Geology and Ore Deposits of the Whitehorse Ore Zone. Yukon Territory, Canada

Abstract

Renewed exploration of the old copper prospect in Whitehorse, Yukon Territory, by field studies, geophysical prospecting and diamond drilling, had led to finding and evaluation of significantly workable ore reserves. The mining operations and shipping activities by the New Imperial Mines Ltd. were opened at the end of 1966.
The ore deposits are of a pyrometasomatic copper deposit type with several kinds of contact-metamorphic silicates. Bornite and chalcopyrite are the principal copper sulphides in most of the deposits, while valleriite is found locally.
Mineralization is in both Triassic limestone and adjoining granitic rocks. There are two distinct. classes of skarn ore bodies as listed below.
(1) Copper sulphides associated with magnetite or magnetite and hematite.
(2) Copper sulphides associated with contact metamorphic silicate minerals.
The former prevails in the central part of the "Copper Belt", while the latter lies in the northernand southernmost parts.
Some diagnostic characters of the deposits are as follows:
(1) Bornite and chalcopyrite are commonly disseminated throughout silicate-and iron-rich skarns while, pyrite is found in relatively small amounts.
(2) The existence of valleriite, cubanite and scheelite suggests that some deposits are formed at fairly high temperatures.
(3) In general, skarn minerals in this "Copper Belt" are of high magnesian content, compared with similar ore deposits in Japan.
(4) A Keewenaw ore deposit resembles the "porphyry copper" type deposit, although its scale is small.