Quitman Mountains caldera volcanic rocks and volcanic rocks of sneed (Cox) Mountain and west of Victorio Peak (TXOGq;0)

State	Texas
Name	Quitman Mountains caldera volcanic rocks and volcanic rocks of sneed (Cox) Mountain and west of Victorio Peak
Geologic age	Oligocene
Lithologic constituents	Major Igneous > Volcanic > Felsic-volcanic > Trachyte (Pyroclastic-ash flow) Igneous > Volcanic > Felsic-volcanic > Quartz-trachyte (Pyroclastic-ash flow, Flow) Minor Igneous > Volcanic > Felsic-volcanic > Rhyolite (Pyroclastic-ash flow, Flow) Incidental Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)
Comments	interbedded flows and pyroclastic rocks of the Square Peak Volcanics and Sneed (Cox) Mountain and west of Victorio Peak--small basalt flow remnants. Square Peak Volcanics comprises more than 1,000 m of crudely layered ash-flow tuffs and lavas that occur in the central Quitman Mountains caldera and were erupted during 3 main caldera-forming stages. Lithologies range from high-K calc-alkaline, metaluminous to peraluminous trachytes (45 percent by volume), quartz trachytes (25 percent by vol.), and rhyolites (30 pecent by vol.) according to Setter and Adams (1986).
Stratigraphic units	Square Peak Volcanics
References	Bureau of Economic Geology, 1968, Van Horn-El Paso Sheet, Geologic Atlas of Texas: Bureau of Economic Geology, The University of Texas at Austin, scale 1:250,000. Setter, J.R.D., and Adams, J.A.S., 1986, Petrology and geochemistry of the Quitman Mountains, Hudspeth County, Texas in Price, J.G., Henry, C.D., Parker, D.F., and Barker, D.S., eds., Igneous geology of Trans-Pecos Texas, field trip guide and research articles: The University of Texas at Austin, Bureau of Economic Geology, Guidebook 23, p. 178-206. Shannon, W.M. and Goodell, P.C., 1986, Lithochemistry of intrusive rocks of the Quitman-Sierra Balnce igneous complex, Hudspeth County, Texas in Price, J.G., Henry, C.D., Parker, D.F., and Barker, D.S., eds., Igneous geology of Trans-Pecos Texas, field trip guide and research articles: The University of Texas at Austin, Bureau of Economic Geology, Guidebook 23, p. 225-236. Huffington, R.M., 1943, Geology of the northern Quitman Mountains, Trans-Pecos Texas: Geological Society of America Bulletin, v. 54, p. 997-1048. 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	Hudspeth

State

Texas

Name

Quitman Mountains caldera volcanic rocks and volcanic rocks of sneed (Cox) Mountain and west of Victorio Peak

Geologic age

Oligocene

Lithologic constituents

Major

Igneous > Volcanic > Felsic-volcanic > Trachyte (Pyroclastic-ash flow)

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

Minor

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

Incidental

Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)

Comments

interbedded flows and pyroclastic rocks of the Square Peak Volcanics and Sneed (Cox) Mountain and west of Victorio Peak--small basalt flow remnants. Square Peak Volcanics comprises more than 1,000 m of crudely layered ash-flow tuffs and lavas that occur in the central Quitman Mountains caldera and were erupted during 3 main caldera-forming stages. Lithologies range from high-K calc-alkaline, metaluminous to peraluminous trachytes (45 percent by volume), quartz trachytes (25 percent by vol.), and rhyolites (30 pecent by vol.) according to Setter and Adams (1986).

Stratigraphic units

Square Peak Volcanics

References

Bureau of Economic Geology, 1968, Van Horn-El Paso Sheet, Geologic Atlas of Texas: Bureau of Economic Geology, The University of Texas at Austin, scale 1:250,000.

Setter, J.R.D., and Adams, J.A.S., 1986, Petrology and geochemistry of the Quitman Mountains, Hudspeth County, Texas in Price, J.G., Henry, C.D., Parker, D.F., and Barker, D.S., eds., Igneous geology of Trans-Pecos Texas, field trip guide and research articles: The University of Texas at Austin, Bureau of Economic Geology, Guidebook 23, p. 178-206.

Shannon, W.M. and Goodell, P.C., 1986, Lithochemistry of intrusive rocks of the Quitman-Sierra Balnce igneous complex, Hudspeth County, Texas in Price, J.G., Henry, C.D., Parker, D.F., and Barker, D.S., eds., Igneous geology of Trans-Pecos Texas, field trip guide and research articles: The University of Texas at Austin, Bureau of Economic Geology, Guidebook 23, p. 225-236.

Huffington, R.M., 1943, Geology of the northern Quitman Mountains, Trans-Pecos Texas: Geological Society of America Bulletin, v. 54, p. 997-1048.

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

Hudspeth