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

Geologic units in Gogebic county, Michigan

[Additional scientific data in this geographic area]

Jacobsville Sandstone (Middle Proterozoic) at surface, covers < 0.1 % of this area

Jacobsville Sandstone - Red, brown, and white quartzose sandstone, and minor siltstone, shale and conglomerate

Lithology: sandstone; siltstone; shale; conglomerate

Jacobsville Sandstone (Middle Proterozoic) at surface, covers 12 % of this area

Jacobsville Sandstone - Red, brown, and white quartzose sandstone, and minor siltstone, shale and conglomerate

Lithology: sandstone; siltstone; conglomerate; shale

Powder Mill Group; Kallander Creek Volcanics (Middle Proterozoic) at surface, covers < 0.1 % of this area

Powder Mill Group; Kallander Creek Volcanics- Basalt, andesite and lesser rhyolite flows. Basalt flows near base of the formation contain plagioclase phenocrysts, some in radiating clusters

Lithology: basalt; andesite; rhyolite

Metabasalt (Late Archean) (Late Archean) at surface, covers 3 % of this area

Metabasalt (Late Archean) - Derived from mafic to intermediate pyroclastic rocks and massive to pillowed lava flows. Unit mapped as Ramsey Formation by Prinz (1981) south of Gogebic Range; mapped as Mona Schist and Kitchi Schist in northern complex of Marquette District.

Lithology: meta-basalt; tuff; schist

Porcupine Volcanics (Middle Proterozoic) at surface, covers < 0.1 % of this area

Porcupine Volcanics - Generally dark-gray basalt, andesite, and felsite flows and subordinate interflow sedimentary rocks

Lithology: rhyolite; basalt; andesite; mixed clastic/volcanic

Baraga Group; Copps Formation (Early Proterozoic) at surface, covers 2 % of this area

Baraga Group; Copps Formation - Fine- to medium-grained graywacke and less abundant gray to black slate. Thin basal conglomerate west of Lake Gogebic contains clasts of underlying Archean rocks in a quartzitic and argillaceous matrix.

Lithology: graywacke; slate; meta-conglomerate

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

Baraga Group; Tyler Formation - Light- to dark-gray, feldspathic, fine-grained sandstone, argillaceous siltstone, and argillite. Near base, ferruginous argillite contains beds of cherty sideritic and pyritic iron-formation

Lithology: sandstone; argillite; iron formation

Copper Harbor Conglomerate; Volcanic member (Early Proterozoic) at surface, covers < 0.1 % of this area

Copper Harbor Conglomerate; Volcanic member - Basaltic to andesitic volcanic flows interbedded within the conglomerate and sandstone

Lithology: andesite

Migmatitic gneiss and amphibolite (Late to Early Archean) (Archean) at surface, covers 11 % of this area

Migmatitic gneiss and amphibolite (Late to Early Archean) - Varied gneisses of mostly unknown age in cores of gneiss domes and fault-bounded uplifts (Archean gneiss terranes). Except for the Watersmeet dome (Late to Early Archean), all dated rocks are Late Archean. Includes granite of Late Archean age that transgresses gneisses and amphibolite.

Lithology: gneiss; migmatite; amphibolite

Menominee Group; Emperor Volcanic Complex (Early Proterozoic) at surface, covers 0.3 % of this area

Menominee Group; Emperor Volcanic Complex - Metamorphosed intermediate to mafic pyroclastic and flow rocks in easternmost part of Gogebic Range

Lithology: meta-basalt; metavolcanic rock

Baraga Group; Michigamme Formation; Mafic to intermediate flows and pyroclastic rocks, including Clarksburg Volcanics member (Early Proterozoic) at surface, covers 0.2 % of this area

Baraga Group; Michigamme Formation; Mafic to intermediate flows and pyroclastic rocks, including Clarksburg Volcanics member - Poorly exposed. Includes Clarksburg Volcanics member which is mostly mafic to intermediate pyroclastic rocks in Marquette trough, between Marquette Bay and Champion

Lithology: metavolcanic rock

Powder Mill Group; Siemens Creek Volcanics (Middle Proterozoic) at surface, covers 2 % of this area

Powder Mill Group; Siemens Creek Volcanics - Dark-gray basalt and minor porphyritic andesite. Generally strongly magnetic with reversed remanent magnetism. Underlain by a thin unit of quartzose sandstone (Bessemer Quartzite).

