Post-Penokean Geon 17 magmatic rocks

Region Central, North Central
Mineral systems
Deposit types
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Focus area shows hypothesized extent of post-collisional A-type volcanic rocks and intrusions in the northern Midcontinent region. Outcrops of these rocks are limited. The 1775 Ma East Central Minnesota Batholith is composed of at least 20 separate intrusions, including granodiorite, gray and red granites, and is cut by late differentiate pegmatites. In Wisconsin, there are multiple, slightly younger (~1760 Ma) rhyolite and granite typically buried under younger rocks.
Identified resources Unknown.
Production Unknown.
Status Unknown.
Estimated resources Unknown.
Geologic maps Minnesota: Boerboom and others (1999), scale 100:000; Boerboom (2009), scale 1:100,000; Wisconsin: Sims (1992), scale 1:500,000.
Geophysical data Inadequate aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Large volumes of post-orogenic granitic magma emplaced during slab roll-back following Penokean orogeny.
Deposits No data.
Evidence from mineral occurrences No data.
Geochemical evidence No data.
Geophysical evidence No data.
Evidence from other sources No data.
Cover thickness and description East Central Minnesota Batholith exposed sporadically through glacial cover. In Wisconsin, small inliers are exposed in river valleys and isolated outcrops in the Paleozoic cover.
Authors Laurel G. Woodruff.
New data needs High resolution geophysical surveys, geological mapping.
Geologic mapping and modeling needs Geological mapping at 1:24:000 scale.
Geophysical survey and modeling needs Need Rank 1 aeromagnetic data and more ground gravity data.
Digital elevation data needs Lidar inadequate for much of the area; adequate in small areas.