- Usage in publication:
-
- Middlefield Granite*
- Modifications:
-
- Overview
- AAPG geologic province:
-
- New England province
Summary:
Used as Middlefield Granite of Devonian age.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
-
- Middlefield Granite*
- Modifications:
-
- Age modified
- AAPG geologic province:
-
- New England province
Summary:
Age of Middlefield Granite, named by Emerson (1898, 1917) and revised by Hatch and others (1970) is changed from Early(?) Devonian to Devonian. [No explanation for age change given.]
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
-
- Middlefield Granite
- Modifications:
-
- Geochronologic dating
- Age modified
- AAPG geologic province:
-
- New England province
Summary:
At Glendale Falls, Middlefield Granite interfingers with Early Ordovician or older Moretown Formation. The granite contains abundant xenoliths of pelitic and mafic schist typical of the Moretown. It is authors' interpretation that the Moretown was deformed and metamorphosed before the intrusion of the Middlefield Granite and that later deformation after intrusion affected both the granite and the schist. Zircons separated from the Middlefield are dated at 447+/3 Ma [Late Ordovician] by evaporation analysis. Age is consistent with interpretation that Middlefield was post-Taconian and pre- or early syn-Acadian.
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 ([ ]).