickite (kaolinite variety) with minor illite and chlorite predate ore deposition; c) large corridor of illite extends from Key Lake to Cigar Lake with subparallel zones of elevated chlorite and dravite; d) regional diagenesis of phosphate minerals such as fluorapatite and aluminum phosphatic sulphate took place at about the same time as pre-ore alteration, ~1650 Ma;

2) deposit scale: a) elevated illite content in the Athabasca Group and basement rocks in proximity to deposits;

b) chlorite and sudoite (Mg-rich chlorite); and c) dissolution of Q1 and related silicification (Q2). Two main alteration styles: a) Egress-type: developed mainly in the sandstones overlying deposits; two end-members: 1) illite and quartz dissolution and 2) kaolinite, dravite and peripheral silicification (Q2); b) ingress-type: basement-hosted deposits; narrow halos of alteration along the structures; grading inside out from illite ± sudoite to sudoite ± illite to Fe-Mg chlorite ± sudoite to fresh rock. Alteration above the deposit is patchy and difficult to connect to the deposit. Geological Ore Controls: 1) Late Paleoproterozoic to Mesoproterozoic intracratonic sedimentary basin development on peneplaned Archean to Paleoproterozoic basement rocks; 2) unconformity surface with paleoweathered regolith;

3) graphitic metapelite units in the basement; 4) ductile faults and other structurally complex features in the basement; 5) repeated brittle reactivations of the ductile faults during and after deposition of the Athabasca Group;

6) other features such as cross faults, breccia zones, fracture zones, and dilatant structures; 7) depletion of the Athabasca Group sedimentary rocks in U; 8) basement rocks enriched in U; and 9) long-lived oxidation/reduction boundaries.

Geochemical Signature: 1) surficial geochemical surveys for anomalous U (>3 ppm), K, B, and radon; 2) regional and local alteration halos of illite, dravite, chlorite (sudoite), silicification (Q2), and quartz dissolution located by sampling till and rock and with gamma-ray spectrometry; 3) short-wave infrared (SWIR) spectrometers to distinguish clay types in systematic samples of surface rock and drill core; 4) anomalous U in the Athabasca Group rocks in clay alteration halos; and 5) K2O/Al2O3 and MgO/Al2O3 ratios to delineate alteration.

Geophysical Signature: 1) radiometric (airborne and ground) to detect near-surface deposits and indirectly through surficial materials; and borehole direct surveying; 2) electromagnetic (airborne and ground) to detect graphitic faults; 3) airborne magnetics for indirectly mapping the basement geology; 4) audiomagnetotellurics (ground) to locate conductors and alteration zones based on resistivity contrasts; 5) gravity (airborne and ground) to detect low-density clay alteration zones and disaggregated rock or high-density silicified zones; and 6) seismic reflection to map out continuous structural features, especially fault offsets of the seismic reflector at the unconformity.

Examples (with grades and tonnages)

Thirty deposits in the Athabasca Basin contain a resource of 587 063 t U at an average grade of 1.97% U.

Examples of inpidual deposits include McArthur River: 1 017 000 t at 22.28% U (production and reserves); Rabbit Lake: 5 840 000 t at 0.27% U (mined); and Sue C Zone: 250 000 t at 4.5% U (mined). Figures are from Jefferson et al. (2007). NI 43-101 compliant Reserve and Resource figures for unmined deposits include Cigar Lake with Reserves of 558 300 t at 17.04% U3O8, Millenium with Resources of 684 000 t at 3.76% U3O8, and Shea Creek (Anne, Kianna, Colette) with Resources of 2 947 000 t grading 1.36% U3O8 (calculated from Sask. Ministry of Energy and Resources, 2010).

Selected Bibliography

Jefferson, C.W. and Delaney, G. (editors) (2007): EXTECH IV: Geology and Uranium EXploration TECHnology of the Proterozoic Athabasca Basin, Saskatchewan and Alberta; Geological Survey of Canada Bulletin 588;

Saskatchewan Geological Society Special Publication 18; Mineral Deposits Division, Geological Association of Canada Special Publication 4, 644p.

Jefferson, C.W., Thomas, D.J., Gandhi, S.S., Ramaekers, P., Delaney, G., Brisbin, D., Cutts, C., Portella, P., and Olson, R.A. (2007): Unconformity-associated uranium deposits of the Athabasca Basin, Saskatchewan, and Alberta; in Jefferson, C.W. and Delaney, G. (eds.), EXTECH IV: Geology and Uranium EXploration

TECHnology of the Proterozoic Athabasca Basin, Saskatchewan and Alberta, Geological Survey of Canada Bulletin 588; Saskatchewan Geological Society Special Publication 18; Mineral Deposits Division, Geological Association of Canada Special Publication 4, p23-68.

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Kyser, K. and Cuney, M. (2009): Chapter 8: Unconformity-related uranium deposits; in Cuney, M. and Kyser, K.

(eds.), Recent and Not-So-Recent Developments in Uranium Deposits and Implications for Exploration,

Mineralogical Association of Canada, Short Course Series, Volume 39, p161-219.

Ruzicka, V. (1995): Unconformity-type uranium deposits; in Kirkham, R.V., Sinclair, W.D., Thorpe, R.I., and Duke J.M. (eds.), Mineral Deposit Modeling, Geological Association of Canada Special Paper 40, p125-150. Saskatchewan Geological Survey (2003): Geology, and mineral and petroleum resources of Saskatchewan;

Saskatchewan Industry and Resources, Miscellaneous Report 2003-7, section p84-97.

Saskatchewan Ministry of Energy and Resources (2010): Saskatchewan exploration and development highlights 2010; Table 1, p6.

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Model Number A-2: Beaverlodge-type Uranium ± Polymetallic

Concise Description: Structurally-controlled uranium ± polymetallic mineralization spatially associated with the unconformity between Archean to Paleoproterozoic basement rocks and the younger Paleoproterozoic intracratonic basin sedimentary rocks of the Martin group.

Geological Environment

Host Rock Types: Primarily hosted by lower to upper amphibolite facies Precambrian basement rocks, but also by the unconformably overlying Paleoproterozoic Martin group, which consists of unmetamorphosed, oxidized, immature, basinal clastic sedimentary rocks interbedded with subordinate alkali basalts. The basement rocks include 3.0 and 2.3 Ga granitoids, 2.33 to 1.93 Ga Murmac Bay group and 1.93 Ga leucogranites. The largest deposits tend to occur in basement rocks with a high mafic mineral content such as amphibolite, chlorite-epidote and chlorite schists, and argillite. Graphitic pelite is a significant component. There is also a general spatial relationship between the major deposits and the Martin group. Basement rocks enriched in uranium such as granite, pegmatite, and paragneiss are potential source rocks.

Rock Textures: Foliated to gneissic basement rocks are commonly transected by faults and shear zones. Primary sedimentary features in the Martin group are overprinted by faults and fractures.

