Carboniferous alkali feldspar granite (muscovite accessory mineral)

Muscovite-biotite granite
State Maine
Name Carboniferous alkali feldspar granite (muscovite accessory mineral)
Geologic age Carboniferous
Lithologic constituents
Major
Igneous > Plutonic > Granitic > Granitemuscovite-biotite granite; U - Unmetamorphosed
Comments Islesboro Formation is of Late Proterozoic age. Consists of interbedded pelite, siltstone and sandstone, limestone and dolomite, conglomerate, rhyolite, and basalt. D.B. Stewart (1990, oral commun.) considers Islesboro to be distal facies of North Haven Greenstone, Ellsworth Schist and schist at Columbia Falls (eastern coastal ME). (ME072) Unit description from USGS GEOLEX website (ME078). GS - Greenschist facies; AA - Low rank amphibolite facies; Protolith N - Limestone and/or dolostone
Stratigraphic units includes plutons: 46 - Sebago (Main phase) (ME101, ME102); 47 - Sebago (Westbrook phase) (ME103).
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.

Aleinikoff, J., 1984, pers. communication, in Moench and others, 1982.

Hayward, J.A., and Gaudette, H.E., 1984, Carboniferous age of the Sebago and Effingham plutons, Maine and New Hampshire: Geol. Soc. Amer., Abs. with Prog., v. 16, p. 22.

Brookins, D.G., and Hussey, A.M., II, 1978, Rb-Sr ages for Casco Bay Group and other rocks from the Portland-Orrs Island area, Maine: Geol. Soc. Amer., Abs. with Prog., v. 10, p. 34.

NGMDB product
Counties Androscoggin - Cumberland - Oxford - York