Geologic units in Carlton county, Minnesota

Slate and graywacke (Paleoproterozoic) at surface, covers 41 % 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).

Sandstone, siltstone, and local conglomerate (Mesoproterozoic) at surface, covers 27 % of this area

Sandstone, siltstone, and local conglomerate. Includes the Hinckley Sandstone and Fond du Lac (youngest detrital zircons ~1,000 Ma) and Solar Church Formations; deposition in eolian, fluvial, and lacustrine environments.

Graywacke and slate (Paleoproterozoic) at surface, covers 9 % of this area

Graywacke and slate

Little Falls Formation (Paleoproterozoic) at surface, covers 7 % of this area

Schist and slate of graywacke-mudstone protolith.

Interlayered volcanic and sedimentary rocks (Paleoproterozoic) at surface, covers 6 % of this area

Interlayered volcanic and sedimentary rocks.

Graywacke and slate with graphitic and sulfidic zones (Paleoproterozoic) at surface, covers 4 % of this area

Graywacke and slate with graphitic and sulfidic zones.

Mille Lacs and North Range Groups and equivalent sedimentary rocks (Paleoproterozoic) at surface, covers 4 % of this area

Includes the Mahnomen and Rabbit Lake Formations and Trout Lake marble. Unit descriptions from GEOLEX - Mahnomen Formation: Upper member described as gray to light-gray siltstone, argillite, and fine-grained quartzose sandstone containing irregularly distributed beds and lenses of iron-formation and allied anomalously iron-rich sedimentary rocks; base of unit defined arbitrarily as the top of the lowermost mappable iron-formation layer of the middle, iron-formation member. Middle, iron-formation member--interlayered cherty and slaty iron-formation that is similar lithologically to the smaller iron-formation lenses within the upper and lower members; contains rocks formerly assigned to the Trommald Formation and the Emily Member of the Rabbit Lake Formation (Morey, 1978). Lower member--predominantly siltstone, fine- to medium-grained quartzose graywacke, and argillite; also includes minor quartz arenite and irregularly distributed layers and lenses of anomalously iron-rich sedimentary rocks. Rabbit Lake Formaiton: gray to very dark-gray slate, siltstone, and very fine-grained graywacke; includes irregularly distributed layers and lenses of carbonaceous slate and also carbonate- and sulfide-facies iron-formation, chiefly in the lower part of the unit.

Sulfidic iron-formation (Paleoproterozoic) at surface, covers 1.0 % of this area

Sulfidic iron-formation.

Interlayered volcanic, volcaniclastic, sedimentary, and hypabyssal intrusive rocks (Paleoproterozoic) at surface, covers 0.4 % of this area

Interlayered volcanic, volcaniclastic, sedimentary, and hypabyssal intrusive rocks. Includes parts of the Mille Lacs Group, North and South Range Groups, and Glen Township Formation.

Chengwatana volcanic rocks (Mesoproterozoic) at surface, covers 0.3 % of this area

Primarily mafic flows.

Bayfield Group; Orienta Sandstone (Middle Proterozoic) at surface, covers 0.1 % of this area

Poorly sorted arkosic sandstone

Bayfield Group; Devil's Island Sandstone (Middle Proterozoic) at surface, covers 0.1 % of this area

Well-sorted quartzose sandstone

Chengwatana Volcanic Group (Middle Proterozoic) at surface, covers < 0.1 % of this area

Gray basalt flows, interflow breccia, tuff, and minor sedimentary rocks

Small mafic intrusive stocks (Mesoproterozoic) at surface, covers < 0.1 % of this area

Diabase, diorite, pyroxenite, and gabbro; reversed magnetic polarity; includes the Esko and Tamarack intrusions emplaced into unit Pas (Slate and graywacke of Animikie Group).