USGS Home
Contact USGS
Search USGS

Mineral Resources > Online Spatial Data > Geology > by state

Geologic units containing felsic metavolcanic rock

Arizona

Early Proterozoic metavolcanic rocks (Early Proterozoic)

Weakly to strongly metamorphosed volcanic rocks. Protoliths include basalt, andesite, dacite, and rhyolite deposited as lava or tuff, related sedimentary rock, and shallow intrusive rock. These rocks, widely exposed in several belts in central Arizona, include metavolcanic rocks in the Yavapai and Tonto Basin supergroups. (1650 to 1800 Ma)

Jurassic sedimentary and volcanic rocks (Jurassic)

Sandstone and conglomerate derived from volcanic rocks with associated intermediate-composition lava flows, breccias, and tuffs. In southern Arizona this unit includes rocks of the Artesa sequence, Pitoikam Formation, Mulberry Wash volcanics, Rudolfo Red Beds, Recreation Red Beds, and Gardner Canyon Formation. In western Arizona it includes the Harquar Formation, rocks of Slumgullion, and related(?) unnamed units in the Kofa and Middle Mountains. This unit is characterized by maroon, brown, and purplish-gray volcanic-lithic sandstone and siltstone, with subordinate to abundant conglomerate, quartz-rich sandstone and sparse limestone. (150-170 Ma)

Jurassic to Cambrian metamorphosed sedimentary rocks (Cambrian to Jurassic)

Highly faulted and folded rocks of units Jv, J_, and Pz, deformed and metamorphosed in Jurassic, Cretaceous and Tertiary time. This unit is restricted to west-central Arizona. (160-540 Ma)

Jurassic volcanic rocks (Jurassic)

Massive quartz-feldspar porphyry, generally interpreted as thick, welded rhyolitic tuffs, with locally abundant lava, and sandstone and conglomerate derived from volcanic rocks. Rare eolian quartzite units are interbedded in southern Arizona. Includes Ali Molina Formation, Mount Wrightson Formation, part of the Canelo Hills Volcanics, Cobre Ridge tuff, Black Rock volcanics, Planet Volcanics, and equivalent rocks. (160-200 Ma)

Connecticut

Collinsville Formation (Middle Ordovician)

Collinsville Formation - Mixture of rock types as described for the two members; in many areas felsic and mafic striped metavolcanic rocks predominate.

Maromas Granite Gneiss (Devonian?)

Maromas Granite Gneiss - Light-gray to buff, medium- to fine-grained granitic gneiss, composed of quartz and microcline with minor plagioclase and biotite. Central body is massive, but outlying strips are foliated and have accessory hornblende or garnet. Massive parts may be young anatectic intrusive rocks; foliated parts may include older felsic metavolcanic rocks belonging to unit Ochv. Pegmatite bodies are common in the vicinity.

Taine Mountain and Collinsville Formations undivided (Middle to Lower? Ordovician)

Taine Mountain and Collinsville Formations undivided - see Ot and Oc.

Georgia

Felsic Metavolcanics (Precambrian-Paleozoic)

Felsic Metavolcanics

Idaho

Quartzite, siltstone, conglomerate, and metavolcanic rocks; Late and Middle Proterozoic, undivided; Atlanta batholith roof pendants (Late and Middle Proterozoic, undivided)

Precambrian, high-grade metamorphic rock

Massachusetts

Metamorphosed felsic metavolcanic rocks (Proterozoic Z)

Metamorphosed felsic metavolcanic rocks .

Washington Gneiss (Proterozoic Y)

Washington Gneiss - Rusty-weathering, muscovite-biotite-sillimanite and/or kyanite-garnet schist; blue-quartz ribbed conglomerate, interlayered garnet-plagioclase-quartz metadacite.

Maryland

Volcanic Complex of Cecil County (Late Precambrian (?))

Volcanic Complex of Cecil County - Metamorphosed andesitic and dacitic volcanic rocks (greenstone, greenschist, quartz amphibolite, and schistose felsite); amygdules and volcano-clastic textures locally preserved; thickness unknown.

