- Usage in publication:
-
- Lindsey Mountain Rhyolite
- Modifications:
-
- Named
- Dominant lithology:
-
- Rhyolite
- Tuff
- AAPG geologic province:
-
- Midcontinent region
Summary:
Lindsey 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, Lindsey, North Bell, Russell, Taum Sauk, Vail, and Wildcat Mountains. Consists of violet-gray, blackish or light-maroon ash-flow tuff with 5 to 20 percent quartz and alkali feldspar phenocrysts; has conchoidal fractures. Thickness 500 to 700 m. Overlies Ironton Rhyolite (new); underlies Russell Mountain Rhyolite (new). Age is Precambrian. Report includes geologic map. Unit named and described on stratigraphic column (table 1).
Lindsey Mountain Rhyolite replaces: Hogan Mountain Rhyolite (North Bell Mountain), Middlebrook Group (Bell and North Bell Mountains), Stouts Creek Rhyolite (Russell, Vail, and Wildcat Mountains, and north slope of Taum Sauk Mountain), and Van East Group (High Top and Lindsey Mountains) as mapped by Tolman and Robertson (1969, Missouri Geol. Survey Rpt. Inv., no. 44); Unit B of tuff of Stouts Creek of Anderson (1970, Missouri Geol. Survey Rpt. Inv., no. 46); and Unit 760 of Berry and Bickford (1972, Bull. Volcanology, v. 36, p. 303-318).
Type section: in S/2 NW/4 sec. 4, T. 33 N., R. 3 E., Ironton quadrangle, Iron Co., MO. Origin of name not stated by author, but probably named from exposures on Lindsey Mountain, Iron and Reynolds Cos., MO.
Source: Modified from GNU records (USGS DDS-6; Denver GNULEX).
- Usage in publication:
-
- Lindsey Mountain Rhyolite
- Modifications:
-
- Revised
- AAPG geologic province:
-
- Midcontinent region
Summary:
Lindsey Mountain Rhyolite, 6th 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 Buck Mountain Shut-ins Formation (revised) of Taum Sauk; underlies Russell 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 ([ ]).