157

RESIDENT GEOLOGIST REPORTS

158

Mineral Exploration Activity in the La Ronge and Athabasca Mining Districts

by A.J. Gracie

Gracie. A.J. (1985}: Mineral exploration activity in the La Ronge and Athabasca Mining Districts; in Summary of Investigations 1984, Saskatchewan Geological Survey; Saskatchewan Energy and Mines. Miscellaneous Report 85-4.

The level of uranium exploration in the mining districts stabilized after two consecutive years of relative decline.

Gold exploration, on the other hand, increased considerably during the year. Gold exploration activity was largely in the La Ronge Domain where the Geological Survey is concentrating its efforts to provide more technical support for the mining industry. A geoscience program, funded through the Federal­Provincial Economic Regional Development Agreement 1984-89 (ERDA). consists of geological mapping and compilation. geochronological investigations, magnetic gradiometer surveys, regional lake sediment surveys, biogeochemistry, mineral deposit investigations and core collection, most of which concern the present mining area.

Grassroots exploration for platinum group elements in ultramafic and mafic rocks. being carried out by Lacana Mining Corporation Ltd .. offers interesting possibilities for new mineral discoveries in the province.

Granges Exploration AB is the only company presently interested in base metal exploration in this area; although this company has two finds between Bigstone and Amisk Lakes. the level of base metal exploration remains low.

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 Ronge or Pnnce Albert much faster.

Gold

GSC Open File 1129 provided lists and maps of gold values obtained through reanalysis of lake sediment samples collected during a 1974 survey of the area extending from the Shield margin to Latitude 57°N and from the Needle Falls Shear Zone to the Manitoba border. Its release in late May resulted in 68,900 ha of new mineral properties being staked in this area.

Production is planned on two gold properties, the Star Lake 21 zone (Starrex Mining Corp./SMDC1 1oint venture) and the adjoining Jolu claims (Mahogany Minerals Resources Inc.). Placer Development Ltd. is now operating all programs on the Komis, EP and Seabee zones through agreements with Waddy Lake Resources Ltd. and Claude Resources Inc., while the Pezirn group of companies have concluded agreements with Mahogany

'Saskatchewan Mining Development Corporation

Minerals Resources Inc., Carina Mineral Resources Corp. and Waddy Lake Resources Inc. Their involvement in the area should ensure the funds needed to sustain exploration and development programs on some of the province's most promising gold prospects. Although junior mining companies still dominate the gold play, SMDC, BP Canada Inc .. Cogema Canada Ltd. and Uranerz Exploration and Mining Ltd. are among the major mining companies interested in gold in Saskatchewan.

La Range Domain

Drill-indicated reserves on the Starrex Mining Corp./ SMDC Star Lake property (Fig. 1) are 208,651 t grading 17.15 g/t (0.5 oz./ton) Au. The SMDC Annual Report for 1984 mentions additional reserves on the Kahn 18, Kahn 28 and Rush zones. A prefeasibility study recommended a conventional mine/mill complex rated at 200 tpd, trackless mining from a decline, blast-hole open stopes, supplementary production from shrinkage slopes, fine grinding and carbon in pulp circuits (Northern Miner. January 3, 1985). Access road construction has begun and the first 305 m of a 853 m decline ramp will be driven this year once the road is complete (Northern Miner. August 1, 1985).

Mahogany Minerals Resources Inc., which plans to bring the adjoining Jolu claims into production, has signed an agreement w1th Canadian Premium Resource Corporation under which the latter can earn a 50 percent interest in the property. A Mahogany Minerals news release on January 30, 1985 estimated that reserves in the Jolu property's Mallard Lake, Rod Main and Rod South zones might total 158,757 t of ore grading 21.6 git (0.63 ozJton) Au (diluted 15 percent) or 24.7 git (0.72 oz./ ton) Au undiluted. The company predicts that a major new drill program later this year will add substantially to these reserves.

The 21 Zone is an auriferous quartz lens with pyrite associated with mylonitized dykes. The Jolu drill targets are combinations of quartz veins in shear zones, shear zone intersections, and geochemical and magnetic highs. The 21 and Rod zones lie inside the compositionally zoned Star Lake intrusive.

There have been no recent attempts to extend known gold zones on the Jotu claims and the 21 zone property onto the Neyrinck venture. SMDC offered 30 percent of the Neyrinck venture for sale in the Northern Miner.

