Ordovician graywacke of the Depot Mountain sequence

Ordovician graywacke of the Depot Mountain sequence
State Maine
Name Ordovician graywacke of the Depot Mountain sequence
Geologic age Ordovician
Lithologic constituents
Major
Sedimentary > Clastic > Sandstone > GraywackeW - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; Protolith K - Calcareous feldspathic sandstone
Comments Named for Chase Lake, Piscataquis Co., north-central ME. Consists of a lower member composed of slate and graywacke and an upper member composed of conglomerate and graywacke. Thickness is at least 610 m. Unconformably overlies Chase Brook Formation; conformably underlies Bluffer Pond Formation. (ME017) Unit description from USGS GEOLEX website (ME078). W - Weakly metamorphosed; contains local occurrences of prehnite and pumpellyite; Protolith A - Pelite
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., 1989, The Depot Mountain Formation; Transition from syn- to post-Taconian basin along the Baie Verte-Brompton line in northwestern Maine, IN Tucker, R.D., and Marvinney, T.G., eds., Studies in Maine geology; structure and stratigraphy; Volume 2: Maine Geological Survey, p. 85-99.

US Geological Survey, 2005, National Geologic Map Database, Geologic Names Lexicon "GEOLEX", http://ngmdb.usgs.gov/Geolex/.

NGMDB product
Counties Aroostook