Silurian undifferentiated sandstones

Silurian undifferentiated sandstones, in part of the Allsbury Formation and in part unnamed
State Maine
Name Silurian undifferentiated sandstones
Geologic age Silurian
Lithologic constituents
Sedimentary > Clastic > SandstoneGS - Greenschist facies; W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; Protolith D - Lithic sandstone
Comments In central Maine trough, Sangerville Formation is mapped as principal sandstone and shale facies, and subdivided into (ascending) Patch Mountain Limestone Member (name revised from Patch Mountain Member to emphasize lithology), consisting of thinly interbedded impure marble, coarsely crystallized calc-silicate rocks, granofels, and pelitic schist (high metamorphic grade), or thinly interbedded, gray micritic metalimestone, limy metasandstone, metasiltstone, and slate or pelitic schist (low metamorphic grade); a conglomerate member; euxinic shale lenses; Taylor Pond Member of Hussey (1983), consisting of feldspathic biotite- and hornblende-biotite granofels, thinly bedded calc-silicate rocks, and sparse garnet-rich laminations (coticule); an unnamed limestone member similar to Patch Mountain Limestone Member but at a higher stratigraphic level; and Thorncrag Hill Member of Hussey (1983), consisting of migmatitic pelitic gneiss and some calc-silicate rocks. Anasagunticook Member of Pankiwskyj and others (1976) and Moench and Pankiwskyj (1988) is tentatively reassigned to Waterville Formation, following usage of Osberg (1988). (ME004) Unit description from USGS GEOLEX website (ME078). GS - Greenschist facies; Protolith I - Conglomerate

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.

NGMDB product
Counties Aroostook - Penobscot