Silurian greenstone rocks of the Fivemile Brook sequence (MESfmg;0)

State	Maine
Name	Silurian greenstone rocks of the Fivemile Brook sequence
Geologic age	Silurian
Original map label	Sfmg
Comments	The informal greenstone member, mostly in the lower part of the formation, consists of a 0 to 1,000 m interval of andesitic igneous rocks which form sills, flows, and pyroclastic layers. An upper lentil of andesitic(?) volcanics is suggested by magnetic anomalies, although no outcrops have been seen. (ME038) Unit description from USGS GEOLEX website (ME078). W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite Protolith V - Basaltic volcanic rocks
Primary rock type	greenstone
Secondary rock type
Other rock types
Lithologic constituents	Major Metamorphic > Metaigneous > GreenstoneW - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite Protolith V - Basaltic volcanic rocks
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. Roy, D.C., 1980, Evaluation of the mineral potential, upper St. John River Valley, Aroostook County, Maine; Appendix A; Bedrock geology of pre-Devonian rocks in northwestern-most Aroostook County, Maine: Maine Geological Survey Open-File Report, no. 80-14b, 34 p., 3 sheets, (incl. geologic map, scale 1:62,500). USGS Geologic Names Lexicon (GEOLEX) [http://ngmdb.usgs.gov/Geolex/]
Geographic coverage	Aroostook