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Mineral Exploration in Northern Saskatchewan, La Ronge, Reindeer, Wollaston and Athabasca Areas

by A.J . Gracie

Gracie, A.J. (1986): Mineral exploration in northern Saskatchewn, La Ronge, Reindeer, Wollaston and Athabasca areas; in Sunrnary of Investigations 1986, Saskatchewan Geological Survey; Saskatchewan Energy and Mines, Miscellaneous Report Bo-4.

The estimated provincial level of uranium exploration rose slightly, from $19. 5 million in 1985 to $22 million in 1986, for the first time in several years. As a contrast, however, estimated gold exploration expenditures have more than doubled from $7 million to greater than $15 million. Funds have become more readily available, in response to flow-through financing initiatives and, more recently, the new Saskatchewan Stock Savings Plan. Grassroots exploration for platinum group elements escalated. Programs were carried out by Cominco Ltd., Lacana Mining Corporation Ltd. and Silver Lake Explorations Ltd. in areas containing mafic and ultramafic rocks. Essa Minerals Ltd., with a new permit surrounding George Lake, south of Wollaston Lake (Fig. l) is the only company in the review area with a base metal exploration program. 1986 saw finalization and introduction of The Crown Minerals Act and The Mineral Disposition Regulations, 1986, which replaced those in place since 1961. The new Regulations implement changes outlined under the Mineral Recovery Program, 1984.

The geoscience program funded through the Federal-Provincial Economic Regional Development Agreement 1984-89 (ERDA), was ongoing with a variety of projects: geological mapping and compilation,

Figure 1 - Northern Saskatchewan in relation to geological domains in the Precambrian Shield. Current uranium mines, potential mines and major exploration locations related to the Athabasca Basin (indicated by dots): (A) Canada Wide Mines Ltd., 'Midwest Lake'; (B) Cigar Lake Mining Corp., Cigar Lake; (C) Cluff Mining Ltd., Cluff Lake; (D) Eldor Resources Ltd., Collins Bay and Eagle Point zones; (E) Eldor Resources Ltd., Rabbit Lake; (F) Key Lake Mining Corp., Key Lake; (G) Saskatchewan Mining Development Corp. (SMDC), Natona Bay, Dawn Lake joint venture; (H) Saskatchewan Mining Development Corp. (SMDC) P2 Zone, McArthur River joint venture; (I) Uranerz Exploration and Mining Ltd., Read Lake joint venture. Current gold mine, potential and major exploration locations (indicated by crosses): (1) Golden Rule Resources Ltd., Tower Lake zone; (2) Mahogany Minerals Resources Inc./Canadian Premium Resources Corp., Rod zone; (3) Placer Developoment Ltd . , Komis and EP zones (Waddy Lake); (4) Placer Development Ltd., Seabee; (5) SMDC, Sulphide Lake joint venture; (6) SMDC, Preview Lake joint venture; (7) Starrex Mining Corp. Ltd./SMDC/UEM, Star Lake Mine.

Current base metal exploration location (indicated by box): A, Esso Minerals Ltd., Spence Lake.

geochronological investigations, magnetic gradiometer surveys, regional lake sediment surveys, biogeochemistry, mineral deposit investigations and core collection, for the most part devoted toward areas of active gold exploration. Three major all - weather highways to Rabbit Lake, Cluff Lake and Key Lake now give access to northern Saskatchewan, while major improvements to Highway 106 make travel to Flin Flan from La Range or Prince Albert much faster.

Production will start from the Star Lake 21 zone mine (Saskatchewan Mining Development Corporation (SMDC), Starrex Mining Corporation Ltd., Uranerz Exploration and Mining Ltd. (UEM)) late in 1986. The adjoining Rod zone on the J olu property (Mahogany Minerals Resources Inc., Canadian Premium Resources Corp.) is scheduled for an underground exploration decline this fall. Placer Development Ltd. may soon announce the results of their exploration work and the plans for

LJ Phanerozoic /

D Athabasca Group ~ Athabasca Group (Helikian) ~(Helik i on) < 500 m to basement

D Pre-Athabasca basement

~ Major shear zone

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future underground development on the Seabee property.