Further north in the La Ronge Doma,n, Placer Development Ltd. made an agreement with Waddy Lake

w

"' ~ <( ....J

D PhanerOloic

D AH1 obcsca Group (He,1kianl

D Pr~+Afhobasco t.ianm~nl

__........ Ma1or sht cr z one-

I .... .j_

r ~0 ·~, ~ L ._ • ·• · ............ --------'--··-·-··-...L.---___;

Figure 1 - Location of the La Range and Athabasca Mining Districts in relation to geological domains in the Precambrian Shield.

Current uranium mmes. potential mines and major exploration locations related to the Athabasca Basin (indicated by dots ): (A) Canada Wide Mines Ltd .. 'Midwest Lake'; (B) Cigar Lake Minmg Corp., Cigar Lake; (C) Cluff Mining Ltd., Cluff Lake: (DJ E!dor Mmes Ltd., Collins Bay and Eagle Point zones; (E) Eldor Mines Ltd .. Rabbit Lake; (F) Key Lake Mining Corp., Key Lake; (GJ Saskatchewan Mining Development Corp., Dawn Lake Joint venture; (H) Minatco Ltd., 'Wally' Pro1ect joint venture. McLean Lake Zones. Heavily patterned area approximately represents the mterior of the basin where the Athabasca Group exceeds 500 m in thickness.

Current gold mine. potential and ma1or exploration locations (indicated by crosses): (1) Carina Mineral Resources Corp., MPP 1132, Brownell Lake; (2) Mahogany Minerals Resources Inc., Mallard. Rod Main and Rod South zones; (3) Placer Development Ltd., Komis and EP occurrences. Waddy Lake; (4) Placer Development Ltd .. Seabee property; (5) Saskatchewan Mining Development Corp. Sulph1de-Preview-Ramsland Lakes Joint venture; (6) Starrex Mmmg Corp. Ltd. SMDC. Star Lake.

Current base metal exploration location (indicated by box): A. Granges Exploration AB. Wapawekka Lake - Oskikebuk River area.

Resources Inc. on the Kom,s property. Placer must complete a feasibility study by September 1, 1989 and spend $1.5 mtllion prior to that {Northern Miner, June 13, 1984) The EP or Eric Partridge zone lies a little to the northeast of the Komis zone on the same property. The EP zone may contain a significant tonnage of ore in the 7 git (0.2 oz./ton) Au range Properties associated with the Byers Fault were largely inactive.

159

At the south end of the La Ronge Domain, SMDC has expanded their holdings in their Sulphide-Prevtew­Ramsland Lakes properties and confirmed previously known gold values in the Sulphide Lake area .. Denison Mines Ltd. is now a member of this joint venture. which is managed by SMDC. The Galena and Studer A, B and F zones make a stratiform gold target where gold is associated with lean iron formation or argillite. Last winter the joint venture tested targets in the area southwest of Preview Lake where mineralized gold zones are found within sheared gabbro (Coombe, 1984). The joint venture has obtained significant gold values in several drill holes in the Ramsland Lake area (SMDC Annual Report 1984). The better intersections in sulphide-rich layers were 3.43glt (0.1 oz./ton) Au over 4.35 m, 10.29 git (0.3 oz./ton) over 1.5 m and 30.18 git (0.88 oz./ton) over 0.5 m.

Glennie Lake Domain In an agreement with Claude Resources Inc. with respect to their Seabee property, Placer Development Ltd. will make a" ___ $3 million pre-production recoverable cash advance to Claude, of which $2 million can be converted to a 10 percent interest in the property and $1 million, including interest can be recovered from production proceeds. Placer can earn an additional 45 percent interest in the property by: spending $2.5 million ($1 million dollars committed in the first 12 months), completing a final bankable feasibility study before July 1988, and spending the funds necessary to take Seabee to commercial production. Placer shall recover Claude's share of the project's capital costs from the proceeds of production and thereafter Placer/Claude are 55 percent/ 45 percent partners in the Seabee operation." (Claude Resources Inc. news release, July 19, 1985).

