- Usage in publication:
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- Piseco Group
- Modifications:
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- Named
- Dominant lithology:
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- Gneiss
- AAPG geologic province:
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- Adirondack uplift
Summary:
Basement rocks of the Adirondack Mountains, consisting of interlayered charnockitic, granitic, and leucogranitic gneisses are here named the Piseco Group. It contains the lower Pharaoh Mountain Gneiss, which is overlain by the Brant Lake Gneiss in the central and eastern Adirondacks, and by leucogranitic gneiss, correlative with the Alexandria Bay Gneiss of the Northwest Lowlands, in the western Adirondack Highlands. Basal quartzo-feldspathic gneiss is the only unit of the Piseco Group in the southern Adirondacks. Unconformably underlies metasedimentary rocks of the Oswegatchie Group in the Northwest Lowlands, and the Lake George Group in the central, eastern, and southern Adirondacks. Regional metamorphism occurred during the Grenville Orogeny of 1.1 Ga is Proterozoic.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
-
- Piseco Group*
- Modifications:
-
- Overview
- AAPG geologic province:
-
- Adirondack uplift
Summary:
The Piseco Group of the Adirondacks of New York State is recognized in the Ontario-New York-New England seismic refraction/wide-angle reflection profile. The unit consists of granitic, charnockitic, and hornblende gneisses with localized mafic and amphibolitic interlayering.
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 ([ ]).