The NICO cobalt-gold-bismuth and Sue-Dianne copper-silver deposits of the Mazenod Lake area, Northwest Territories, are currently being drill-delineated by Fortune Minerals Limited. They are the only known significant Canadian examples of the Proterozoic iron oxide-hosted polymetallic class, more commonly referred to as hydrothermal iron oxide copper-gold deposits. NICO and Sue-Dianne are located in the southern part of the Great Bear magmatic zone, the central tectonic subdivision of the Bear Structural Province. It is a post-collisional plutonic terrane with related continental volcanic rocks dating from 1867 Ma and culminating with the emplacement of A-type rapikivi granite plutons at approximately 1856 Ma. Iron oxide occurrences are widely distributed within the Great Bear magmatic zone, ranging from Salobo-type magnetite-rich schists and ironstones in receptive basement rocks to Kiruna-type magnetite-apatite-rich veins and Olympic Dam-type sulphidized magnetite-hematite breccias in overlying volcanic rocks. NICO is hosted in iron- and potassium-altered, brecciated basement sedimentary rocks at and beneath the volcanic unconformity, showing similarities to the Salobo-type. The host "black rock" amphibole-magnetite-biotite schists and ironstones are capped by potassium feldspar-magnetite "red rock" felsite. In contrast, Sue-Dianne shows the essential characteristics of Olympic Dam-type ores, with mineralization hosted within a well-zoned diatreme breccia complex crosscutting a rotated ash flow tuff succession above the unconformity. At both NICO and Sue-Dianne, ongoing detailed paragenetic studies demonstrate that early, reduced, high-temperature mineral assemblages are overprinted by late, oxidative, low-temperature assemblages. These together with stratigraphic relationships, indicate fluid mixing at shallow crustal levels was important in deposit formation. Proximity of the NICO and Sue-Dianne deposits to subvolcanic porphyries, rapakivi granite and various other phases of the Marian River Batholith, together with geochronology and mineralogy studies, suggest they are all genetically related. The occurrence of diverse iron oxide deposit types within the Great Bear magmatic zone, makes this region favourable for exploration and for the study of the Proterozoic iron oxide class as a whole.

The Southeast Missouri Iron Metallogenic Province is comprised of eight known major and numerous minor magnetite and hematite deposits. It is hosted by the Middle Proterozoic St. Francois granite-rhyolite terrane. Host rocks are rhyolites, trachytes, and andesites. Ore is associated with, although not necessarily hosted by, magnetite trachytes. Deposits are associated with caldera subsidence structures and, sometimes, trachyte ring intrusions. Deposits are within or near margins of these structures. Areal association of the deposits with a major Proterozoic tectonic zone, possibly a transform fault, suggests additional tectonic/ structural control on ore emplacement. Magnetite and hematite have been produced in the province; currently, only magnetite is produced. Potential exists for production of rare earth elements, copper, and gold.

A characteristic alteration suite is associated with the iron oxide mineralization. The suite includes silicification, potassium metasomatism, and alteration of host rock to actinolite, chlorite, garnet and epidote. While several alteration types are associated with each deposit, every type is not seen at each deposit.

Chemistry suggests that magnetite and hematite deposits in the province have a unique chemical signature when compared to magnetite not directly associated with the major deposits. In addition, hematite that is an oxidation product of magnetite has a different chemical signature than presumed primary hematite.

The Salobo iron oxide copper-gold deposit is located in the Carajas Mineral Province, northern Brazil. The copper-gold ore is hosted by the Archean Salobo-Pojuca Group, which is formed by a sequence of amphibolites, banded iron formations, metagraywackes and quartzites. These rocks were deposited in a trondhjemitic basement, where a continental rift basin, that has been further described as a pull apart basin, was developed. Principal ore assemblages are magnetite-bornite-chalcocite and magnetite-bornite-chalcopyrite, with magnetite dominant and variable amounts of copper sulphides. The iron oxide copper-gold ore shows elevated concentrations of Ag, U, Co, Mo, F and LREE. Differences in geochemistry and textures between magnetite of iron-rich rocks and magnetite of banded iron formation suggest a hydrothermal origin for the mineralization. Fluid inclusion data for quartz veins and apatite indicate the involvement of highly saline fluids in the deposit formation. Adominantly magmatic source of the sulphur is indicated by isotope ratios determined for chalcopyrite and bornite (834S between 0.2%o and 1.6%o). Petrographic evidence supported by preliminary geochronological data indicates that the mineralization post-dates the metamorphism. Hydrothermal alteration effects on host amphibolites have been also investigated. The studied amphibolites occur as lenses or layers close to the contact with the gneissic basement or included in metagraywackes of the Salobo-Pojuca Group. Trace element chemistry of these rocks indicates that they are subalkaline basalts with tholeiitic affinity. Based on the K.,0 content, three alteration groups have been defined and informally named "less altered", "medium altered" and "very altered" types. They characterize rocks affected by different degrees of alkali metasomatism, resulting in major compositional changes. "Less altered" rocks (<0.5 wt% K.,0) show minor chemical modifications compared to the inferred average compositions of unaltered precursors. "Medium altered" rocks (0.5-3.5 wt% K20) show alkali metasomatism expressed by incipient sodic alteration (up to 4.5 wt% Na20) and superposed potassic alteration. "Very altered" rocks are characterized by extensive potassic alteration, with K-feldspar and biotite formation and high K20 (>3.5 wt%) values. The spatial association of "very altered" rocks with the main ore zone suggests a relationship between alkali metasomatism and mineralization. Similarities in the the hydrothermal alteration pattern combined with the ore mineralogy and chemistry indicate that the Salobo deposit belongs to the class of iron oxide (Cu-U-Au-REE) deposits.

