PB-ZN-AG OREBODIES IN CAMBRIAN CARBONATES DEPOSITED ON THE WESTERN CRATONIC PLATFORM AND IN THE ADJACENT WHITE RIVER TROUGH, SOUTHEASTERN BRITISH COLUMBIA

Cambrian carbonates in the southern Rocky Mountain region of B. C. host numerous Pb-Zn-Ag orebodies and pyrite occurrences ranging from showings to deposits with extensive exploration and production histories. The sulfides, widely associated with Mg-rich exhalite deposits, hydrothermal dolostone, magnesite, and talc are concentrated in three belts: 1) Kicking Horse Rim, along the east margin of White River Trough, 2) the west side of the latter trough, where Cambrian strata onlap Windermere High, and 3) the axial region of White River Trough near Late Devonian alkaline intrusions. Mississippi-Valley-Type (MTV) orebodies predominate but sedimentary-exhalative, vein, and oxide deposits occur. Along both sides of White River Trough, the Cambrian is dominated by quartzite of the Gog Group and overlying platform carbonates that pass basinward into slope and basin facies of the Chancellor Group. The age of the MVT Pb-Zn-Zn mineralization along Kicking Horse Rim and west side of White River Trough is poorly constrained. None of the sulphide orebodies are currently being mined.

Along Kicking Horse Rim, most sulphides occur in the Middle Cambrian Cathedral, Eldon, and Takakkaw formations and are closely associated with platform-margin escarpments and the fabulous Burgess Shale and Stephen fossils. But some orebodies lie as high as the Upper Cambrian Sullivan Formation. Along Kicking Horse Rim, the Monarch and Kicking Horse mines were past producers. Other orebodies along the trend (Shag, Hawk Creek) saw extensive exploration work.

Along the western flank of White River Trough, the Middle and Upper Cambrian Jubilee Formation contains numerous Pb-Zn-Ag sulphide deposits. Most are small, but several have been extensively explored (Lead Mountain, Legacy) and the Silver Giant was a significant producer. The Pb-Zn-Ag orebodies at the Silver Giant Mine on the southwestern side of Jubilee Mountain are MTV and vein deposits hosted by the Jubilee. Carbonate-hosted ore deposits in the belt differ from those along Kicking Horse Rim by containing barite instead of dolomite as the main gangue mineral. Several barite showings and producing barite mines that contain minor galena and sphalerite and resemble those along the eastern flank of Windermere High also occur in the Jubilee on the eastern side of the Rocky Mountain Trench.