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IOA-IOCG

IOA-IOCG systems form in both subduction- and rift-related magmatic provinces. IOA deposits form as hot brine discharged from subvolcanic mafic to intermediate composition intrusions reacts with cool country rocks. Albitite uranium deposits form at deeper levels where brines albitize country rocks. IOCG deposits form on the roof or periphery of IOA mineralization at lower temperatures, often with involvment of external fluids. Polymetallic skarn, replacement and vein deposits occur out board from IOCG deposits. Mn replacement and lacustrine Fe deposits form near or at the paleosurface.
Color on map:

Deposit types

Name Commodities Critical minerals
Albitite uranium U U
Iron oxide apatite Fe REE
Iron oxide copper gold Cu, Au, U, Co, Se U, Co
Skarn iron Fe, P REE, Ge
Polymetallic sulfide S-R-V Ni, Co, Mo, Cu, Zn, Pb, Ag, Au Co, Re, Ge, Ga, In, Bi, Te, Sb, As
Replacement manganese Mn Mn, Co
Lacustrine iron Fe not-applicable

References

Source: Hofstra, A.H., and Kreiner, D.C., 2020, Systems-Deposits-Commodities-Critical Minerals Table for the Earth Mapping Resources Initiative: U.S. Geological Survey Open-File Report 2020-1042, 24 p., https://doi.org/10.3133/ofr20201042.

List of Earth MRI focus areas with mineral system = IOA-IOCG

23 focus areas match these criteria.

Focus area Region States Mineral Systems Deposit types Commodities
Kasaan Peninsula (Prince of Wales Island) Alaska Alaska IOA-IOCG Iron oxide copper gold; Polymetallic sulfide S-R-V copper; gold; iron; lead; molybdenum; silver
Seward Peninsula IOCG Alaska Alaska IOA-IOCG Iron oxide copper gold; Polymetallic sulfide S-R-V copper; gold; iron; lead; molybdenum; silver
Peavey Pond Complex North Central Michigan; Wisconsin IOA-IOCG Iron oxide apatite; Iron oxide copper gold copper; gold; iron; selenium; uranium
Post-Penokean Geon 17 magmatic rocks North Central Iowa; Michigan; Minnesota; Wisconsin IOA-IOCG Iron oxide apatite; Iron oxide copper gold copper; gold; iron; selenium; uranium
Spencer Intrusive Complex North Central Iowa IOA-IOCG Iron oxide apatite; Iron oxide copper gold copper; gold; iron; selenium; uranium
Western Upper Peninsula, IOCG North Central Michigan; Wisconsin IOA-IOCG Iron oxide apatite; Iron oxide copper gold copper; gold; iron; selenium; uranium
Wolf River Batholith North Central Wisconsin IOA-IOCG Iron oxide apatite; Iron oxide copper gold copper; gold; iron; selenium; uranium
Adirondack magnetite-apatite deposits Northeast New York; Vermont IOA-IOCG Iron oxide apatite iron
Cornwall Mines Northeast Pennsylvania IOA-IOCG Polymetallic sulfide S-R-V; Skarn iron copper; gold; iron; lead; molybdenum; phosphorus; silver; sulfur
Port Leyden mine area Northeast New York IOA-IOCG Iron oxide apatite iron
Copper Camp Northwest Idaho IOA-IOCG Iron oxide copper gold copper; gold; selenium; uranium
Idaho Cobalt Belt Northwest Idaho IOA-IOCG Iron oxide copper gold; Polymetallic sulfide S-R-V copper; gold; lead; molybdenum; selenium; silver; uranium
Indian Creek Mining District Northwest Idaho IOA-IOCG Iron oxide copper gold; Polymetallic sulfide S-R-V copper; gold; lead; molybdenum; selenium; silver; uranium
Manganese in Igneous Rocks South Central Missouri IOA-IOCG Replacement manganese iron
South-Central IOA-IOCG province South Central Arkansas; Illinois; Iowa; Missouri; Ohio; Wisconsin IOA-IOCG Iron oxide apatite; Iron oxide copper gold copper; gold; iron; silver; uranium
Southeast Missouri Iron Metallogenic Province South Central Missouri IOA-IOCG Iron oxide apatite; Iron oxide copper gold copper; gold; iron; selenium
SE Piedmont Rift Zones uranium (Coles Hill type) Southeast North Carolina; Virginia IOA-IOCG Albitite uranium arsenic; barium; nickel; phosphorus; REE; scandium; uranium
Cortez Mountains Southwest Nevada IOA-IOCG Iron oxide apatite iron
Humboldt Mafic Complex Southwest Nevada IOA-IOCG Iron oxide apatite; Iron oxide copper gold; Polymetallic sulfide S-R-V copper; iron; gold; lead; molybdenum; selenium; silver; uranium
Iron Axis Southwest Utah IOA-IOCG Skarn iron iron; phosphorus
Jackson Mountains Southwest Nevada IOA-IOCG Iron oxide apatite iron
Jurassic Arc Southwest California; Nevada IOA-IOCG Iron oxide apatite; Iron oxide copper gold copper; gold; iron; silver; uranium
Lower Colorado River IOCG Southwest Arizona; California IOA-IOCG Iron oxide copper gold; Skarn iron copper; gold; iron; phosphorus; selenium; uranium