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Tm2 and Tm3 units of Morita Ranch Formation (possibly from Cienega Mountain area)

Tm2 and Tm3 units of Morita Ranch Formation (possibly from Cienega Mountain area)
State Texas
Name Tm2 and Tm3 units of Morita Ranch Formation (possibly from Cienega Mountain area)
Geologic age Phanerozoic | Cenozoic | Tertiary | Oligocene
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.
Primary rock type basalt
Secondary rock type trachyte
Other rock types
Lithologic constituents
Major
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)
Minor
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Pyroclastic, ash-flow)
Igneous > Volcanic > Felsic-volcanic > Trachyte (Flow)
Map references
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
Unit 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.
Counties Presidio