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Geologic units containing granulite

Arizona

Early Proterozoic metamorphic rocks (Early Proterozoic)

Undivided metasedimentary, metavolcanic, and gneissic rocks. (1600-1800 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.

Trap Falls Formation (Middle or Lower Ordovician)

Trap Falls Formation (may be equivalent in part to Golden Hill Schist) - Gray to silvery, partly rusty weathering, medium-grained generally well layered schist, composed of quartz, sodic plagioclase, biotite, muscovite, and garnet, locally with sillimanite or kyanite, interlayered with two-mica gneiss and granulite and with amphibolite.

Trap Falls Formation plus Ordovician? granitic gneiss (Middle or Lower Ordovician)

Trap Falls Formation plus Ordovician? granitic gneiss - Trap Falls Formation (may be equivalent in part to Golden Hill Schist) - Gray to silvery, partly rusty weathering, medium-grained generally well layered schist, composed of quartz, sodic plagioclase, biotite, muscovite, and garnet, locally with sillimanite or kyanite, interlayered with two-mica gneiss and granulite and with amphibolite. Ordovician? granitic gneiss (including local terms Ansonia, Mine Hill, "Tyler Lake," "Siscowit") - White, light-gray, buff, or pink, generally foliated granitic gneiss, composed of sodic plagioclase, quartz, microcline, muscovite, and biotite, and locally garnet or sillimanite. Commonly contains numerous inclusions or layers of mica schist and gneiss.

Massachusetts

Erving Formation (Lower Devonian)

Erving Formation - Granofels and schist where mapped separately.

Fitchburg Complex (Lower Devonian or younger)

Fitchburg Complex - Dfgd containing many zones of foliated biotite-muscovite granite gneiss and inclusions of mica schist and feldspathic granulite.

Maryland

Wissahickon Formation; Lower Pelitic Schist (Late Precambrian (?))

Wissahickon Formation; Lower Pelitic Schist - (Formerly mapped as oligoclase facies of Wissahickon Formation.) Medium- to coarse-grained biotite-oligoclase-muscovite-quartz schist with garnet, staurolite, and kyanite; fine- to medium-grained semipelitic schist; and fine-grained granular to weakly schistose psammitic granulite; psammitic beds increase upward; apparent thickness 5,500 feet or more.

Maine

Ordovician - Cambrian Megunticook Formation (Ordovician - Cambrian)

Ordovician - Cambrian Megunticook Formation

Precambrian Z Coombs Limestone (Precambrian Z)

Precambrian Z Coombs Limestone

North Carolina

Migmatitic Biotite-Hornblende Gneisses (Middle Proterozoic)

Migmatitic Biotite-Hornblende Gneisses (1214 my) - unconformity; layered biotite-granite gneiss, biotite-hornblende gneiss, amphibolite, calc-silicate rock; locally contains relict granulite facies rock.

Nevada

Igneous and metamorphic complex (Paleozoic sedimentary rocks with Mesozoic intrusive rocks)

IGNEOUS AND METAMORPHIC COMPLEX-Pegmatitic granite and other granitic rocks complexly intermixed with metasedimentary rocks. Considered to be Mesozoic igneous complex intruding lower Paleozoic and possibly Precambrian Z sedimentary rocks. Grades into units shown on map as lower Paleozoic. Ruby Mountains and East Humboldt Range, Elko County

New York

Charnockite, granitic and quartz syenite gneiss (Middle Proterozoic)

Charnockite, granitic and quartz syenite gneiss - variably leucocratic, containing varying amounts of hornblende, pyroxenes, biotite; may contain interlayered amphibolite, metasedimentary gneiss, migmatite. Overprint signifies inequigranular texture or phacoidal structure.

Charnockite, granitic and quartz syenite gneiss (Middle Proterozoic)

Charnockite, granitic and quartz syenite gneiss - variably leucocratic, containing varying amounts of hornblende, pyroxenes, biotite; may contain interlayered amphibolite, metasedimentary gneiss, migmatite. Overprint signifies inequigranular texture or phacoidal structure.

Charnockite, mangerite, pyroxene-quartz syenite gneiss (Middle Proterozoic)

Charnockite, mangerite, pyroxene-quartz syenite gneiss - overprint signifies inequigranular texture.

Charnockite, mangerite, pyroxene-quartz syenite gneiss (Middle Proterozoic)

Charnockite, mangerite, pyroxene-quartz syenite gneiss - overprint signifies inequigranular texture.

Dolomitic and calcitic marbles interlayered with significant amounts of calcsilicate rock (Middle Proterozoic)

Dolomitic and calcitic marbles interlayered with significant amounts of calcsilicate rock - metasedimentary amphibolite, pyroxene granulite, and various gneisses; includes interlayered diopsidic and tremolitic marble and quartzite, and talc-tremolite rock (mined in Balmat-Edwards belt, northwest Adirondacks).

Fordham Gneiss (A member) (Precambrian - Middle Proterozoic )

Fordham Gneiss (A member) - fa: garnet-biotite-quartz-plagioclase gneiss, amphibolite, biotite-hornblende-quartz-plagioclase gneiss, quartz-feldspar granulite.

Fordham Gneiss, undivided (Precambrian - Middle Proterozoic )

Fordham Gneiss, undivided - fe: garnet-biotite-quartz-plagioclase gneiss, and amphibolite; fd: sillimanite-garnet schistose gneiss, quartzite; fc: biotite- hornblende-quartz-plagioclase gneiss, quartz-feldspar lenses, amphibolite, biotite and/or hornblende-quartz-feldspar gneiss; fb: amphibolite, biotite and/or hornblende-garnet-quartz-plagioclase gneiss; fa: garnet-biotite-quartz-plagioclase gneiss, amphibolite, biotite-hornblende-quartz-plagioclase gneiss, quartz-feldspar granulite.

