Mineral Resources On-Line Spatial Data
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Geologic units in Brown county, Minnesota
- Upper Cambrian, undivided (Late Cambrian) at surface, covers 0.8 % of this area
Upper Cambrian, undivided - Jordan Sandstone; dolomite, glauconite, and silty glauconite rocks of the St. Lawerence and Franconia Formation; Ironton and Galesville Sandstones; sandy and shaly rocks of the Eau Claire Formation; and the Mt. Simon Sandstone.
- Migmatitic gneiss, amphibolite, and granite (Middle to Early Archean) at surface, covers 4 % of this area
Migmatitic gneiss, amphibolite, and granite - Montevideo and Morton Gneisses (3600-3000 m.y.) in the Minnesota River Valley, southwestern Minnesota; McGrath Gneiss (2750 m.y.) east of Mille Lacs Lake; components of Hillman Migmatite southwest of Mille Lacs Lake; and Sartell Gneiss in Stearns County. Inferred to include various younger rocks, including granitoid intrusions in the Hillman Migmatite and pillowed basalt in poorly exposed areas of southwestern Minnesota.
- Late-tectonic intrusions of the Penokean orogen (Early Proterozoic) at surface, covers 0.1 % of this area
Late-tectonic intrusions of the Penokean orogen - Includes the St. Cloud and Rockville Granites and Reformatory granodiorite of east-central Minnesota, the Section 28 granite, the Cedar Mountain Complex, and other unnamed intrusions exposed along the Minnesota River Valley in southwestern Minnesota
- Cretaceous rocks, undivided (Cretaceous) at surface, covers 94 % of this area
Cretaceous rocks, undivided - Dakota, Graneros, Greenhorn, Carlie, Niobara, and Pierre formations and their nonmarine equivalents in northwestern, southwestern, and southeastern Minnesota
- Sioux Quartzite (Early Proterozoic) at surface, covers 0.9 % of this area
Sioux Quartzite - Red quartzite of fluvial to possibly marginally marine origin. Includes quartz-pebble conglomerate, claystone (catlinite, also called pipestone), a basal (rhyolite) pebble conglomerate in Pipestone County, and a basal (granite, quartz, chert, iron-formation) conglomerate in Nicollet County on the Minnesota River
- Syntectonic to pretectonic granitoid rocks (Late Archean) at surface, covers 0.6 % of this area
Syntectonic to pretectonic granitoid rocks - Granite and granodiorite of the Vermilion Granitic Complex, the Giants Range and Bemidji batholiths, as well as smaller intrusions of tonalite and monzonite of the Algoman orogen in northern Minnesota. Also includes the Odessa, Sacred Heart, and Fort Ridgely Granites exposed along the Minnesota River Valley in southwestern Minnesota.