Catface copper-molybdenum porphyry, westcentral Vancouver Island, British Columbia: An update

Special Volume, Vol. SV 46, No. 1995, 1995

Catface is a calc-alkalic, Cu-Mo deposit situated on the rugged west coast of Vancouver Island. The claims covering the property are owned by Falconbridge Limited. A partially defined resource known as the Cliff zone contains 124 million tonnes grading 0.46% Cu. To the north, a higher grade but smaller mineralized zone known as the Irishman Creek zone was discovered, but not delineated. Mineralization is related to a small, mid-Eocene, porphyritic quartz diorite to granodiorite stock that intruded older quartz monzonite and Triassic Karmutsen Group basalt. Disseminated and fracture-controlled chalcopyrite, bornite and minor molybdenite are hosted by all these lithologies. The best copper grades are directly related to high fracture density, particularly within quartz monzonite and altered basalt. Potassic alteration, as secondary biotite, is associated with copper mineralization, but other features such as a quartz stockwork, phyllic alteration and a well defined pyrite halo are absent at Catface. Recent sampling of the Cliff zone showed low gold content in the order of 50 ppb. Results from a recent airborne magnetometer survey, flown in 1989, show a direct response to the intrusion beneath the Cliff zone and also indicate the presence of a buried stock in the upper Irishman Creek basin. The I.P./ resistivity survey responded directly to copper mineralization over the Cliff zone. A chargeability anomaly indicates a south extension of untested mineralization. Metallurgical work completed to date shows that the best copper grades lie beneath partially oxidized low-grade material which causes variable copper recoveries. The environmental base-line studies at Catface showed that a mining operation is unlikely to generate acid mine water.

Keywords: Calc-alkalic, Cu-Mo deposit, Cliff zone, Mineralization, Chalcopyrite, Bornite, Molybdenite