Geologic units in Greenlee county, Arizona

Additional scientific data in this geographic area

Middle Miocene to Oligocene volcanic rocks (Oligocene to Middle Miocene) at surface, covers 64 % of this area

Lava, tuff, fine-grained intrusive rock, and diverse pyroclastic rocks. These compositionally variable volcanic rocks include basalt, andesite, dacite, and rhyolite. Thick felsic volcanic sequences form prominent cliffs and range fronts in the Black (Mohave County), Superstition, Kofa, Eagletail, Galiuro, and Chiricahua Mountains. This unit includes regionally extensive ash-flow tuffs, such as the Peach Springs tuff of northwestern Arizona and the Apache Leap tuff east of Phoenix. Most volcanic rocks are 20-30 Ma in southeastern Arizona and 15 to 25 Ma in central and western Arizona, but this unit includes some late Eocene rocks near the New Mexico border in east-central Arizona. (11-38 Ma)

Pliocene to middle Miocene deposits (Middle Miocene to Pliocene) at surface, covers 23 % of this area

Moderately to strongly consolidated conglomerate and sandstone deposited in basins during and after late Tertiary faulting. Includes lesser amounts of mudstone, siltstone, limestone, and gypsum. These deposits are generally light gray or tan. They commonly form high rounded hills and ridges in modern basins, and locally form prominent bluffs. Deposits of this unit are widely exposed in the dissected basins of southeastern and central Arizona. (2-16 Ma)

Oligocene to Paleocene[?] sedimentary rocks (Paleocene(?) to Oligocene) at surface, covers 3 % of this area

Light colored, weakly to moderately consolidated conglomerate and sandstone deposited largely or entirely before mid-Tertiary volcanism and extensional faulting. Most sediment was deposited by early Cenozoic streams that flowed northeastward onto the Colorado Plateau from areas to the southwest that are now lower in elevation than the Plateau. Sediments of this map unit, other than the Chuska Sandstone in northeasternmost Arizona, are commonly referred to as "rim gravels" because they now rest on or near the Mogollon Rim, which is the southwestern edge of the Colorado Plateau. (30-65 Ma)

Early Pleistocene to latest Pliocene surficial deposits (Late Pliocene to Early Pleistocene) at surface, covers 3 % of this area

Coarse relict alluvial fan deposits that form rounded ridges or flat, isolated surfaces that are moderately to deeply incised by streams. These deposits are generally topographically high and have undergone substantial erosion. Deposits are moderately to strongly consolidated, and commonly contain coarser grained sediment than younger deposits in the same area. (0.75-3 Ma)

Quaternary surficial deposits, undivided (Quaternary) at surface, covers 2 % of this area

Unconsolidated to strongly consolidated alluvial and eolian deposits. This unit includes: coarse, poorly sorted alluvial fan and terrace deposits on middle and upper piedmonts and along large drainages; sand, silt and clay on alluvial plains and playas; and wind-blown sand deposits. (0-2 Ma)

Proterozoic granitic rocks (Proterozoic) at surface, covers 2 % of this area

Undivided Early and Middle Proterozoic granitic rocks (units Xg and Yg). (1400-1800 Ma)

Mississippian, Devonian, and Cambrian sedimentary rocks (Cambrian, Devonian, and Mississippian) at surface, covers 1 % of this area

Brown to dark gray sandstone grades upward into green and gray shale, overlain by light to medium gray or tan limestone and dolostone. This unit includes the Tapeats Sandstone, Bright Angel Shale, Muav Limestone, Temple Butte Formation and Redwall Limestone in northern Arizona, and the Bolsa Quartzite, Abrigo Formation, Martin Formation, and Escabrosa Limestone in southern Arizona. These rocks record intermittent sea-level rise and inundation in early Paleozoic time. (330-540 Ma)

Holocene surficial deposits (Holocene) at surface, covers 0.5 % of this area

Unconsolidated deposits associated with modern fluvial systems. This unit consists primarily of fine-grained, well-sorted sediment on alluvial plains, but also includes gravelly channel, terrace, and alluvial fan deposits on middle and upper piedmonts. (0-10 ka)

