Silurian Sangerville Formation (MESs;0)

State	Maine
Name	Silurian Sangerville Formation
Geologic age	Silurian
Original map label	Ss
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). AA - Low rank amphibolite facies AB - Medium rank amphibolite facies AC - High rank amphibolite facies GS - Greenschist facies E - Epidote-amphibolite facies Protolith R - Interbedded pelite and limestone and/or dolostone
Primary rock type	sandstone
Secondary rock type	shale
Other rock types	limestone; calc-silicate rock; granofels; schist; metasedimentary rock; conglomerate
Lithologic constituents	Major Sedimentary > Clastic > Mudstone > ShaleAA - Low rank amphibolite facies AB - Medium rank amphibolite facies AC - High rank amphibolite facies GS - Greenschist facies E - Epidote-amphibolite facies Protolith R - Interbedded pelite and limestone and/or dolostone Sedimentary > Clastic > SandstoneAA - Low rank amphibolite facies AB - Medium rank amphibolite facies AC - High rank amphibolite facies GS - Greenschist facies E - Epidote-amphibolite facies Protolith R - Interbedded pelite and limestone and/or dolostone Incidental Metamorphic > MetasedimentaryAA - Low rank amphibolite facies AB - Medium rank amphibolite facies AC - High rank amphibolite facies GS - Greenschist facies E - Epidote-amphibolite facies Protolith R - Interbedded pelite and limestone and/or dolostone Metamorphic > SchistAA - Low rank amphibolite facies AB - Medium rank amphibolite facies AC - High rank amphibolite facies GS - Greenschist facies E - Epidote-amphibolite facies Protolith R - Interbedded pelite and limestone and/or dolostone Sedimentary > Clastic > ConglomerateAA - Low rank amphibolite facies AB - Medium rank amphibolite facies AC - High rank amphibolite facies GS - Greenschist facies E - Epidote-amphibolite facies Protolith R - Interbedded pelite and limestone and/or dolostone Metamorphic > Granoblastic > GranofelsAA - Low rank amphibolite facies AB - Medium rank amphibolite facies AC - High rank amphibolite facies GS - Greenschist facies E - Epidote-amphibolite facies Protolith R - Interbedded pelite and limestone and/or dolostone Metamorphic > Metasedimentary > Calc-silicate-rockAA - Low rank amphibolite facies AB - Medium rank amphibolite facies AC - High rank amphibolite facies GS - Greenschist facies E - Epidote-amphibolite facies Protolith R - Interbedded pelite and limestone and/or dolostone Sedimentary > Carbonate > LimestoneAA - Low rank amphibolite facies AB - Medium rank amphibolite facies AC - High rank amphibolite facies GS - Greenschist facies E - Epidote-amphibolite facies Protolith R - Interbedded pelite and limestone and/or dolostone
Map references	Digital bedrock data downloaded from Maine Office of GIS in September 2005 from http://apollo.ogis.state.me.us/catalog/catalog.asp?state=2&extent=cover#bedrock Bedrock units table (publication date 11/15/2002) downloaded from same site. Permission to redistribute these data granted by Dr. Robert Marvinney, State Geologist of Maine, in September 2006. [http://apollo.ogis.state.me.us/catalog/catalog.asp?state=2&extent=cover#bedrock]
Unit 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. Moench, R.H., Boone, G.M., Bothner, W.A., Boudette, E.L., Hatch, N.L., Jr., Hussey, A.M., III, Marvinney, R.G. and Aleinikoff, J.N., 1995, Geologic map of the Sherbrooke-Lewiston area, Maine, New Hampshire, and Vermont, United States, and Quebec, Canada: U.S. Geological Survey Miscellaneous Investigations Series Map, I-1898-D, 56 p., 2 sheets, scale 1:250,000, Prepared in cooperation with the Maine Geological Survey and the New Hampshire Geological Survey. [http://pubs.er.usgs.gov/publication/i1898D] Berry, W.B.N., pers. communication, 1983. Osberg, P.H., 1968, Stratigraphy, structural geology, and metamorphism of the Watervill-Vassalboro area, Maine: Maine Geol. Surv., Bull. 20, 64 p. Pankiwskyj, K.A., Ludman, A., Griffin, J.R., and Berry, W.B.N., 1976, Stratigraphic relationships on the southeast limb of the Merrimack synclinorium in central and eastern Maine: Geol. Soc. Amer., Memoir 146, p. 263-280. USGS Geologic Names Lexicon (GEOLEX) [http://ngmdb.usgs.gov/Geolex/]
Geographic coverage	Androscoggin - Franklin - Kennebec - Oxford - Penobscot - Piscataquis - Somerset