Basal member [of The Straits Schist]

( = Russell Mountain Formation of Massachusetts) - Distinguished by presence of layers of amphibolite, marble, calc-silicate rock, and quartzite within more uniform schist like that on either side. Minor, unevenly distributed mineralization in W, Bi, Cu, Ni, and other metals.
State Connecticut
Name Basal member [of The Straits Schist]
Geologic age Silurian
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metacarbonate > Marble
Metamorphic > Amphibolite
Metamorphic > Schist
Minor
Metamorphic > Metasedimentary > Calc-silicate-rock
Metamorphic > Metasedimentary > Metaclastic > Quartzite
Comments Part of Central Lowlands; Iapetus (Oceanic) Terrane - Connecticut Valley Synclinorium; Hartland Belt
References

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

NGMDB product
Counties Fairfield - Hartford - Litchfield - New Haven