Lithology: basalt; andesite

Menominee Group; unexposed magnetic unit (Early Proterozoic) at surface, covers 4 % of this area

Menominee Group; unexposed magnetic unit- Surrounds gneiss domes in Gogebic County, Mich. and Vilas County, Wisc., and occurs in north-central Dickinson County. Probably correlative with part of Blair Creek Formation (unit Xbc). Previously correlated with uppermost unit of Blair Creek Formation (Sims and others, 1984).

Lithology: iron formation; slate

Menominee Group; unexposed magnetic unit (Early Proterozoic) at surface, covers < 0.1 % of this area

Menominee Group; unexposed magnetic unit - Surrounds gneiss domes in Gogebic County, Mich. and Vilas County, Wisc., and occurs in north-central Dickinson County. Probably correlative with part of Blair Creek Formation (unit Xbc). Previously correlated with uppermost unit of Blair Creek Formation (Sims and others, 1984).

Lithology: iron formation; slate

Copper Harbor Conglomerate (Middle Proterozoic) at surface, covers 5 % of this area

Copper Harbor Conglomerate - Red lithic conglomerate and sandstone; mafic to felsic volcanic flows similar to those of the unnamed formation (unit Yu) are interlayered with the sedimentary rocks.

Lithology: conglomerate; sandstone; lava flow

Powder Mill Group; Siemens Creek Volcanics (Middle Proterozoic) at surface, covers < 0.1 % of this area

Powder Mill Group; Siemens Creek Volcanics- Dark-gray basalt and minor porphyritic andesite. Generally strongly magnetic with reversed remanent magnetism. Underlain by a thin unit of quartzose sandstone (Bessemer Quartzite).

Lithology: basalt; andesite

Oronto Group; Freda Sandstone; Conglomerate member (Middle Proterozoic) at surface, covers < 0.1 % of this area

Oronto Group; Freda Sandstone; Conglomerate member

Lithology: conglomerate

Baraga Group; Michigamme Formation, undivided (Early Proterozoic) at surface, covers 11 % 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

Porcupine Volcanics (Middle Proterozoic) at surface, covers 6 % of this area

Porcupine Volcanics - Generally dark-gray basalt, andesite, and felsite flows and subordinate interflow sedimentary rocks

Lithology: basalt; andesite; rhyolite; medium-grained mixed clastic

Oronto Group; Nonesuch Shale (Middle Proterozoic) at surface, covers 0.8 % of this area

Oronto Group; Nonesuch Shale - Gray, green, and brown lithic siltstone, shale, and sandstone. Copper sulfides and native copper occur locally near base

Lithology: siltstone; shale; sandstone

Menominee Group; Ironwood Iron-formation (Early Proterozoic) at surface, covers < 0.1 % of this area

Menominee Group; Ironwood Iron-formation- Interbedded cherty and slaty iron-formation. Locally, secondary enrichment has formed "soft ore" bodies. In eastern part of Gogebic Range, Ironwood Iron-formation is intercalated with pyroclastic rocks of Emperor Volcanic Complex, and in eastern half of T. 47 N., R. 43 W. (where mapped within unit Xip) consists entirely of black slate

Lithology: iron formation; slate

Gneiss and amphibolite (Late Archean, 2.640-2.750 Ma) (Late Archean) at surface, covers 5 % of this area

Gneiss and amphibolite (Late Archean, 2.640-2.750 Ma) - Interlayered quartzofeldspathic gneiss and amphibolite in Marenisco, Mich., area and northwestern Wisconsin. Protoliths are bimodal intermediate and mafic volcanic rocks (Sims and others, 1984).

Lithology: gneiss; amphibolite

Oronto Group; Freda Sandstone (Middle Proterozoic) at surface, covers < 0.1 % of this area

Oronto Group; Freda Sandstone - Mainly reddish-brown, medium- to fine-grained lithic arkosic sandstone, siltstone, and micaceous silty shale.

Lithology: arkose; siltstone; shale

Powder Mill Group; Kallander Creek Volcanics (Middle Proterozoic) at surface, covers 1 % of this area

Powder Mill Group; Kallander Creek Volcanics - Basalt, andesite and lesser rhyolite flows. Basalt flows near base of the formation contain plagioclase phenocrysts, some in radiating clusters

Lithology: basalt; andesite; rhyolite

Oronto Group; Freda Sandstone (Middle Proterozoic) at surface, covers 2 % of this area

Oronto Group; Freda Sandstone - Mainly reddish-brown, medium- to fine-grained lithic arkosic sandstone, siltstone, and micaceous silty shale.

