CORE SHACK Epigenetic gold in Val D’Or

The Kierens Zone is an epigenetic gold deposit on Aur Resources’ First Canadian property, 10 miles west of Val d’Or, Que. Based on surface drilling results, the deposit is estimated to contain drill-indicated reserves of 700,000 tons of ore grading 0.20 oz gold per ton over a strike length of 1,000 ft and to a depth of 800 ft. The zone is open along strike and to depth. Gold was initially discovered in the Kierens Zone in the 1960s by surface drilling and was developed in 1964-66 from the end of the 750-ft level of the Norlartic mine. This mine produced 1.2 million tons of ore grading 0.13 oz gold per ton from 1959 to 1966. About 50,000 tons were mined from the Kierens Zone.

Aur Resources optioned the property from First Canadian Gold Corp. in 1984 a nd has since earned a 100% interest in the three claims. First Canadian retains a 10% net profits interest in any production from the property. Aur Resources completed magnetic, VLF and geological mapping surveys in 1984. Three holes drilled in late 1985 confirmed the presence of the Kierens Zone on the First Canadian property.

Regionally the property is underlain by Archean metavolcanic and intrusive rocks of the Abitibi greenstone belt. The Lower Malartic Group, which consists predominantly of komatiites and tholeiites, is overlain by the volcanic rocks of the Upper Malartic Group and the Cadillac and Pontiac Group sedimentary rocks. These groups are intruded by the Bourlamaque and Lacorne felsic intrusive rocks.

The deposit lies within the 200-ft wide, northwest-striking Kierens deformation zone in the Lower Malartic Group. Within the deformation zone, talc-chlorite schist is the predominant rock type in a rapidly alternating sequence of intermediate sills, schist and recrystallized mafic volcanic rocks. The gold mineralization is largely confined to a 100-ft-wide silicified, carbonatized and albitized zone within the shear.

Gold occurs in three types of veins within the altered zone: high-grade single vein structures, sill stockworks and laminated veins in recrystallized mafic volcanic rocks. The single vein structures are vertically-dipping, vary from 6 inches to 3 ft in width (containing chlorite inclusions) and are localized at the intermediate sill-mafic volcanic and mafic volcanic-talc- chlorite schist contacts. Leafy native gold is associated with pyrite and minor molybdenite, chalcopyrite, pyrrhotite and sphalerite. These single veins generally assay in excess of one ounce gold per ton.

The white quartz vein stockworks comprise up to 30% of the intermediate sills which may contain up to 5% disseminated pyrite and, locally, native gold. Assays from the stockwork mineralization range from 0.08 to 0.30 oz gold per ton. Visible gold commonly occurs in the large and small veinlets as well as in association with disseminated pyrite in the intermediate sill and mafic volcanic rocks.

Bluish-grey to white, 0.25-in-wide laminated quartz-carbonate veins and lenses occur within recrystallized, carbonatized mafic volcanic rocks with up to 5% pyrite. The veins are vertically-dipping, concordant, parallel and comprise up to 30% of the host rock. Seven-to-seventy-micron-size free gold grains occur erratically within both the veins and the recrystallized mafic volcanic rocks.

In late 1986 a 2-compartment shaft was sunk on the Kierens Zone to a depth of 750 ft and a drill drift was driven on the 750-ft level. The weighted average grade of the first 66 underground drill holes was 0.41 oz gold per ton over an average width of 11.7 ft. The deposit remains unexplored below a depth of 1,200 ft in this area and below 800 ft to the east. Aur Resources is deepening the shaft to 1,400 ft and plans to drift on the 1,300-ft level to provide a platform for additional drilling prior to completing a production feasibility study. They plan to bring the Kierens Zone into production in 1988.

Only 3,000 ft on strike to the east, in the Kierens deformation zone, Aur Resouces is drilling the Main zone on the Norlartic property, which has drill- indicated ore reserves of 861,000 tons grading 0.13 oz gold per ton based on surface drilling results. One interpretation suggests that the Kierens Zone and the Norlartic property Main zone may connect at depth. Pamela Phillips is a Toronto-based consulting geologist. She would like to thank Aur Resources for supplying the information and also Howard Stockford and George Mannard for their assistance.