The Salobo 3 Alpha Deposit is found in the southeast of the Amazon Craton, north of the Serra dos Carajas, in the State of Para, Brazil. The deposit is contained in supracrustal rocks of Igarape Salobo Group of Archean age, represented by iron-rich schists, metagreywackes, amphibolites and quartzites. This sequence overlies the basement gneisses of the Xingu Complex composed of partially migmatized gneisses. The original stratigraphic relationships are masked by intense ductile-brittle shear zones responsible for the generation of allochthonous rocks. The deposit extends over an area of approximately 4000 metres along strike (NW), is 100 to 600 metres wide and has been recognised to depths of 750 metres below the surface. The estimated mineral resources are of the order of 789 Mt with 0,96% Cu and 0,52 g/t Au. Copper mineralization occurs as chalcocite and bomite, with subordinate quantities of chalcopyrite, together with variable proportions of molybdenite, cobaltite, covellite, gold and silver, lodged in schists with variable proportions of magnetite, amphibole, olivine, garnet, biotite, quartz and piagioclase. Brittle-ductile shear zone deformation has resulted in lenticular shaped ore shoots that characteristically show close associations between copper mineralization and magnetite contents. The host rocks were progressively metamorphosed to pyroxene hornfels facies, at equilibrium temperatures of 750°C, resulting from sinistral transcurrent transpressive shearing accompanied by oblique thrusting. A first hydrothermal event developed at temperatures between 650 to 550°C causing partial substitution of chalcopyrite by bornite and chalcocite, accompanied by intense K-metasomatism. This was followed by sinistral transcurrent transtensive shear zone formation, causing green schist facies metasomatism, characterized by intense chloritization and partial substitution of bornite by chalcocite. Several hypotheses have been proposed for the genesis of the deposit. Based on similarities in the ore mineralogy and the hydrothermal alteration pattern, this deposit could be ascribed to the large class of iron oxide copper-gold deposits.

The Igarape Bahia Au-Cu-(REE-U) deposit is located in the Carajas Mineral Province - Northern Brazil - and is hosted by an Archaean low-grade metamorphosed volcanosedimentary sequence characterized by metavolcanic rocks of the footwall and metavolcanoclastic/metasedimentary rocks of the hangwall. An intense hydrothermal alteration occurred in this sequence, promoting intense chloritization, Fe-metasomatism, Cu-sulphidation (chalcopyrite and bornite), carbonatization, silicification, tourmalinization and biotitization.

The Alemao copper-gold deposit is located within the Carajas Mineral Province of Northern Brazil and was discovered in 1996 by DOCEGEO using geophysical and geological techniques. Alemao is hosted by the Igarape Bahia Group, which comprises two lithological and stratigraphic domains: a lower metavolcanic unit composed of metavolcanic rocks and acid to intermediate volcanoclastics; and an upper clastic-chemical metasedimentary unit with volcanoclastic rocks. The Alemao ore body is covered by a 250 metres thick unconfonnable siliciclastic unit referred as the Aguas Claras Formation. The ore body, which is 500 metres in length and 50 to 200 metres wide, strikes NE-SW and dips steeply to the NW, being emplaced along the contact between the two stratigraphic domains of the Igarape Bahia Group. In the ore zone, the hydrothermal paragenesis is marked by ferric minerals (magnetite-hematite), sulphides (chalcopyrite, pyrite), chlorite, carbonate (siderite, calcite, ankerite) and biotite, with minor quartz, tourmaline, fluorite, apatite, uraninite, gold and silver. Sericite and albite are rare. The mineralisation is represented by hydrothermal breccias and "hydrothermalites" classified into two types: (1) the BMS type, composed of massive bands of magnetite and chalcopyrite and by polymitic breccias with a matrix comprising magnetite, chalcopyrite, siderite, chlorite, biotite and amphiboles; (2) the BCLS type breccia which comprises brecciated hydrothermalised volcanic rocks with chalcopyrite, bornite, pyrite, chlorite, siderite, ankerite, tourmaline and molybdenite in the matrix, as well as dissemination in the rock. The geochemical association of Fe-Cu-Au-U-REE in iron rich, heterolithic, hydrothermal breccias at the Alemao Cu-Au Deposit, as well as its possible association with an extensional tectonic setting, suggests a correlation with Olympic Dam type mineralization. The total estimated ore resources based on a krigging method is 170 Mt @ 1.5% Cu and 0.8g/tAu.

