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

Geologic units in Houghton county, Michigan

[Additional scientific data in this geographic area]

Copper Harbor Conglomerate; Volcanic member (Early Proterozoic) at surface, covers 0.3 % of this area

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

Lithology: andesite

Powder Mill Group; Siemens Creek Volcanics (Middle Proterozoic) at surface, covers 0.3 % 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

Jacobsville Sandstone (Middle Proterozoic) at surface, covers 61 % of this area

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

Lithology: sandstone; siltstone; conglomerate; shale

Baraga Group; Michigamme Formation, undivided (Early Proterozoic) at surface, covers 7 % 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

Oronto Group; Nonesuch Shale (Middle Proterozoic) at surface, covers 0.7 % 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

Copper Harbor Conglomerate (Middle Proterozoic) at surface, covers 3 % 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

Paleozoic undivided (Paleozoic) at surface, covers < 0.1 % of this area

Paleozoic undivided

Lithology: limestone; dolostone (dolomite); sandstone

Oronto Group; Freda Sandstone (Middle Proterozoic) at surface, covers 16 % 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

Mellen Intrusive Complex; Granite (about 1000 Ma) (Middle Proterozoic) at surface, covers < 0.1 % of this area

Mellen Intrusive Complex; Granite (about 1000 Ma)

Lithology: granite

Portage Lake Volcanics (Middle Proterozoic) at surface, covers 11 % of this area

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

Lithology: basalt; andesite; rhyolite; mudstone