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Mineral Resources > Online Spatial Data > Geology > by state > Arizona Geology

Geologic units in Cochise county, Arizona

[Additional scientific data in this geographic area]

silicic flows, domes, and associated pyroclastic rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area

Lower Oligocene silicic (or felsic) flows, domes, and associated pyroclastic rocks and intrusions; includes Mimbres Peak Formation

Lithology: lava flow; tuff; felsic volcanic rock; conglomerate; pyroclastic

Mississippian, Devonian, and Cambrian sedimentary rocks (Cambrian, Devonian, and Mississippian) at surface, covers 2 % 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)

Lithology: sandstone; siltstone; mudstone; shale; chert; dolostone (dolomite); limestone; conglomerate; arkose; orthoquartzite

Middle Miocene to Oligocene sedimentary rocks (Oligocene to Middle Miocene) at surface, covers 0.6 % 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)

Lithology: conglomerate; sandstone; sedimentary breccia; siltstone; limestone; mudstone; landslide

Early Tertiary to Late Cretaceous muscovite-bearing granitic rocks (Late Cretaceous to Early Tertiary) at surface, covers 0.1 % of this area

Light-colored peraluminous muscovite granite with or without garnet; commonly forms sills and is associated with abundant pegmatite dikes and sills. This unit includes granites in the Harcuvar and Harquahala Mountains of western Arizona and in the Santa Catalina, Rincon, Tortolita, Picacho, and Coyote Mountains of south-central Arizona. These granites typically represent the youngest phase of voluminous magmatism during the Laramide orogeny in Arizona. This unit also includes several muscovite-bearing granites in southern Arizona that are associated with calc-alkaline granites of unit TKg, and a batholith in the Cabeza Prieta area of southwestern Arizona. (50-80 Ma)

Lithology: granite; pegmatite; aplite; greisen

Middle Miocene to Oligocene granitic rocks (Oligocene to Middle Miocene) at surface, covers 0.7 % of this area

Granite to diorite representing solidified magma chambers that were the likely source of overlying and nearby volcanic rocks of map unit Tv. The granitic rocks are typically equigranular and fine- to medium-grained. (14-26 Ma)

Lithology: granodiorite; granite; diorite; porphyry; quartz diorite; aplite; gabbro; pegmatite; hornblendite; hornfels; gabbro

Jurassic granitic rocks (Jurassic) at surface, covers 0.8 % of this area

Granite to diorite, locally foliated and locally alkalic; includes Triassic(?) granitoids in the Trigo Mountains. This unit includes two dominant assemblages of igneous rocks. The Kitt Peak-Trigo Peaks superunit includes, from oldest to youngest: dark, foliated or gneissic diorite, medium-grained equigranular to porphyritic granodiorite, and small, irregular intrusions of light-colored, fine-grained granite. The Ko Vaya superunit, limited to south-central Arizona, includes texturally heterogeneous K-feldspar-rich granitic rocks. (150-180 Ma)

Lithology: granodiorite; granite; diorite; pegmatite; leucogranite; aplite; granodiorite; porphyry; quartz monzonite; syenite; hornblendite

andesite and basaltic andesite flows and associated volcaniclastic units (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area

Lower Tertiary, (Lower Oligocene and Eocene) andesite and basaltic andesite flows, and associated volcaniclastic units. Includes Rubio Peak Formation, and andesite of Dry Leggett Canyon

Lithology: andesite; basalt; intermediate volcanic rock; mafic volcanic rock; mixed clastic/volcanic

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

Undivided metasedimentary, metavolcanic, and gneissic rocks. (1600-1800 Ma)