Ages of the Host Rocks and Mineralization: Host rocks include the Archean to Paleoproterozoic basement rocks and the ca. 1.82 Ga Martin group. The main hydrothermal, ore-forming event was at about 1.78 Ga, although several generations of pitchblende are present which indicate a number of subsequent events.

Depositional Environment: Mobilization of uranium and other elements by oxidized, basinal, hydrothermal fluids along the basement–Martin group unconformity with deposition at structural/reduction traps that occurred at, above, or below the unconformity. Uranium may have been largely sourced from basement granites that formed from crustal melting. Extensive early ductile deformation of basement rocks may have provided the ground preparation for access by hydrothermal fluids and mobilization of uranium. Periodic events occurred which led to remobilization and further concentration at favourable sites.

Tectonic Setting: Post-collisional, intracratonic Paleoproterozoic sedimentary basin(s) deposited on deformed and metamorphosed Archean to Paleoproterozoic basement rocks. Deposits are spatially associated with the unconformity. Deposits are structurally controlled and associated with three major fault sets: east, northeast, and northwest trending. Subsidiary splays to the major faults are favourable sites. Secondary features such as bends or warps, rock contacts, competency contrasts, sharp changes in the attitude of the wall rock, breccia zones, and shear zones are favourable. Strong association with D3 (northeast) and D4 (southeast) fracture sets.

Associated Deposit Types: Athabasca Basin unconformity-associated uranium ± polymetallic deposits postdate the Beaverlodge-type but probably developed through very similar processes. The generally larger sizes and higher grades of the Athabasca Basin deposits may reflect the influence of a much larger sedimentary basin and associated larger hydrothermal systems, and mineralizing processes that operated over a much longer period of time. Some different deposits north of Lake Athabasca such as the Nicholson Bay and Gunnar have historically been included in the Beaverlodge camp. The Nicholson Bay deposit is a nickel-rich, polymetallic, sheared vein system in the same geological setting as the other Beaverlodge deposits. The Gunnar deposit is hosted by desilicified granite and apparently at one time underlay the unconformity beneath the Athabasca Group (Trueman, 2006) which would indicate that it could be an Athabasca Basin unconformity-associated deposit type.

Deposit Description

Mineralogy: Simple and complex types. Simple type is more common and consists of: dominant pitchblende with coffinite, brannerite, nolanite, pyrite, chalcopyrite and galena (e.g., Eldorado’s Ace-Fay-Verna). Complex type is similar to those of the Athabasca Basin and consists of dominant pitchblende with coffinite, thucholite, sulphides, arsenides and selenides of nickel, cobalt, copper, lead and zinc; native gold, silver and platinum group metals (e.g., Nicholson Bay). Gangue minerals include hematite, calcite, chlorite, quartz and feldspar. Pyrobitumen coats pitchblende in a number of places.

Textures and Styles of Mineralization: Pitchblende occurs as epigenetic massive and colloform veins in joints and fractures, and as veins, stockworks or disseminations in breccia and shear zones. Most deposits, due to their fault control, are tabular to lensoidal in shape with large vertical and horizontal dimensions. The breccia-hosted Gunnar deposit is pipe like.

Alteration: Red, dusty, weak to pervasive hematite alteration is very common, with associated calcite and chlorite. Alteration is either disseminated through the vein material and wall rock or concentrated around the grain boundaries.

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Geological Ore Controls: 1) fertile U-bearing basement granites formed from crustal melting; 2) extensive ductile deformation of basement rocks; 3) Martin group intracratonic sedimentary basin development on Archean to Paleoproterozoic basement rocks; 4) unconformity surface; 5) major brittle fault sets; 6) subsidiary faults and secondary structural and contact features; 7) D3 and D4 fracture sets; 8) graphitic metapelites of the Murmac Bay group; and 9) oxidation/reduction boundaries (reduced sulphide-bearing and graphitic basement). Geochemical Signature: 1) surficial geochemical surveys for anomalous U and radon and 2) hematite, chlorite and calcite alteration and secondary supergene yellow, orange, and green uranium minerals located by prospecting and sampling rock and glacial till and float.

Geophysical Signature: 1) radiometric (airborne and ground) to detect near-surface deposits and indirectly through surficial materials and 2) electromagnetic (airborne and ground) to detect graphitic faults.

Examples (with grades and tonnages)

Sixteen deposits were mined in the period from 1953 to 1982, however, the Eldorado Ace-Fay-Verna (16 035 t U) and Gunnar (6892 t U) mines accounted for most of the production. Ore grades were generally in the range of 0.15 to 0.25% U but in places up to 0.4% U (Sask. Geological Survey, 2003)

Selected Bibliography

Ashton, K.E. (2009): Compilation bedrock geology, Tazin Lake, NTS area 74N; Saskatchewan Ministry of Energy and Resources, Report 246A, 1:250 000-scale map with marginal notes.

Beck, L.S. (1969): Uranium deposits of the Athabasca region, Saskatchewan; Saskatchewan Department of Mineral Resources, Report 126, 139p.

__________ (1986): General geology and uranium deposits of the Beaverlodge district; in Chapter 3, Hudsonian classical vein deposits; in Evans, E.L. (ed.), Uranium Deposits of Canada, Canadian Institute of Mining and Metallurgy, Special Volume 33, p85-94.

Saskatchewan Geological Survey (2003): Geology, and mineral and petroleum resources of Saskatchewan;

Saskatchewan Industry and Resources, Miscellaneous Report 2003-7, section p97-100.

Trueman, E.A.G. (2006): The Beaverlodge uranium district; in Quirt, D. (ed.), Uranium: Athabasca Deposits and Analogues, Canadian Institute of Mining and Metallurgy Field Conference, Saskatoon, Sept. 13 to 14, Abstracts Volume, p119-121.

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Model Number A-3: Unconformity-associated Copper-Silver ± Polymetallic

Concise Description: Structurally-controlled copper-silver ± polymetallic mineralization spatially associated with the unconformities between Archean to Paleoproterozoic basement rocks and younger Paleoproterozoic basin sedimentary rocks of the Thluicho Lake group and the Waugh Lake group.

Geological Environment

Host Rock Types: There are two settings that host this deposit type in the Rae Province in the northwest corner of the province. Both are spatially related to prominent unconformities between Archean to Paleoproterozoic basement rocks and overlying Paleoproterozoic, basinal, clastic sedimentary rocks. The basement rocks are dominated by orthogneisses with minor granitoid rocks and paragneisses. The principal setting is associated with the greenschist facies Thluicho Lake group of the Zemlak Domain which consists of an upward-fining sequence of basal conglomerate, feldspathic arenite, and argillite. More specifically, all of the showings are spatially associated with the lower, coarser-grained, more permeable Powder Lake formation strata (Yeo, 2005). The secondary setting is associated with the lower greenschist facies Waugh Lake group of the Taltson Domain which consists of sandstone, mudstone, and volcanic rocks. The principal hosts in both settings are the basement rocks but significant mineralization is also found in the overlying basal sedimentary rocks.