Lithology: arkose; siltstone; shale

Puritan Quartz Monzonite (Late Archean) (Late Archean) at surface, covers 15 % of this area

Puritan Quartz Monzonite (Late Archean) - Pink to pinkish-gray, medium- to coarse-grained, equigranular to inequigranular granite to granodiorite in Puritan batholith south of Gogebic Range. Age 2710 +/- 140 Ma (Sims and others, 1977)

Lithology: granite; granodiorite

Menominee Group; Blair Creek Formation (Early Proterozoic) at surface, covers 6 % of this area

Menominee Group; Blair Creek Formation - Dominantly dark-gray, massive, porphyritic tholeiitic basalt. Includes a basal conglomerate and a lean iron-formation in middle of formation

Lithology: basalt; iron formation; conglomerate

Porcupine Volcanics; Rhyolite (Middle Proterozoic) at surface, covers 0.2 % of this area

Porcupine Volcanics; Rhyolite

Lithology: rhyolite

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

Baraga Group; Tyler Formation (Early Proterozoic) at surface, covers 0.8 % of this area

Baraga Group; Tyler Formation - Light- to dark-gray, feldspathic, fine-grained sandstone, argillaceous siltstone, and argillite. Near base, ferruginous argillite contains beds of cherty sideritic and pyritic iron-formation

Lithology: sandstone; siltstone; iron formation; argillite

Metagraywacke (Late Archean) (Late Archean) at surface, covers 2 % of this area

Metagraywacke (Late Archean) - Gray, fine-grained, thin- to thick-bedded, commonly graded graywacke and slate in Marenisco, Mich. area

Lithology: metasedimentary rock; slate

Biotite schist (Lake Archean) (Late Archean) at surface, covers 0.9 % of this area

Biotite schist (Lake Archean) - Quartz-plagioclase-biotite schist of probably intermediate volcanic protolith in area south of Gogebic Range

Lithology: mica schist; gneiss

Metabasalt (Late Archean) (Late Archean) at surface, covers < 0.1 % of this area

Metabasalt (Late Archean) - Derived from mafic to intermediate pyroclastic rocks and massive to pillowed lava flows. Unit mapped as Ramsey Formation by Prinz (1981) south of Gogebic Range; mapped as Mona Schist and Kitchi Schist in northern complex of Marquette District.

Lithology: meta-basalt; tuff; schist

Portage Lake Volcanics (Middle Proterozoic) at surface, covers 7 % of this area

Portage Lake Volcanics - Lava flows, mostly basalt, andesite and felsite flows and subordinate interflow sedimentary rocks.

Lithology: basalt; andesite; rhyolite; mudstone

Portage Lake Volcanics (Middle Proterozoic) at surface, covers < 0.1 % of this area

Portage Lake Volcanics - Lava flows, mostly basalt, andesite and felsite flows and subordinate interflow sedimentary rocks.

Lithology: basalt; andesite; rhyolite; mudstone

Menominee Group; Ironwood Iron-formation (Early Proterozoic) at surface, covers 2 % of this area

Menominee Group; Ironwood Iron-formation - Interbedded cherty and slaty iron-formation. Locally, secondary enrichment has formed "soft ore" bodies. In eastern part of Gogebic Range, Ironwood Iron-formation is intercalated with pyroclastic rocks of Emperor Volcanic Complex, and in eastern half of T. 47 N., R. 43 W. (where mapped within unit Xip) consists entirely of black slate

Lithology: iron formation; slate

Puritan Quartz Monzonite (Late Archean) (Late Archean) at surface, covers < 0.1 % of this area

Puritan Quartz Monzonite (Late Archean) - Pink to pinkish-gray, medium- to coarse-grained, equigranular to inequigranular granite to granodiorite in Puritan batholith south of Gogebic Range. Age 2710 +/- 140 Ma (Sims and others, 1977)

Lithology: granite; granodiorite

Powder Mill Group; Kallander Creek Volcanics; Upper rhyolite member (Middle Proterozoic) at surface, covers < 0.1 % of this area

Powder Mill Group; Kallander Creek Volcanics; Upper rhyolite member

Lithology: rhyolite

Powder Mill Group; Kallander Creek Volcanics; Upper rhyolite member (Middle Proterozoic) at surface, covers < 0.1 % of this area

Powder Mill Group; Kallander Creek Volcanics; Upper rhyolite member

Lithology: rhyolite