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

Geologic units in Gunnison county, Colorado

[Additional scientific data in this geographic area]

Pre-ash-flow andesitic lavas, breccias, tuffs, and conglomerates (Phanerozoic | Cenozoic | Tertiary) at surface, covers 16 % of this area

Includes several named units

Lithology: andesite; tuff; volcanic breccia (agglomerate)

Granitic rocks of 1400- and 1700-m.y. age groups, undivided, or, in Taylor River region, rocks with characteristics of Xg but U-Th-Pb zircon ages of Yg (Proterozoic | Paleoproterozoic Mesoproterozoic) at surface, covers 6 % of this area

Granitic rocks of 1400- and 1700-m.y. age groups, undivided, or, in Taylor River region, rocks with characteristics of Xg but U-Th-Pb zircon ages of Yg

Lithology: granitoid

Gravels and alluviums (Phanerozoic | Cenozoic | Quaternary) at surface, covers 1 % of this area

Includes Broadway and Louviers Alluviums

Lithology: gravel; alluvium

Mesaverde Group or Fm--Upper part (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.4 % of this area

In Moffat and Rio Blanco Counties, sandstone, shale, and coal beds above Sego Sandstone. Along Grand Hogback south of Colorado River, sandstone and shale above coal-bearing sequence

Lithology: sandstone; shale; coal

Mancos Shale (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 7 % of this area

In northwest and west-central: Intertongues complexly with units of overlying Mesaverde Group or Fm; lower part consists of a calcareous Niobrara equivalent and Frontier Sandstone and Mowry Shale Members; in areas where the Frontie

Lithology: shale; sandstone

Ancient alluvium (Phanerozoic | Cenozoic | Tertiary Quaternary) at surface, covers 0.2 % of this area

In isolated patches that may not all be of the same age

Lithology: alluvium

Intrusive rocks (Phanerozoic | Paleozoic | Cambrian) at surface, covers 0.2 % of this area

Alkalic and mafic intrusive rocks in small plutons, and diabase dikes

Lithology: diabase

Rhyolitic intrusive rocks and flows of late-volcanic bimodal suite (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area

Lithology: rhyolite

Morrison Fm and Entrada Sandstone (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area

Lithology: mudstone; sandstone

Glacial drift (Phanerozoic | Cenozoic | Quaternary) at surface, covers 4 % of this area

Includes some unclassified glacial deposits

Lithology: glacial drift

Dakota, Burro Canyon, Morrison, and Junction Creek Fms (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers 2 % of this area

Burro Canyon is locally absent

Lithology: sandstone; mudstone; shale

Middle Tertiary intrusive rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers 6 % of this area

Intermediate to felsic compositions

Lithology: plutonic rock (phanerit

Minturn and Belden Fms (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers 2 % of this area

Lithology: sandstone; shale; limestone; conglomerate

Alkalic and mafic rocks in small plutons, and diabase and gabbro dikes (Proterozoic | Mesoproterozoic) at surface, covers < 0.1 % of this area

Alkalic and mafic rocks in small plutons, and diabase and gabbro dikes

Lithology: granitoid; diabase; gabbro

Leadville Limestone, Williams Canyon Limestone, and one or more of: Fremont Limestone, Harding Sandstone, and Manitou Limestone (Phanerozoic | Paleozoic | Ordovician Silurian(?) Devonian(?) Carboniferous Mississippia) at surface, covers < 0.1 % of this area

Lithology: limestone; sandstone

Maroon Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers 2 % of this area

Arkosic sandstone, siltstone, conglomerate, and local limestone

Lithology: sandstone; siltstone; conglomerate; limestone

Dakota Sandstone or Group (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.4 % of this area

Lithology: sandstone

Dakota and Morrison Fms (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers < 0.1 % of this area

Lithology: sandstone; mudstone; shale

Basalt flows and associated tuff, breccia, and conglomerate of late-volcanic bimodal suite (Phanerozoic | Cenozoic | Tertiary) at surface, covers 2 % of this area

Includes basalts of Hinsdale Fm in San Juan Mountains - Servilleta Fm in San Luis Valley and many other occurrences

Lithology: basalt; tuff; volcanic breccia (agglomerate); conglomerate

Intra-ash flow andesitic lavas (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.4 % of this area

Lithology: andesite

Ash-flow tuff of main volcanic sequence (Phanerozoic | Cenozoic | Tertiary) at surface, covers 9 % of this area

Includes many named units

Lithology: ash-flow tuff

Granitic rocks of 1400-m.y. age group (Proterozoic | Mesoproterozoic) at surface, covers 0.9 % of this area

Includes Silver Plume, Sherman, Cripple Creek, St. Kevin, Vernal Mesa, Curecanti, Eolus, and Trimble Granites or Quartz Monzonites; also, San Isabel Granite of Boyer (1962) and unnamed granitic rocks

Lithology: granite; granodiorite; quartz monzonite

Minturn Fm in west-central and south-central and other units (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers 0.2 % of this area

Arkosic sandstone, conglomerate, shale, and limestone. Includes Madera Fm and Sharpsdale Fm of Chronic (1958) in Sangre de Cristo Range and Gothic Fm of Langenheim (1952) in Elk Mountains. Other units of Middle Pennsylvanian age.

