Non-Midcontinent Rift mafic/ultramafic intrusions

Region Central, North Central
Mineral systems
Deposit types
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Mafic, ultramafic, and mixed phase sanukatoid-type intrusions (locally with mafic-ultramafic inclusions) in Minnesota, Wisconsin, Iowa, and Michigan that have plausible potential for magmatic sulfide and/or oxide mineralization.
Identified resources Unknown.
Production Unknown.
Status Unknown.
Estimated resources No data.
Geologic maps Jirsa and others (2012), scale 1:500,000; Reed and Daniels (1987), scale 1:500.000; Mudrey and others (1982), scale 1:100,000; Anderson (2006), scale 1:1,000,000.
Geophysical data Adequate to inadequate Rank 2 to 4 aeromagnetic coverage and inadequate aeroradiometric coverage.
Favorable rocks and structures Various types of mafic-ultramafic and multi-phase sanukatoid intrusions.
Deposits No data.
Evidence from mineral occurrences No data.
Geochemical evidence Highly variable; see Jirsa and others (2006).
Geophysical evidence Variable.
Evidence from other sources Variable.
Comments The GIS polygon for Minnesota is based on Jirsa and others (2006) with modifications based on subsequent published county atlas maps and the statewide geologic map (Jirsa and others, 2012, S-21).
Cover thickness and description Locally exposed but commonly covered with up to 200-300 meters of unconsolidated Quaternary sediment and local poorly consolidated Cretaceous sedimentary rocks.
Authors Benjamin J. Drenth, George Hudak, David Dahl, Amy Block.
New data needs Geological mapping with associated petrographic, geochemical, geochronological studies and subsurface investigations (drilling). Geophysical studies include bedrock topography (passive seismic) and detailed infill gravity.
Geologic mapping and modeling needs Geochemical analysis subsurface vein and deposit model.
Geophysical survey and modeling needs Magnetic survey to determine underlying basement control on sedimentary cover mineralization.
Digital elevation data needs Lidar variable; adequate, inadequate, and in progress.