Interlayered gabbroic or noritic metanorthosite (Middle Proterozoic)

Interlayered gabbroic or noritic metanorthosite - mangerite or charnockite, and the Yach lithology.

Inwood Marble (Early Cambrian - Lower Ordovician)

Inwood Marble - dolomite marble, calc-schist, granulite, and quartzite, overlain by calcite marble; grades into underlying patchy Lowerre Quartzite of Early Cambrian age.

Texas

Packsaddle Schist (preCambrian-Proterozoic [Llano])

Packsaddle Schist

Virginia

Layered Biotite Granulite and Gneiss (Proterozoic Y)

Layered biotite granulite and gneiss.

Layered Porphyrobliastic Pyroxene Granulite (Proterozoic Y)

Layered porphyroblastic pyroxene granulite

Layered Pyroxene Granulite (Proterozoic Y)

Layered pyroxene granulite

Leucocratic Granulite and Gneiss (Proterozoic Y)

Leucocratic granulite and gneiss.

Vermont

Cavendish Formation, Dolomite and Marble (Cambrian?)

Cavendish Formation, Dolomite and Marble - Buff dolomite; minor white to pink calcite marble; actinolitic and diopsidic marbles and beds of actinolite diopside granulite common in Chester dome. The Cavendish Formation is reinstated and considered part of the Mount Holly Complex in VT. Usage follows Thompson (1950), but is extended to include some rocks on Star Hill, including inner and outer cover rocks assigned by Downie (1982) to Hoosac and Pinney Hollow Formations. Formation is divided into four map units: calc-silicate rock and gneiss, marble, feldspathic schist or granofels, and the Gassetts Schist Member. The Cavendish correlates with the Wilcox Formation of the Mount Holly Complex in the Green Mountain massif, and therefore, is of Middle Proterozoic age (Ratcliffe, in press).

Fitch Formation (Silurian)

Fitch Formation - Quartz-plagioclase-biotite granulite; actinolite-diopside granulite; impure limestone and dolomite; mica schist; the carbonate-rich beds are typically an inch or two thick and segmented so as to give the weathered outcrop a characteristic pitted appearance. (Southeastern Vermont).

gneiss, quartzite, calc-silicate granulite (Precambrian)

Gneiss, quartzite, calc-silicate granulite.

Missisquoi Formation, Moretown Member (Ordovician)

Missisquoi Formation, Moretown Member - Quartzite and quartz-plagioclase granulite, in layers 1/8 to several inches thick, separated by "pinstripe" partings that contain muscovite, chlorite, epidote, biotite, and locally garnet; also greenish quartz-sericite-chlorite phyllite and schist, and minor carbonaceous phyllite. Schist and phyllite commonly contain biotite and garnet porphyroblasts in southern Vermont.

Mount Holly Complex (Precambrian)

Mount Holly Complex - Mainly fine- to medium-grained biotitic gneiss, locally muscovitic, and in western areas chloritic; massive and granitoid in some localities, fine-grained or schistose and compositionally layered in others; also abundant amphibolite and hornblende gneiss, and minor beds of mica schist, quartzite, and calc-silicate granulite; includes numerous small bodies of pegmatite and gneissoid granitic rock. Includes a suite of metatonalites, metatrondhjemite, and possible metadacite with chemical characteristics of a calc-alkaline volcanic-plutonic suite. Mappable units are College Hill Granite Gneiss and 10 unnamed subdivisions including several varieties of gneiss as well as schist, amphibolite, and quartzite. U-Pb zircon upper intercept ages of 1.35 to 1.30 Ga have been determined and interpreted as age of crystallization (Ratcliffe and others, unpub. data). Cores of abraded zircon obtained from College Hill Granite Gneiss of Mount Holly Complex have a U-Pb upper intercept age of 1245 +/-14 Ma, interpreted as crystallization age for that granite (Aleinikoff and others, 1990). Dust collected by abrasion of zircons, thought to represent migmatitic overgrowth, has a Pb-Pb age of approx 1100 Ma. These data suggest that College Hill Granite Gneiss was intruded at 1245 Ma and migmatized at 1100 Ma. On north and south slopes of College Hill, College Hill Granite Gneiss grades outward into migmatitic biotite granite gneiss of Mount Holly Complex. College Hill is discordant to contacts and folds in paragneiss units of Mount Holly Complex. Dacitic metavolcanics are found within Washington Gneiss of Berkshire massif of MA (Ratcliffe and Zartman, 1968). They are interbedded with thick succession of rusty-weathering, quartz-pebble gneisses, calc-silicate rocks and garnet-sillimanite schist similar to, but much thicker than, the rusty-weathering gneiss and schist unit of Mount Holly Complex exposed in Green Mountains of VT. It is possible that the metadacitic and metatrondhjemitic suite of VT constitutes a lateral, south-to-north facies of the Washington Gneiss of MA (Ratcliffe, in press).

Mount Holly Complex, calcite and dolomite marbles (Precambrian)

Mount Holly Complex, calcite and dolomite marbles - locally coarse grained; commonly contain phlogopite, actinolite, and diopside, and are interbedded with medium- to coarse-grained calc-silicate granulite; includes minor amounts of other types of Precambrian rock.

Washington

Pre-Upper Jurassic metamorphic rocks of the low-grade zone (Jurassic)

Greenschist, phyllite, and slate; includes some limestone, quartzose phyllite, schistose metaconglomerate, breccia, and basic igneous rocks. Includes schist locally.