In late 1985, Golden Rule Resources Ltd., Goldsil Resources Ltd. and SMDC agreed to split up the Tower, Oven and Neyrinck projects into 29 different projects (SMDC News Release, October 28, 1985), thereby unlocking an exploration stalemate on these properties caused by lack of agreement on programs. Under the new division, one of the three major partners has a controlling interest in each of the projects. SMDC, Starrex Mining Corporation Ltd. and UEM have an agreement with Claude Resources Inc. to acquire 66% of the J ojay and Tamar properties for $2 million over four years (George Cross Newsletter, July 23, 1986). These properties may contain the ore necessary to keep the 21 zone mill operating beyond the present three year life expectancy.

Last winter several joint ventures announced drillholes with excellent grades (e.g., at Tower, Preview and Laonil Lakes), indicating a continuing potential for high-grade gold mineralization in the La Range and Glennie Lake Domains.

Junior exploration companies still predominate in the La Range Domain, although Cogema Canada Ltd., Denison Mines Ltd., UEM, SMDC, Placer Development Ltd. and International Corona Resources Ltd. through its subsidiaries now make an essential contribution.

La Range Domain

Drill indicated reserves on the SMDCIStarrex Mining Corp. Ltd./UEM Star Lake property (Fig. l) are still 208,65 l t grading 17 .2 git (0. 5 oz./ton) Au. An l l.5 km all-weather road joins Highway 102 to the new mine site. At the end of August a 1200 m spiral ramp, development on four levels and drilling to define the orebody between levels down to the 130 m level had been completed. In addition, mill construction was over half finished, ahead of schedule and on budget. The mine plans to pour the first gold bar around the turn of the year.

Drill-indicated gold reserves from the Mahogany Minerals Resources Inc./Canadian Premium Resources Corporation Rod zone on the J olu property have surpassed those on the nearby 21 zone. Bechtel Civil and Minerals Inc. estimates that the Rod contains around 810,000 t of ore grading 20. 9 git (0./61 oz./ton) Au (Stockwatch, June 2, 1986). Last winter's exploration outlined five new zones on the Rod, although two of these, the B and C zones, contain most of the reserves (Company News Release, April 28, 1986). Mahogany completed an all-weather road to the J olu property this summer from the Star Lake mine access road. Work on a decline to test the upper levels of the Rod will begin this fall. Royex Gold Mining Corp. have agreed to provide up to $15

million of exploration and development financing for Canadian Premium Resoures Corp. (Stockwatch, Feb. 24, 1986) who may acquire a 50% interest in the property. A Golden Rule Resources Ltd. (40 percent)IGoldsil ( 40 percent)ISMDC (20 percent) joint venture discovered the PAM zone by testing the northeast extension of the Rod zone on their Blind man property. Here DOH 6 intersected 2.8 m of 27 .4 git (0. 798 oz./ton) Au from 97 .08 to 99 .88 m (Stockwatch, Feb. 24, 1986).

The Byers Fault is a new target for gold exploration in the La Range Domain. The three new drillholes with high -grade gold mineralization announced by Golden Rule Resources Ltd. (Company News Release, April 28, 1986) from their Tower Lake property dramatically demonstrate the potential of this regional structure. DOH T86-22 cut 3 m of 4.8 git (0.14 oz./ton) Au from 76 to 79 m, and 23 m of 12. 9 git (0. 38 oz./ton) Au from 98 to 121 m. Included in the second intersection, known as the PAT zone, is a 3 m interval, from 115 to 118 m, assaying 59.4 git ( l. 73 oz./ton) Au. The gold mineralization is in sheared granodiorite quartz-eye porphyry which intrudes metavolcanic rocks adjacent to the Byers Fault. The property is owned jointly by Golden Rule Resources Ltd. (37.5 percent), Goldsil Resources Ltd. (37.5 percent), SMDC (20 percent) and Comaplex Resources International Ltd. (5 percent).

