| Summary: | Many diverse ore systems are classified together as iron oxide copper-gold (IOCG) deposits based on an empirical definition arising primarily from geochemical features that do not specify tectonic setting, geologic environment, or sources of ore-forming fluid, metals, or other ore components. Such deposits have (1) Cu, with or without Au, as economic metals; (2) hydrothermal ore styles and strong structural controls; (3) abundant magnetite and/or hematite; (4) Fe oxides with Fe/Ti greater those in most igneous rocks and bulk crust; and (5) no clear spatial associations with igneous intrusions as, for example, displayed by porphyry and skarn ore deposits. IOCG deposits commonly have a space-time association with Kiruna-type apatite-bearing oxide Fe ores and many examples of the latter contain sulfide minerals, Cu, and Au. Most IOCG deposits display a broad spacetime association with batholithic granitoids, occur in crustal settings with very extensive and commonly pervasive alkali metasomatism, and many are enriched in a distinctive, geochemically diverse suite of minor elements including various combinations of F, P, Co, Ni, As, Mo, Ag, Ba, LREE, and U. Iron oxide Cu-Au systems are numerous and widely distributed in space and time; they occur on all continents and range in age from the present at least back into the Late Archean. In economic terms, the most important IOCG deposits are those in the Carajás district, Brazil (Archean, Amazon craton); in the Gawler craton and Cloncurry districts, Australia (late Paleoproterozoic to Mesoproterozoic debated intracratonic or distal subduction-related settings), and in the Jurassic-Cretaceous extended continental margin arc of the coastal batholithic belt in Chile and Peru. IOCG deposits and associated features define distinct metallogenic belts in which other types of Cu and Au deposits are rare or absent. The largest deposits include Salobo, Cristallino, Sossego, and Alemão (Carajás), Olympic Dam (Gawler craton), Ernest Henry (Cloncurry district), and Candelaria-Punta ...
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