GOLD-BEARING IRON-FORMATION IN A GRANULITE TERRANE OF THE CANADIAN SHIELD - A POSSIBLE DEEP-LEVEL EXPRESSION OF AN ARCHEAN GOLD-MINERALIZING SYSTEM

Gold occurs in metamorphosed iron-formation within a migmatized paragn eiss terrane in the Eastern Superior Province of the Canadian Shield. The main gold prospect, which is located 100 m from a tonalite pluton, has undergone skarn-like metamorphism that occurred late during the g ranulite grade metamorphism. Despite its occurrence in a high-grade me tamorphic host-rock, the mineralization shares many of the characteris tics of lower-grade Archean greenstone belt gold mineralization, such as: (1) enrichment in Au, As, S, Sb, W, U and FeO; (2) a low base-meta l/gold ratio; (3) the inclusion of gold in arsenopyrite; (4) the proxi mity to a felsic pluton; (5) an iron-rich, fractured host-rock; and (6 ) a similar mineralization time (around 2650 Ma). This gold occurrence occurs near the metamorphic peak and represents a deep level expressi on of the widespread crustal-scale mineralizing system documented for the late Archean. The main conclusion of this work is that the princip al characteristics of Archean gold mineralization are present in the d eep crust, and do not come from the leaching of upper-level rock piles , such as greenstone belts.