The North Caribou terrane is one of the largest blocks with continental affinities in the western Superior Province. This paper reviews field relationships at the southern margin of this terrane in the western Uchi belt between Trout Lake, north-west Ontario, and Lake Winnipeg, Manitoba. After an introduction on the regional geological framework, the paper describes the Trout Lake Batholith, the Red Lake-Garner Lake lobe, the Bloodvein-Wanipigow River corridor, the English Lake magmatic complex, and the eastern Lake Winnipeg area. Implications of the observations for crustal architecture are discussed.

The Goldcorp high grade zone at the Red Lake mine in northern Ontario is currently the best Canadian example of high-grade gold mineralization. It provides an opportunity to define the fundamental geological parameters controlling the formation of high-grade gold ore and to assist in developing exploration guidelines for such mineralization. This report updates an ongoing study of the Red Lake high grade zone, beginning with a review of the local geological setting and a description of the southeast-trending structural lineament known as the Red Lake mine trend, defined by folds, faults, and an associated corridor of alteration & mineralization. The report then describes the structure, veins, ore zones, and alteration assemblages in the high grade zone and discusses the chronology of gold replacement, gold remobilization, and the geological controls on formation of the high grade zone.