- Usage in publication:
-
- Roaring Mountain Member*
- Modifications:
-
- Named
- Dominant lithology:
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- Rhyolite
- AAPG geologic province:
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- Yellowstone province
Summary:
Named as a member of Plateau Rhyolite (new). Comprises the Crystal Spring, Odsidian Cliff, Cougar Creek, and Riverside flows which constitute the type area, northwest Yellowstone province, WY. The locality Roaring Mountain is in vicinity of Crystal Spring and Obsidian Cliff flows. All the flows are extracaldera phenocryst-free or very phenocryst poor rhyolites which contain abundant fresh obsidian. Phenocrysts, where present, are quartz, sanidine, plagioclase, and opaque oxides. Includes Riverside, Cougar Creek, Obsidian Cliff, and Crystal Spring flows. Overlies Lava Creek Tuff (new) of Yellowstone Group (rank raised), Swan Lake Flat Basalt, and parts of Obsidian Creek Member (new) of Plateau. Is overlain by Madison River Basalt (new). Obsidian from four flows dated (K-Ar method) range from 400,000 to 75,000 years. Reliability of dates is uncertain.
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 ([ ]).