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Menominee Group; Blair Creek Formation

Menominee Group; Blair Creek Formation - Dominantly dark-gray, massive, porphyritic tholeiitic basalt. Includes a basal conglomerate and a lean iron-formation in middle of formation
State Michigan
Name Menominee Group; Blair Creek Formation
Geologic age Early Proterozoic
Comments continental margin assemblage (north of Niagara Fault)
Primary rock type basalt
Secondary rock type iron formation
Other rock types conglomerate
Lithologic constituents
Major
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)
Minor
Sedimentary > Chemical > Banded-iron-formation (Bed)
Metamorphic > Metasedimentary > Metaclastic > Metaconglomerate (Bed)metaconglomerate
Map references
Sims, P.K., 1992, Geologic map of Precambrian rocks, southern Lake Superior region, Wisconsin and northern Michigan: U.S. Geological Survey Miscellaneous Investigations Map I-2185, scale= 1:500,000
Unit references
Sims, P.K., 1992, Geologic map of Precambrian rocks, southern Lake Superior region, Wisconsin and northern Michigan: U.S. Geological Survey Miscellaneous Investigations Map I-2185, scale= 1:500,000
Counties Gogebic - Ontonagon