The Boot Heel volcanic field is located in the Bootheel region of southwest

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

, adjacent areas of southeastern

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

, and northwest

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. The field covers an area of more than 24,000 km².Baldridge, W. Scott, ''Geology of the American Southwest,'' Cambridge, 2004, pp. 219-223 The field includes nine

volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

s ranging in age from 26.9 to 35.3 Ma. Extrusive products include rhyolitic ignimbrites along with

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 ...

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 ...

, and

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 ...

lava 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 un ...

flows. The major ash flow

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock cont ...

sheets produced, range in volume from 35 to 650 km³. Activity throughout most of the Boot Heel volcanic field paused between 33 and 28 million years ago. The earlier pulse of activity involved less

evolved Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation t ...

magmas, while the later pulse was relatively depleted in

volatiles Volatiles are the group of chemical elements and chemical compounds that can be readily vaporized. In contrast with volatiles, elements and compounds that are not readily vaporized are known as refractory substances. On planet Earth, the term ' ...

. The pause in activity has been interpreted as a period of tectonic reorganization along the west coast of North America, including the birth of the

San Andreas fault The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonics, tectonic boundary between the Pacific Plate and the North American Plate, and its motion is Fault (geology)#Strike-slip fau ...

, that temporarily shifted volcanism to the east. The field includes the Geronimo- Animas volcanic field and the Palomas volcanic field.

Geronimo volcanic field

The Geronimo volcanic field (also known as the San Bernardino volcanic field) is a monogenetic

volcanic field A volcanic field is an area of Earth's crust that is prone to localized volcanic activity. The type and number of volcanoes required to be called a "field" is not well-defined. Volcanic fields usually consist of clusters of up to 100 volcanoes ...

and a sub-section of the Boot Heel volcanic field in southeastern Arizona, US.

Calderas

The calderas of the Boot Heel field and their associated ignimbrites include: * Pyramid Mountains ** Muir caldera 35.3 Ma (tuff of Woodhall Canyon) * Peloncillo Mountains ** Steins caldera 34.4 Ma (tuff of Steins) * Animas Mountains ** Juniper caldera 33.5 Ma (Oak Creek Tuff) ** Animas Peak caldera 33.5 Ma (tuff of Black Bill Canyon) ** Tullous caldera 35.1 Ma (Bluff Creek Tuff) * Chiricahua Mountains ** Geronimo Trail caldera 32.7 Ma (Gillespie Tuff) ** Clanton Draw caldera 27.4 Ma (Park Tuff) ** Portal caldera 27.6 Ma (tuff of Horseshoe Canyon) ** Turkey Creek caldera 26.9 Ma (Rhyolite Canyon Tuff)

References

{{DEFAULTSORT:Boot Heel volcanic field Volcanic fields of Arizona New Mexico Bootheel Volcanic fields of New Mexico Landforms of Hidalgo County, New Mexico Monogenetic volcanic fields Landforms of Cochise County, Arizona Calderas of Arizona Calderas of New Mexico Eocene calderas Oligocene calderas

Geronimo volcanic field

Calderas

See also

References