CORE SHACK BOUSQUET #2

The Bousquet #2 stratiform gold deposit, 40 km east of Rouyn-Noranda, Que., and 2 km east of the Bousquet #1 deposit, has ore reserves of 7.1 million tonnes grading 6.4 g of gold per tonne. The deposit, discovered by lac Minerals in 1986, is hosted by felsic volcanic rocks of the Blake River Group. It averages 300 m in strike length, up to 25 m in thickness and is open to depth. The deposit strikes roughly east-west, dips steeply south, and plunges steeply to the west. Lac Minerals acquired the Bousquet property in the mid-1970s with the intent to drill the property to test known low-grade mineralization and explore for new deposits. Diamond drilling of induced polarization (ip) anomalies led to the discovery of the Bousquet #1 deposit, which was put into production in the late seventies. In the fall of 1986, after news of significant drill results by Dumagami Mines to the east, a major drill program resulted in the discovery of the Bousquet #2 deposit, 2 km east and along strike from the Bousquet #1 Mine.

Regionally, the Bousquet #2 deposit lies with the stratigraphic top of the Archean Blake River Group of the Abitibi Greenstone Belt. At Bousquet, the Blake River Group consists of an east-striking, steeply south-dipping, south- facing stratigraphic sequence. From north to south, the sequence consists of mafic volcanic rock, felsic volcanic rock, mixed intermediate pyroclastic and volcaniclastic rock, and felsic volcanic rock. All rocks are intruded by the Mooshla granitic stock and northeast- striking diabase dikes. The sequence has been metamorphosed to the upper greenschist facies and retrograded to the lower greenschist facies. All rocks have undergone two periods of deformation.

Host rock to the Bousquet #2 consists of chloritic mafic tuff with abundant garnet near the ore. It is stratigraphically overlain to the south by the ore sequence of pyritic quartz- sericite schist with massive and disseminated sulphide minerals. These rocks are intercalated with slightly graphitic silicious rock and andalusite- rich aluminous rock. Farther south and stratigraphically overlying the ore sequence are felsic fragmental and volcaniclastic rocks which, in turn, are overlain by greywacke. The greywacke is intruded by a diorite sill. The sequence, from the garnet-bearing chloritic tuff to the top of the felsic fragmental rock averages 100 m in thickness.

In the ore sequence, massive sulphide is the main host to gold mineralization and generally grades greater than 8 g of gold per tonne. Massive sulphide grades laterally along strike to pyritic quartz-sericite schist averaging 5 g of gold per tonne containing single or multiple layers of massive sulphide. Still farther from the centre of the deposit, the rock grades to pyritic quartz-sericite schist with erratic distribution of gold but averaging a few grams of gold per tonne. Pyrite, the most abundant sulphide mineral, occurs as disseminated grains in the quartz-sericite schist and as coarse anhedral aggregates of annealled grains in the massive sulphide. Chalcopyrite and bornite fill fractures in the massive sulphide. Sphalerite, most abundant in the hangingwall, occurs as fine disseminated grains. Most of the gold occurs as fine blebs and as fracture filling within pyrite grains or coating on pyrite grain boundaries. It also occurs as very fine flakes within the silicate groundmass. Distinctive metal zoning is characteristic of Bousquet #2. Both gold- and copper-enrichment are present in the footwall rocks to ore, although this is negligible in the hangingwall rocks. There is a copper-rich core that is elongated in the westerly plunge direction, and it is smaller than the gold deposit at the central footwall parts of the ore. The zinc content is greatest in the immediate hangingwall to the ore, and zinc-enrichment extends laterally in an east-west direction away from the ore, forming a hangingwall “blanket” to the ore, with a longer dimension than the gold deposit.

Ip survey results exhibit distinct chargeability and metal factor anomalies above ore. Resistivity changes aid significantly in correlating stratigraphic units along strike across the property. The Bousquet #2 deposit is scheduled to begin production in late 1989 at a rate of 1,000 tonnes per day increasing to 2,000 tonnes per day by 1991. The deposit will be mined by bulk open stope method and backfilled with rockfill. Pamela Phillips is a geologist and project co-ordinator for Greenstone Resources. She would like to thank LAC Minerals for supplying the information and, in particular, J. Cook, R. Valliant, and P. Irwin of LAC Minerals for their help. — 30 —