Southington Mountain Member [of The Straits Schist]

Gray to silvery, non-rusty, medium-grained, well-layered alternating schist and granofels, composed of quartz, oligoclase, muscovite, biotite, and garnet, commonly with staurolite and kyanite (or sillimanite); schist commonly graphitic. Metamorphosed strata named Southington Mountain Schist by Fritts (1963) is traceable into southern Bristol quad., and is here revised as Southington Mountain Member of The Straits Schist. Consists of alternating bands of quartz-feldspar granulite and of graphitic, muscovite-biotite schist. Unit is characterized by distinct, widespread, graded bedding and locally abundant staurolite. Unit may correlate with the Goshen Formation of the Heath quad, MA-VT, of Middle Silurian to Early Devonian age (Simpson, 1990).
State Connecticut
Name Southington Mountain Member [of The Straits Schist]
Geologic age Devonian or Silurian or both
Lithologic constituents
Major
Metamorphic > SchistGray to silvery, non-rusty, medium-grained, well-layered alternating schist and granofels, composed of quartz, oligoclase, muscovite, biotite, and garnet, commonly with staurolite and kyanite (or sillimanite); schist commonly graphitic.
Metamorphic > Granoblastic > GranofelsGray to silvery, non-rusty, medium-grained, well-layered alternating schist and granofels, composed of quartz, oligoclase, muscovite, biotite, and garnet, commonly with staurolite and kyanite (or sillimanite).
Comments Part of Central Lowlands; Iapetus (Oceanic) Terrane - Connecticut Valley Synclinorium; Hartland Belt Secondary unit description per CT008.
References

Rodgers, John, compiler, 1985, Bedrock Geological Map of Connecticut: Connecticut Geological and Natural History Survey, Hartford, Connecticut, 2 sheets, scale 1:125,000.

Simpson, H.E., 1990, Bedrock geology of the Bristol quadrangle, Hartford, Litchfield, and New Haven Counties, Connecticut: U.S. Geological Survey Bulletin, 1573, 13 p.

https://pubs.er.usgs.gov/publication/b1573

NGMDB product
Counties Hartford - Litchfield - New Haven