Open Collections

Geology of the Island Copper mine, Port Hardy, British Columbia

University of British Columbia

The Island Copper deposit at Port Hardy, approximately 200 miles northwest of Vancouver, B.C., consists of two ore zones with total reserves of 280,000,000 tons of 0.52 percent copper and 0.029 percent molybdenite. Ore zones occur in Jurassic andesitic rocks in the hanging wall and footwall of a quartz-feldspar porphyry dyke. Breccias with volcanic and intrusive fragments cap the dyke and occur along the margins. Chalcopyrite and molybdenite occur in all rocks, but ore grade concentrations are restricted to volcanic rocks and marginal breccias. The rocks have been subjected to contact thermal meta-morphism and to hydrothermal alteration. The metamorphic aureole can be subdivided into an inner zone, adjacent to the dyke, characterized by biotite and magnetite; an intermediate, transitional zone characterized by chlorite; and an outer zone characterized by epidote. The ore zone is associated with the inner (biotite) zone and the inner part of the intermediate (transitional) zone. The hydrothermal alteration which occurs in volcanic rocks, breccias and the porphyry dyke is characterized by formation of sericite, pyrophyllite and a kaolin group mineral. Pyrophyllite is largely restricted to the breccia which caps the dyke. Sericite and the kaolin group mineral(s) occur in the marginal breccias and in sericite envelopes on quartz veins and open fractures cutting volcanic rocks and the porphyry dyke. There are five stages of chalcopyrite deposition and three stages of molybdenite deposition. However, field evidence supported by statistical study indicates that the first stage of copper deposition accounts for the bulk of metal in the orebody. Most of the chalcopyrite was deposited before the bulk of the molybdenite. GEOLOG format proved a quick and effective method of recording wall rock alteration observed in drill core. Statistical study of correlation, between abundance of alteration minerals and copper and molybdenite grades, yielded information on the importance of different stages of sulphide deposition to the ore zone. However a knowledge of age relations of alteration and ore minerals was essential to an interpretation of the statistical results.

Text

2010-02-05

For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.

http://hdl.handle.net/2429/19613

Geological Sciences

University of British Columbia

Graduate