Middle Miocene to Oligocene shallow intrusions

Generally very fine-grained, porphyritic rhyolite to dacite in small, irregular-shaped bodies formed as subvolcanic intrusions in volcanic fields of southern and western Arizona, or in concentrated zones of dikes in the Mohave and Black Mountains of northwestern Arizona. The unit consists of mafic tuff, breccia and shallow intrusions at Buell Park in northeastern Arizona. (14-35 Ma)
State Arizona
Name Middle Miocene to Oligocene shallow intrusions
Geologic age Oligocene to Middle Miocene
Lithologic constituents
Major
Igneous > Hypabyssal > Felsic-hypabyssal > Hypabyssal-rhyolite (Dike or sill)
Igneous > Hypabyssal > Felsic-hypabyssal > Hypabyssal-dacite (Dike or sill)
Igneous > Volcanic > Mafic-volcanic (Pyroclastic-tuff, Volcaniclastic-volcanic breccia)The unit consists of mafic tuff, breccia and shallow intrusions at Buell Park in northeastern Arizona.
Comments Includes Navajo volcanic field minettes
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.

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

Spencer, J.E., and Reynolds, S.J., 1989, Middle Tertiary tectonics of Arizona and adjacent areas, in Jenney, J.P., and Reynolds, S.J., editors, Geologic evolution of Arizona: Arizona Geological Society Digest 17, p. 539-574.

NGMDB product
Counties Apache - Cochise - Graham - La Paz - Maricopa - Mohave - Pima - Yuma