Age of Mineralization and ‘Mine Dykes’ at Copper Mountain Alkaline Copper-Gold-Silver Porphyry Deposit (NTS 092H/07), South-Central British Columbia

Un der ground mass min ing tech niques have en abled prof it able ex trac tion of the deep por tions of por phyry de pos its at minesites world wide. Of ten con sid ered a rel a tively new in no va tion, block cav ing was orig i nally de vel oped for cop per min ing in Utah in 1906 (Barger and Schurr, 1944). Ex am ples of block cave min ing of cop per por phyry de pos its in clude the re cently de com mis sioned San Manuel Cu mine in Ar i zona, and the cur rently ac tive alkalic Cu-AuAg Ridgeway de posit in New South Wales, Aus tra lia. Prof it able un der ground min ing of large ton nage, low-grade de pos its com bined with the re cent strength in metal com mod ity prices has prompted deep ex plo ra tion of por phyry de pos its in Brit ish Co lum bia, es pe cially within the pro lific Quesnel terrane (Fig ure 1). For ex am ple, in the Iron Mask batholith near Kamloops, New Gold Inc. has out lined 44.4 mil lion tonnes at a grade of 0.98% Cu, 0.72 g/t Au and 2.27 g/t Ag (New Gold Inc., 2007) be neath the for mer Afton pit and has started de vel op ment. Cop per Moun tain Min ing Cor po ra tion has sim i larly dem on strated the po ten tial for subsurface ex ten sions to min er al iza tion that was ex tracted from open pits at Copper Mountain, about 15 km south of Princeton, in south-central BC (Figure 2).