Rock Textures: Foliated and metamorphosed basement rocks are commonly cataclastized and mylonitized and affected by later brittle deformation. Primary sedimentary features in the Thluicho Lake and Waugh Lake groups may have been affected by deformation features such as faults, folds, and fracture zones.

Ages of the Host Rocks and Mineralization: Host rocks include the Archean to Paleoproterozoic basement rocks, the 1.93 to 1.82 Ga Thluicho Lake group, and the 2.02 to 1.97 Ga Waugh Lake group. The epigenetic mineralization therefore postdates the Thluicho Lake group (≤1.82 Ga) and the Waugh Lake group (≤1.97 Ga).

Depositional Environment: Mobilization of copper and other elements by oxidized, basinal, hydrothermal fluids along the basement–Thluicho Lake group and basement–Waugh Lake group unconformities with deposition at structural/reduction traps that occur at, above, or below the unconformities. Fluid movement appears to have been promoted by the coarser-grained, permeable, basal sedimentary strata. Diabase dyke swarms, dated at 1.82 Ga, in the vicinity of many of the Thluicho Lake group associated showings, may have had an influence on fluid flow and could have provided some of the heat for the hydrothermal processes.

Tectonic Setting: Paleoproterozoic sedimentary basins deposited on deformed and metamorphosed Archean to Paleoproterozoic basement rocks. The Thluicho Lake group is interpreted to have been deposited in an intermontane basin during the latter part of the Taltson Orogeny. The Waugh Lake group is interpreted to have been deposited in an intra-arc basin. Occurrences are spatially associated with the unconformities. The mineralization is structurally controlled and associated with gneissosity surfaces, and brittle fault and fracture zones.

Associated Deposit Types: The Beaverlodge-type uranium ± polymetallic deposit type is interpreted to have formed through similar processes associated with the basement–Martin group unconformity.

Deposit Description

Mineralogy: Principal chalcopyrite and pyrite, with common malachite and azurite, and local bornite, chalcocite, galena, niccolite, erythrite, annabergite, sphalerite, arsenopyrite, argentite, pitchblende, and native silver. Gangue minerals in fractures may include quartz, calcite, hematite, amphibole, and fluorite.

Textures and Styles of Mineralization: The mineralization is structurally controlled and occurs as disseminations along foliation planes, within fault-fracture zones, often as stockworks, and locally as breccia infill. Alteration: None reported, although the associated gangue minerals; quartz, calcite, and hematite are likely associated with local alteration.

Geological Ore Controls: 1) development of Thluicho Lake group and Waugh Lake group sedimentary basins on Archean to Paleoproterozoic basement rocks; 2) unconformity surfaces; 3) coarser-grained basal sedimentary strata;

4) multiple-stage structural deformation to form early structural/metamorphic fabrics and late open fault-fracture zones; 5) diabase dyke swarms; and 6) oxidation/reduction boundaries.

Geochemical Signature: Surficial geochemical surveys for anomalous Cu, Ag, and other elements. Geophysical Signature: 1) disseminated and fracture stockwork mineralization should be responsive to ground induced polarization/resistivity surveys and 2) airborne and ground magnetic and electromagnetic surveys may be a useful aid in the indirect mapping of bedrock and structures.

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Examples (with grades and tonnages)

Thluicho Lake group–associated locations include those in the Dianne Lake, Webb Lake, Bob Lake, Thluicho Lake, and Ellis Bay areas. Of these, the Dianne Lake locations are the best known with an estimated historical resource of 5 million tons grading 0.4 oz./ton Ag and 0.4% Cu (SMDI 1347).

Waugh Lake group–associated occurrences include SMDI locations 1519, 1527, and 1529.

Selected Bibliography

Ashton, K.E. and Hunter, R.C. (2003): Geology of the LeBlanc–Wellington lakes area, eastern Zemlak Domain, Rae Province (Uranium City Project); in Summary of Investigations 2003, Volume 2, Saskatchewan Geological Survey, Saskatchewan Industry and Resources, Miscellaneous Report 2003-4.2, CD-ROM, Paper A-1, 15p.

____________ (2004): Geology of the Camsell Portage area, southern Zemlak Domain, Rae Province (Uranium City Project); in Summary of Investigations 2004, Volume 2, Saskatchewan Geological Survey, Saskatchewan Industry and Resources, Miscellaneous Report 2004-4.2, CD-ROM, Paper A-8, 12p.

Coombe Geoconsultants Ltd. (1991): Base metals in Saskatchewan; Saskatchewan Energy and Mines, Open File Report 91-1, section p99-105.

Scott, B.T. (1978): The Geology of an area east of Thluicho Lake, Saskatchewan (part of NTS area 74N-11);

Saskatchewan Mineral Resources, Report 167, 51p.

__________ (1987): Geology and geochemistry of silver occurrences near Dianne Lake (NTS 74N-10), Saskatchewan; Saskatchewan Energy and Mines, Open File Report 87-1, 46p.

Yeo, G.M. (2005): Stratigraphy and metallogeny of the Paleoproterozoic Thluicho Lake group, northwestern Saskatchewan (NTS 74N-11); in Summary of Investigations 2005, Volume 2, Saskatchewan Geological

Survey, Saskatchewan Industry and Resources, Miscellaneous Report 2005-4.2, CD-ROM, Paper A-2, 20p.

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Model Number A-4: Sedimentary-hosted Copper ± Polymetallic

Synonyms: Stratiform copper; red-bed copper.

Concise Description: Stratabound to typically stratiform, disseminated copper sulphide ± (Co, Ag, Pb, Zn, U) mineralization hosted by reduced clastic and/or carbonate sedimentary rocks.

Geological Environment

Host Rock Types: Host rocks consist of reduced clastic and/or carbonate sedimentary rocks. These may include sandstone, siltstone, shale, conglomerate, limestone, dolomite and marl, which may contain carbonaceous or organic matter. Evaporites are commonly associated. The host sequence overlies, or lies within, a continental, oxidized, red-bed sequence of clastic sedimentary rocks. The basal reduced units of the host sequence are the favoured host rocks. In Saskatchewan, the principal locations occur in two areas, Pendleton Lake (Janice Lake) and Duddridge Lake, both within Wollaston Supergroup rocks of the Wollaston Domain. In the Pendleton Lake area, the occurrences are hosted by the lower Geikie River Group, within a “mottled” conglomerate and at its upper contact with arkosic, pelitic, and semi-pelitic rocks. All occurrences are within magnetite-bearing, reduced strata, in contrast to the associated hematitic, oxidized, red-bed sequences. The conglomerate has been interpreted as either a red-bed fanglomerate related to tectonic activity (Delaney et al., 1995), or as a pseudoconglomerate resulting from the metamorphism and deformation of oxidation-reduction mottling of arkoses (Coombe, 1994). Metamorphosed evaporites and carbonates (calc-silicates) are in stratigraphic proximity. At Duddridge Lake the locations are contained by reduced, carbonaceous arkose lenses within a hematitic arkose sequence in the upper portion of the Daly Lake Group.

