Core Shack COURAGEOUS LAKE GOLD

The Tundra deposit, in the Courageous Lake area of the Northwest Territories, has undiluted possible reserves of 26.4 million tons grading 0.18 oz gold per ton and is owned by both the project operator, Noranda Exploration (51%), and Getty Resources (49%). The northeast-trending, vertically- dipping deposit, which consists of a series of auriferous shear zones, is 125 km northeast of Yellowknife, N.W.T. The shear zones occur within an area 4,750 ft long, 600 ft in width and has been drilled to a vertical depth of 3,800 ft. The deposit is open both along strike and at depth. Gold was first discovered in the area by Dr W. Brown in 1938 while he was exploring for a company called Territorial Exploration. The initial discoveries eventually resulted in the development of the Tundra mine in 1964 and the Salmita mine in 1982. In 1979, Getty and Noranda formed a joint venture to explore for base metals in the Courageous Lake Greenstone Belt. But as the price of gold went up, exploration was focused on precious metals instead. In 1982, diamond drilling in an area of frost-heaved auriferous felsic volcanic rocks yielded intersections with values up to 0.2 oz gold per ton over 23 ft. Further geological mapping, geophysical surveying and diamond drilling resulted in two gold discoveries: the Tundra deposit in 1982 and the Carbonate zone deposit in 1984.

Regionally, the Tundra deposit lies within the north-trending, steeply dipping, east-facing Archean-age Courageous Lake volcanic belt. It consists of the Western Volcanic Complex, composed predominantly of mafic volcanic rocks, and the stratigraphically overlying Matthews Lake Volcanic Complex, of felsic pyroclastic rocks intermixed with minor mafic flows and sedimentary rocks. The Matthews Lake Volcanic Complex hosts the Tundra and Carbonate zone deposits and is overlain by turbidites belonging to the Yellowknife Group. Gabbro, diabase, and feldspar porphyry dikes and sills intrude all of these rocks.

On a property scale, the Matthews Lake Volcanic Complex consists of two cycles of predominantly felsic volcanic rocks. The Lower Cycle is characterized by: rhyodacite flows of up to 1,300 ft thick; a sequence of calcareous sedimentary rocks with coarse fragmental interbeds (which hosts the Carbonate zone deposit); and the Gully sedimentary rocks, which mark the top of the Lower Cycle. The Upper Cycle consists of felsic tuffs and agglomerates up to 1,000 ft thick, the Tundra deposit, and overlying felsic volcaniclastic rocks. The Upper Cycle is overlain by the sedimentary rocks of the Yellowknife Group.

The Tundra deposit consists of a series of parallel, vertically dipping, conformable, altered shear zones within a 600-ft-wide zone of disseminated arsenopyrite, pyrite and pyrrhotite. Alteration of the shear zones consists of silicification in the form of quartz veining and as irregularly shaped, blue-grey-to-dark-grey quartz bodies; sericitization that varies from patchy to pervasive; and sulphidization. Arsenopyrite occurs as acicular disseminated grains and, locally, as dense masses within the sericitized rocks. Pyrite and pyrrhotite are most commmonly associated with the quartz veining. Chalcopyrite, sphalerite and schellite are rare.

Gold occurs as fracture filling in arsenopyrite and, to a lesser extent, in pyrite and arsenopyrite. Visible gold is rare and is confined to quartz veining. Metallurgical studies indicate recoveries of 98% using pressure oxidation technology to decompose the sulphide minerals.

Plans are under way to begin construction of a 425-m vertical exploration shaft to define the grade, continuity and mineability of the deposit. On the 425-m level, a drift along the length of the deposit, with drill stations cut every 50 m, is planned. Geologist Pamela Phillips is project co-ordinator for Greenstone Resources in Toronto. She would like to thank Getty Resources and Noranda Inc. for the information. Thanks also go to Reginald Comeau of Getty Resources and David Powers, Richard Kemp and Eric Seraphin of Noranda for their assistance.