Geologic units in Rio Arriba county, New Mexico

Additional scientific data in this geographic area

San Jose Formation (Eocene) at surface, covers 31 % of this area

San Juan Basin

Mancos Shale (Cenomanian to Campanian) at surface, covers 10 % of this area

Divided into Upper and Lower parts by Gallup Sandstone.

Los Pinos Formation of Lower Santa Fe Group (Miocene and upper Oligocene) at surface, covers 7 % of this area

Includes Carson Conglomerate (Dane and Bachman, 1965) in Tusas Mountains-San Luis Basin area.

Lower Santa Fe Group (Upper Miocene to uppermost Oligocene) at surface, covers 6 % of this area

Includes Hayner Ranch, Rincon Valley, Popotosa, Cochiti, Tesuque, Chamita, Abiquiu, Zia, and other formations.

Dakota Sandstone (Cenomanian) at surface, covers 4 % of this area

Includes Oak Canyon, Cubero, and Paguate Tongues; includes Clay Mesa Tongue of Mancos Shale.

Chinle Group (Upper to middle Triassic) at surface, covers 3 % of this area

Map unit includes Moenkopi Formation (Middle Triassic) at base in many areas; in eastern part of state the following five formations are mapped: TRr, TRb, TRt, TRg, and TRs.

Mesaverde Group (Campanian to Turonian) at surface, covers 3 % of this area

Includes Cliff House Sandstone, Menefee Formation, and Point Lookout Sandstone.

Lewis Shale (Campanian) at surface, covers 3 % of this area

Marine shale and mudstone.

Landslide deposits and colluvium (Holocene to Pleistocene) at surface, covers 2 % of this area

Landslide deposits on western flanks of Socorro Mountains not shown for clarity.

Animas Formation (Paleocene and upper Cretaceous) at surface, covers 2 % of this area

Volcaniclastic sedimentary rocks of intermediate composition in northern San Juan Basin.

Piedmont alluvial deposits (Holocene to lower Pleistocene) at surface, covers 2 % 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 Santa Fe Group (Middle Pleistocene to uppermost Miocene) at surface, covers 2 % of this area

Includes Camp Rice, Fort Hancock, Palomas, Sierra Ladrones, Arroyo Ojito, Ancha, Puye, and Alamosa Formations.

Paleogene sedimentary units (Paleogene) at surface, covers 2 % of this area

Includes Baca, Galisteo, El Rito, Blanco Basin, Hart Mine, Love Ranch, Lobo, Sanders Canyon, Skunk Ranch, Timberlake, and Cub Mountain Formations.

Alluvium (Holocene to upper Pleistocene) at surface, covers 2 % of this area

Alluvium

Cutler Formation (Wolfcampian to Upper Pennsylvanian) at surface, covers 2 % of this area

Used in northern areas and Chama embayment only.

Lower middle Tertiary volcanic rocks (Lower Oligocene to upper Eocene (older than 31 Ma)) at surface, covers 2 % of this area

Mostly intermediate lavas of the lower Datil Group and intermediate volcaniclastic sediments of the lower Spears Group (Tla+Tvs). Locally includes ash-flow tuffs of the upper Datil Group (Tlrp). Includes intermediate volcaniclastic sedimentary rocks of the Conejos Formation in northern New Mexico.

Silicic to intermediate volcanic rocks (Neogene, mostly Miocene) at surface, covers 2 % 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.

Basaltic to andesitic lava flows (Pliocene) at surface, covers 2 % of this area

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

Lower middle Tertiary rhyolitic to dacitic pyroclastic rocks of the Datil Group, ash-flow tuffs (Lower Oligocene to upper Eocene (31-36 Ma)) at surface, covers 1 % of this area

Regional ash-flow tuffs include Hell's Mesa, Kneeling Nun, Caballo Blanco, Datil Well, Leyba Well, Rock House Canyon, Blue Canyon, Sugarlump, Oak Creek, Bluff Creek, Gillespie, Box Canyon, Cooney and Chiquito Peak Tuffs; the tuffs of Steins Mountain, Black Bill Canyon, Woodhaul Canyon, and Farr Ranch; tuffs of the Organ cauldron; and lower tuffs in the Bell Top Formation. Includes some locally erupted lavas and tuffs within thick intra-caldera units; includes minor volcaniclastic sedimentary units and lavas between thin outflow sheets.

Paleoproterozoic quartzite (Paleoproterozoic) at surface, covers 1 % of this area

Includes 1.70 Ga Ortega Quartzite and equivalents in northern New Mexico and 1.67 Ga quartzites in central New Mexico.