Rock Textures: In general the host rocks are characterized by fluvial, lacustrine, and/or shallow marine sedimentary features. Well-developed bedding and crossbedding is typical. Fluvial channel conglomerates are common. Features such as algal mats, mud cracks, and scours may occur in the associated continental rocks.

Age of Host Rocks and Mineralization: On a world scale the age range is Paleoproterozoic to Tertiary. The mineralization is generally believed to be early diagenetic to postdiagenetic in origin, developing from the time when the sediments were unconsolidated to late-stage basin development. The larger deposits likely underwent prolonged periods of fluid flow and mineral deposition. In Saskatchewan the host Wollaston Supergroup and mineralization is Paleoproterozoic.

Depositional Environment: On a world scale there are two general environments, continental margin and fault-controlled, intracratonic troughs. These consist of fluvial, lacustrine, and/or shallow marine environments within low-paleolatitude, arid to semi-arid settings. They are characterized by a general setting in which reduced, marine sedimentary rocks were transgressive over oxidized (red-bed), continental, clastic sedimentary rocks. A second more restricted setting is one of reduced sedimentary basins developed within continental red-bed sequences.

In Saskatchewan the Daly Lake and Geikie River groups, that contain the mineralization, mainly consist of shallow marine metasedimentary rocks, which are interpreted to have been deposited in a foreland basin on the eastern edge of the Hearne Craton. This forms the upper portion of a rift–passive margin–foreland basin succession. Tectonic Setting: For the two general environments, the continental margin represents a stable tectonic environment, whereas the intracratonic trough is an active tectonic environment characterized by syndepositional normal faulting. At Pendleton Lake the occurrences are proximal to a zone of normal, listric faulting.

Associated Deposit Types: On a local scale associations may include the sandstone-hosted uranium, volcanic-hosted copper, and evaporite deposit types. On a regional scale there may be an association with the sandstone-hosted lead-zinc-(silver) and Mississippi Valley–type lead-zinc deposit types.

Deposit Description

Mineralogy: Principal minerals may include chalcopyrite, bornite, chalcocite, covellite, and pyrite. Subordinate minerals may include native copper, sphalerite, galena, carrolite, native silver, cobaltiferous pyrite, uraninite, and Ge minerals. A wide range of other minerals may also occur in trace to minor amounts. In the general model there is an upward and outward zonation from the core of the deposit as follows: from native copper to chalcocite to bornite to chalcopyrite to galena to sphalerite to pyrite.

In the Pendleton Lake area in Saskatchewan, the mineralogy consists of native copper and chalcocite with subordinate malachite, covellite, bornite, magnetite, and hematite. At Duddridge Lake the principal mineralogy consists of uraninite, chalcopyrite, bornite, and covellite, with minor galena, sphalerite, molybdenite, erythrite, and skutterudite.

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Textures and Styles of Mineralization: Stratabound to typically stratiform mineralization that occurs as fine-grained, disseminated, laminated to bedded sulphides. Locally larger clots, blebs, and veinlets may develop. Copper minerals may cluster around carbonaceous matter and replace pyrite. Deposits are commonly characterized by exceptional stratigraphic control. Generally tabular, lenticular to blanket-like deposits, although there are many examples of linear to channel-shaped bodies, particularly in restricted settings. Lateral extent may be on the order of kilometres to tens of kilometres.

Alteration: Zones of reduction (grey, white, green) in the underlying oxidized red-bed sedimentary rocks. Oxidized and bleached zones in the host sequence. The interpreted oxidation-reduction mottling of the “conglomerate” in the Pendleton Lake area could be a local example. In large basins there may be regional hematitic, sodic, potassic,

and/or magnesium alteration related to large-scale, prolonged, hydrothermal fluid flow.

Geological Ore Controls: In the general model: 1) Paleoproterozoic or younger age; 2) continental margin or fault-controlled intracratonic basin environments; 3) reduced marine sedimentary host sequence transgressive over an oxidized, continental sedimentary sequence marked by an unconformity; 4) a thick and permeable footwall red-bed sequence is favourable; 5) associated evaporites as a source of sulphur; 6) probable source of copper was from the oxidized sedimentary footwall rocks and in some cases associated volcanic rocks; 7) pyrite and carbonaceous matter acted as reductants; and 8) features such as basement paleotopography, unconformity surfaces, facies changes, stratigraphic pinchouts, folds, faults, and fracture zones to focus the basinal fluid flow.

Geochemical Signature: Laterally extensive (up to kilometres) geochemical anomalies in the host sequence with a possible enrichment in Cu, Ag, Pb, and Zn and less commonly U, Co, Ge, Mo, and V.

Geophysical Signature: 1) airborne and ground gravity, magnetic, and electromagnetic surveys to help map basement topography, bedrock geology, and graphitic material in paleochannels; 2) seismic surveys to help locate paleochannels, unconformity contacts and faults; and 3) ground induced-polarization/resistivity surveys to locate disseminated mineralization.

Examples (with grades and tonnages)

World examples include the African Copperbelt; Kupferschiefer, Europe; and White Pine, Michigan.

In the Wollaston Domain there are two main areas with occurrences of this type of mineralization, the Pendleton Lake and Duddridge Lake areas. Both areas contain a number of locations with significant stratabound to stratiform, disseminated copper mineralization.

The Pendleton Lake area contains the Janice Lake, Kaz Lake, Rafuse Lake, and Juno occurrences. The Thor location at Duddridge Lake contains significant uranium and copper mineralization with a reported historical resource estimate of 320 700 tons grading 1.84 lb/ton U3O8 with Cu not reported (SMDI 0700a).

Other Saskatchewan examples interpreted as this deposit type include minor occurrences in the Hurwitz Group (SMDI 0659), and Mudjatik (SMDI 1054 and 1059) and Virgin River (SMDI 1116 and 1117) domains.

Selected Bibliography

Coombe, W. (1994): Sediment-hosted base metal deposits of the Wollaston Domain, northern Saskatchewan;

Saskatchewan Energy and Mines, Report 213, 108p.

Coombe Geoconsultants Ltd. (1991): Base metals in Saskatchewan; Saskatchewan Energy and Mines, Open File Report 91-1, 218p.

Delaney, G.D. (1993): A re-examination of the context of U-Cu, Cu, and U mineralization, Duddridge Lake, Wollaston Domain; in Summary of Investigations 1993, Saskatchewan Geological Survey, Saskatchewan Energy and Mines, Miscellaneous Report 93-4, p73-85.

