Skip to main content

Ordovician - Cambrian Chase Brook Formation

Ordovician - Cambrian Chase Brook Formation
State Maine
Name Ordovician - Cambrian Chase Brook Formation
Geologic age Ordovician - Cambrian
Comments Named for Chase Brook, Piscataquis Co., north-central ME. Consists of gray, black, and green-gray slate with interbedded limestone and siltstone. Thickness is 760 m. Unconformably underlies Chase Lake Formation. Age is Cambrian(?). (ME017) Unit description from USGS GEOLEX website (ME078). W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite Protolith Z - Melange
Primary rock type slate
Secondary rock type limestone
Other rock types siltstone
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > SlateW - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite Protolith Z - Melange
Minor
Sedimentary > Carbonate > LimestoneW - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite Protolith Z - Melange
Sedimentary > Clastic > SiltstoneW - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite Protolith Z - Melange
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.
Hall, B.A., 1970, Stratigraphy of the southern end of the Munsungun anticlinorium, Maine: Maine Geol. Surv., Bull. 22, 63 p.
USGS Geologic Names Lexicon (GEOLEX)
Counties Aroostook - Piscataquis