Upper and Middle Jurassic rocks, undivided (Upper and Middle Jurassic) at surface, covers 1 % of this area

In southwest includes the basalt-bearing Broken Jug Formation.

Hinsdale Basalt (Miocene and upper Oligocene) at surface, covers 1 % of this area

Northern Taos and eastern Rio Arriba Counties; basalt flows interbedded with Los Pinos Formation.

Bandelier Tuff (Lower Pleistocene) at surface, covers 0.8 % of this area

Includes large blocks of older andesite in caldera-collapse breccia facies locally exposed on resurgent dome of the Valles caldera.

Basaltic to andesitic lava flows (Miocene) at surface, covers 0.7 % of this area

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

Paleoproterozoic calc-alkaline plutonic rocks (Paleoproterozoic) at surface, covers 0.6 % of this area

Granodiorite, diorite, and gabbro complexes; 1.78-1.71 Ga; interpreted to be intrusive part of juvenile volcanic arc basement.

Nacimiento Formation (Paleocene) at surface, covers 0.6 % of this area

San Juan Basin

San Rafael Group (Middle Jurassic) at surface, covers 0.6 % of this area

Consists of Entrada Sandstone, Todilto and Summerville Formations, Bluff Sandstone, and locally Zuni Sandstone (or only Acoma Tongue of Zuni).

Morrison Formation (Upper Jurassic) at surface, covers 0.6 % of this area

Upper Jurassic nonmarine rocks.

Paleoproterozoic metasedimentary rocks (Paleoproterozoic) at surface, covers 0.6 % of this area

Pelitic schist, quartz-muscovite schist, immature quartzite, and subordinate amphibolite; includes parts of Vadito Group in northern New Mexico, immature metasedimentary rocks of central New Mexico, and Bullard Peak Series mixed supracrustal rocks in Burro Mountains.

Paleoproterozoic granitic plutonic rocks (Paleoproterozoic) at surface, covers 0.5 % of this area

Variably foliated granites and granitic gneisses; 1.71 - 1.65 Ga in northern New Mexico; 1.66 - 1.65 Ga in central and southern New Mexico.

Madera Group (Pennsylvanian) at surface, covers 0.5 % of this area

In Manzano Mountains includes Wild Cow Formation and Los Moyos Limestone; in Lucero Mesa includes Red Tanks, Atrasado, Gray Mesa Formations; in Sacramento Mountains includes the non-Madera Holder, Beeman and Gobbler Formations. May include strata lumped as Magdalena Group in a few areas.

Intermediate to silicic volcanic rocks (Neogene) at surface, covers 0.5 % of this area

Mostly andesitic to dacitic strato volcanoes. Includes rhyolite lavas and tuffs in the Jemez Mountains, Volcanoes in Jemez Mountains and eastern Colfax County are upper Miocene. Mount Taylor and composite volcanoes in the Taos Plateau volcanic field are Pliocene.

Paleoproterozoic rhyolite and felsic volcanic schist (Paleoproterozoic) at surface, covers 0.3 % of this area

Includes 1.70 Ga Vadito Group in northern New Mexico and 1.68 Ga Sevilleta Metarhyolite in central New Mexico.

Basaltic to andesitic lava flows (Holocene to middle Pleistocene) at surface, covers 0.3 % of this area

Flows south of Grants and west of Carrizozo are Holocene. Includes minor vent deposits.

Permian and Pennsylvanian rocks, undivided (Permian and Pennsylvanian) at surface, covers 0.3 % of this area

Includes Concha, Scherrer, Colina, Epitaph, and Earp Formations (Permian) and Horquilla Limestone (Permian to Pennsylvanian).

Paleoproterozoic mafic metavolcanic rocks with subordinate felsic metavolcanic rocks (Paleoproterozoic) at surface, covers 0.2 % of this area

Includes the 1.78-1.72 Ga Moppin (Tusas Mountains), Gold Hill (Taos Range), and Pecos (Sangre de Cristo Mountains) complexes; interpreted to be supracrustal part of juvenile volcanic arc basement.

Kirtland and Fruitland Formations (Campanian) at surface, covers 0.2 % of this area

Coal-bearing, primarily in the Fruitland.

Mesoproterozoic and Paleoproterozoic plutonic rocks, undivided (Mesoproterozoic and Paleoproterozoic) at surface, covers 0.2 % of this area

Mesoproterozoic and Paleoproterozoic plutonic rocks, undivided

Mesoproterozoic granitic plutonic rocks (Mesoproterozoic) at surface, covers 0.2 % of this area

Mainly 1.45 - 1.35 Ga megacrystic granites, generally weakly foliated except locally at their margins.