__________ (1994): Geological setting of sediment-hosted copper mineralization in the area southwest of Janice Lake, Wollaston Domain; in Summary of Investigations 1994, Saskatchewan Geological Survey, Saskatchewan Energy and Mines, Miscellaneous Report 94-4, p53-62.

Delaney, G.D., Maxeiner, R.O., Rawsthorne, M.L., Reid, J., Hartlaub, R., and Schwann, P. (1995): Geological setting of sediment-hosted copper mineralization in the Janice Lake area, Wollaston Domain; in Summary of Investigations 1995, Saskatchewan Geological Survey, Saskatchewan Energy and Mines, Miscellaneous Report 95-4, p30-48.

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Hitzman, M., Kirkham, R., Broughton, D., Thorson, J., and Selley, D. (2005): The sediment-hosted stratiform copper ore system; in Hedenquist, J.W., Thompson, J.F.H., Goldfarb, R.J., and Richards, J.P. (eds.), Economic Geology One Hundredth Anniversary Volume 1905-2005, Society of Economic Geologists, p609-642. Rogers, M.C. (1995): Sedimentary-hosted copper (Cu-(Pb-Zn-Co-Ag)); in Rogers, M.C., Thurston, P.C., Fyon, J.A., Kelly, R.I., and Breaks, F.W. (comps.), Descriptive Mineral Deposit Models of Metallic and Industrial Deposit Types and Related Mineral Potential Assessment Criteria, Ontario Geological Survey, Open File Report 5916, p43-47.

Saskatchewan Geological Survey (2003): Geology, and mineral and petroleum resources of Saskatchewan;

Saskatchewan Industry and Resources, Miscellaneous Report 2003-7, section p17-19.

Yeo, G.M. and Delaney, G. (2007): The Wollaston Supergroup, stratigraphy and metallogeny of a Paleoproterozoic Wilson cycle in the Trans-Hudson Orogen, Saskatchewan; in EXTECH IV: Geology and Uranium Exploration TECHnology of the Proterozoic Athabasca Basin, Saskatchewan and Alberta, (eds.) C.W. Jefferson and G.

Delaney; Geological Survey of Canada Bulletin 588; Saskatchewan Geological Society Special Publication 18;

Geological Association of Canada, Mineral Deposits Division, Special Publication 4, p89-117.

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Model Number A-5: Sandstone-hosted Uranium

Concise Description: Epigenetic uranium mineralization deposited from oxidized groundwater in local reduced environments within permeable fluvial, and less common, lacustrine and deltaic sandstones.

Geological Environment

Host Rock Types: Arkosic to quartzose sandstones with original high porosity-permeability and oxidized and reduced facies. Deposits are found in the reduced facies which are typically light grey to white. Fossil wood, if present, is usually coalified. Oxidized facies are red, buff, or tan in colour, reflecting the iron oxide content. Impermeable shale and/or mudstone units are often interbedded with the sandstones in the sedimentary sequence and commonly occur immediately above and below the host sandstone.

Rock Textures: Fine to coarse-grained sandstones, characterized by high initial porosities and permeabilities. Primary fluvial sedimentary features are typical.

Age of Host Rocks and Mineralization: Paleoproterozoic or younger, but mainly Phanerozoic, especially Mesozoic and Cenozoic. Mineralization is interpreted to be epigenetic, forming soon after the deposition and burial of the host rocks.

Depositional Environment: Fluvio-lacustrine molasse-type sequences within intermontane basins, broad intracratonic piedmonts, and marginal marine plains. In most locations the uranium is believed to have been sourced by oxidizing fluids from local felsic volcanic ash and/or eroding granitic intrusive rocks near the sediment source. Movement of the uranium-bearing groundwater occurred through permeable host sandstones, typically fluvial channel and bar deposits, with uranium deposition at specific sites in response to geochemical and reduced permeability factors. Confining impermeable shale/mudstone units often played a role in focussing the fluid flow. In most situations, reduction of the oxidizing fluids is thought to have been the principal factor in precipitating the uranium. Reducing/adsorping materials include humic matter (e.g., coalified wood), carbonaceous material, petroleum, and biogenic H2S and authigenic pyrite.

Tectonic Setting: Stable platform or foreland basins and shelf margins. Major basin margin uplifts (generally orogenic) are necessary to supply the molasse-type clastic sediments.

Associated Deposit Types: Sedimentary-hosted copper ± polymetallic and uraniferous lignite.

Deposit Description

Mineralogy: Uraninite (pitchblende), coffinite, uraniferous organic matter, and pyrite.

Textures and Styles of Mineralization: Stratabound deposits that are typically localized within reduced sandstone units. There are two main styles: 1) tabular or lens-shaped deposits, concordant with bedding, elongate parallel to the sedimentary trend, and usually found in paleochannels incised in underlying sedimentary units; and 2) crescent-shaped “roll-fronts” that cross-cut bedding at the redox boundary. The roll-front deposits may be remobilized from tabular-style mineralization. Two other styles of secondary importance are: 1) basal-type deposits occur in poorly- sorted and consolidated sediments in paleovalleys cut into basement rocks and capped by volcanic flows or impermeable sediments and 2) tectonolithologic deposits are hosted by sandstone close to a permeable fault zone. Deposit geometries can be highly variable and the mineralization is not uniformly distributed. Contacts with the country rock may be sharp or irregular and diffuse. Uranium minerals occur intimately admixed with humin in pore spaces; as replacements of carbonaceous material; as interstitial microcrystalline minerals; and in rare deposits where reductants are absent, uranium is adsorped by iron oxides, zeolites, clays, and/or titanium oxides. Alteration: Oxidation “incursions” into reduced strata related to the movement of oxidized groundwater. Leaching of iron may occur from detrital magnetite-ilmenite by humic acid-bearing fluids leaving relict TiO2 minerals. In roll-front deposits the redox boundary separates oxidized iron minerals from reduced iron minerals.

Geological Ore Controls: 1) permeable fluvial channel sandstones; 2) felsic volcanic ash and granitic intrusive rocks are favoured uranium sources; 3) mobilization of uranium into solution by oxidizing groundwater; 4) movement of uranium-bearing groundwater through the permeable sandstones which are often confined by impermeable

shale/mudstone units; 5) precipitation of uranium mainly in response to reduction of the oxidizing fluids at a redox interface; and 6) principal reductants are humin, petroleum, carbonaceous material, and biogenic sulphur in the form of H2S and pyrite.

Geochemical Signature: Uranium, with commonly associated elements V, Mo, Se, and locally Cu and Ag. Zoning of V, Mo, and Se may occur in some deposits in relation to U. Oxidation of uranium minerals may occur to produce secondary minerals such as carnotite and tyuyamunite with characteristic yellow and orange colours.

