| State | Texas |
|---|---|
| Name | Tm2 and Tm3 units of Morita Ranch Formation (possibly from Cienega Mountain area) |
| Geologic age | Oligocene |
| Lithologic constituents |
Major
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)
Minor
Igneous > Volcanic > Felsic-volcanic > Trachyte (Flow)
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Pyroclastic-ash flow)
|
| Comments | Sev. lava flows of distinctive porphyritic basalt, containing ca 25 percent tabular plagioclase phenocrysts as much as 2 cm long, make up unit 2 of Rix (1953). A thick quartz trachyte lava overlies the basalts east of Shafter and is included in unit 2 of Rix. rhyolite ash-flow tuffs, v. fine-grained, hard, med. grayish red, med. brownish gray. |
| References | Bureau of Economic Geology, 1979, Emory Peak--Presidio Sheet, Geologic Atlas of Texas, University of Texas at Austin.Rix, C.C., 1953, Geology of Chinati Peak quadrangle, Presidio County, Trans-Pecos Texas: University of Texas, Austin, Ph.D. dissertation, 188 p.Bureau of Economic Geology, 1992, Geologic Map of Texas: University of Texas at Austin, Virgil E. Barnes, project supervisor, Hartmann, B.M. and Scranton, D.F., cartography, scale 1:500,000. |
| NGMDB product | |
| Counties | Presidio |