Geologic units in Hubbard county, Minnesota

Granitic intrusion (Neoarchean) at surface, covers 26 % of this area

Granitic intrusion. Includes the Sacred Heart (~2592, 2,603 Ma) and Ortonville granites, the Shannon Lake Granite (~2,674), and other intrusions having low gravity and magnetic signatures.

Mafic metavolcanic rocks (Neoarchean) at surface, covers 21 % of this area

Mafic metavolcanic rocks. Includes minor volcaniclastic and hypabyssal intrusive rocks metamorphosed to lower greenschist to lower amphibolite facies; includes the Ely Greenstone (~2,722 Ma).

Foliated to gneissic tonalite, granodiorite, and diorite (Neoarchean) at surface, covers 14 % of this area

Foliated to gneissic tonalite, granodiorite, and diorite. Includes the Lookout Mountain tonalite (~2,718 Ma) of the Giants Range batholith and other intrusions within batholithic complexes defined by a low-to-moderate gravity signature with magnetic foliation apparent from aeromagnetic maps.

Granite to granodiorite (Neoarchean) at surface, covers 9 % of this area

Granite to granodiorite. Variably magnetic.

Volcaniclastic rocks of felsic to intermediate composition (Neoarchean) at surface, covers 9 % of this area

Volcaniclastic rocks of felsic to intermediate composition.

Volcanogenic graywacke and mudstone (Neoarchean) at surface, covers 8 % of this area

Volcanogenic graywacke and mudstone. Includes the Lake Vermilion Formation.

Slate and graywacke (Paleoproterozoic) at surface, covers 8 % of this area

Slate and graywacke. Includes the Rove (~1,836 to 1,777 Ma), Virginia (~1,832 Ma near base), and Thompson Formations (youngest zircons in the Thompson Formation ~1,790 Ma).

Gabbro, peridotite, pyroxenite, lamprophyre, and metamorphic equivalents (Neoarchean) at surface, covers 4 % of this area

Gabbro, peridotite, pyroxenite, lamprophyre, and metamorphic equivalents. Includes the Oaks intrusion (~2,671 Ma) in the Wabigoon subprovince, and a ~2,639 Ma lamprophyre in the western Wawa subprovince; locally defined by variably high gravity and magnetic signatures.

Calc-alkalic volcanic and volcaniclastic rocks (Neoarchean) at surface, covers 0.8 % of this area

Calc-alkalic volcanic and volcaniclastic rocks.