Early Tertiary to Late Cretaceous granitic rocks (Late Cretaceous to Early Tertiary) at surface, covers 0.4 % of this area

Porphyritic to equigranular granite to diorite emplaced during the Laramide orogeny. Larger plutons are characteristically medium-grained, biotite +/- hornblende granodiorite to granite. Smaller, shallow-level intrusions are typically porphyritic. Most of the large copper deposits in Arizona are associated with porphyritic granitic rocks of this unit, and are thus named 'porphyry copper deposits'. (50-82 Ma)

Early Pleistocene to late Miocene basin deposits (Late Pliocene to Early Pleistocene) at surface, covers 0.4 % of this area

Poorly sorted, variably consolidated gravel and sand that range widely in age. These sediments are generally light gray or tan. This unit is generally mapped in areas of deep late Cenozoic stream incision and landscape degradation where thin Quaternary deposits (map units Qy, Qm, Qo) discontinuously blanket older deposits (map units Tsy or Tsm) and the two cannot be differentiated at the scale of this map. (0.75-10 Ma)

Permian to Pennsylvanian sedimentary rocks (Pennsylvanian to Permian) at surface, covers 0.3 % of this area

Interbedded sandstone, shale, and limestone usually characterized by ledgy outcrops. Orange to reddish sandstone forms cliffs near Sedona. This unit includes Supai Group and Hermit Shale in northern Arizona and Naco Group in southern Arizona. It was deposited in coastal-plain to shallow-marine settings during time of variable and changing sea level. Rocks of this map unit in southern Arizona may be in part equivalent to Permian rocks of map unit P in central and northern Arizona. (280-310 Ma)

Middle Miocene to Oligocene sedimentary rocks (Oligocene to Middle Miocene) at surface, covers 0.2 % of this area

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)

Cretaceous sedimentary rocks (Cretaceous) at surface, covers 0.2 % of this area

Tan sandstone (Dakota Sandstone) overlain by gray shale (Mancos Shale); deposited in beach, river delta, and shallow sea settings. The Mancos Shale is overlain by the Mesaverde Group (map unit Kmv). This unit includes related sandstone and shale exposed near Show Low, Morenci (Pinkard Formation), and around Deer Creek south of Globe. (about 88-97 Ma)

Paleozoic sedimentary rocks (Paleozoic) at surface, covers 0.1 % of this area

Undivided Paleozoic limestone, dolostone, quartzite, shale, and related sedimentary rocks. (248-544 Ma)

Early Proterozoic metasedimentary rocks (Early Proterozoic) at surface, covers 0.1 % of this area

Metasedimentary rocks, mostly derived from sandstone and shale, with minor conglomerate and carbonate rock. Includes quartz-rich, mostly nonvolcanic Pinal Schist in southeastern Arizona and variably volcanic-lithic sedimentary rocks in the Yavapai and Tonto Basin supergroups in central Arizona. (1600-1800 Ma)

Upper middle Tertiary basaltic andesites and andesites of the Mogollon Group (Lower Miocene and uppermost Oligocene (22-26 Ma)) at surface, covers < 0.1 % of this area

Includes Bearwallow Mountain Andesite and basaltic andesite of Mangas Mountain; also near vent basaltic lavas and shallow intrusions in the Chuska Mountains.

Gila Group, Formation, or Conglomerate (Middle Pleistocene to uppermost Oligocene?) at surface, covers < 0.1 % of this area

Includes Mimbres Formation and several informal units in southwestern basins.

Lower-upper middle Tertiary basaltic andesites and andesites of the Mogollon Group (Upper Oligocene (26-29 Ma)) at surface, covers < 0.1 % of this area

Includes La Jara Peak Basaltic Andesite, Uvas Basaltic Andesite, basaltic andesites of Poverty Creek and Twin Peaks, Squirrel Springs Canyon Andesite, Razorback Basalt, Bear Springs Basalt, flows of Gila Flat, Salt Creek Formation, Middle Mountain Formation, and the Alum Mountain Group. Pre-Amalia-Tuff lavas in the Questa caldera are dominantly silicic andesites and dacites; elsewhere silicic lavas are a minor component of Tual.

