- Usage in publication:
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- Marcy anorthosite
- Modifications:
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- Named
- Dominant lithology:
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- Anorthosite
- AAPG geologic province:
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- Adirondack uplift
Summary:
Named the Marcy anorthosite for Mount Marcy, Essex Co., NY, after Cushing (1899) called it "Mount Marcy type" anorthosite. The Marcy is by far the most abundant facies of anorthosite of the Adirondacks. The most typical portion is very coarse-grained, light to dark bluish gray, and consists very largely of basic plagioclase feldspar, mainly labradorite, much of it practically devoid of foliation. Unit is of Precambrian age.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
-
- Marcy Anorthosite*
- Modifications:
-
- Overview
- AAPG geologic province:
-
- Adirondack uplift
Summary:
The Marcy Anorthosite is recognized in the Ontario-New York-New England seismic refraction/wide-angle reflection profile. The unit is a plutonic complex that was intruded into the middle crust during the Grenvillian orogeny. It forms a series of metamorphosed igneous products, including anorthosite, norite, gabbro, and a pyroxene-ilemite ore.
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 ([ ]).