Holocene to middle Pliocene basaltic rocks

Mostly dark-colored basaltic lava and cinders young enough that some original volcanic landforms are still apparent. Includes a small amount of andesite, dacite, and rhyolite. Rocks of this map unit are largely restricted to six areas widely distributed in Arizona: San Francisco and Uinkaret volcanic fields in northern Arizona (0-4 Ma); Springerville (0-4 Ma) and San Carlos (0-2 Ma) volcanic fields in east-central Arizona; and San Bernardino (0-1 Ma) and Sentinel (1-4 Ma) volcanic fields in southern Arizona. Rocks of this unit are also present in the extreme southwestern part of Arizona where they were erupted at the edge of the Pinacate volcanic field (0-2 Ma) in northwestern Sonora. (0-4 Ma)
State Arizona
Name Holocene to middle Pliocene basaltic rocks
Geologic age Middle Pliocene to Holocene
Lithologic constituents
Major
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)
Minor
Igneous > Volcanic > Mafic-volcanic > Andesite (Flow)
Igneous > Volcanic > Felsic-volcanic > Dacite (Pyroclastic)
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Pyroclastic)
Comments Largely in six volcanic fields: San Francisco, Unikaret, Springerville, San Carlos, San Bernardino, and Sentinal.
References

Richard, S.M., Reynolds, S.J., Spencer, J.E., and Pearthree, P.A., 2000, Geologic Map of Arizona: Arizona Geological Survey Map 35, 1 sheet, scale 1:1,000,000.

Lynch, D.J., Neogene volcanism in Arizona: the recognzable volcanoes, in Jenney, J.P., and Reynolds, S.J., editors, Geologic evolution of Arizona: Arizona Geological Society Digest 17, p. 681-700.

Nealey, L.D., and Sheridan, M.F., 1989, Post-Laramide volcanic rocks of Arizona and northern Sonora, Mexico, and their inclusions, in Jenney, J.P., and Reynolds, S.J., editors, Geologic evolution of Arizona: Arizona Geological Society Diges

NGMDB product
Counties Apache - Cochise - Coconino - Gila - Graham - Maricopa - Mohave - Navajo - Yuma