Prairie du Chien Group
Trenton Limestone
Trempealeau Formation
Black River Limestone
Munising Formation
Includes andesite tuff. Occurs in northeastern Wisconsin. Dacite has age of 1866 +/- 39 Ma.
Dominantly tholeiitic basalt and basaltic andesite flows and tuffs; associated with sheet dikes, massive and layered metagabbro, and ultramafic rocks. In northeastern Wisconsin, rocks have been named the Quinnesec Formation.
Mafic to ultramafic bodies defined and delineated principally by positive magnetic and gravity anomalies; includes diorite bodies. Comagmatic with unit Xmi
Massive to flow-banded rocks of greenschist metamorphic grade in northeastern Wisconsin; virtually undeformed.
Exposed in northeastern Wisconsin
Thick and stratigraphically varied formation of sedimentary and less abundant volcanic rocks. Metamorphosed graywacke is predominant rock of Michigamme Formation. Calcareous concretions common. Metamorphosed from cholorite to sillimanite grade (Cannon, 1986). Mapped undivided in poorly exposed areas
Pink, coarse-grained granite to granodiorite containing nearly equal amounts of microcline microperthite, plagioclase, and quartz and 5-10 percent biotite and (or) hornblende. Mafic minerals are interstitial and give a clotty appearance.
Dolomite with some sandstone and shale; includes Shakopee and Oneota Formations
Sandstone with some dolomite and shale, undivided; includes Trempealeau, Tunnel City, and Elk Mound Formations
Dolomite with some limestone and shale; includes Galena, Decorah, and Platteville Formations
Dominantly tholeiitic basalt and basaltic andesite flows and tuffs; associated with sheet dikes, massive and layered metagabbro, and ultramafic rocks. In northeastern Wisconsin, rocks have been named the Quinnesec Formation.
Includes andesite tuff. Occurs in northeastern Wisconsin. Dacite has age of 1866 +/- 39 Ma.
Massive to flow-banded rocks of greenschist metamorphic grade in northeastern Wisconsin; virtually undeformed.
Exposed in northeastern Wisconsin
Pink, coarse-grained granite to granodiorite containing nearly equal amounts of microcline microperthite, plagioclase, and quartz and 5-10 percent biotite and (or) hornblende. Mafic minerals are interstitial and give a clotty appearance. (1836 +/- 15 Ma)
In northern Wisconsin, granite to granodiorite of varied texture. In southern Wisconsin (not mapped separately), red to pink alkali-feldspar granophyric granite associated with rhyolites of both peraluminous and metaluminous affinities (unit Xr of Marshfield terrane).
Mafic to ultramafic bodies defined and delineated principally by positive magnetic and gravity anomalies; includes diorite bodies. Comagmatic with unit Xmi