Geologic units containing meta-basalt

Metabasalt

A low-grade, mafic metavolcanic rock with preserved evidence of its original basaltic character

This category is also used for meta-basalt.

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Colorado

Felsic and hornblendic gneisses, either separate or interlayered (Proterozoic | Paleoproterozoic): Includes metabasalt, metatuff, and interbedded metagraywacke; locally contains interlayered biotite gneiss. Derived principally from volcanic rocks

Massachusetts

Nassau Formation (Lower Cambrian and Proterozoic Z): Nassau Formation - Dark-green to greenish brown, massive to well foliated stilpnomelane-chlorite-oligoclase-epidote metabasalt and basaltic tuff.
Washington Gneiss (Proterozoic Y): Washington Gneiss - Coarse- to medium-grained hornblende-garnet amphibolite, hornblende-plagioclase gneiss and phlogopite-hornblende-plagioclase amphibolite (metabasalt).

Maryland

Catoctin Metabasalt (Late Precambrian): Catoctin Metabasalt - Thick-bedded metabasalt with amygdaloidal layers and secondary veins of quartz, calcite, and epidote; interbedded green tuffaceous phyllite and blue amygdaloidal metaandesite.
Sams Creek Metabasalt (Late Precambrian (?)): Sams Creek Metabasalt - Grayish-green, massive to schistose, amygdaloidal metabasalt.

Michigan

Menominee Group; Emperor Volcanic Complex (Early Proterozoic): Menominee Group; Emperor Volcanic Complex - Metamorphosed intermediate to mafic pyroclastic and flow rocks in easternmost part of Gogebic Range
Metabasalt (Late Archean) (Late Archean): Metabasalt (Late Archean) - Derived from mafic to intermediate pyroclastic rocks and massive to pillowed lava flows. Unit mapped as Ramsey Formation by Prinz (1981) south of Gogebic Range; mapped as Mona Schist and Kitchi Schist in northern complex of Marquette District.

Minnesota

Mafic metavolcanic rocks (Late Archean): Mafic metavolcanic rocks - Dominantly basalt that contains thin sedimentary units, including iron-formation. Includes parts of the Ely Greenstone and the Newton Lake Formation in northeastern Minnesota. Also includes metabasalt exposed in the Minnesota River Valley.

Montana

Purcell basalt (Proterozoic | Mesoproterozoic): Purcell basalt: dark greenish-gray altered effusive basalt; in Glacier National Park it is near base of Missoula group; but in other localities, mainly in Canada, it is reported in other stratigraphic positions.

North Carolina

Chilhowee Group, Grandfather Mountain Formation; Greenstone (Late Proterozoic): Greenstone - schistose to massive, amygdaloidal; interlayered with metasedimentary rocks. Includes Montezuma Member (metabasalt) in upper part.

New Hampshire

Ammonoosuc Volcanics, Metabasalt (Middle - Upper Ordovician): Ammonoosuc Volcanics, Metabasalt.
Frontenac Formation, Metabasalt interbeds (Silurian?): Metabasalt interbeds.
Jim Pond Formation (Upper Cambrian): Jim Pond Formation - Pillow metabasalt member. Lenses within the Hurricane Mountain Formation of northern New Hampshire interpreted as tectonic rafts of Jim Pond Formation.
Smalls Falls Formation, Metabasalt member (Upper to Middle Silurian (Ludlovian and Wenlockian)): Smalls Falls Formation, Metabasalt member.

New Jersey

Metabasalt (Late Proterozoic): Metabasalt - Sequence of conformably layered volcanic rocks of fine-grained to aphanitic, greenish-gray, retrogressively metamorphosed greenstone, greenschist, and basalt. Greenschist contains clots and lenses of blue quartz and abundant sulfide. Unit does not crop out and is known only from subsurface borings and artificial exposures. Interpreted to be Late Proterozoic by Volkert and Drake (1993) on the basis of geochemical similarity to Late Proterozoic metadiabase dikes in New Jersey Highlands.

Oregon

Colebrooke Schist (Mesozoic or Paleozoic) (Paleozoic or Mesozoic): Metamorphosed pelitic sedimentary rocks and subordinate metamorphosed submarine pillow lavas and pyroclastic beds of basaltic composition. Metamorphic age is Early Cretaceous (about 130 Ma), according to Coleman (1972), and protolith may be Jurassic or older in age
Volcanic rocks (Triassic and Permian) (Permian to Triassic): Massive flows of porphyritic meta-andesite, metabasalt, spilite, and keratophyre, volcanic breccia, and subordinate amounts of fine-grained volcaniclastic rocks. In eastern Oregon probably mostly Late Triassic in age, but includes some Permian rocks (OR084). Includes Clover Creek Greenstone (OR035), Gold Creek greenstone (informal name; OR029), and greenstone of Ashley (OR081)

Pennsylvania

Metabasalt (Precambrian): Metabasalt - Dark-gray, fine-grained intrusives; locally, mineralogy is altered and unit has greenish color.
Sams Creek Metabasalt (Probably lower Paleozoic): Sams Creek Metabasalt - Altered basaltic flows, some amygdaloidal; green, schistose, containing hornblende, epidote, chlorite, and quartz.

Virginia

Actinolite Schist Metabasalt (Proterozoic): Actinolite schist metabasalt
Catoctin Formation - Hyaloclastite pillow breccia (Proterozoic Z-Cambrian): Catoctin Formation - Hyaloclastite pillow breccia
Catoctin Formation - Metabasalt (Proterozoic Z-Cambrian): Catoctin Formation - Metabasalt.
Catoctin Formation - Metabasalt breccia (high titanium) (Proterozoic Z-Cambrian): Catoctin Formation - Metabasalt breccia (high titanium)
Catoctin Formation -Metabasalt breccia (low titanium) (Proterozoic Z-Cambrian): Catoctin Formation - Metabasalt breccia (low titanium)

Wisconsin

Metabasalt (Late Archean) (Late Archean): Metabasalt (Late Archean) - Derived from mafic to intermediate pyroclastic rocks and massive to pillowed lava flows. Unit mapped as Ramsey Formation by Prinz (1981) south of Gogebic Range; mapped as Mona Schist and Kitchi Schist in northern complex of Marquette District.