Neoarchean Greenstone Belts of Minnesota, North Dakota and South Dakota

Region Central, North Central
Mineral systems
Deposit types
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Archean and younger granites suspected to have significant potential for LCT pegmatites, based on their setting (see Selway and others, 2005).
Identified resources None known.
Production No known production.
Status Unknown.
Estimated resources No data.
Geologic maps Sims and others (1991), scale 1:1,000,000.
Geophysical data Inadequate Rank 5 aeromagnetic data with poor ground gravity coverage in central and western North and South Dakota. Inadequate Rank 3 aeromagnetic data in coverage areas of northern and southern MN. Inadequate aeroradiometric coverage.
Favorable rocks and structures Archean and Paleoproterozoic granites, some with known pegmatites.
Deposits No data.
Evidence from mineral occurrences No data.
Geochemical evidence No data.
Geophysical evidence Weakly magnetized granites.
Evidence from other sources Favorable comparisons to areas with known potential (see Selway and others, 2005).
Cover thickness and description Total cover is variable from 0-1000 feet; The most common overburden is Quaternary glacial sediment (till) which can range from 0-over 500 feet thick. Patchy Mesozoic (Cretaceous) and Paleozoic strata up to ~300 feet thick are locally present beneath glacial sediments. Locally saprolite of several tens of feet covers solid Precambrian bedrock.
Authors Benjamin J. Drenth, Amy Block.
New data needs New mapping; high resolution geophysics.
Geologic mapping and modeling needs More detailed mapping, to the extent allowed by glacial cover.
Geophysical survey and modeling needs Rank 1 aeromagnetic data, also radiometric data.
Digital elevation data needs Lidar adequate over part of focus area, inadequate over others.