Iron Oxide ± Cu ± Au Deposits in the Iron Range, Purcell Basin, Southeastern British Columbia

摘要

The Iron Range iron oxide + Cu ± Au deposits in southeastern British Columbia comprise massive lenses and veins of hematite and martite with lesser magnetite in the Iron Range fault zone, which crosscuts the Pro-terozoic Aldridge Formation and Moyie sills. The mineralized zones are flanked by albite-quartz-iron oxide breccia within sedimentary rocks and by chlorite-altered iron oxide breccia where they are in contact with Moyie sills. Oxygen isotope analyses indicate 340° to 400°C precipitation temperatures for the albite-quartz-magnetite assemblages in the mineralized zones. Magnetite trace element compositions closely compare with those in iron oxide-(copper-gold) (IOCG) to porphyry-type mineralization worldwide. Paleomagnetic studies show consistent paleopole orientations concordant with Cretaceous poles and support links to a porphyry-type genesis associated with phases of the nearby 80 to 105 Ma magnetite-bearing Bayonne Suite plutonic rocks. The Iron Range iron oxide mineralized zones share many characteristics of major IOCG deposits, with the exception of economic Cu (± Au) concentrations in the exposed rocks; however, recent drilling intersected minor chalcopyrite, pyrite, and gold.