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

Geologic units in Florence county, Wisconsin

[Additional scientific data in this geographic area]

Paint River Group; Upper part (Early Proterozoic) at surface, covers 4 % of this area

Paint River Group; Upper part - Dominantly Fortune Lakes Slate, but includes other rocks in poorly exposed areas. Correlated with upper part of Baraga Group.

Lithology: slate

Mafic metavolcanic rocks (Early Proterozoic) at surface, covers 0.1 % 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

Paint River Group; Lower part (Early Proterozoic) at surface, covers 2 % of this area

Paint River Group; Lower part- Includes Stambaugh Formation, Hiawatha Graywacke, Riverton Iron-formation, and Dunn Creek Slate (James and others, 1968). Correlated with lower part of Baraga Group

Lithology: graywacke; iron formation; slate

Mafic metavolcanic rocks (Early Proterozoic) at surface, covers 33 % 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

Baraga Group; Michigamme Formation, undivided (Early Proterozoic) at surface, covers 18 % of this area

Baraga Group; Michigamme Formation, undivided - 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

Lithology: graywacke

Dacite and volcanogenic graywacke (Early Proterozoic) at surface, covers 1 % of this area

Dacite and volcanogenic graywacke - Includes andesite tuff. Occurs in northeastern Wisconsin. Dacite has age of 1866 +/- 39 Ma.

Lithology: dacite; graywacke; andesite

Menominee and Chocolay Groups, undivided (Early Proterozoic) at surface, covers < 0.1 % of this area

Menominee and Chocolay Groups, undivided - Mapped where units are too thin to show separately on map

Lithology: metasedimentary rock; metavolcanic rock

Paint River Group; Upper part (Early Proterozoic) at surface, covers 0.3 % of this area

Paint River Group; Upper part - Dominantly Fortune Lakes Slate, but includes other rocks in poorly exposed areas. Correlated with upper part of Baraga Group.

Lithology: slate

Baraga Group; Michigamme Formation, undivided (Early Proterozoic) at surface, covers < 0.1 % of this area

Baraga Group; Michigamme Formation, undivided - 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

Lithology: graywacke; metasedimentary rock

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

Badwater Greenstone - Dark-greenish-gray, pillowed to massive tholeiitic basalt and pyroclastic rocks. Correlated with the Hemlock Formation on basis of geology and similarity in chemical composition.

Lithology: basalt; pyroclastic

Granite-tonalite (Early Proterozoic) at surface, covers 27 % of this area

Granite-tonalite - Gray to pinkish-gray, medium-grained, generally equigranular granite to tonalite and granitoid gneiss; locally includes diorite. Intrudes older metavolcanic rocks. Zircon ages range from 1852 +/- 15 to 1862 +/- 5 Ma

Lithology: granite; tonalite; gneiss

Metagabbro (Early Proterozoic) at surface, covers 0.9 % 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

Spikehorn Granite and Bush Lake Granites, undivided (1835 +/- 6 Ma) (Early Proterozoic) at surface, covers 4 % of this area

Spikehorn Granite and Bush Lake Granites, undivided (1835 +/- 6 Ma) - Gray to pinkish-gray, fine- to medium-grained, massive granite containing scattered phenocrysts of potassium feldspar. Exposed in northeastern Wisconsin

Lithology: granite

Badwater Greenstone (Early Proterozoic) at surface, covers 0.1 % of this area

Badwater Greenstone - Dark-greenish-gray, pillowed to massive tholeiitic basalt and pyroclastic rocks. Correlated with the Hemlock Formation on basis of geology and similarity in chemical composition.

Lithology: basalt; pyroclastic

Chocolay Group, undivided (Early Proterozoic) at surface, covers < 0.1 % of this area

Chocolay Group, undivided - In Dickinson County, Mich., includes Randville Dolomite, Sturgeon Quartzite, and Fern Creek Formation. In Marquette range, between Marquette Bay and Champion, includes Wewe Slate, Kona Dolomite, Mesnard Quartzite, and Enchantment Lake Formation

Lithology: quartzite; dolostone (dolomite); slate

Quartz diorite (Early Proterozoic) at surface, covers 2 % of this area

Quartz diorite - Includes Marinette Quartz Diorite of Dunbar Dome (Sims and others, 1985a) and nearby Twelve Foot Falls Quartz Diorite

Lithology: quartz diorite

Chocolay Group, undivided (Early Proterozoic) at surface, covers 0.9 % of this area

Chocolay Group, undivided - In Dickinson County, Mich., includes Randville Dolomite, Sturgeon Quartzite, and Fern Creek Formation. In Marquette range, between Marquette Bay and Champion, includes Wewe Slate, Kona Dolomite, Mesnard Quartzite, and Enchantment Lake Formation

Lithology: quartzite; dolostone (dolomite); slate