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Mafic magmatic

Mafic magmatic systems generally form in large igneous provinces related to mantle plumes meteorite impacts. Nickel-copper sulfide ores with PGEs result from settling and accumulation of immiscible sulfide liquids in mafic layered intrusions and ultramafic magma conduits. In layered intrusions, Fe-Ti oxides, chromite and PGE minerals crystalize from evolving parental magmas and are con-centrated by physical processes in cumulate layers. In anorthosites, Fe-Ti oxides ± apatite crystalize from residual magmas entrained in plagioclase-melt diapirs. In convergent settings, Alaskan-type intrusions with Fe-Ti oxides and PGE form from mantle melts.
Color on map:

Deposit types

Name Commodities Critical minerals
Chromite Cr Cr
Nickel-copper-PGE sulfide Ni, Cu, Co, PGE, Ag, Au, Se, Te Co, PGE, Te
PGE (low sulfide) PGE PGE
Iron-titanium oxide Fe, Ti, V, P Ti, V, REE

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 = Mafic magmatic

77 focus areas match these criteria.

Focus area Region States Mineral Systems Deposit types Commodities
Chugach Mountains-Kodiak Island PGE Alaska Alaska Mafic magmatic Chromite; Nickel-copper-PGE sulfide copper; gold; selenium; silver
Goodnews Bay (Kilbuk Terrane) PGE Alaska Alaska Mafic magmatic Chromite; Nickel-copper-PGE sulfide copper; gold; selenium; silver
Kokrine Hills-Yukon Flats (Tozitna and Angayucham Terranes) PGE Alaska Alaska Mafic magmatic Chromite; Nickel-copper-PGE sulfide copper; gold; selenium; silver
Northern Brooks Range (Angayucham Terrane) PGE Alaska Alaska Mafic magmatic Chromite; Nickel-copper-PGE sulfide copper; gold; selenium; silver
Southeast Alaska Fairweather trend PGE Alaska Alaska Mafic magmatic Chromite; Nickel-copper-PGE sulfide copper; gold; selenium; silver
Southeast Alaska PGE Alaska Alaska Mafic magmatic Chromite; Nickel-copper-PGE sulfide copper; gold; selenium; silver
Southern Brooks Range (Angayucham Terrane) PGE Alaska Alaska Mafic magmatic Chromite; Nickel-copper-PGE sulfide copper; gold; selenium; silver
Talkeetna Mountains-Eastern Alaska Range PGE Alaska Alaska Mafic magmatic Chromite; Nickel-copper-PGE sulfide copper; gold; selenium; silver
Yukon-Tanana Upland (Seventymile Terrane) PGE Alaska Alaska Mafic magmatic Chromite; Nickel-copper-PGE sulfide copper; gold; selenium; silver
Eastern Upper Peninsula mafic intrusion North Central Michigan Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Mentor Intrusive Complex North Central Minnesota Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Midcontinent Rift conduit-type magmatic sulfide Ni-Cu-PGE North Central Michigan; Minnesota; Wisconsin Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Midcontinent Rift large mafic intrusions North Central Minnesota; Wisconsin Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Midcontinent Rift layered Ti-Fe in the Duluth Complex North Central Minnesota Mafic magmatic Iron-titanium oxide iron; phosphorus
Midcontinent Rift mafic-ultramafic satellite intrusions North Central Michigan; Wisconsin Mafic magmatic Iron-titanium oxide; Nickel-copper-PGE sulfide copper; gold; iron; phosphorus; selenium; silver
Midcontinent Rift oxide-ultramafic intrusions (OUIs) North Central Minnesota Mafic magmatic Iron-titanium oxide; Nickel-copper-PGE sulfide copper; gold; iron; phosphorus; selenium; silver
Midcontinent Rift 'reef'-type PGE North Central Minnesota; Wisconsin Mafic magmatic PGE (low sulfide) (none)
Neoarchean Greenstone Belts of Minnesota, North Dakota and South Dakota North Central Minnesota; North Dakota; South Dakota Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Non-Midcontinent Rift mafic/ultramafic intrusions North Central Iowa; Michigan; Minnesota Mafic magmatic Iron-titanium oxide; Nickel-copper-PGE sulfide copper; gold; iron; phosphorus; selenium; silver
