- Usage in publication:
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- Hunsaker Member
- Modifications:
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- Named
- Dominant lithology:
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- Rhyolite
- AAPG geologic province:
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- Permian basin
Summary:
Named as middle member of the Huelster Formation. Probably named for the old Hunsaker ranch, Jeff Davis Co, TX, in the Permian basin. No type locality designated. Is a massive tuff-breccia occurring in the Madera Canyon, northern Davis Mountains of west-central TX, about 2 km northeast of the old Hunsaker ranch. Composed of angular fragments of up to approximately 25 cm diameter of sparsely porphyritic gray rhyolite. This rhyolite is set in a variable amount of tuffaceous matrix. Mostly the tuff-breccia is structureless, forming rounded, light-brown, moderately rugged outcrop. In several localities crude bedding occurs. A maximum thickness of about 300 m is reached in a small canyon about 1 km south of entrance to Madera Canyon. Overlies mafic lava and sedimentary rock of Huelster Formation; underlies either Gomez Tuff or trachytic lava. Geologic map. Chemical analyses. Correlation chart. Of Oligocene age.
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 ([ ]).