Tectono-stratigraphic setting of the Galore Creek Cu-Au alkaline porphyry deposits, British Columbia

2006

The Galore Creek property, operated by NovaGold Canada Inc. is an alkalic-porphyry-copper-gold-silver deposit located approximately 200 kilometers north of Stewart, British Columbia. As of May 2005, based on an equivalent copper cut-off grade of 0.35%, the deposit has a combined Measured and Indicated resource of 516.7 Mt containing 0.59% copper, 0.36g/t gold, and 4.5g/t silver. NovaGold completed 63,349 meters of drilling in 252 holes during 2005. This drilling resulted in the forth successful discovery in three field seasons. Upper Triassic volcanoclastic strata of the Stuhini group and hypabyssal intrusions host disseminated chalcopyrite and bornite mineralization. Disseminated sulfide in the volcanoclastic strata shows increased concentration parallel to gross lithological layering. Alteration mineralogy also reveals geometries indicative of chemical control by protolith chemistry. The Stuhini sediments contain mud-matrix debris flows derived from resedimented pyroclastic material and pillowed lavas. Interbedded D-E turbidites and bedded chert reveal a sub-wave base depositional environment, and the lack of terrigenous material suggests deposition in a protected basin isolated from a continental sediment source. The Indonesian island arc may proxy as a modern-day analog. A deep extensional basin located between the Java trench and the arc-centered islands of Java and Sumatra represents the tectono-stratigraphic setting envisaged at Galore. Eruptive centers, such as Krakatoa, feed pyroclastic material that resediments by mass gravity flow into the adjacent basin. Syenite sills and stocks intrude partially lithified sediments and form the mineralizing hydrothermal system.

Keywords: Gold, Copper, Alkaline Porphyry, Galore Creek, Stuhini, British Columbia