The Dickens Lake project just north of Otter Rapids, in which Draw International Resources Corp. will earn an interest from SMDC, also covers a wide zone of alteration and mineralization linked to an east-west regional fault (Stockwatch, April 14, 1986). Assays from surface samples have reached 57.3 git (l.67 oz./ton) Au. In the Sulphide Lake area, an SMDCIUEMIWindora Minerals Ltd. joint venture is evaluating Pap Lake gold zones controlled by shears in gabbro-diorite and felsic volcanics. Concordant quartz veins with pyrite, arsenopyrite and free gold are present in the shear zones. Consistently good gold values were obtained in shears in eight out of ten holes drilled last winter (Stockwatch, May 30, 1986). DOH PR 86-18 cut 0.5 m of 20.5 git (0.60 oz./ton) Au from l. l to l.6 m, 0.8 m of 3.8 git (0.11 oz./ton) Au from 6.4 to 7.2 m, and 17. l m of 12.2 git (0. 36 oz./ton) Au from 35. 5 to 52.6 m. New drill programs could expand the PAP zones, although the size of the enclosing mafic bodies is limited. Results at Ramsland Lake on the same project have been less predictable so far. Four out of ten drill holes gave significant gold values last winter (Stockwatch, May 30, 1986).

The Sulphide Lake Galena, Studer A, Band F zones make a stratiform gold target, where the gold is linked to lean iron formation (Coombe, 1984), which is a formational conductor running along a volcaniclmetasedimentary contact. Claimed reserves are 907, 180 t grading 2. 3 git (0.07 oz./ton) Au in the A and B zones. The A and B Zone figures include 158, 757 tat 7.6 git (0.22 oz./ton) Au. An additional 16,329 tat 14.4 git (0.42 oz./ton) Au is

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recognized in the C zone located in close proximity to a second conductive zone (Stockwatch, Feb. 21 and April 18, 1986). The SMDC, Denison Mines Ltd. and Torex Minerals Ltd. joint venture added to the tonnage on the A and B zones with sixteen new holes last winter (Stockwatch, April 18th), but did not improve the grade; however, improved grades and possibly also tonnage were indicated for the C Zone.

Glennie Lake Domain

Placer Development Ltd. have not released any definite information about ore reserves or future plans for the Seabee property. The company's drill programs should have added to previously estimated proven and probable reserves in the 2, 5, 11 and 14 zones of 562,454 t grading 18.2 g/t (0.53 oz./ton) Au uncut, or 11.0 g/t (0. 32 oz./ton) Au cut to 34. 3 g/t (1.0 oz./ton) Au to a depth of 183 m (Gummer, 1985).

The winter drill program sought to extend the shear zones which host vein systems 2 and 5 to depth and out under Laonil Lake (Northern Miner, April 28, 1986). Diamond-drill hole 161 crossed two excellent gold intersections 244 m west of the mineralized section of zone 5 in the same major shear structure. Recorded ore 12. 3 m (true width 7.9 m) of 17.4 g/t (0.51 oz./ton) Au from 65 to 78.3 m and 3.2 m (true width 2.06 m) of 14.2 g/t (0.41 oz./ton) Au from 120. 5 to 123. 7 m. Placer also carried out work to advance other drill targets on the Seabee property and the surrounding three claim blocks.

Cogema Canada Ltd. worked on their permit to the west, and six junior companies ran preliminary grassroots programs this summer to the east and south. In the wider area Carina Mineral Resources Corp. is also active on MPP 1132 surrounding Brownell Lake.

