- Usage in publication:
-
- Russell Mountain Rhyolite
- Modifications:
-
- Named
- Dominant lithology:
-
- Rhyolite
- Tuff
- AAPG geologic province:
-
- Midcontinent region
Summary:
Russell Mountain Rhyolite. Unit is part of sequence of Precambrian volcanic rocks associated with Taum Sauk caldera in western part of St. Francois Mountains, southeast Missouri (Midcontinent region). Notable exposures on Bell, High Top, Lee, Lindsey, North Bell, Russell, Taum Sauk, Vail, and Wildcat Mountains. Consists of brick-red to dark-maroon ash-flow tuff with abundant, large fiamme and 2-5 percent white feldspar phenocrysts. Thickness 300 m. Overlies Lindsey Mountain Rhyolite (new); underlies Wildcat Mountain Rhyolite (new). Age is Precambrian. Report includes geologic map. Unit named and described on stratigraphic column (table 1).
Russell Mountain Rhyolite replaces: Hogan Mountain Rhyolite (Bell, Lee, and North Bell Mountains), Stouts Creek Rhyolite (Russell, Taum Sauk, Vail, and Wildcat Mountains), and Van East Group (Lindsey and High Top Mountains) as mapped by Tolman and Robertson (1969, Missouri Geol. Survey Rpt. Inv., no. 44); Unit C of tuff of Stouts Creek of Anderson (1970, Missouri Geol. Survey Rpt. Inv., no. 46); and Unit 770 of Berry and Bickford (1972, Bull. Volcanology, v. 36, p. 303-318).
Type section: in NE/4 SW/4 sec. 2, T. 33 N., R. 3 E., Ironton quadrangle, Iron Co., MO. Named from exposures on east slope of Russell Mountain, [probably in Reynolds or Iron Co.], MO.
Source: Modified from GNU records (USGS DDS-6; Denver GNULEX).
- Usage in publication:
-
- Russell Mountain Rhyolite
- Modifications:
-
- Revised
- AAPG geologic province:
-
- Midcontinent region
Summary:
Russell Mountain Rhyolite, 7th formation from base (of 12) of /Taum Sauk Group (new) of /St. Francois Mountains Volcanic Supergroup (revised). Study area is St. Francois Mountains, southeast Missouri (Midcontinent region). Overlies Lindsey Mountain Rhyolite (revised) of Taum Sauk; underlies Wildcat Mountain Rhyolite (revised) of Taum Sauk. Age is Precambrian Y. Nomenclature listed in table 1.
[Conflicts with nomenclature guidelines (ACSN, 1970; NACSN, 1983, 2005, 2021): name Taum Sauk used for both group and formation within it (Taum Sauk Rhyolite has priority); name St. Francois Mountains applied concurrently to two different units in same area; a [supergroup] name combines a geographic name with the term ["supergroup,"] and no lithic designation is included.]
Source: Modified from 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 ([ ]).