- Usage in publication:
-
- Cooke Granite*
- Modifications:
-
- Named
- Dominant lithology:
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- Granite
- AAPG geologic province:
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- Northern Rocky Mountain region
Summary:
Named for exposures near Cooke, sec 25, T9S, R14E, Park Co, MT in Northern Rocky Mountain region. No type locality designated. Is a medium-grained, unmetamorphosed pink granite in which quartz and pink orthoclase make up the bulk of the rock and ferromagnesian minerals--hornblende and biotite--are sparse. Crystals usually measure 3 mm in diameter. Pegmatitic facies found in or near Goose Creek granite (new). Inclusions of schist and Goose Creek have been observed. Cuts the Goose Creek at many places. Occurs at five major areas on the geologic map. Assigned an Archean age.
Source: GNU records (USGS DDS-6; Denver 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 ([ ]).