| he Ernest Henry deposit is a Proterozoic iron-oxide-copper-gold deposit hosted by rocks of the Cloncurry-Selwyn zone of the Mt. Isa Inlier, NW Queensland, Australia. It consists of a 50;A new core logging system, and newly developed data manipulation and presentation techniques, enable delineation of numerous breccia types defined by mineral assemblages and textures. The three main breccia types are: (a) unmineralized marble matrix breccia (footwall), (b) magnetite-rich ore breccias containing most of the mineralization, and (c) late, calcite-barite-quartz-rich breccias.;Beneath weathered ore, chalcopyrite and gold are the only ore minerals. Copper correlates strongly with iron, nickel, gold, uranium, molybdenum and chalcopyrite concentrations, and less strongly with pyrite, arsenic, bismuth, cobalt, lead and antinomy. Barium has a negative correlation with copper and gold.;Whole rock analyses show that the Al/Ti ratio of red-rock altered host rocks remained constant during brecciation and mineralization. Mass balance calculations (e.g., Gresens, 1967), and textural evidence indicate that ore breccias formed by replacement host rocks. Replacement probably occurred at or near constant volume. Breccia formation involved additions of Fe, Cu, Pb and volatiles ;Regional sodic ;Thermodynamic and stable isotope studies indicate that mineralization formed around 450... |
