Western Upper Peninsula, IOCG

Region Central, North Central
Mineral systems
Deposit types
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Permissive focus area is bounded by the Mesoproterozoic Midcontinent Rift System on the west and east, Lake Superior to the north, and the Niagara suture zone to the south.
Identified resources Unknown.
Production Unknown.
Status Past exploration drilling by Prime Meridian near Wilson Creek prospect.
Estimated resources No data.
Geologic maps Cannon (1986), scale 1:250,000.
Geophysical data Recent adequate USGS-acquired aeromagnetic data in limited areas (<25%), otherwise inadequate; inadequate aeroradiometric coverage.
Favorable rocks and structures Multiple favorable rock types throughout the western Upper Peninsula, including early Proterozoic (1750-1680 Ma) gneiss dome structures and related metamorphic nodes. Post-Penokean orogeny retrograde hydrothermal overprinting related to doming produced trace Cu-Fe sulfide and REE-bearing fluor-apatite and monazite, diagnostic of a possible IOCG signature.
Deposits No data.
Evidence from mineral occurrences No data.
Geochemical evidence Prime Meridian core from the Wilson Creek area (Michigan) has veins of massive chalcopyrite with trace Au, Sn, and Bi, along with magnetite, fluorite, epidote, K-spar, tourmaline, albite, and chlorite alteration, mineral assemblages, and structural features characteristic of IOCG mineralization. Mineralization consists of disseminated and/or fracture controlled veinlets of chalcopyrite-pyrite and lesser scheelite (< 2%) with magnetite/hematite as well as trace molybdenite locally.
Geophysical evidence No data.
Evidence from other sources No data.
Cover thickness and description Covered by Paleozoic rocks in the east (assumed to be <1 km) and glacial materials and recent alluvium in most other areas.
Authors Laurel G. Woodruff.
New data needs New mapping, high resolution geophysics.
Geologic mapping and modeling needs Need new geologic mapping.
Geophysical survey and modeling needs Need aeromagnetic, radiometric, and gravity data collection.
Digital elevation data needs Lidar adequate.