Other Areas

The level of gold exploration north of Lake Athabasca remained low. Possible volcanics to the north of Stony Rapids still offer an opportunity for grassroots exploration in a neglected area. These rocks lie within the Western Craton which here consists of retrogressively metamorphosed granulite facies terrain. Because Highway 105 is now within 130 km of Black Lake and Stony Rapids, the area is now somewhat more accessible. Colchis Resources Ltd. began work on its properties in August 1986 and Cominco Ltd. staked four new claim blocks for gold in the Grease River area.

Elsewhere Claude Resources Inc. took out a new permit on the Virgin River Domain and Rex Silver Mines Ltd. completed some work on their old permit in the Mudjatik Domain. Both permits cover rocks interpreted as volcanic.

Uranium

Uranium exploration was mainly in the eastern Athabasca Basin and the Carswell Structure, areas which contain producing uranium mines at Key Lake, Rabbit Lake-Collins Bay and Cluff Lake and all of the major undeveloped deposits including the massive Cigar Lake Mining Corporation (CLMC) orebody at Cigar Lake. Work on the Cigar Lake shaft and the development of two levels will begin next year (Northern Miner, Sept. 1, 1986). Uranium exploration continued where the Athabasca Group exceeds 500 m in thickness, although no work was carried out in the centre of the basin or along its northern and southwestern perimeters.

Athabasca Group Perimeter

Production at Key Lake totalled 4,270 t U in 1985 (SMDC Annual Report, 1985) and recoverable reserves as of December 31, 1985 were 67 ,ODD t U. This operation is the world's largest producing uranium mine. The Gaertner orebody will be mined out by year end and work has already started to develop the Deilmann orebody. Eldorado Resources Ltd. produced only 824 tonnes U at Rabbit Lake in 1985. A $1 DD million development and expansion program completed in 1985 will return the Rabbit Lake mill capacity to a minimum of 2,000 t U per year (Eldorado Annual Report, 1985). Milling of the Collins Bay ore where Eldorado has reserves of 12,000 t U required the installation of new mill circuitry which was commissioned in the last quarter of 1985.

Exploration programs still concentrate on the detection of conductor- and/or fault-related unconformity deposits using the Key Lake model as a basis. Geophysical techniques have been used to detect basement conductors since the discovery of Key Lake in 1975, and sites of known uranium mineralization are now quite numerous. However, in proximity to Key Lake itself, despite the experience gained over ten years plus new money and expertise from companies with farm-in agreements such as Minatco Ltd., Central Electricity Generating Board (Canada) Ltd. (CEGB), Denison Mines Ltd. and LIEM, no venture has defined another commercial deposit of uranium.

New mineralized holes continue to be drilled. For example, SMDC found unconformity mineralization on their Dawn Lake venture at Natona Bay on Waterbury Lake, which is on strike and approximately 20 km northeast of Cigar Lake (Fig. 1 ). Diamond-drilling cut values of up to 4. 7 percent U over 5.3 m under 260 m of sandstone (SMDC Annual Report, 1985). SMDC has also reported sandstone-hosted mineralization from the BJ location on the McArthur River project. At BJ, diamond-drilling found up to 2. 7 percent U over 4.0 m at a depth of 400 m. One of these new mineralized holes may lead to the discovery of a new uranium orebody comparable to Cigar Lake.

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Athabasca Group Interior

The Cigar Lake Mining Corporation was formed by SMDC (50.57 percent), Idemitsu Uranium Exploration Canada Ltd. (12.875 percent), Cogema Canada Ltd. (32.625 percent) and Corona Grande Exploration Corp. (3. 75 percent) in May 1985. The Corporation wishes to develop the huge reserves of ore in the Cigar Lake deposit for commercial production by the first part of the next decade. CLMC must demonstrate a feasible mining method and design and construct a 4,600 t U/yr mill. To this end the company has announced a test mining schedule, beginning in 1987, which will entail sinking of a 488 m shaft and development of two levels above and below the orebody (Northern Miner, Sept. 1, 1986).

