Northeast Iowa intrusive complex (NEIIC)

Region Central, North Central
Mineral systems
Deposit types
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Geophysical expression indicates a very large volume of mafic/ultramafic rocks; geophysical expression is also consistent with large volume of alkaline rocks, including carbonatites and large alkaline complexes.
Identified resources Unknown.
Production Unknown.
Status Limited past exploration (4 boreholes).
Estimated resources No data.
Geologic maps Jirsa and others (2012), scale 1:500,000.
Geophysical data Adequate aeromagnetic coverage for southern half, inadequate for northern half; inadequate aeroradiometric coverage.
Favorable rocks and structures Large volumes of mafic/ultramafic intrusive rocks, significant portion of these may be alkaline complexes, including perhaps carbonatites. Located at the intersection of two major crustal-scale (lithospheric-scale?) fault zones: the Belle Plaine and Fayette structural zones. Possible rock type and presence of major structural zone permissive for occurrence of critical minerals, although none are known.
Deposits No data.
Evidence from mineral occurrences No data.
Geochemical evidence No data.
Geophysical evidence Gravity highs and complex magnetic anomalies.
Evidence from other sources No data.
Cover thickness and description Covered by 200-700 m of Paleozoic sedimentary cover.
Authors Benjamin J. Drenth.
New data needs New mapping, high resolution geophysics.
Geologic mapping and modeling needs Basement geologic map needed.
Geophysical survey and modeling needs Need Rank 1 aeromagnetic data and more ground gravity data over the northern half of focus area.
Digital elevation data needs Lidar in progress or planned for the area, but not needed (concealed).