- Usage in publication:
-
- Topaz Mountain Rhyolite*
- Modifications:
-
- Named
- Dominant lithology:
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- Rhyolite
- AAPG geologic province:
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- Great Basin province
Summary:
Named for Topaz Mountain. Type locality designated in secs 8, 9, 16, and 17, T13S, R11W, Juab Co, UT, Great Basin province. Unconformably overlies rocks of Oligocene to Paleozoic age. Consists of flows and extrusive domes of alkali rhyolite, vitrophyre, and interbedded tuff. The tuff is stratified, tan. The alkali rhyolite and vitrophyre are gray to red. Four F-T and two K-Ar dates from the flows range from 6.1 +/-0.4 to 6.8 +/-0.3 m.y. Two F-T dates on flows in Keg Mountains are about 8 m.y. Has a maximum thickness of 800 m. Assigned to the late Miocene.
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 ([ ]).