Geology of the copper-zinc deposits of stall lake mines lts., snow lake area, n. manitoba

The copper-zinc deposits of Stall Lake Mines Ltd. in the Snow Lake area of Manitoba are interpreted as being of metamorphosed volcanogenic origin. Some of the massive chalcopyrite and sphalerite ores occur in highly elongate, stratiform lenses. Known deposits occur in the uppermost layers of a thick rhyolitic ash formation, now resembling quartz "porphyry," near its contact with overlying basaltic tuffs and flows. Metamorphism to the amphibolite facies has caused extensive conversion of pyrite to pyrrhotite. Plastic deformation and remobilization of the sulfide ores has probably yielded a preferential enrichment of the more plastic minerals, especially chalcopyrite and sphalerite.