Lithology: schist; gneiss; amphibolite; granofels; calc-silicate schist; granulite; greenschist; marble; diorite; gabbro; granite; granodiorite; metasedimentary rock; migmatite; phyllite; quartzite

rhyolitic pyroclastic rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area

Upper Oligocene rhyolitic pyroclastic rocks (ash-flow tuffs); includes Davis Canyon Tuff, South Crosby Peak Formation, La Jencia, Vick's Peak, Lemitar, South Canyon, Bloodgood Canyon, Shelley Peak Tuffs, tuff of Horseshoe Canyon, Park Tuff, Rhyolite Canyon Tuff, Apache Springs Tuff, Diamond Creek, Jordan Canyon, Garcia Camp Tuffs, the Turkey Springs Tuff, the tuff of Little Mineral Creek, the Amalia Tuff, and others. Some contain volcaniclastic and reworked volcaniclastic rocks, and eolian sandstone; (24-29 Ma)

Lithology: tuff; pyroclastic; rhyolite; andesite; mixed clastic/volcanic; eolian

Jurassic sedimentary and volcanic rocks (Jurassic) at surface, covers 0.3 % of this area

Sandstone and conglomerate derived from volcanic rocks with associated intermediate-composition lava flows, breccias, and tuffs. In southern Arizona this unit includes rocks of the Artesa sequence, Pitoikam Formation, Mulberry Wash volcanics, Rudolfo Red Beds, Recreation Red Beds, and Gardner Canyon Formation. In western Arizona it includes the Harquar Formation, rocks of Slumgullion, and related(?) unnamed units in the Kofa and Middle Mountains. This unit is characterized by maroon, brown, and purplish-gray volcanic-lithic sandstone and siltstone, with subordinate to abundant conglomerate, quartz-rich sandstone and sparse limestone. (150-170 Ma)

Lithology: sandstone; conglomerate; argillite; mudstone; siltstone; phyllite; dacite; meta-conglomerate; intermediate metavolcanic rock; meta-rhyolite; wacke; quartz-feldspar schist; rhyolite; schist; sedimentary breccia; pelitic schist; andesite; greenschist; arenite; basalt; granofels; hornfels; latite; limestone; felsic metavolcanic rock; orthoquartzite; quartzite; trachyandesite; alkaline basalt; trachybasalt

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

Red-brown shale and sandstone, buff to orange quartzite, limestone, basalt, black shale, and sparse conglomerate. This unit includes the Grand Canyon Supergroup, Apache Group, and Troy Quartzite. These rocks were deposited in shallow marine, coastal nonmarine, and fluvial settings. (700-1300)

Lithology: sandstone; limestone; arenite; argillite; arkose; basalt; chert; dolostone (dolomite); claystone; conglomerate; diabase; sedimentary breccia; arkose; mudstone; orthoquartzite; shale; siltstone; tholeiite; meta-conglomerate; phyllite; quartzite; schist

Holocene surficial deposits (Holocene) at surface, covers 4 % 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)

Lithology: sand; gravel; mud; silt

silicic pyroclastic rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area

Lower Oligocene silicic pyroclastic rocks (ash-flow tuffs); includes Hell's Mesa, Kneeling Nun, lower part of Bell Top Formation, Caballo Blanco, Datil Well, Leyba Well, Rock House Canyon, Blue Canyon, Sugarlump and Tadpole Ridge Tuffs, the tuffs of the Organ cauldron, Treasure Mountain Tuff (now known as Chiquito Peak Tuff), Bluff Creek Tuff, Oak Creek Tuff, tuff of Steins Mountain, tuff of Black Bill Canyon, tuff of Farr Ranch, Woodhaul Canyon, Gillespie and Box Canyon Tuffs, Cooney Tuff, and other volcanic and interbedded fluvial and pumiceous units; (31-36.5 Ma)

Lithology: pyroclastic; tuff; felsic volcanic rock; volcanic rock (aphanitic); mixed clastic/volcanic

Middle Miocene to Oligocene volcanic rocks (Oligocene to Middle Miocene) at surface, covers 11 % 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)

Lithology: dacite; rhyolite; andesite; basalt; porphyry; diorite; granite; granodiorite; latite; trachybasalt; trachyte; conglomerate; sandstone; sedimentary breccia; serpentinite

Early Tertiary to Late Cretaceous granitic rocks (Late Cretaceous to Early Tertiary) at surface, covers 0.5 % 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)

