Penobscot Formation

Penobscot Formation
State Maine
Name Penobscot Formation
Geologic age Ordovician - Cambrian
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > Slate (Amphibolite epidote-amphibolite, Greenschist)AA - Low rank amphibolite facies; AB - Medium rank amphibolite facies; AC - High rank amphibolite facies; E - Epidote-amphibolite facies; GS - Greenschist facies; Protolith C - Sulfidic/carbonaceous pelite
Metamorphic > Schist (Amphibolite epidote-amphibolite, Greenschist)AA - Low rank amphibolite facies; AB - Medium rank amphibolite facies; AC - High rank amphibolite facies; E - Epidote-amphibolite facies; GS - Greenschist facies; Protolith C - Sulfidic/carbonaceous pelite
Metamorphic > Metasedimentary > Metaclastic > Quartzite (Amphibolite epidote-amphibolite, Greenschist)AA - Low rank amphibolite facies; AB - Medium rank amphibolite facies; AC - High rank amphibolite facies; E - Epidote-amphibolite facies; GS - Greenschist facies; Protolith C - Sulfidic/carbonaceous pelite
Comments GS - Greenschist facies; W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; Protolith W - mafic to felsic volcanic rocks
References

Osberg, P.H., Hussey, A.M., and Boone, G.M., 1985, Bedrock geologic map of Maine: Maine Geological Survey, Dept. of Conserv., scale 1:500,000.

Smith, G.O., Bastin, E.S. and Brown, C.W., 1907, Description of the Penobscot Bay quadrangle [Maine]: U.S. Geological Survey Geologic Atlas of the United States, Penobscot Bay folio, no. 149, 14 p.

https://pubs.er.usgs.gov/publication/gf149

Boucot, A.J., Brookins, D.G., Forbes, W.H., and Guidotti, C.V., 1972, Staurolite zone, Caradoc (Middle-Late Ordovician) age, Old World province brachiopods from Penobscot Bay, Maine: Geol. Soc. Amer., Bull., v. 83, p. 1953-1960.

US Geological Survey, 2005, National Geologic Map Database, Geologic Names Lexicon "GEOLEX", http://ngmdb.usgs.gov/Geolex/.

NGMDB product
Counties Hancock - Knox - Waldo - Washington