Northeast Iowa intrusive complex (NEIIC) North Central Iowa; Minnesota; Wisconsin Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Otter Creek complex and related Iowa intrusions North Central Iowa Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
South Dakota mafic intrusions North Central Nebraska; South Dakota Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Walsh County gabbro North Central North Dakota Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Boil Mountain Complex Northeast Maine Mafic magmatic Chromite; Nickel-copper-PGE sulfide asbestos; copper; gold; selenium; serpentinite; silver; talc
CAMP event-Newark-Gettysburg Basin Northeast Maryland; New Jersey; New York; Pennsylvania Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Connecticut Ni-Co-Cu sulfides Northeast Connecticut Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Hartford-Deerfield Mesozoic Basin Northeast Connecticut; Massachusetts Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Maryland Ni-Co-Cu sulfides Northeast Maryland Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Moxie Pluton Northeast Maine Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Ore Mountain (Katahdin Iron Works) Northeast Maine Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Sanford Lake-Tahawas Mining District Northeast New York Mafic magmatic Iron-titanium oxide iron; phosphorus
Saratoga Nickel District Northeast New York Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
St. Lawrence Pyrites Complex Northeast New York Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
State Line district/BMC (Baltimore Mafic Complex) Northeast Delaware; Maryland; New Jersey; Pennsylvania Mafic magmatic Chromite asbestos; serpentinite; talc
Union-Warren nickel sulfide deposits Northeast Maine Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Vermont ultramafic belt Northeast Vermont Mafic magmatic Chromite asbestos; serpentinite; talc
Washington County intrusive rocks Northeast Maine Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Bitterroot Range anorthosite Northwest Montana Mafic magmatic Iron-titanium oxide iron; phosphorus
Blue Mountains province Northwest Oregon Mafic magmatic Chromite (none)
California Coastal Ranges chromite Northwest California Mafic magmatic Chromite (none)
Klamath Mountains chromite Northwest California; Oregon Mafic magmatic Chromite (none)
Ingalls ophiolite Northwest Washington Mafic magmatic Chromite; Nickel-copper-PGE sulfide copper; gold; iron; selenium; silver
Lady of the Lake mafic intrusive Northwest Montana Mafic magmatic PGE (low sulfide) gold
Moyie Northwest Idaho; Montana; Washington Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
North-Central Washington ultramafics Northwest Washington Mafic magmatic Chromite; Nickel-copper-PGE sulfide copper; gold; iron; selenium; silver
Red Lodge chromite Northwest Montana Mafic magmatic Chromite (none)
Sierra Nevada foothills chromite Northwest California Mafic magmatic Chromite (none)
Stillwater Complex Northwest Montana Mafic magmatic Chromite; Nickel-copper-PGE sulfide; PGE (low sulfide) copper; gold; selenium; silver
Tobacco Root chromite Northwest Montana Mafic magmatic Chromite (none)
Wolf Creek pluton/Ruby Mountains Northwest Montana Mafic magmatic Chromite; Nickel-copper-PGE sulfide copper; gold; selenium; silver
Central Laramie Range Rocky Mountains Wyoming Mafic magmatic Chromite; Iron-titanium oxide; Nickel-copper-PGE sulfide copper; gold; iron; lead; phosphorus; selenium; silver
