Infiernito caldera volcanic rocks including Capote Mountain Tuff, Tsh2 of Shely Group, Buckshot Ignimbrite, and Tm1 of Morita Ranch Formation (TXEOin;0)

State	Texas
Name	Infiernito caldera volcanic rocks including Capote Mountain Tuff, Tsh2 of Shely Group, Buckshot Ignimbrite, and Tm1 of Morita Ranch Formation
Geologic age	Late Eocene
Lithologic constituents	Major Igneous > Volcanic > Felsic-volcanic > Trachyte (Flow) Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow, Pyroclastic-ash flow) Minor Igneous > Volcanic > Mafic-volcanic > Basaltic-andesite (Flow) Incidental Sedimentary > Clastic > Mixed-clastic > Conglomerate-sandstone (Bed) Igneous > Hypabyssal > Felsic-hypabyssal > Hypabyssal-rhyolite (Laccolith) Sedimentary > Clastic > Conglomerate (Bed) Igneous > Hypabyssal > Felsic-hypabyssal (Dike or sill) Igneous > Hypabyssal > Felsic-hypabyssal > Hypabyssal-quartz-trachyte (Dike or sill)
Comments	Present in Presidio Co.,TX. From older to younger--precollapse rhyolitic to trachytic lavas, Infiernito Tuff--a rhyolitic, thick intracaldera and thin outflow ash-flow tuff and interbedded caldera-collapse breccia, post-collapse lavas--coarsely porphyritic quartz trachyte lava and caldera-fill sediments (interbedded tuffaceous sediments, conglomerate, and debris-flow deposits), rhyolite dome, and the major intrusion of the infiernito caldera, the Ojo Bonito quartz monzonite. The possible maximum thickness of Infiernito Ignimbrite is estimated to be 5,900 ft. (Henry and others, 1992). Capote Mountain Tuff is one of seven formations of Vieja Group. The Capote Mt Tuff (on Marfa Sheet, 1979) contains fine-grained, vitric, tuffaceous sandst. and siltst., a few interbeds of conglomerate. In the north it is v. lt. gray and few pale red beds; in south, lower 2/3 is pale red, upper 1/3 v. lt. gray. Thickness 600-1,200 ft. Contains vertebrate mammalian fossils believed by some in 1979 to be Oligocene in age. Tsh2 of Shely Group--trachyte, to 400 ft thick, exposed at north end of Chinati Mountains.
Stratigraphic units	Ojo Bonito intrusion, Infiernito Tuff
References	Bureau of Economic Geology, 1979, Marfa Sheet, Geologic Atlas of Texas: Bureau of Economic Geology and The University of Texas at Austin, scale 1:250,000. Amsbury, D.L., 1958, Geology of the Pinto Canyon area, Presidio County, Texas: University of Texas at Austin, Bureau of Economic Geology Geologic Quadangle Map 22, scale 1:63,360. Henry, C.D., Price, J.C., Duex, T.W., and James, E.W., 1992, Geology of the Infiernito caldera and magmatic evolution of the Chinati Mountains, Trans-Pecos Texas: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations no. 206, 56 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	NGMDB product page for 68390
Counties	Presidio

State

Name

Infiernito caldera volcanic rocks including Capote Mountain Tuff, Tsh2 of Shely Group, Buckshot Ignimbrite, and Tm1 of Morita Ranch Formation

Geologic age

Late Eocene

Lithologic constituents

Major

Igneous > Volcanic > Felsic-volcanic > Trachyte (Flow)

Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow, Pyroclastic-ash flow)

Minor

Igneous > Volcanic > Mafic-volcanic > Basaltic-andesite (Flow)

Incidental

Sedimentary > Clastic > Mixed-clastic > Conglomerate-sandstone (Bed)

Igneous > Hypabyssal > Felsic-hypabyssal > Hypabyssal-rhyolite (Laccolith)

Sedimentary > Clastic > Conglomerate (Bed)

Igneous > Hypabyssal > Felsic-hypabyssal (Dike or sill)

Igneous > Hypabyssal > Felsic-hypabyssal > Hypabyssal-quartz-trachyte (Dike or sill)

Comments

Present in Presidio Co.,TX. From older to younger--precollapse rhyolitic to trachytic lavas, Infiernito Tuff--a rhyolitic, thick intracaldera and thin outflow ash-flow tuff and interbedded caldera-collapse breccia, post-collapse lavas--coarsely porphyritic quartz trachyte lava and caldera-fill sediments (interbedded tuffaceous sediments, conglomerate, and debris-flow deposits), rhyolite dome, and the major intrusion of the infiernito caldera, the Ojo Bonito quartz monzonite. The possible maximum thickness of Infiernito Ignimbrite is estimated to be 5,900 ft. (Henry and others, 1992). Capote Mountain Tuff is one of seven formations of Vieja Group. The Capote Mt Tuff (on Marfa Sheet, 1979) contains fine-grained, vitric, tuffaceous sandst. and siltst., a few interbeds of conglomerate. In the north it is v. lt. gray and few pale red beds; in south, lower 2/3 is pale red, upper 1/3 v. lt. gray. Thickness 600-1,200 ft. Contains vertebrate mammalian fossils believed by some in 1979 to be Oligocene in age. Tsh2 of Shely Group--trachyte, to 400 ft thick, exposed at north end of Chinati Mountains.

Stratigraphic units

Ojo Bonito intrusion, Infiernito Tuff

References

Bureau of Economic Geology, 1979, Marfa Sheet, Geologic Atlas of Texas: Bureau of Economic Geology and The University of Texas at Austin, scale 1:250,000.

Amsbury, D.L., 1958, Geology of the Pinto Canyon area, Presidio County, Texas: University of Texas at Austin, Bureau of Economic Geology Geologic Quadangle Map 22, scale 1:63,360.

Henry, C.D., Price, J.C., Duex, T.W., and James, E.W., 1992, Geology of the Infiernito caldera and magmatic evolution of the Chinati Mountains, Trans-Pecos Texas: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations no. 206, 56 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

NGMDB product page for 68390

Counties

Presidio