Lithology: sandstone; conglomerate; shale; limestone

Belden Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers < 0.1 % of this area

Shale, limestone, and sandstone. Includes Kerber Fm in south-central

Lithology: shale; limestone; sandstone

Leadville Limestone, Williams Canyon Limestone , Manitou Limestone, and Sawatch Quartzite (Phanerozoic | Paleozoic | Cambrian Ordovician(?) Silurian(?) Devonian(?) Carboniferous) at surface, covers 2 % of this area

Lithology: limestone; quartzite

Felsic and hornblendic gneisses, either separate or interlayered (Proterozoic | Paleoproterozoic) at surface, covers 5 % of this area

Includes metabasalt, metatuff, and interbedded metagraywacke; locally contains interlayered biotite gneiss. Derived principally from volcanic rocks

Lithology: felsic gneiss; mafic gneiss; meta-basalt; meta-graywacke

Intra-ash flow quartz latitic lavas (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area

Lithology: quartz latite

Dakota, Purgatoire, Morrison, Ralston Creek, and Entrada Fms in southeast. Dakota, Morrison, and Entrada Fms in central mountains. Dakota, Burro Canyon, Morrison, Wanakah, and Entrada Fms in Gunnison River area. Dakota, Morriso (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers 0.7 % of this area

Lithology: sandstone; mudstone; limestone

Landslide deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers 6 % of this area

Locally includes talus, rock-glacier, and thick colluvial deposits

Lithology: landslide; talus; colluvium

Dakota, Burro Canyon, Morrison, and Wanakah Fms (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers 0.1 % of this area

Lithology: sandstone; mudstone; limestone

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

South-central: Arkosic sand and bouldery gravel of Echo Park Alluvium. Southwest: includes Telluride Conglomerate and Blanco Basin Fm (arkosic mudstone, sandstone, and conglomerate)

Lithology: sandstone; conglomerate; mudstone

Morrison Fm and Wanakah Fm (Junction Creek Sandstone Member at or near top; Pony Express Limestone Member at base) (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area

Wanakah Fm: Sandstone, shale, limestone, and local gypsum

Lithology: mudstone; sandstone; limestone; evaporite

Granitic rocks of 1700-m.y. age group (Proterozoic | Paleoproterozoic) at surface, covers 5 % of this area

Includes Boulder Creek -M.Y. AGE GROUP (AGE 1650-1730 M.Y.)--Includes Boulder Creek, Cross Creek, Denny Creek, Kroenke, Browns Pass, Powderhorn, Pitts Meadow, Bakers Bridge, and Tenmile Granites, Quartz Monzonites, or Granodiorites;

Lithology: granite; granodiorite; quartz monzonite

Laramide intrusive rocks (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers 0.2 % of this area

Mainly intermediate to felsic compositions; some mafic

Lithology: granitoid

Mesaverde Fm, undivided (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 5 % of this area

In northwest and west-central: Major coal beds in lower part; Rollins Sandstone Member at base in Delta, Gunnison, and Pitkin Counties. In southwest: sandstone and shale.

Lithology: sandstone; shale; coal

Biotitic gneiss, schist, and migmatite (Proterozoic | Paleoproterozoic) at surface, covers 3 % of this area

Locally contains minor hornblende gneiss, calc-silicate rock, quartzite, and marble. Derived principally from sedimentary rocks

Lithology: biotite gneiss; schist; migmatite; quartzite; marble

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

Intermediate to felsic compositions

Lithology: plutonic rock (phanerit

Oligocene sedimentary rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.9 % of this area

Northwest: includes Duchesne River Fm (sandstone and shale; includes some rocks of Eocene age) and Bishop Conglomerate near Utah border. South-central: includes Florissant Lake Beds (tuffaceous shale and tuff) and Antero Fm (lime

Lithology: sandstone; shale; conglomerate

Morrison Fm and Junction Creek Sandstone (Phanerozoic | Mesozoic | Jurassic) at surface, covers 0.6 % of this area

In Gunnison River area east of wedgeout of all units of Wanakah Fm (Jmw) except the Junction Creek Member

Lithology: mudstone; sandstone

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

Lithology: glacial drift

Wasatch Fm (including Fort Union equivalent at base) and Ohio Creek Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 7 % of this area

Claystone, mudstone, sandstone, and conglomerate

Lithology: mudstone; sandstone; shale; conglomerate

Modern alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers 2 % of this area

Includes Piney Creek Alluvium and younger deposits

Lithology: alluvium

Mafic rocks of 1700-m.y. age group (Proterozoic | Paleoproterozoic) at surface, covers 0.2 % of this area

Gabbro and mafic diorite and monzonite

Lithology: gabbro; diorite; monzonite