The Coastal Cordillera of Chile hosts several world-class FeOx CuAu deposits, including Candelaria, Mantos Blancos, Manto Verde, and El Soldado. Despite this comparatively little has been published on Chilean FeOx CuAu systems. This paper presents observations from two small Chilean FeOx CuAu deposits of Lower Cretaceous age; Panulcilio and Teresa de Colmo.

Panulcilio is a pseudo-stratiform FeOx CuAu / Skarn deposit located within the metamorphic aureole of a monzodioritic intrusive. Chalcopyrite, bornite, pyrite and pyrrhotite occur with calcic amphibole as disseminations and microveinlets in K-feldspar-albite-silica altered meta-andesites, magnetite-albite-scapolite rich mcta-andcsites and in overlying garnet skam.

La Candelaria is the largest of the iron oxide Cu-Au(-Zn-Ag) deposits in the Punta del Cobre belt, which also hosts the Punta del Cobre district, sensu strictu. The Punta del Cobre belt lies within an Early Cretaceous continental volcanic arc/marine back-arc basin terrane. The volcanic arc and marine carbonate back-arc sequences are intruded by Early Cretaceous granitoid plutons that form part of the Chilean Coastal Batholith. The deposits of the Punta del Cobre belt occur along the eastern margin of the batholith within (e.g., La Candelaria) or just outside the contact metamorphic aureole (e.g., the Punta del Cobre district). Andesitic volcanic and volcaniclastic host rocks are intensely altered by biotite-quartz-magnetite. This style of alteration extends much further to the east of the intrusive contact than the metamorphic mineral associations in the overlying rocks that are clearly zoned outboard. Local areas of intense calcic amphibole veining that overprints all rock types occur within the contact metamorphic aureole.

Gold-copper-bismuth deposits of the Tennant Creek district, Northern Territory, Australia, are distinctive as some of the highest grade deposits within the Fe-oxide Cu-Au global family. They are unified by an association with epigenetic magnetite ± hematite - rich 'ironstones' that are hosted by a sequence -I860 Ma, low metamorphic grade, Fe-oxide rich greywacke, siltstone and shale. While many of the high grade gold orebodies are dominated by magnetite - chlorite ± minor hematite, muscovite and pyrite, there are significant variations representing a spectrum of styles from reduced (pyrrhotite-bearing) Cu-Au-Bi deposits to oxidised hematitic Au-Bi(Cu) deposits. Shear-hosted Au-Cu mineralisation outside ironstones further adds to the diversity of styles present in the district. Ironstones predated syn- to late-deformational ~1825-1830 Ma introduction of Au, Cu and Bi in ~-300-350°C, acidic, low-moderate salinity or hypersaline fluids, which were in places carbonic and nitrogenous. The very wide range of oxidation-reduction conditions during ore deposition across the district is interpreted as the product of both reduced (magnetite ± pyrrhotite stable, H2S > S04=) and oxidised (hematite stable, S04= > H2S) fluids reacting with ironstones and/or mixing. Oxygen and hydrogen isotope data point to an hybrid ore fluid source with input of evolved surficial or formation waters, whereas Sm-Nd reconnaissance data and sulfur isotope compositions are consistent with contributions from igneous sources.

Cu-Au(-Mo) mineralisation at the Portia-North Portia prospect is located under cover on the eastern flank of the Benagerie Ridge Magnetic Complex, within the Curnamona Province and approximately 125 km WNW of Broken Hill. The mineralisation is located within rocks which have a SHRIMP U-Pb zircon age of 1703 + 6 Ma, which is similar to Willyama Supergroup ages obtained from the Broken Hill and Olary Domains. The meta-sedimentary unit that hosts the mineralisation is approximately 200m thick and is overlain by carbonaceous phyllite, and underlain by a unit which is dominated by albite-magnetite-hematite. The host units contain numerous carbonate-rich domains intercalated with meta-evaporitic sediments. The sequence had undergone low-grade metamorphism and fabric development and was subsequently intensely albitised. Hydrothermal monazites formed during this albitisation event give SHRIMP II in situ U-Pb ages of ~1630 Ma. The albitised meta-sediments proved to be an excellent host to the later Cu-Au(-Mo) mineralisation. Abundant monazite associated with the mineralisation yield SHRIMP II ages of ~1605 Ma. It is possible that the numerous, highly fractionated and altered diorite bodies known to be present on the Benagerie Ridge, may have produced some of the metals. The "Hiltaba age" (-1585-1590 Ma) granites of the area cannot be considered as a source of the metals.