Upper middle Tertiary rhyolitic lavas and local tuffs (Upper Oligocene (24-29 Ma)) at surface, covers < 0.1 % of this area

Includes Taylor Creek Rhyolite, Fanney Rhyolite, rhyolite of Rocky Canyon, rhyolite of Hardy Ridge, and upper rhyolite members of the Luis Lopez and Sawmill Canyon formations.

Piedmont alluvial deposits (Holocene to lower Pleistocene) at surface, covers < 0.1 % of this area

Includes deposits of higher gradient tributaries bordering major stream valleys, alluvial veneers of the piedmont slope, and alluvial fans. May locally include uppermost Pliocene deposits.

Upper middle Tertiary rhyolitic pyroclastic rocks of the Mogollon Group, ash-flow tuffs (Upper Oligocene (24-30 Ma)) at surface, covers < 0.1 % of this area

Regional ash-flow tuffs include the La Jencia, Vick's Peak, Lemitar, South Canyon, Bloodgood Canyon, Shelley Peak, Davis Canyon, Park, Rhyolite Canyon, Apache Springs, and Amalia Tuffs; the tuffs of Horseshoe Canyon, Diamond Creek, Garcia Camp, Caronita Canyon, Turkey Springs, and Little Mineral Creek; and the Jordan Canyon Formation. Includes some locally erupted lavas and tuffs within thick intra-caldera units; includes minor volcaniclastic sedimentary units between thin outflow sheets.

Basaltic to andesitic lava flows (Neogene) at surface, covers < 0.1 % of this area

Includes minor vent deposits. Flows are commonly interbedded in the Santa Fe and Gila Groups.

Silicic to intermediate volcanic rocks (Neogene, mostly Miocene) at surface, covers < 0.1 % of this area

Rhyolite and dacite flows with associated minor tuffs. Commonly interbedded with Santa Fe or Gila Group sedimentary units. Dacitic lavas in northern Jemez Mountains are Pliocene.

Middle Tertiary volcaniclastic sedimentary units (Oligocene to upper Eocene) at surface, covers < 0.1 % of this area

Mostly syneruptive volcaniclastic sedimentary aprons. Lower units dominantly derived from volcanic highlands of andesitic to dacitic composition. Locally includes minor lavas and tuffs. Younger units (above and intertongued with Mogollon Group tuffs, Turp) include upper Bell Top Formation, South Crosby Peak Formation, and upper Spears Group units near Quemado. Older units (below and intertongued with Datil Group tuffs, Tlrp) include Palm Park, lower Bell Top, Espinaso and Pueblo Creek Formatios and lower Spears Group formations such as Rincon Windmill, Chavez Canyon, and Dog Springs.

Lower middle Tertiary rhyolitic lavas and local tuffs (Lower Oligocene to upper Eocene (31-36 Ma)) at surface, covers < 0.1 % of this area

Includes Mimbres Peak Formation, rhyolite of Cedar Hills, and other units in the Bootheal region.

Basaltic to andesitic lava flows (Miocene) at surface, covers < 0.1 % of this area

Includes minor vent deposits. Flows are commonly interbedded in the Santa Fe and Gila Groups.

Alluvium (Holocene to upper Pleistocene) at surface, covers < 0.1 % of this area

Alluvium

Lower middle Tertiary andesitic to dacitic lavas and pyroclastic flow breccias (Upper to middle Eocene (33-43 Ma)) at surface, covers < 0.1 % of this area

Includes Rubio Peak Formation, Orejon Andesite, andesite of Dry Leggett Canyon, andesite of Telephone Canyon, and other units in southwestern, central, and northern New Mexico. Locally includes minor mafic lavas. Ancient landslide blocks of Mader Limestone, as much as one mile long, occur within Rubio Peak lavas in the central Black Range, west of Winston.