Geology, hydrothermal alteration and mineralization of the gold eagle deposit: A new discovery in the Red Lake Camp, Canada.

摘要

Greenstone belts have been recognized as highly prospective settings for high grade gold mineralization, and are host to a number of world class quartz-carbonate vein deposits, which account for approximately 13% of the cumulative global gold production. In Canada, the Archean Red Lake Greenstone Belt hosts one of Canada's richest gold districts (cumulative production to 2008 of over 24 M oz at 0.461 oz/t). Recently, there have been many discoveries in the district including the Gold Eagle occurrence (also referred to as the Bruce Channel Deposit and Cochenour project), which has an inferred resource of 2.7 million ounces of gold at an average grade of 11.04 g/t Au. The auriferous ore zones in the Gold Eagle Deposit are hosted in volcano-sedimentary rocks of the Balmer Assemblage (2.99-2.96 Ga), which is controlled by a major north trending, west dipping deformation corridor sub-parallel to the Balmer Assemblage-Bruce Channel Assemblage contact. The vertical extent of the mineralization is controlled by the "Cochenour Thrust" that extends into the adjacent Cochenour-Willans Mine. The four main ore zones are structurally controlled within a NS, west dipping fault corridor and consist of: 1) the quartz-actinolite zone; 2) banded iron formations, 3) sulphide replacement zones and 4) footwall ore zones. The deposit has undergone pervasive pre-ore biotite and carbonate alteration, two gold events with the first associated with silicification and late actinolite-tremolite and the second associated with arsenopyrite sulphidation and iron-rich biotite and post-ore quartz and carbonate veinlets. Late faults (including black line faults) have contributed to the complexity and discontinuity of the ore bodies.