Maine

Cambrian Jim Pond Formation (Cambrian)

Cambrian Jim Pond Formation

Ordovician - Precambrian Z Cape Elizabeth Formation mafic to felsic volcanic member (Ordovician - Precambrian Z)

Ordovician - Precambrian Z Cape Elizabeth Formation mafic to felsic volcanic member

Ordovician - Precambrian Z Cushing Formation (Ordovician - Precambrian Z)

Ordovician - Precambrian Z Cushing Formation

Minnesota

Metasedimentary rocks, undivided (Late Archean)

Metasedimentary rocks, undivided - Graywacke, slate, local units of conglomerate, arenite, graphitic slate, fine-grained felsic volcanogenic, and volcaniclastic rocks, lean oxide iron-formation and its metamorphic equivalents. Includes the Knife Lake Group and the Lake Vermilion Formation in northeastern Minnesota.

Mixed metavolcanic rocks (Late Archean)

Mixed metavolcanic rocks - Mafic to felsic volcanic sequences that have variable amounts of felsic volcanogenic and volcaniclastic rocks and lean iron-formation. Includes parts of the Ely Greenstone and the Soudan Iron-formation in northeastern Minnesota.

North Carolina

Chilhowee Group, Grandfather Mountain Formation; Felsic metavolcanic rocks and metasedimentary rocks (Late Proterozoic)

Felsic metavolcanic rocks and metasedimentary rocks (820my) - tentatively correlated with Grandfather Mountain Formation.

Chilhowee Group, Grandfather Mountain Formation; Porphyritic felsic volcanic rock (Late Proterozoic)

Porphyritic felsic volcanic rock (820 my) - phyllitic to schistose, contains euhedral to subhedral phenocrysts of gray quartz and pink potassic feldspar. Resembles quartzite and meta-arkose.

Cid Formation; Felsic Metavolcanic Rock (Cambrian/Late Proterozoic)

(southwest of Asheboro); Felsic Metavolcanic Rock - metamorphosed dacitic to rhyolitic flows and tuffs, light gray to greenish gray; interbedded with mafic and intermediate metavolcanic rock, meta-argillite, and metamudstone.

Cid Formation; Mafic Metavolcanic Rock (Cambrian/Late Proterozoic)

(Southwest of Asheboro); Mafic Metavolcanic Rock - metamorphosed basaltic flows and tuffs, dark green to black; interbedded with felsic and intermediate metavolcanic rock and metamudstone.

Felsic Metavolcanic Rock (Cambrian/Late Proterozoic)

Felsic Metavolcanic Rock - metamorphosed dacitic to rhyolitic flows and tuffs, light gray to greenish gray; interbedded with mafic and intermediate metavolcanic rock, meta-argillite, and metamudstone.

Felsic Metavolcanic Rock (Cambrian/Late Proterozoic)

Felsic Metavolcanic Rock - metamorphosed dacitic to rhyolitic flows and tuffs, light gray to greenish gray; minor mafic and intermediate metavolcanic rock.

Felsic Metavolcanic Rock (Cambrian/Late Proterozoic)

Felsic Metavolcanic Rock - metamorphosed dacitic to rhyolitic flows and tuffs, light gray to greenish gray; interbedded with mafic and intermediate metavolcanic rock, meta-argillite, and metamudstone.

Intermediate Metavolcanic Rock (Cambrian/Late Proterozoic)

Intermediate Metavolcanic Rock - metamorphosed andesitic tuffs and flows, medium to dark grayish green; minor felsic and mafic metavolcanic rock.

Intermediate Metavolcanic Rock (Cambrian/Late Proterozoic)

Intermediate Metavolcanic Rock - metamorphosed andesitic tuffs and flows, medium to dark grayish green; minor felsic and mafic metavolcanic rock.

Mafic Metavolcanic Rock (Cambrian/Late Proterozoic)

Mafic Metavolcanic Rock - metamorphosed basaltic flows and tuffs, dark green to black; interbedded with felsic and intermediate metavolcanic rock and metamudstone.

Mafic Metavolcanic Rock (Cambrian/Late Proterozoic)

Mafic Metavolcanic Rock - metamorphosed basaltic to andesitic tuffs and flows, grayish green to black. Locally includes hypabyssal intrusives and minor felsic metavolcanic rock.

Mafic Metavolcanic Rock (Cambrian/Late Proterozoic)

Mafic Metavolcanic Rock - metamorphosed basaltic flows and tuffs, dark green to black; interbedded with felsic and intermediate metavolcanic rock and metamudstone.

