Huckleberry porphyry copper deposit, Tahtsa Lake district, west-central British Columbia

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

The Huckleberry copper-molybdenum porphyry system is located in the Tahtsa Lake district of west-central British Columbia. The system contains two copper-molybdenum zones that are associated with porphyritic hornblende-biotite-feldspar granodiorite intrusions of Late Cretaceous age (Bulkley Intrusions) which have intruded Jurassic Hazelton Group volcanic rocks. Mineralization in both zones is largely within hornfelsed Hazelton Group volcanic rocks surrounding the porphyritic intrusions, although significant mineralization also occurs within the East zone stock. Mineralization in both zones occurs within a stockwork system of fractures and veinlets of chalcopyrite with lesser molybdenite and gangue minerals including pyrite, quartz and anhydrite. The strength of development of mineralization is directly related to the intensity of biotitization and albitization of both the host volcanic rocks and the granodioritic porphyries. The ore zones at Huckleberry are enclosed by an easterlyoriented zone of alteration approximately 4 km long and 1 km to 2 km wide. The Main zone occurs along the eastern periphery of a subcircular stock located in the western part of the alteration zone and is further centred on an apophysis of the stock. Most of the mineralization occurs in an arc measuring 500 m by 100 m. The FAST zone occurs within and surrounding a similar porphyritic stock in the eastern part of the system and is approximately 900 m by 300 m and remains open at depth. The East zone appears to be centered on an apophysis of the East zone stock. The Main zone contains a fully diluted in situ reserve of 53. 7 million tonnes grading 0.445% Cu, 0.013% Mo and 0.06 gl t Au, based on a 0.30% Cu cutoff. The East zone contains an in situ reserve of 108.4 million tonnes grading 0.484% Cu, 0.014% Mo and 0.055 gl t Au at a cutoff grade of 0.30% Cu.

Keywords: Copper-molybdenum, Porphyry, Mineralization, Zone of alteration.