Medicine Bow Mountains Rocky Mountains Colorado; Wyoming Mafic magmatic Chromite; Iron-titanium oxide; Nickel-copper-PGE sulfide copper; gold; iron; lead; phosphorus; selenium; silver
Sierra Madre Rocky Mountains Colorado; Wyoming Mafic magmatic Chromite; Nickel-copper-PGE sulfide copper; gold; iron; lead; selenium; silver; vermiculite
Sweetwater Arch Rocky Mountains Wyoming Mafic magmatic Chromite; Nickel-copper-PGE sulfide copper; gold; selenium; silver
Wet Mountains Rocky Mountains Colorado Mafic magmatic Iron-titanium oxide; Nickel-copper-PGE sulfide iron; phosphorus; silver
Wyoming Metasedimentary and Metavolcanic Belts Rocky Mountains Wyoming Mafic magmatic Chromite; Iron-titanium oxide; Nickel-copper-PGE sulfide copper; gold; iron; phosphorus; selenium; silver
Elliot County peridotite South Central Kentucky Mafic magmatic Chromite; PGE (low sulfide) (none)
Wichita event—Glen Mountains Complex South Central Oklahoma Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
CAMP event-Virginia, North Carolina Mesozoic basins Southeast North Carolina; Virginia Mafic magmatic Nickel-copper-PGE sulfide; PGE (low sulfide) copper; gold; selenium; silver
Concord-Salisbury Plutonic Suite Southeast Georgia; North Carolina; South Carolina Mafic magmatic Chromite dimension stone
South Central Triassic basins Southeast Alabama; Florida; Georgia; North Carolina; South Carolina Mafic magmatic Chromite; Nickel-copper-PGE sulfide; PGE (low sulfide) copper; gold; selenium; silver
Southeast Ultramafics Cr-Mg; Blue Ridge belt Southeast Georgia; North Carolina; Virginia Mafic magmatic Chromite anthophyllite; asbestos; olivine; serpentine; talc-soapstone
Southeast Ultramafics Cr-Mg; Carolina Slate belt Southeast North Carolina Mafic magmatic Chromite anthophyllite; asbestos; olivine; serpentine; talc-soapstone
Southeast Ultramafics Cr-Mg; Charlotte belt Southeast North Carolina Mafic magmatic Chromite anthophyllite; asbestos; olivine; serpentine; talc-soapstone
Southeast Ultramafics Cr-Mg; Eastern Slate belt Southeast North Carolina Mafic magmatic Chromite anthophyllite; asbestos; olivine; serpentine; talc-soapstone
Southeast Ultramafics Cr-Mg; Georgia, undifferentiated Southeast Georgia Mafic magmatic Chromite anthophyllite; asbestos; olivine; serpentine; talc-soapstone
Southeast Ultramafics Cr-Mg; Inner Piedmont Southeast Alabama Mafic magmatic Chromite anthophyllite; asbestos; olivine; serpentine; talc-soapstone
Southeast Ultramafics Cr-Mg; Inner Piedmont, Smith River Allochthon, Sauratown Mountain Southeast North Carolina Mafic magmatic Chromite anthophyllite; asbestos; olivine; serpentine; talc-soapstone
Southeast Ultramafics Cr-Mg; Raleigh belt Southeast North Carolina Mafic magmatic Chromite anthophyllite; asbestos; olivine; serpentine; talc-soapstone
Southeast Ultramafics Cr-Mg; South Carolina, undifferentiated Southeast South Carolina Mafic magmatic Chromite anthophyllite; asbestos; olivine; serpentine; talc-soapstone
Virginia nelsonites Southeast Virginia Mafic magmatic Iron-titanium oxide iron; phosphorus
Yadkin-Richland Mining District Southeast North Carolina Mafic magmatic Iron-titanium oxide iron; phosphorus
Friday Mine Southwest California Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Pecos Southwest New Mexico; Texas Mafic magmatic Nickel-copper-PGE sulfide; PGE (low sulfide) copper; gold; selenium; silver
San Gabriel Mountains anorthosite Southwest California Mafic magmatic Iron-titanium oxide iron; phosphorus
Southwest diabase province Southwest Arizona Mafic magmatic Nickel-copper-PGE sulfide copper; gold; selenium; silver
Zuni Mountains PGE Southwest New Mexico Mafic magmatic PGE (low sulfide) (none)