Metavolcanic Rock (Cambrian/Late Proterozoic)

Metavolcanic Rock - interbedded felsic to mafic tuffs and flowrock.

Metavolcanic Rock (Cambrian/Late Proterozoic)

Metavolcanic Rock - interbedded felsic to mafic tuffs and flowrock.

Mount Rogers Formation; Metafelsite (Late Proterozoic)

Metafelsite (820 my) - light-colored porphyritic extrusive rock.

Uwharrie Formation; Felsic Metavolcanic Rock (Cambrian/Late Proterozoic)

(at Asheboro and to south); Felsic Metavolcanic Rock - metamorphosed dacitic to rhyolitic flows and tuffs, light gray to greenish gray; interbedded with mafic and intermediate metavolcanic rock, meta-argillite, and metamudstone.

New Hampshire

Ammonoosuc Volcanics, Felsic metavolcanic rocks (Middle - Upper Ordovician)

Ammonoosuc Volcanics, Felsic metavolcanic rocks.

Littleton Formation, Volcanic lentils (Lower Devonian)

Littleton Formation, Volcanic lentils - Both mafic and felsic

Perry Mountain and Rangeley Formations, undivided (Silurian)

Perry Mountain and Rangeley Formations, undivided.

Perry Mountain Formation, Sedimentary and subordinate distal felsic and mafic volcanic facies in Piermont allochthon (Lower?- Middle? Silurian)

Perry Mountain Formation, Sedimentary and subordinate distal felsic and mafic volcanic facies in Piermont allochthon.

Rangeley Formation, Felsic metavolcanic rocks (Lower Silurian (Llandoverian))

Rangeley Formation, Felsic metavolcanic rocks - Found in south-central New Hampshire.

Rangeley Formation, undivided (Lower Silurian (Llandoverian))

Rangeley Formation, undivided.

Smalls Falls Formation, Felsic metavolcanic member (Upper to Middle Silurian (Ludlovian and Wenlockian))

Smalls Falls Formation, Felsic metavolcanic member.

New Mexico

metamorphic rocks (Proterozoic | Paleoproterozoic)

Lower Proterozoic metamorphic rocks, dominantly felsic volcanic, volcaniclastic and plutonic rocks (1650-1700+ Ma); includes Vadito Group; locally includes high-grade felsic gneisses of unknown age

South Carolina

Battleground Formation, Felsic metavolcanic rocks (Neoproterozoic)

Battleground Formation, Felsic metavolcanic rocks

Felsic metavolcanic rocks and felsic gneiss interpreted to the metavolcanics (Ordovician to Neoproterozoic)

Felsic metavolcanic rocks and felsic gneiss interpreted to the metavolcanics

Flat Swamp Formation (AKA Flat Swamp Member of Cid Formation) (Ordovician to Neoproterozoic)

Flat Swamp Formation (AKA Flat Swamp Member of Cid Formation): crystal and lithic metatuff of rhyolite to rhyodacite composition

Lincolnton Metadacite (Neoproterozoic)

Lincolnton Metadacite

Metavolcanic rocks, interlayered felsic to mafic, undivided (Ordovician to Neoproterozoic)

Metavolcanic rocks, interlayered felsic to mafic, undivided

Virginia

Interlayered Mafic and Felsic Volcanic Rocks (Proterozoic Z)

Interlayered mafic and felsic metavolcanic rocks.

Metavolcanic and Metasedimentary Rocks - Felsic metatuff, mica schist, and gneiss. (Cambrian)

Metavolcanic and Metasedimentary Rocks - Felsic metatuff, mica schist, and gneiss.

Phyllite and Metatuff (Proterozoic Z)

Phyllite and metatuff.

Vermont

Missisquoi Formation, Cram Hill Member (Ordovician)

Missisquoi Formation, Cram Hill Member - Pale greenish-gray to black phyllite grades locally into gray to black slate; felsic to mafic volcanic rocks.

Wisconsin

Mafic to felsic metavolcanic rocks (Early Proterozoic)

Mafic to felsic metavolcanic rocks - Volcanic rocks in areas of sparse geologic data and nondefinitive magnetic and gravity data

Rhyolite to dacite (Early Proterozoic)

Rhyolite to dacite - Massive to flow-banded rocks of greenschist metamorphic grade in northeastern Wisconsin; virtually undeformed.