- Usage in publication:
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- Ketcherside Mountain ignimbrite
- Modifications:
-
- Named
- Dominant lithology:
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- Ignimbrite
- Trachyte
- AAPG geologic province:
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- Midcontinent region
Summary:
Named as in informal field term, probably for its occurrence at Ketcherside Mountain in southern St. Francois Mountains, southeast MO, Midcontinent region. Consists of dark-gray, porphyritic, quartz-alkali trachyte with phenocrysts of perthitic orthoclase (1.5%) and quartz (0.1%); characterized by low phenocryst content, abundant small fiamme outlines, and small, white, bleached zones giving a mottled appearance to matrix. Overlies the Glover formation (new, informal field term) [rank term "formation" should not be used after geographic name for informal units]; underlies unnamed bedded tuffs and volcaniclastic units. Ketcherside Mountain and Grassy Mountain Ignimbrite replace Stouts Creek Rhyolite (not used) of Tolman and Robertson (1969). Mapped. Table 1 compares nomenclature used in area. Detailed petrographic description in Appendix 1. Precambrian age.
[Authors' intentions are unclear as to which, if any, of the geologic units discussed should have formal status.]
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 ([ ]).