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Geologic units containing ultramafic intrusive rock

Alabama

Dadeville Complex; Ropes Creek Amphibolite (Precambrian to Paleozoic)

Ropes Creek Amphibolite - layered and massive amphibolite; locally includes hornblende migmatite and ultramafic pods.

Connecticut

Ultramafic rock (Ordovician or older)

Ultramafic rock - Ultramafic rock, originally composed of olivine and pyroxene, now generally altered to tremolite, talc, chlorite, or serpentine.

Georgia

Ultramafic rocks undifferentiated (Precambrian-Paleozoic)

Ultramafic rocks undifferentiated

Massachusetts

Belchertown Complex (Devonian)

Belchertown Complex (intrudes De) - Intrusive breccia, mafic and ultramafic fragments in quartz diorite matrix.

Cumberlandite (Precambrian to Phanerozoic)

Cumberlandite - Black to dark-brown , coarse-grained rock containing magnetite, ilmenite, olivine, labradorite, and spinel.

Intimately interfolded Littleton and Partridge Formations (Lower Devonian and Middle Ordovician)

Intimately interfolded Littleton and Partridge Formations - In areas of poor exposure and incomplete mapping.

Partridge Formation (Middle Ordovician)

Partridge Formation (includes Brimfield Schist of Emerson, 1917) - Lenses of ultramafic rock, commonly hornblendite with or without olivine, orthopyroxene, spinel, cummingtonite, anthophyllite, ilmenite and chlorite.

Maine

Cambrian gabbro/diorite/ultramafic rocks (Cambrian)

Cambrian gabbro/diorite/ultramafic rocks

Cambrian ultramafic rocks (Cambrian)

Cambrian ultramafic rocks

Carboniferous gabbro/diorite/ultramafic rocks (Carboniferous)

Carboniferous gabbro/diorite/ultramafic rocks undivided

Cretaceous gabbro/diorite/ultramafic rocks (Cretaceous)

Cretaceous gabbro/diorite/ultramafic rocks

Cretaceous quartz diorite - gabbro/diorite/ultramafic rocks (Cretaceous)

Cretaceous quartz diorite - gabbro/diorite/ultramafic rocks - Cretaceous biotite quartz diorite and gabbro/diorite/ultramafic rocks

Devonian gabbro/diorite/ultramafic rocks (Devonian)

Devonian gabbro/diorite/ultramafic rocks

Devonian gabbro/diorite/ultramafic rocks - quartz diorite (Devonian)

Devonian gabbro/diorite/ultramafic rocks - quartz diorite - Devonian gabbro/diorite/ultramafic rocks to biotite quartz diorite - gabbro, diorite, ultramafic rocks, biotite monzodiorite, biotite syenite, and biotite quartz diorite.

Devonian gabbro - ultramafic rocks (Devonian)

Devonian gabbro - ultramafic rocks

Mesozoic gabbro/diorite/ultramafic rocks (Mesozoic)

Mesozoic gabbro/diorite/ultramafic rocks

Ordovician gabbro/diorite/ultramafic rocks (Ordovician)

Ordovician gabbro/diorite/ultramafic rocks

Silurian gabbro/diorite/ultramafic rocks (Silurian)

Silurian gabbro/diorite/ultramafic rocks

Silurian - Precambrian Z ultramafic rocks (Silurian - Precambrian Z)

Silurian - Precambrian Z ultramafic rocks

Silurian ultramafic rocks (Silurian)

Silurian ultramafic rocks

Michigan

Mafic metavolcanic rocks (Early Proterozoic)

Mafic metavolcanic rocks - Dominantly tholeiitic basalt and basaltic andesite flows and tuffs; associated with sheet dikes, massive and layered metagabbro, and ultramafic rocks. In northeastern Wisconsin, rocks have been named the Quinnesec Formation.

Metagabbro (Early Proterozoic)

Metagabbro - Mafic to ultramafic bodies defined and delineated principally by positive magnetic and gravity anomalies; includes diorite bodies. Comagmatic with unit Xmi

Montana

Stillwater complex (Archean Proterozoic(?) preCambrian-Proterozoic(?) preCambrian(?) Phanerozoic | Paleozoic(?) Mesozoic(?) Cenozoic | Cambrian(?) Ordovician(?) Silurian(?) Devonian(?) Carboniferous(?) Permian(?) Triassic(?) Jurassic(?) Cretaceous(?) Tertiary)

Stillwater complex: consists chiefly of ultrabasic intrusive rocks and metamorphic rocks not yet named or subdivided.

North Carolina

Metagraywacke, Amphibolite, and Kyanite Schist (Cambrian/Late Proterozoic)

Metagraywacke, Amphibolite, and Kyanite Schist - metagraywacke (biotite gneiss) interlayered and gradational with amphibolite and kyanite schist; minor ultramafic and granitic rock.

New Hampshire

Hurricane Mountain Formation (Upper Cambrian?)

Hurricane Mountain Formation - Rusty-weathered, dark siliceous scaly slate or schist of flaser structure, polymictic fragments from a few mm to (in Maine) several hundred meters. A melange consisting of metasedimentary, felsic/mafic metavolcanics, and ultramafic rocks..

South Carolina

Burkes Mountain complex, ultramafic rock (Cambrian or Neoproterozoic)

Burkes Mountain complex, ultramafic rock

Hammett Grove Meta-igneous Suite - ultramafic rocks (Paleozoic or Neoproterozoic)

Hammett Grove Meta-igneous Suite - ultramafic rocks: metamorphosed ultramafic rocks: hornblendite, pyroxenite, serpentinite and talc schist

Ultramafic rock (Paleozoic or Neoproterozoic)

Ultramafic rock

Vermont

Ultramafic Rocks (Ordovician)

Ultramafic Rocks - Undifferentiated ultramafic rocks.

Washington

Pre-Tertiary volcanic rocks, undivided (Probably mostly Jurassic)

Andesite and basalt flows, and greenstone; includes minor interbedded limestone, arkose, quartzite, and chert beds.

Wisconsin

Mafic metavolcanic rocks (Early Proterozoic)

Mafic metavolcanic rocks - Dominantly tholeiitic basalt and basaltic andesite flows and tuffs; associated with sheet dikes, massive and layered metagabbro, and ultramafic rocks. In northeastern Wisconsin, rocks have been named the Quinnesec Formation.

Metagabbro (Early Proterozoic)

Metagabbro - Mafic to ultramafic bodies defined and delineated principally by positive magnetic and gravity anomalies; includes diorite bodies. Comagmatic with unit Xmi