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Mineral Resources > Online Spatial Data > Geology > by state > Wisconsin Geology

Geologic units in Lincoln county, Wisconsin

Alkali feldspar granite of 1835 Ma age group (Early Proterozoic) at surface, covers 0.4 % of this area

Alkali feldspar granite of 1835 Ma age group - Red to pink, medium-grained leucocratic alkali feldspar granite; contains miarolitic cavities; biotite is altered to opaque oxide minerals; contains fluorite locally. Called red granite previously (Sims, 1990). Exposed in both Pembine-Wausau and Marshfield terranes.

Lithology: granite

Felsic metavolcanic rocks of 1835- to 1845-Ma age group (Early Proterozoic) at surface, covers 9 % of this area

Felsic metavolcanic rocks of 1835- to 1845-Ma age group - Rhyolite to dacite and, locally, andesite tuff, breccia, and minor sedimentary rocks, including conglomerate. Exposed in central Wisconsin.

Lithology: meta-rhyolite; metavolcanic rock; tuff

Bimodal mafic and felsic metavolcanic rocks (Early Proterozoic) at surface, covers < 0.1 % of this area

Bimodal mafic and felsic metavolcanic rocks - High-aluminum basalt to low-silica andesite pillowed flows and interlayered dacite to rhyolite tuffs and porphyries in Monico and Mountain areas, northeastern Wisconsin. A rhyolite porphyry at Jennings (Oneida County) has an age of 1869 +/- 6 Ma. Rocks are host to massive sulfide deposits (Crandon and Pelican River)

Lithology: basalt; andesite; dacite; rhyolite

Mafic metavolcanic rocks (Early Proterozoic) at surface, covers 8 % of this area

Mafic metavolcanic rocks - 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.

Lithology: basalt; andesite; gabbro; ultramafic intrusive rock

Gabbro (Early Proterozoic) at surface, covers 6 % of this area

Gabbro - Massive to layered intrusive gabbroic rocks; weakly metamorphosed and deformed. Exposed in both Pembine-Wausau and Marshfield terranes

Lithology: gabbro

Metagabbro (Early Proterozoic) at surface, covers 1 % of this area

Metagabbro - Mafic to ultramafic bodies defined and delineated principally by positive magnetic and gravity anomalies; includes diorite bodies. Comagmatic with unit Xmi

Lithology: gabbro; ultramafic intrusive rock; diorite

Granodiorite-tonalite (Early Proterozoic) at surface, covers 12 % of this area

Granodiorite-tonalite - Gray, medium-grained intrusive rocks, including intrusion breccias. Exposed in central Wisconsin. Zircon ages range from 1837 to 1847 Ma

Lithology: granodiorite; tonalite

Mafic to felsic metavolcanic rocks (Early Proterozoic) at surface, covers 57 % of this area

Mafic to felsic metavolcanic rocks - Volcanic rocks in areas of sparse geologic data and nondefinitive magnetic and gravity data

Lithology: mafic metavolcanic rock; felsic metavolcanic rock

Gneiss and amphibolite (Early Proterozoic) at surface, covers 8 % of this area

Gneiss and amphibolite - Interlayered quartzofeldpathic gneiss and amphibolite between Athens shear zone and Owen fault, central Wisconsin

Lithology: gneiss; amphibolite