Reserves are 110,000 t U grading 11.8 percent U in the main zone. Inferred reserves at the western end of the deposit are 38, 500 t U grading 3.82 percent U. These figures indicate that the Cigar Lake orebody, which lies below Athabasca Group sandstones at an average depth of 430 m, may be double the size of the Key Lake orebody. This spectacular find, together with improved geophysical methods and the lack of new discoveries in the immediate area of Key Lake, has prompted other companies to test deep basement targets at 500 m or more below surface.

Exploration methods are the same in the Athabasca Group interior as in the deeper parts of the perimeter area, although exploration is clearly more difficult and costly. The increased interest observed in 1984-85 was maintained this year, in part due to improved geophysical methods (e.g., large loop UTEM and Pulse EM), which can outline conductors at much greater depth. Several companies ran new airborne and ground geophysical survey programs and three completed major drill programs. Cogema Canada Ltd. attempted to prove an orebody around DOH CLC5-0l l which cut unconformity mineralization on the Close Lake venture south of Blixrud Lake (Imperial Metals News Release, April 22, 1985). SMDC tested sandstone mineralization on the P2 location 8 km northwest of the BJ prospect on the McArthur River project. Core from P2 assayed up to 1.19 percent U over 7. 3 m at a depth of 525 m (SMDC Annual Report, 1985). UEM, in joint venture with SMDC and Kerr Addison Mines Ltd., continued to drill close to the P2 location on the Read Lake property (Fig. l).

Carswell Structure

Cluff Lake Mining, owned by Amok Ltd./Ltee. (80 percent) and SMDC (20 percent), produced 835 t U in 1985 from the Claude, OP and Dominique-Peter zones. Production in 1986 is from the Claude open pit and the Dominique-Peter underground mine where an undercut and fill method has been successfully introduced. Recoverable reserves as of

December 31, 1985 were 32,400 t U. The company also plans to extract gold and uranium from highly radioactive tails from the Phase l mining of the D zone.

The Carswell Structure uranium deposits are of unconformity type and, for the most part, related to mylonite zones surrounding gneiss domes at the contact of Peter River and underlying Earl River Gneisses (Laine, Alonso and Svab, 1985).

Crystalline Basement

In general, companies have continued to show little interest in the uranium potential of rocks outside of the Athabasca Group Basin, although Eldorado Resources Ltd. has identified combined reserves at Eagle North and South of more than 50,000 t U, significantly in excess of those in the Collins Bay zones. Geological reserves at Eagle South are more than 30,000 t U while those at Eagle North are now estimated at 20,000 t U averaging 2.2 percent U based on a cutoff grade of 0.42 percent U.

Platinum Group Elements

Exploration for platinum group metals is still in its infancy in the province, although the level is increasing. Lacana Mining Corp. and Cominco Ltd. have grassroot programs in the Peter Lake Domain, a region dominated by locally layered mafic bodies cut by later granites. Colchis Resources Ltd. and Silver Lake Resources Ltd. are examining mafic intrusive prospects in the Western Craton. American Platinum and others are actively searching in the Rottenstone Domain for ultramafic-mafic bodies similar to that which hosted the Rottenstone Mine. This deposit was reported to contain 45,000 to 55,000 t of ore grading 2 percent Ni, 2 percent Cu, 7. 5 g/t (0. 22 oz./ton) Pt and 5.1 g/t (0.15 oz./ton) Pd (Northern Miner, April 15, 1965). Intrusions in the La Ronge Domain are also being examined.

Base Metals

Exploration for base metals is limited to a very small program on the Esso Minerals Ltd. permit in the Spence Lake area of the Wollaston Domain.

References

Coombe, W. ( 1984): Gold in Saskatchewan; Sask. Energy Mines, Open File Rep. 84-1, l 34p.

Gummer, P.K. (1985): The Seabee Gold Deposit; Saskatchewan, Canada; Prospectors and Developers Assoc., March 1985.

Laine, R., Alonso, D. and Svab, M. (1985): The Carswell Structure Uranium Deposits; Geol. Assoc. Can., Spec. Pap. 29.