Ojo Alamo Formation (Paleocene) at surface, covers 0.1 % of this area

San Juan Basin

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.

Middle Tertiary volcanic rocks, undifferentiated (Lower Miocene to upper Eocene) at surface, covers < 0.1 % of this area

Includes the predominantly andesitic to dacitic stratovolcano complex at Sierra Blanca (Oligocene to upper Eocene) and many smaller outliers.

Older rhyolite lavas and early volcaniclastic sedimentary fill deposits of the Valles caldera (Lower Pleistocene) at surface, covers < 0.1 % of this area

Units are associated with resurgent doming or predate doming of the caldera core. Includes minor middle Pleistocene tuffs of the upper Valles Rhyolite on north side of caldera.

Pictured Cliffs Sandstone (Campanian) at surface, covers < 0.1 % of this area

Prominent cliff-forming marine sandstone.

Tertiary mafic intrusive rocks (Pliocene to upper Eocene) at surface, covers < 0.1 % of this area

Includes many long basaltic andesite dikes of Oligocene age near Pie Town, Acoma, Riley, Chupadera, Truth or Consequences, Roswell, Raton, and Dulce; and several elongate or shoestring-like sills of basalt or basaltic andesite. Also includes basaltic necks of Pliocene age that dot the landscape northeast of Mount Taylor. Where dikes extend into Quaternary alluvium the contact is an unconformity.

Paleoproterozoic pelitic schist (Paleoproterozoic) at surface, covers < 0.1 % of this area

Includes Rinconada Formation in northern New Mexico and Blue Springs Schist in Manzano Mountains.

Santa Fe Group, undivided (Middle Pleistocene to uppermost Oligocene) at surface, covers < 0.1 % of this area

Basin fill of the Rio Grande rift. Locally represents upper Miocene formations of the middle Santa Fe Group in the northern Albuquerque Basin.

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.

Los Pinos Fm (Tertiary) at surface, covers < 0.1 % of this area

Volcaniclastic conglomerate interbedded with basalt flows of Hinsdale Fm (Tbb) on east flank of San Juan Mountains. Grades laterally into Santa Fe Fm of San Luis Valley

Basalt flows and associated tuff, breccia, and conglomerate of late-volcanic bimodal suite (Tertiary) at surface, covers < 0.1 % of this area

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

Mancos Shale (Cretaceous) at surface, covers < 0.1 % 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 Frontier and Mowry Members (Kmfm), or these and the Dakota Sandstone (Kfd) are distinguished, map unit (Km) consists of shale above Frontier Member. In Southwest: Lower part contains Juana Lopez Member (Kmj)

Panther Seep Formation (Virgilian) at surface, covers < 0.1 % of this area

In Organ, Franklin, and San Andres Mountains.

Eolian deposits (Holocene to middle Pleistocene) at surface, covers < 0.1 % of this area

Eolian deposits.

Pictured Cliffs Sandstone and Lewis Shale (Cretaceous) at surface, covers < 0.1 % of this area

Pictured Cliffs Sandstone and Lewis Shale

Modern alluvium (Quaternary) at surface, covers < 0.1 % of this area

Includes Piney Creek Alluvium and younger deposits

Ash-flow tuff of main volcanic sequence (Tertiary) at surface, covers < 0.1 % of this area

Includes many named units

Abo Formation (Wolfcampian) at surface, covers < 0.1 % of this area

Red beds, arkosic at base, finer and more mature above; Wolfcampian; may include limestone beds of Pennsylvanian age (Virgilian) in Zuni Mountains. In Robledo Mountains the Abo may be considered a member of the Hueco Formation.

Pre-ash-flow andesitic lavas, breccias, tuffs, and conglomerates (Tertiary) at surface, covers < 0.1 % of this area

Includes several named units

Mesaverde Fm, undivided (Cretaceous) at surface, covers < 0.1 % 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.

Tertiary intrusive rocks of intermediate to silicic composition (Pliocene to Eocene) at surface, covers < 0.1 % of this area

Includes monzonitic to granitic plutons, stocks, laccoliths, and porphyritic dikes in deeply eroded magmatic centers; and andesitic, dacitic, or rhyolitic plugs and dikes near cauldrons or stratovolcanoes. In the Latir field, fine-grained rhyolitic dikes commonly cut coarse-grained granitic plutons. Includes alkaline laccoliths, plugs, and dikes in Colfax County. North-trending dikes near Capitan include some mafic diabase dikes.