Middle Proterozoic granitic rocks

Mostly porphyritic biotite granite with large microcline phenocrysts, with local fine-grained border phases and aplite. Associated pegmatite and quartz veins are rare. This unit forms large plutons, including the Oracle Granite, Ruin Granite, granite in the Pinnacle Peak - Carefree area northeast of Phoenix, and several bodies west of Prescott. (1400-1450 Ma)
State Arizona
Name Middle Proterozoic granitic rocks
Geologic age Middle Proterozoic
Lithologic constituents
Igneous > Plutonic > Granitic > Granite (Pluton)
Igneous > Plutonic > Granitic > Leucocratic-granitic > Aplitelocal fine-grained border phases and aplite
Igneous > Plutonic > Granitic > Leucocratic-granitic > Pegmatite (Dike or sill)associated pegmatite and quartz veins are rare
Comments ~ 1.4 Ga
Stratigraphic units Oracle Granite, Ruin Granite

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.

Anderson, J.L., 1989, Proterozoic anorogenic granites of the southwestern United States, in Jenney, J.P., and Reynolds, S.J., editors, Geologic evolution of Arizona: Arizona Geological Society Digest 17, p. 211-238.

NGMDB product
Counties Cochise - Gila - Graham - La Paz - Maricopa - Mohave - Pima - Pinal - Santa Cruz - Yavapai - Yuma