- Usage in publication:
-
- Salem gabbro-diorite*
- Modifications:
-
- [Principal reference]
- Dominant lithology:
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- Diorite
- Gabbro
- Quartz diorite
- Granodiorite
- Tonalite
- Amphibolite
- AAPG geologic province:
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- New England province
Summary:
Pg. 178-181, and map. Salem gabbro diorite. Includes several types of rock. Most characteristic and widely distributed rock contains quartz, labradorite, hornblende, augite, and biotite, and might be called a quartz-augite diorite, a quartz-hornblende gabbro, or an augite-hornblende tonalite, or better still, a quartz gabbro-diorite. Grades into quartz diorite and granodiorite and into hornblende diorite and amphibolite. [Gabbro at Nahant treated as distinct formation.] [Age is considered early Paleozoic.]
Named from occurrence at Salem, northeastern MA.
Source: US geologic names lexicon (USGS Bull. 896, p. 1889).
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 ([ ]).