A maior drill program begun by Placer in August aims to increase the Seabee ore reserves at depth and on trend from the No. 2 and No. 6 zones. The new drill program also intends to define new ore reserves in other known gold zones lying parallel and in close proximity to the main ore lenses Drill-proven and probable geological reserves in four zones to a vertical depth of about 183 m are approximately 562,454 t averaging 18.18 git (0.53 oz./ ton) Au uncut. or 10.98 git (0.32 oz./ton) Au when the average grade across ore intervals is cut to 34.3 git (1 oz./ ton) Au (Gummer, 1985). Placer is also active on the three claim blocks surrounding the Seabee property, which 1t optioned from Currie Rose Gold Mines Ltd.

Carina Mineral Resources Corp. completed a drill program on their permit south of Brownell Lake 1n the fall of 1984 and this summer ran a reduced program on the Kalix zone on the east side of the permit. The Kalix zone shears, fractures and quartz veins which range up to 54.54 g/t (1.59 oz./ton) Au across 1.5 m may present an open pit mining prospect. Exploration work to date is limited to stripping, grab and chip sampling. (Northern Miner, June 20 and August 15, 1985; George Cross Newsletter, June 5, 1985). Control of Carina Mineral Corp. has now passed to the Pezim group.

Other Areas

T~e (ev~I of gold exploration in the Athabasca Mining D1stnct 1s very low. Volcanic rocks north of Stony Rapids offer an opportunity for grassroots exploration in a neglected area. These rocks are part of the Western Craton tectonic unit, which consists of retrogressively metamorphosed granulite facies rocks. Because Highway 905 to the Wollaston Lake area is within 130 km of Stony Rapids and Black Lake, access to a find in this area is no longer the problem it once was. SMDC owns MPP 1143 which covers the extension of the Ennadai volcanic belt into northern Saskatchewan at Hammill Lake.

Uranium

Uranium exploration has been mainly in the eastern Athabasca Basin and the Carswell Structure. New exploration is being directed at those areas which contain the province's three producing uranium mines at Cluff Lake, Key Lake and Rabbit Lake, and in the vicinity of the massive new find by Cogema Canada Ltd. at Cigar Lake. Uranium exploration has also expanded into areas where the Athabasca Group exceeds 500 m in thickness, although little work was carried out in the centre of the basin or along its northern or southwestern margins.

Athabasca Group Perimeter

Production at Key Lake totalled 4,000 t U in 1984 (SMOG Annual Report, 1984), while recoverable reserves as of December 31, 1985 were 71,000 t U; the company planned to produce 4,600 t U or design capacity in 1985. The Rabbit Lake ore deposit is mined out, but Eldor Mines Ltd. produced 1,361 t U from stockpiled Rabbit Lake pit ore in 1984. Production from the Rabbit Lake mill will be maintained at approximately 2000 t U per year by ore mined from the Collins Bay B zone where reserves are 12,000 t U. The company has not mined any ore from this zone yet (Eldorado Annual Report 1984).

Exploration drill programs concentrated on the detection of conductor- and/or fault-related unconformity deposits using the Key Lake model as a basis. Over ten separate drill programs were run in the perimeter zone last winter in the area between Stony Rapids, Key Lake and Wollaston Lake. Minatco Ltd. can earn a 33.3 percent interest in the Wolly Project by spending $23 million on exploration and feasibility studies. The budget for the first phase of this agreement is $5 million over the next four years (Northern Miner, February 21, 1985). The Central Electricity Generating Board Exploration (Canada) Ltd./ Minatco/Uranerz venture will earn an interest in six projects in the area northeast of Key Lake. Denison Mines Ltd. plans to earn an interest in three properties in the southwestern portion of the active perimeter area. Central Electricity Generating Board Exploration (Canada) Ltd., PNC Exploration Canada Ltd. and SMDC have staked the ground which lapsed inside the southwestern part of the Athabasca Basin perimeter area. These new farm-in

160

agreements represent a significant investment. This new money and the high level of technical expertise which the companies bring with them offer a good chance of continued uranium discoveries in the Athabasca perimeter area.

