Geologic units in Norman county, Minnesota

Mafic metavolcanic rocks (Neoarchean) at surface, covers 29 % 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).

Calc-alkalic volcanic and volcaniclastic rocks (Neoarchean) at surface, covers 25 % of this area

Calc-alkalic volcanic and volcaniclastic rocks.

Granitoid intrusion (Neoarchean) at surface, covers 17 % of this area

Granitoid intrusion. Constrained solely by low gravity and magnetic signatures.

Foliated to gneissic tonalite, granodiorite, and diorite (Neoarchean) at surface, covers 17 % 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 5 % of this area

Granite to granodiorite. Variably magnetic.

Schist of sedimentary protolith (Neoarchean) at surface, covers 3 % of this area

Schist of sedimentary protolith. Metamorphosed to upper greenschist to amphibolite facies.

Gabbro, peridotite, pyroxenite, lamprophyre, and metamorphic equivalents (Neoarchean) at surface, covers 2 % 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.

Magnetic intrusions, undifferentiated (Archean) at surface, covers 2 % of this area

Magnetic intrusions, undifferentiated. Typically too small to ascertain gravity expression.

Belle Fourche-Skull Creek, Undivided (Lower to Upper Cretaceous) at surface, covers < 0.1 % of this area

Belle Fourche Formation (as described in Kb). Mowry Formation: medium- to dark-gray shale; marine offshore sediment; as thick as 55 metres (180 feet). Newcastle Formation: light-gray, fine- to medium-grained sandstone; marine shoreline and offshore sediment; as thick as 45 metres (150 feet). Skull Creek Formation: medium-gray to dark-gray shale; marine offshore sediment; as thick as 40 metres (140 feet).

Precambrian Rocks (Precambrian) at surface, covers < 0.1 % of this area

Greenschists and amphibolites; banded iron formation; stretched pebble conglomerates; metabasalt; serpentinite; felsic tuff; mylonite; intermediate felsic plutonic rocks; migmatite; layered gneiss.

Inyan Kara (Lower Cretaceous) at surface, covers < 0.1 % of this area

Light-gray, fine to coarse sandstone and gray shale; river, lake, and nearshore marine sediment; as thick as 135 metres (450 feet).

Biotite schist of graywacke protolith, and schist-rich migmatite (Neoarchean) at surface, covers < 0.1 % of this area

Biotite schist of graywacke protolith, and schist-rich migmatite.

Mafic to ultramafic hypabyssal intrusive complexes composed of gabbro, pyroxenite, diorite, and anorthosite (Neoarchean) at surface, covers < 0.1 % of this area

Mafic to ultramafic hypabyssal intrusive complexes composed of gabbro, pyroxenite, diorite, and anorthosite. Includes the Mentor and Deer Lake complexes, intrusions of the Newton Lake Formation, all within the Wawa subprovince; and the UBD intrusion (~2,685 to 2,695 Ma) in the Wabigoon subprovince.