- Usage in publication:
-
- Ute Ridge Tuff*
- Modifications:
-
- Named
- Dominant lithology:
-
- Tuff
- AAPG geologic province:
-
- San Juan Mountains province
Summary:
Named for excellent exposures on the lower slopes of Ute Ridge, its type area, Rio Grande Pyramid 7 1/2 min quad, Hinsdale Co, CO in the San Juan Mountain province. Is a densely welded red-brown phenocryst-rich quartz latite. Contains 30-40 percent phenocrysts of plagioclase, sanidine, biotite, and augite. Is a multiple-flow ash-flow sheet as much as 200 ft thick. Originally covered an area in excess of 60,000 sq km and an initial volume of at least 300 km. Has been traced as far north as Storm King Mountain, 33 km north of Ouray, southeast as far as Weminuche Creek 36 km southeast of Silverton, and as erosional remnants on high ridges west of San Juan caldera. Probably erupted from the Ute Creek caldera. Has reverse magnetic polarity. Is older than Blue Mesa Tuff and younger than San Juan, Picayune, or Lake Fork Formations. Assigned to the Oligocene; has a K-Ar age of 28.4 m.y.
Source: GNU records (USGS DDS-6; Denver GNULEX).
- Usage in publication:
-
- Ute Ridge Tuff*
- Modifications:
-
- Areal extent
- Overview
- AAPG geologic province:
-
- San Juan Mountains province
Summary:
Is more than 300 m thick and has a volume of more than 500 cubic km. Source area was the Ute Creek caldera. Occurs in Hinsdale, Ouray, and San Juan Cos, CO in the San Juan Mountain province. Distribution map. Has a 28.4 m.y. 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 ([ ]).