Athabasca Group Interior

The new Cigar Lake Mining Corporation owns a massive uranium deposit close to Waterbury Lake which overshadows other known deposits in the Athabasca Basin. The Cigar Lake Mining Corporation (CLMC) is a new company formed by SMDC (50.75 percent), Idemitsu Uranium Exploration Canada Ltd. (12.875 percent), Cogema Canada Ltd. (32.625 percent) and Corona Grande Exploration Corp. (3.75 percent). The Cigar Lake reserves (SMDC Annual Report 1984) are 110,000 t U at an average grade of 12 percent U. Inferred reserves at the western end of the deposit are 38,000 t U at a grade of about 4 percent U. These figures indicate the Cigar Lake orebody may be double the size of the Key Lake orebody. Consequently, some other known uranium deposits in the Wollaston Lake area (i.e. Dawn Lake and Midwest Lake) which were awaiting development, will likely now be re­examined in relation to this discovery. CLMC will consider the most suitable underground mining method (Northern Miner, June 13, 1985) for the Cigar Lake orebody which lies below Athabasca Group sandstones at an average ~epth of 430 m. This spectacular discovery, together with improved geophysical methods and the lack of new discoveries in the immediate area of Key Lake. has prompted other comapnies to test basement targets close to 500 rn 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. Interest in the interior area has increased over previous years, in part due to improved geophysical methods (e.g., large loop UTEM and Pulse EM) which can outline basement conductors at much greater depths. A press release by Imperial Metals Corporation Ltd. on April 22, 1985 reported that hole CLC 5--0011 on the Cogema­operated Close Lake venture south of Blixrud Lake cut 10.18 percent U over 2.5 m (from 641 to 643.5 m). This technical success clearly shows that uranium discoveries can be made in the interior of the basin, while reserves at Cigar Lake prove that these discoveries can be very significant. E and B Explorations Ltd., Saarberg lnterplan and Uranerz Exploration and Mining Ltd. have all staked new ground in the interior area. Some of these claim blocks are due west of the Close Lake project and the Read Lake prospect, which was drill tested by Uranerz Exploration and Mining ltd. this summer.

Carswell Structure

Cluff Lake Mining Ltd., owned jointly by Amok Ltd./ltee. (80 percent) and SMDC (20 percent) produced 615 t U in 1984 from an underground mining operation on the

Dominique-Peter orebody. Current recoverable reserves are approximately 13,800 t U.

Amok Ltd./Ltee .. who have the entire area under disposition in various ioir,t ventures, continue to carry out major surface percussion and diamond drill hole programs. The 1984 exploration program, managed by Amok, found the new Domirnque-Janine deposit one kilometer southwest of the Dominique-Peter orebody (SMDC Annual Report 1984). The Dominique-Janine is an area of near-surface or open pit mineralization in basement rocks about 200 m long and 70 m in width. The Carswell Structure uranium finds are unconformity deposits which are usually related to mylonite zones at the contact of the Peter River Gneisses and the Earl River Gneiss Domes (Laine, Alonso and Svab, 1985).

Crysta/fine Basement

161

In general, companies have continued to show little interest in the uranium potential of rocks at any distance from the Athabasca Basin, although mineralization is known at some considerable depth below the Athabasca Group unconformity (e.g. the Eagle Point deposit in Collins Bay). Drill programs completed before 1984 indicated geological reserves of 14,600 t U at a grade of 1.6 percent U at Eagle Point North (SMDC Annual Report, 1984).

Platinum Group Elements

Exploration for platinum group elements is new in the province. Lacana Mining Corp. has begun a regional, grassroots exploration program to find platinum group

elements in the Peter Lake Domain. The program is based on the idea that the Peter Lake Domain is a layered ultrabasic intrusion cut by later granites. Basic and ultrabasic intrusions in the La Ronge and Rottenstone Domains and the Western Craton also have potential for platinum group elements. In connection with the ERDA Geoscience Program, L. Hulbert of Energy, Mines and Resources Canada is working on the metallogeny of ultrarnafic and mafic rocks in Manitoba and Saskatchewan (see L. Hulbert, this volume).

Base Metals Exploration for base metals is limited to jrnnt ventures operated by Granges Exploration AB in the Wapawekka Lake/Oskikebuk River area. Granges drilled extensively in this area last winter. These programs are testing volcanic rocks close to or under the Phanerozoic cover.

References Coombe, W. (1984): Gold in Saskatchewan; Sask.

Energy Mines, Open File Rep. 84-1 , 134p.

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

Harper, C.T. (1982): Geology of the Carswell Structure, central part; Sask. Miner. Resour., Rep. 214, 6p.

Laine, R., Alonso, D. and Svab, M. (1985): The Carswell Structure uranium depostts; Geol. Assoc. Can., G.A.C. Spec. Pap. 29.