- Usage in publication:
-
- Ryan Spring Formation*
- Modifications:
-
- Named
- Geochronologic dating
- Dominant lithology:
-
- Tuff
- Rhyolite
- Andesite
- AAPG geologic province:
-
- Great Basin province
Summary:
Named as a formation of the Needles Range Group (rank raised) for exposures near Ryan Spring, Beaver Co, UT in the Great Basin province. Type section designated in NE1/4 sec 35 and NW1/4 sec 36, T28S, R19W, Miners Cabin quad. Includes two named cooling units, the Greens Canyon and Mackleprang Tuff Members, and two unnamed units, the andesite flow and rhyolite flow members. Lies between the intracaldera member of Wah Wah Springs Formation and Lund Formation. Is within the Indian Peak caldera. Is found very locally outside the caldera. Principal reference section designated in secs 19, 30, and 31, T31S, R17W, and secs 24 and 25, T31S, R18W where the rhyolite flow and andesite flow members are present. Rhyolite flow member dated as 28.4 +/-1.2 m.y. (Zr F-T).
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 ([ ]).