Lithology: granodiorite; granite; diorite; porphyry; quartz diorite; aplite; gabbro; pegmatite; skarn

alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers < 0.1 % of this area

Alluvium; upper and middle Quaternary

Lithology: alluvium

Pliocene to late Miocene basaltic rocks (Late Miocene to Pliocene) at surface, covers 0.4 % of this area

Mostly dark, inconspicuously flat, low-lying or mesa-forming basalt deposited as lava flows. Rocks included in this unit are located almost entirely in the large volcanic fields south and west of Flagstaff, in smaller fields in northwesternmost Arizona, and in the Hopi Buttes volcanic field on the Navajo and Hopi Indian Reservations north of Holbrook. Original volcanic landforms have been obscured by erosion. (4-8 Ma)

Lithology: basalt; alkaline basalt; tholeiite; claystone; conglomerate; limestone; sandstone; sedimentary breccia; siltstone; tuff; chert; gypsum

Paleozoic sedimentary rocks (Paleozoic) at surface, covers 1 % of this area

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

Lithology: limestone; sandstone; marble; gneiss; granofels; schist; gypsum; phyllite; quartzite; quartz-feldspar schist; schist; pelitic schist

Holocene to middle Pliocene basaltic rocks (Middle Pliocene to Holocene) at surface, covers 3 % of this area

Mostly dark-colored basaltic lava and cinders young enough that some original volcanic landforms are still apparent. Includes a small amount of andesite, dacite, and rhyolite. Rocks of this map unit are largely restricted to six areas widely distributed in Arizona: San Francisco and Uinkaret volcanic fields in northern Arizona (0-4 Ma); Springerville (0-4 Ma) and San Carlos (0-2 Ma) volcanic fields in east-central Arizona; and San Bernardino (0-1 Ma) and Sentinel (1-4 Ma) volcanic fields in southern Arizona. Rocks of this unit are also present in the extreme southwestern part of Arizona where they were erupted at the edge of the Pinacate volcanic field (0-2 Ma) in northwestern Sonora. (0-4 Ma)

Lithology: alkaline basalt; basalt; andesite; hawaiite; trachyte; alkali rhyolite; dacite; latite; rhyolite; tholeiite; trachyandesite; conglomerate; sandstone; sedimentary breccia

Jurassic volcanic rocks (Jurassic) at surface, covers 0.3 % of this area

Massive quartz-feldspar porphyry, generally interpreted as thick, welded rhyolitic tuffs, with locally abundant lava, and sandstone and conglomerate derived from volcanic rocks. Rare eolian quartzite units are interbedded in southern Arizona. Includes Ali Molina Formation, Mount Wrightson Formation, part of the Canelo Hills Volcanics, Cobre Ridge tuff, Black Rock volcanics, Planet Volcanics, and equivalent rocks. (160-200 Ma)

Lithology: rhyolite; felsic metavolcanic rock; metarhyolite; conglomerate; dacite; felsic metavolcanic rock; quartz-feldspar schist; sandstone; arenite; arkose; granite; porphyry; meta-conglomerate; orthoquartzite; quartzite

piedmont alluvial deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers < 0.1 % of this area

Piedmont alluvial deposits: upper and middle Quaternary; includes deposits of higher gradient tributaries bordering major stream valleys, alluvial veneers of the piedmont slope, and alluvial fans

Lithology: alluvium

Holocene river alluvium (Holocene) at surface, covers 1 % of this area

Unconsolidated to weakly consolidated sand and gravel in river channels and sand, silt, and clay on floodplains. Also includes young terrace deposits fringing floodplains. (0-10 ka)

Lithology: sand; gravel; mud; silt

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)

Lithology: gravel; sand; mud; silt

Middle Proterozoic granitic rocks (Middle Proterozoic) at surface, covers 3 % of this area

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)

Lithology: granite; granodiorite; quartz diorite; quartz monzonite; pegmatite; aplite

Pliocene to middle Miocene deposits (Middle Miocene to Pliocene) at surface, covers 14 % 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)

Lithology: conglomerate; sandstone; gravel; sand; gypsum; limestone; mudstone; siltstone

sedimentary and vocaniclastic sedimentary rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area

