- Usage in publication:
-
- Coys Hill Porphyritic Granite Gneiss*
- Modifications:
-
- Overview
- AAPG geologic province:
-
- New England province
Summary:
Used as Coys Hill Porphyritic Granite Gneiss of Early Devonian age. [No explanation given for revision of name.]
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
-
- Coys Hill Porphyritic Granite Gneiss*
- Modifications:
-
- Revised
- Redescribed
- AAPG geologic province:
-
- New England province
Summary:
Coys Hill Granite named by Emerson (1898) of Early Devonian age is here renamed Coys Hill Porphyritic Granite Gneiss to more accurately reflect its character in MA. Characterized by variously deformed tabular microcline and locally sodic plagioclase phenocrysts 3 to 10 cm long in a finer matrix of quartz, plagioclase, and biotite with or without muscovite, garnet, and sillimanite (Field, 1975). May be continuous with Cardigan pluton of Kinsman Quartz Monzonite of Billings (1956) (P.J. Thompson, 1983, unpub. data). (Authors note that Kinsman should also be called a granite under current terminology.) Lenses of hornblende-pyroxene gneiss within the Coys Hill unit are separately mapped on
Source: GNU records (USGS DDS-6; Reston GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).