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Geophysical Signature: 1) airborne and ground radiometric surveys to locate uranium mineralization directly or through mobile daughter products, and borehole surveys for direct detection; 2) magnetic, gravity, and seismic surveys to help to map paleotopography and outline paleochannels; 3) induced-polarization/resistivity surveys to locate conductive, disseminated material in paleochannels; 4) electromagnetic surveys to locate continuous, conductive material in paleochannels; and 5) ground-penetrating radar may be useful in delineating the geometry of shallow paleochannels.

Examples

World examples include the Colorado Plateau, U.S.A.; Niger, Africa; Permian sandstones, Europe; Tertiary sandstones, Japan; Kazakhstan; and Australia.

Recent exploration in the southwest corner of the province has resulted in the intersection of a number of uranium intervals in drill holes, in Ravenscrag Formation fluvial sandstones, with a best of 0.028% eU3O8 over 1.2 m (d0e4fe06f524ccbff0218498, 2009).

There are a number of potential settings in the far south of the province: 1) a Tertiary fluvial molasse sequence in the southwest corner of the province that consists of the relatively thick (>170 m) Oligocene Cypress Hills Formation, basal Upper Eocene Swift Current Creek Beds (<20 m), and overlying Miocene Wood Mountain Formation

(<20 m). These consist of sandstone, quartzite and conglomerate, interchannel lacustrine marlstone with minor volcanic ash beds, and abundant fossils; 2) the Paleocene Ravenscrag Formation, which extends over much of the far south of the province. It is a thick sequence (<245 m) that consists of buff, grey, and white fluviatile-lacustrine sandy claystone, and green-grey to buff feldspathic sandstone, siltstone, and shale, with coal and kaolinite beds. The coal has been found to contain sporadic values in the 0.01% to 0.05% U3O8 range and rarely up to 0.35% U3O8 (Energy and Resources assessment work files); and 3) the Upper Cretaceous Frenchman Formation, which outcrops in the southwest corner of the province. It consists of a <60 m sequence of grey-green, massive, cross-bedded, fluviatile-lacustrine sandstone that is locally dolomitic, calcareous, kaolinitic, or carbonaceous with thin lignite beds. Minor rock types include mudstone and non-marine red and green shale. Fossils are common.

Interpreted occurrences of Paleoproterozoic age are found along the extreme western margin of the southern Wollaston Domain (SMDI 1961, 1974, 1982, 1983, 1985, 2469, and 2470) and in similar rocks of the eastern Mudjatik Domain (SMDI 1930, 1958, and 1965). These uranium occurrences are hosted by reduced pelitic and calc-silicate rocks within general sequences of psammitic to meta-arkosic gneisses and pelitic to psammopelitic gneisses. Graphite is common and Cu and Mo are locally present in minor amounts.

Selected Bibliography

DeVoto, R.H. (1978): Uranium in Phanerozoic sandstone; in Uranium Deposits, Their Mineralogy and Origin, Short Course Handbook, Mineralogical Association of Canada, Volume 3, p293-295.

Kelley, L. (2005): Uranium exploration in southern Saskatchewan: a historical review; Calgary Mining Forum, Abstract Volume, p24.

Kyser, K. and Cuney, M. (2009): Chapter 9: Sandstone-hosted uranium deposits; in Cuney, M. and Kyser, K. (eds.), Recent and Not-So-Recent Developments in Uranium Deposits and Implications for Exploration, Mineralogical Association of Canada, Short Course Series Volume 39, p221-240.

Macdonald, R. and Slimmon, W.L. (comp.) (1999): Geological Map of Saskatchewan; Saskatchewan Energy and Mines, 1:1 000 000-scale map.

Nash, J.T., Granger, H.C., and Adams, S.S. (1981): Geology and concepts of genesis of important types of uranium deposits; in Skinner, B.J. (ed.), Economic Geology 75th Anniversary Volume, Society of Economic Geologists, p63-116.

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Model Number A-6: Sandstone-hosted Lead-Zinc-(Silver)

Concise Description: Stratabound to stratiform galena and/or sphalerite hosted by basal sequences of reduced, quartz-rich sandstones.

Geological Environment

Host Rock Types: Host rocks are reduced quartzites, quartz-rich sandstones and minor conglomerates with a high primary porosity and permeability. They may contain carbonaceous or organic matter. Associated rock types may include shale, siltstone, local evaporites and carbonate rocks, and sialic basement rocks. The principal host rocks in Saskatchewan are the basal quartzites of the Souter Lake and Daly Lake groups of the Wollaston Supergroup of the Wollaston Domain.

Rock Textures: Primary sedimentary features include bedding, laminations, crossbedding, shallow-water sedimentary structures and paleochannels.

Age of Host Rocks and Mineralization: On a world scale the age range is Paleoproterozoic to Cretaceous. In Saskatchewan the host Wollaston Supergroup is Paleoproterozoic. The mineralization is generally believed to be diagenetic in origin and formed when the sediments were still unconsolidated.

Depositional Environment: Passive margin setting with a shallow marine or a combined continental–shallow marine environment. This includes fluvial, lagoon, tidal beach, tidal channel, and deltaic settings. The host rocks are typically overlain by a transgressive marine sedimentary sequence. The host sequence usually developed on a deeply-weathered, tectonically-stable, peneplaned sialic basement, generally at low paleolatitudes. There was a common concentration of mineralization in basement paleovalleys and paleochannels. In some cases the organic matter that accumulated in the paleochannels may have acted as a reductant to precipitate and concentrate the mineralization.

The Wollaston Supergroup was deposited on Archean sialic basement rocks mainly consisting of granitic gneisses. The Souter Lake Group is interpreted to have formed in a passive margin environment and developed on the Archean basement. The basal portion of the Daly Lake Group, which contains the host quartzites, is interpreted to have developed in the initial stage of a foreland basin, and was also locally deposited on the Archean basement. Tectonic Setting: Stable tectonic environment. Pre-existing faults, fracture systems, and paleotopography may have had an influence on the fluid flow and location of the mineralization.

Associated Deposit Types: Regional-scale associations in the sedimentary basin may include the sedimentary-hosted Cu ± polymetallic, sedimentary-exhalative massive sulphide Zn-Pb-(Ag), and Mississippi Valley–type Pb-Zn deposit types.

Deposit Description

Mineralogy: The mineralogy is simple and normally includes varying proportions of galena, sphalerite, and pyrite. Barite, fluorite, and carbonate may be variably present. A wide range of other sulphide, sulphosalt, and hydrous minerals may be present in minor or trace quantities. Quartz is the dominant gangue mineral and carbonate can be significant. The locations in northern Saskatchewan consist of galena, sphalerite, pyrite, pyrrhotite, and minor magnetite. Gahnite (zinc spinel) is common in some locations.

