Early Tertiary to Late Cretaceous volcanic rocks

Rhyolite to andesite and closely associated sedimentary and near-surface intrusive rocks; commonly dark gray to dark greenish gray or greenish brown. In the ranges west of Tucson, this unit includes thick welded ash-flow tuffs. Volcanic rocks of this unit are inferred to be derived from vents and volcanoes above magma chambers that solidified to form the granitic rocks of map unit TKg. These rocks are restricted to southeastern Arizona except for a small outcrop near Bagdad. (50-82 Ma)
State Arizona
Name Early Tertiary to Late Cretaceous volcanic rocks
Geologic age Late Cretaceous to Early Tertiary
Lithologic constituents
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow)
Igneous > Volcanic > Felsic-volcanic > Dacite (Flow)
Igneous > Volcanic > Mafic-volcanic > Andesite (Flow)
Sedimentary > Clastic (Tuffaceous)
Comments Related, broadly, to unit TKg
Stratigraphic units Williamson Canyon Volcanics

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.

Titley, S.R., and Anthony, E.Y., 1989, Laramide mineral deposits in Arizona, in Jenney, J.P., and Reynolds, S.J., editors, Geologic evolution of Arizona: Arizona Geological Society Digest 17, p. 485-514.

NGMDB product
Counties Cochise - Gila - Graham - Pima - Pinal - Santa Cruz - Yavapai