- Usage in publication:
-
- Crossen Trachyte [Member]
- Modifications:
-
- Mapped 1:250k
- Dominant lithology:
-
- Trachyte
- AAPG geologic province:
-
- Permian basin
Summary:
Crossen Trachyte [Member] (Map unit Tpct), in lower part of Pruett Formation, massive, pophyritic, stubby feldspar phenocrysts in fine-grained, grayish- to reddish-brown groundmass, hard, brittle; weathers to rusty-brown pitted surface; thickness about 150 feet, crops out in Crossen Mesa north of Green Valley.
Source: Publication.
- Usage in publication:
-
- Crossen Trachyte
- Modifications:
-
- Geochronologic dating
- AAPG geologic province:
-
- Permian basin
Summary:
Pg. 13. Crossen Trachyte. Trachyte sample from Whirlwind Spring quadranlge, Brewster County, southwestern Texas, yielded a K-Ar age of 38.6 +/-1.6 Ma (whole-rock). Data from S.S. Goldich and M.A. Elms, 1949 (GSA Bull., v. 60, p. 1133-1182), R.A. Maxwell and J.W. Dietrich, 1965 (West Texas Geol. Soc. Pub. 65-51, p. 11-33), and W.N. McAnulty, 1955 (GSA Bull., v. 66, p. 531-578); age recalculated using decay constants of Steiger and Jager, 1977 (Earth Planet. Sci. Letters, v. 36, p. 359-362).
[Age considered Eocene; Eocene-Oligocene boundary 36.6 (38-34) Ma (from Geologic Names Committee, USGS, 1983 ed. geol. time scale, with additions from N.J. Snelling, 1985, The Geol. Soc. Mem., no. 10).]
Source: Publication.
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 ([ ]).