Textures and Styles of Mineralization: Stratabound to stratiform mineralization that generally occurs as fine to medium-grained disseminations and clots that form intergranular cement. Typically occurs as lenses that can be laterally extensive, in some cases on the order of kilometres. Occurrences of semi-massive to massive layers may exist locally. Generally sharp upper contacts are determined by impermeable strata such as shale or pelite. Local structural remobilization may occur.

Alteration: Not significant. Paleoweathering of the underlying sialic basement rocks is an important genetic feature. Geological Ore Controls: 1) sialic basement rocks that may be Pb rich; 2) deep paleoweathering of the basement;

3) transgressive passive margin to early foreland basin, reduced, quartzose sandstone sequence deposited over the basement rocks; 4) Paleoproterozoic age of the host rocks; 5) high porosity and permeability of the host sandstone sequence; 6) commonly localized in paleochannels developed in basement lows; and 7) features such as faults, fractures, and facies changes that influence the fluid flow.

Geochemical Signature: 1) anomalous Pb and Zn in the host rock sequence and in associated surficial material (e.g., boulder tracing); 2) there may be a Pb enrichment in the sialic basement rocks; 3) in some deposits there is an upward and outward zonation from Pb to Zn; and 4) there may be a Ba, F, and Ag enrichment in the basal portions of some deposits.

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Geophysical Signature: 1) seismic surveys to outline the commonly associated paleochannels and the basement/sandstone unconformity; 2) airborne and ground electromagnetic surveys to detect conductive sedimentary units with graphitic material within the paleochannels; 3) ground induced-polarization/resistivity surveys to detect the disseminated mineralization; 4) magnetic surveys over the northern Saskatchewan locations have provided very useful information as an aid to geological mapping; and 5) airborne and ground electromagnetic surveys have also proved useful as an aid to geological mapping.

Examples (with grades and tonnages)

World examples include Yava, Nova Scotia; Laisvall, Sweden; and Largentiere, France.

In the Wollaston Domain there are two main areas with occurrences of this type of mineralization. These are the Morell Lake and Foster River areas. Both areas contain a number of locations with stratabound to stratiform, disseminated sphalerite, galena, pyrite, and pyrrhotite in concentrations up to 20%. Gahnite is common in the Foster River area. The Morell Lake area locations are hosted by Souter Lake Group quartzites. The Foster River area occurrences are hosted by quartzites near the base of the Daly Lake Group. Both rest unconformably on Archean basement in their respective locations.

Locations in the Morell Lake area include George Lake, Johnson (Mariana), Simon Lake, Hills Lake, and Joannie. The George Lake deposit has a 2003 geological resource of 2 630 880 t grading 3.67% Zn and 0.53% Pb (SMDI 0663). Mineralization in the George Lake area has been traced for a strike length of 8 km.

In the Foster River area there are about ten separate locations concentrated in the Sito Lake and Fable Lake areas.

Selected Bibliography

Bjorlykke, A. and Sangster, D.F. (1981): An overview of sandstone lead deposits and their relation to red-bed copper and carbonate-hosted lead-zinc deposits; in Skinner, B.J. (ed.), Economic Geology 75th Anniversary Volume, Society of Economic Geologists, p179-213.

Coombe, W. (1994): Sediment-hosted base metal deposits of the Wollaston Domain, Northern Saskatchewan;

Saskatchewan Energy and Mines, Report 213, 108p.

Coombe Geoconsultants Ltd. (1991): Base metals in Saskatchewan; Saskatchewan Energy and Mines, Open File Report 91-1, 218p.

Delaney, G.D., Jankovic, Z., MacNeil, A., McGowan, J., and Tisdale, D. (1997): Geological investigations of the Courtenay Lake–Cairns Lake Fold Belt and the Hills Lake Embayment, Johnson River Inlier, Wollaston

Domain, Saskatchewan; in Summary of Investigations 1997, Saskatchewan Geological Survey, Saskatchewan Energy and Mines, Miscellaneous Report 97-4, p90-101.

Delaney, G.D. and Savage, D. (1998): Geological investigations of the context of quartzite-hosted Zn-Pb mineralization, Sito-Adams lakes area, Wollaston Domain (parts of NTS 74A-4 and -5); in Summary of

Investigations 1998, Saskatchewan Geological Survey, Saskatchewan Energy and Mines, Miscellaneous Report 98-4, p29-35.

Rogers, M.C. (1995): Sandstone-hosted Pb-Zn; in Rogers, M.C., Thurston, P.C., Fyon, J.A., Kelly, R.I., and Breaks,

F.W. (comps.), Descriptive Mineral Deposit Models of Metallic and Industrial Deposit Types and Related

Mineral Potential Assessment Criteria; Ontario Geological Survey, Open File Report 5916, p39-42. Sangster, D.F. (1984): Sandstone lead; in Eckstrand, O.R. (ed.), Canadian Mineral Deposit Types: A Geological Synopsis, Geological Survey of Canada, Economic Geology Report 36, p26.

Saskatchewan Geological Survey (2003): Geology, and mineral and petroleum resources of Saskatchewan;

Saskatchewan Industry and Resources, Miscellaneous Report 2003-7, section p17-19.

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Model Number A-7: Placer and Paleoplacer

Concise Description: Concentrations of minerals with high specific gravities deposited with clastic sediments in fluvial, beach, and less commonly in alluvial fan, colluvial, deltaic, near-shore, and glacial environments.

Geological Environment

Host Rock Types: Generally mature, well-sorted, fine to coarse-grained, quartz-rich sands and sandstones, and mature, well-rounded, clast-supported, quartz-rich gravels and conglomerates.

Rock Textures: Fine to coarse-grained, clastic sediments and sedimentary rocks,that display a decrease in the grain size away from the source. Mature, clean, well sorted and well rounded. Well-developed bedding and crossbedding are common.

Ages of the Host Rocks and Mineralization: May be of any age from Precambrian to Quaternary. Tend to more commonly be of Tertiary and Quaternary age, which is probably related to erosion removing older deposits. Placer deposits in the province are postglacial, and paleoplacer examples are found in both the Precambrian and Phanerozoic.

Depositional Environment: Initial weathering and erosion of mineralized source rocks and preconcentration of high specific gravity (heavy) minerals near to the source. Fluvial placer concentrations occur in large stream channels and in steep-gradient, high-energy streams. Gravity and stream dynamics act to concentrate the heavy minerals in favourable locations, commonly on eroded bedrock surfaces at the base of channels, and particularly at irregularities. The placers are generally associated with the coarsest sediment fractions. Relative low-energy locations such as at the base of waterfalls and rapids, in the downstream pressure shadows of boulders, islands, or bars, inside meander bends, and in vegetation mats are favourable deposition sites. There is an overall decrease in the grain size of the heavy minerals and sediments downstream with the decrease in energy. A relative sorting of the heavy minerals also occurs, based on specific gravities, with the relatively lighter minerals concentrating further from source. There is also a corresponding relative sorting based on grain size, with lighter larger grains potentially occurring with heavier smaller grains. Multiple stages of erosion and reworking of placers is a favourable and commonly necessary factor in increasing concentrations. Alluvial fan and deltaic deposits are found in less-confined settings characterized by massive or graded sands and gravels. Placer accumulations in beach and near-shore environments are formed by the winnowing action of waves and long-shore currents.

