The Taos Plateau volcanic field is an area of extensive

volcanism Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called a ...

Taos County, New Mexico Taos County is a county in the U.S. state of New Mexico. As of the 2010 census, the population was 32,937. Its county seat is Taos. The county was formed in 1852 as one of the original nine counties in New Mexico Territory. Taos County compris ...

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. It is the largest volcanic field in the

Rio Grande Rift The Rio Grande rift is a north-trending continental rift zone. It separates the Colorado Plateau in the west from the interior of the North American craton on the east. The rift extends from central Colorado in the north to the state of Chihua ...

, spreading over . The total erupted volume is estimated at . The age of most of the vents and associated

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or und ...

s in the field is estimated to be between 1.8 and 4 million years, with a few 22-million-year-old vents. The composition of the lavas varies from tholeiitic

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...

. Landforms include sheet flows,

cinder cone A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions o ...

s, and

shield volcano A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more v ...

es. The sheet flows of the Servilleta Basalt are well-exposed in the

Rio Grande Gorge The Rio Grande Gorge is a geological feature in northern New Mexico where the watercourse of the Rio Grande follows a tectonic chasm. Beginning near the Colorado border, the approximately gorge runs from northwest to southwest of Taos, New Mexico ...

carved by the

Rio Grande The Rio Grande ( and ), known in Mexico as the Río Bravo del Norte or simply the Río Bravo, is one of the principal rivers (along with the Colorado River) in the southwestern United States and in northern Mexico. The length of the Rio G ...

. The highest point of the field is San Antonio Mountain at .

Notable vents

The field contains at least 35 vents, arranged in a rough concentric pattern across. The central part of the field is the most

mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...

, consisting of

tholeiitic basalt The tholeiitic magma series is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma i ...

es, with

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomi ...

vents further out and

rhyodacite Rhyodacite is a volcanic rock intermediate in composition between dacite and rhyolite. It is the extrusive equivalent of those plutonic rocks that are intermediate in composition between monzogranite and granodiorite. Rhyodacites form from rapid ...

vents in the outer part of the field. Two small

domes in the center of the field are exceptions to this pattern. Ute Moutain (New Mexico)

Origin

The field lies near the intersection of the

Jemez Lineament The Jemez Lineament is a chain of late Cenozoic volcanic fields, long, reaching from the Springerville and White Mountains volcanic fields in East-Central Arizona to the Raton-Clayton volcanic field in Northeastern New Mexico. The lineament ...

with the Rio Grande rift. Here hot mantle rock has bulged upwards into the rift, allowing a high degree of decompressional melting to produce the tholeiitic magmas. The outer zone of andesites and rhyodacites is interpreted as a lower degree of melting, while the two rhyolite domes are interpreted as resulting from fractional crystallization of magma in the shallow crust.

Economic resources

Perlite Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. It is an industrial m ...

is mined from the rhyolite flows and domes at No Agua. The production here has contributed to making New Mexico the leading producer of perlite in the United States.

References

External links

Documentary: Sleeping Monsters, Sacred Fires: Volcanos Of New Mexico
* Volcanic fields of New Mexico Landforms of Taos County, New Mexico Miocene volcanoes Pliocene volcanoes Pleistocene volcanoes Rift volcanoes Neogene geology of New Mexico Quaternary geology of New Mexico Miocene United States Pliocene United States Pleistocene United States Basin and Range Province {{NewMexico-geo-stub

Notable vents

Origin

Economic resources

References

Further reading

External links