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Middle Miocene to Oligocene sedimentary rocks

Con-glomerate, sandstone, mudstone, limestone, and rock-avalanche breccia (sheet-like deposits of crushed rock) deposited and tilted during widespread normal faulting and basin development. Sediments, mostly conglomerate and sandstone, are commonly medium to dark brown, reddish brown, or brownish gray; younger strata are generally lighter colors. Most deposits are 20 to 30 Ma in southeastern Arizona and 15 to 25 Ma in central and western Arizona. (11-32 Ma)
State Arizona
Name Middle Miocene to Oligocene sedimentary rocks
Geologic age Oligocene to Middle Miocene
Comments Middle Tertiary syntectonic or synextensional sucpracrustal rocks
Primary rock type conglomerate
Secondary rock type sandstone
Other rock types sedimentary breccia; siltstone; limestone; mudstone; landslide
Lithologic constituents
Major
Sedimentary > Clastic > Conglomerate (Bed)
Sedimentary > Clastic > Sandstone (Bed)
Minor
Sedimentary > Clastic > Sedimentary-breccia (Bed)
Incidental
Sedimentary > Clastic > Siltstone (Bed)
Sedimentary > Clastic > Mudstone (Bed)
Sedimentary > Carbonate > Limestone (Bed)
Sedimentary > Carbonate > Marlstone (Bed)
Sedimentary > Chemical > Evaporite > Gypsum (Bed)
Sedimentary > Clastic > Sedimentary-breccia (Tuffaceous)
Sedimentary > Clastic > Conglomerate (Tuffaceous)
Sedimentary > Clastic > Sandstone (Tuffaceous)
Map 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.
Unit 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.
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.
Counties Cochise - Gila - Graham - Greenlee - La Paz - Maricopa - Mohave - Pima - Pinal - Santa Cruz - Yavapai - Yuma