Tectonic Settings: 1) stable intracratonic basin, platform, and intermontane plateau settings characterized by long periods of erosion and reworking of clastic sediments and 2) accretionary orogenic belts, commonly in proximity to major faults that expose the bedrock sources to weathering and erosion.

Associated Deposit Types: The source mineral deposit type will determine the type of placer deposit (e.g., a lode gold deposit will erode to produce placer gold).

Deposit Description

Mineralogy: Potential economic minerals may include native gold, electrum, platinum group minerals, diamond, ilmenite, rutile, zircon, cassiterite, wolframite, scheelite, monazite, apatite, xenotime, uraninite, thorianite, gem corundum (sapphire, ruby), emerald, topaz, and garnet. Associated heavy minerals may include magnetite, hematite, pyrite, tourmaline, chromite, sphene, and a wide range of sulphides and sulphosalts.

Textures and Styles of Mineralization: In fluvial settings the deposits generally occur as thin (<2 m) stratiform lenses of discrete grains, which are variable in dimensions and laterally discontinuous. In alluvial fan, deltaic, beach, and near-shore settings they consist of zones and layers of disseminated grains that are thin and commonly laterally extensive. Grain size decreases with distance from source. Also grains become more rounded and better sorted with increasing distance from source and degree of working. With increased travel and mechanical action gemstones display an increase in quality. This is the result of flawed and fractured grains breaking down, leaving only the competent high-quality stones.

Alteration: None associated with the placer accumulation.

Geological Ore Controls: 1) weathered bedrock source; 2) water erosion, transport, and concentration of heavy minerals in fluvial, beach, and less common alluvial fan, colluvial, deltaic, near-shore, and glacial environments; 3) gravity and water dynamics act to concentrate the placer minerals in favourable locations; 4) decrease in grain size away from the source; 5) highest placer concentrations occur close to the source; 6) reworking of placers is an important factor in increasing concentrations; and 7) increased gemstone quality is associated with a greater degree of transport and mechanical action.

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Geochemical Signature: 1) anomalous concentrations of economic or related elements in stream sediments or favourable stratigraphy; and 2) kimberlite indicator minerals (pyrope garnet, chrome diopside, magnesian ilmenite) for diamond placers and paleoplacers.

Geophysical Signature: 1) magnetic, gravity, and seismic surveys to map paleotopography and outline paleochannels; 2) induced-polarization/resistivity surveys to locate conductive disseminated mineralization;

3) electromagnetic surveys may be useful in detecting conductive material in paleochannels; 4) ground-penetrating radar may be useful in delineating the geometry of shallow channels and deposits; and 5) radiometric surveys to locate radioactive heavy-mineral concentrations.

Examples (with grades and tonnages)

On a world scale the Klondike district in the Yukon is a well known gold placer mining district, and placer diamond mining is very important in southern Africa. Paleoplacer examples include the Elliot Lake uranium district in Ontario, and the Witwatersrand gold district in South Africa. Marine beach and near-shore placers are a principal source of titanium.

In Saskatchewan, placer gold deposits in the North Saskatchewan River have been commercially produced starting in 1859 and continuing on a small scale to present. Dredging was done in the late 1800s and early 1900s.

Interpreted paleoplacer locations include those in the Precambrian Athabasca Group SMDI 1617 (U-Th) and SMDI 1149 (Th-zircon), and common magnetite along bedding planes; Precambrian Beaverlodge Domain [Archie Lake (SMDI 1552) - monazite]; Precambrian Wollaston Domain [SMDI 0702 (ilmenite, U, and Au)]; Cambrian Deadwood Formation [Ennis Lake (gold)]; and U. Miocene to Eocene Cypress Hills Formation [Simmie Occurrence (gold)]. A placer beach sand location occurs at Jack Lake (NTS 73O) where anomalous Th and U are associated with zircon concentrations.

Two areas may have potential to contain paleoplacer diamond concentrations. In the Fort à la Corne area the diamondiferous kimberlite volcanoes erupted in an interpreted coastal environment coeval with the Cretaceous continental to marginal marine Mannville Group and the shallow marine Joli Fou Formation. Erosion of the volcanoes in this environment likely yielded diamonds that may have formed placer accumulations. The Miocene Wood Mountain Formation in southern Saskatchewan locally contains relatively abundant kimberlite indicator minerals, notably G9 pyrope garnets. It is conceivable that diamonds may also be present.

The Mannville Group oil sands in west-central Saskatchewan may contain paleoplacer oxide minerals, as they do in Alberta.

Selected Bibliography

Beck, L.S. (2004): Alluvial gold in the Upper Miocene to Eocene Cypress Hills Formation of southwest Saskatchewan; Saskatchewan Industry and Resources, Open File Report 2004-1, 15p.

Boyle, R.W. (1979): The Geochemistry of Gold and its Deposits; Geological Survey of Canada, Bulletin 280, section p310-389.

Coombe Geoconsultants Ltd. (1984): Gold in Saskatchewan; Saskatchewan Energy and Mines, Open File Report 84-1, sections p6, 8-10.

Force, E.R. (1986): Descriptive model of shoreline placer Ti; in Cox, D.P. and Singer, D.A. (eds.), Mineral Deposit Models, United States Geological Survey, Bulletin 1693, p270.

Garnett, R.H.T. and Bassett, N.C. (2005): Placer deposits; in Hedenquist, J.W., Thompson, J.F.H., Goldfarb, R.J., Richards, J.P. (eds.), Economic Geology One Hundredth Anniversary Volume 1905-2005, Society of Economic Geologists, p813-843.

Levson, V.M. (1995): Surficial placers; in Lefebure, D.V. and Ray, G.E. (eds.), Selected British Columbia Mineral Deposit Profiles, British Columbia Geological Survey, Open File 1995-20, p21-23.

Levson, V.M. and Giles, T.R. (1995): Buried-channel placers; in Lefebure, D.V. and Ray, G.E. (eds.), Selected British Columbia Mineral Deposit Profiles, British Columbia Geological Survey, Open File 1995-20, p25-28.

McLeod, C.R. (1984): Placer gold; in Ecstrand, O.R. (ed.), Canadian Mineral Deposit Types: A Geological Synopsis, Geological Survey of Canada, Economic Geology Report 36, p23.

Yeend, W.E. (1986): Descriptive model of placer Au-PGE; in Cox, D.P. and Singer, D.A. (eds.),Mineral Deposit Models, United States Geological Survey, Bulletin 1693, p261.

Sask. Ministry of Energy and Resources 17 Open File Report 2011-57

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