Mostly Oligocene and upper Eocene sedimentary and volcaniclastic sedimentary rocks with local andesitic to intermediate volcanics; includes Espinaso, Spears, Bell Top, and Palm Park Formations

Lithology: clastic; mixed clastic/volcanic; volcanic rock (aphanitic); unconsolidated deposit

Early Tertiary to Late Cretaceous volcanic rocks (Late Cretaceous to Early Tertiary) at surface, covers 2 % of this area

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)

Lithology: andesite; dacite; basalt; latite; rhyolite; conglomerate; siltstone; volcanic breccia (agglomerate); wacke

Cretaceous to Late Jurassic sedimentary rocks with minor volcanic rocks (Late Jurassic to Cretaceous) at surface, covers 6 % of this area

Sandstone and conglomerate, rarely forms prominent outcrops; massive conglomerate is typical near base of unit and locally in upper part. These deposits are nonmarine except in southeastern Arizona, where prominent gray marine limestone (Mural Limestone) forms the middle of the Bisbee Group. Sandstones are typically medium-bedded, drab brown, lithic-feldspathic arenites. Includes Bisbee Group (largely Early Cretaceous) and related rocks, Temporal, Bathtub, and Sand Wells formations, rocks of Gu Achi, McCoy Mountains Formation, and Upper Cretaceous Fort Crittenden Formation and equivalent rocks. (80-160 Ma)

Lithology: conglomerate; sandstone; arenite; argillite; limestone; mudstone; sedimentary breccia; shale; siltstone; wacke; andesite; dacite; intermediate metavolcanic rock; meta-conglomerate; metarhyolite; phyllite; quartz-feldspar schist; rhyolite; schist; landslide; calcarenite; evaporite

Gila Group (Phanerozoic | Cenozoic | Tertiary Quaternary) at surface, covers < 0.1 % of this area

Gila Group. Includes Mimbres Formation and several informal units in southwestern basins; Middle Pleistocene to uppermost Oligocene

Lithology: conglomerate; sandstone; basalt

Late and middle Pleistocene surficial deposits (Middle to Late Pleistocene) at surface, covers 0.6 % of this area

Unconsolidated to weakly consolidated alluvial fan, terrace, and basin-floor deposits with moderate to strong soil development. Fan and terrace deposits are primarily poorly sorted, moderately bedded gravel and sand, and basin-floor deposits are primarily sand, silt, and clay. (10-750 ka)

Lithology: gravel; sand; mud; silt

Early Proterozoic granitic rocks (Early Proterozoic) at surface, covers 0.6 % of this area

Wide variety of granitic rocks, including granite, granodiorite, tonalite, quartz diorite, diorite, and gabbro. These rocks commonly are characterized by steep, northeast-striking foliation. (1600-1800 Ma)

Lithology: granodiorite; granite; diabase; diorite; gabbro; pegmatite; quartz diorite; tonalite; anorthosite; gneiss; gabbro; greisen; migmatite; porphyry; pyroxenite; rhyolite; schist; trondhjemite

Permian to Pennsylvanian sedimentary rocks (Pennsylvanian to Permian) at surface, covers 2 % 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)

Lithology: sandstone; siltstone; gypsum; mudstone; orthoquartzite; siltstone; sedimentary breccia; dolostone (dolomite); limestone; conglomerate; shale; calcarenite; evaporite

Middle Miocene to Oligocene shallow intrusions (Oligocene to Middle Miocene) at surface, covers 1 % of this area

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)

Lithology: dacite; rhyolite; porphyry; rhyolite; conglomerate; sandstone; sedimentary breccia

Quaternary surficial deposits, undivided (Quaternary) at surface, covers 40 % 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)

Lithology: sand; gravel; mud; silt

silicic flows and massess and associated pyroclastic rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area

Upper Oligocene silicic (or felsic) flows and masses and associated pyroclastic rocks; includes Taylor Creek, Fanney, and Rocky Canyon Rhyolites

Lithology: felsic volcanic rock; pyroclastic; rhyolite