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Silurian - Ordovician Aroostook River Formation

Silurian - Ordovician Aroostook River Formation
State Maine
Name Silurian - Ordovician Aroostook River Formation
Geologic age Silurian - Ordovician
Comments Aroostook River Formation here named in northeastern ME. Unit is thin-bedded gray to green-gray calcareous slate interlayered with graywacke and siltstone. 600 m thick. Overlies Madawaska Lake Formation; conformably underlies Frenchville Formation. (ME029) Unit description from USGS GEOLEX website (ME078). W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite Protolith Q - Interbedded pelite and sandstone
Primary rock type slate
Secondary rock type graywacke
Other rock types siltstone
Lithologic constituents
Major
Sedimentary > Clastic > SiltstoneW - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite Protolith Q - Interbedded pelite and sandstone
Metamorphic > Metasedimentary > Metaclastic > Slate (Bed)W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite Protolith Q - Interbedded pelite and sandstone
Sedimentary > Clastic > Sandstone > ArkoseW - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite Protolith Q - Interbedded pelite and sandstone
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.
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., and Mencher, E., 1976, Ordovician and Silurian stratigraphy of northeastern Aroostook County, Maine: Geol. Soc. Amer., Memoir 148, p. 25-52.
USGS Geologic Names Lexicon (GEOLEX)
Counties Aroostook