Volcanic field in the context of "Alkali basalt"

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⭐ Core Definition: 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 such as cinder cones. Lava flows may also occur. They may occur as a monogenetic volcanic field or a polygenetic volcanic field.

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👉 Volcanic field in the context of Alkali basalt

Alkali basalt or alkali olivine basalt is a dark-colored, porphyritic volcanic rock usually found in oceanic and continental areas associated with volcanic activity, such as oceanic islands, continental rifts and volcanic fields. Alkali basalt is characterized by relatively high alkali (Na2O and K2O) content relative to other basalts and by the presence of olivine and titanium-rich augite in its groundmass and phenocrysts, and nepheline in its CIPW norm.

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Volcanic field in the context of Pajarito Plateau

The Pajarito Plateau is a volcanic plateau in north central New Mexico, United States. The plateau, part of the Jemez Mountains, is bounded on the west by the Sierra de los Valles, the range forming the east rim of the Valles Caldera, and on the east by the Puye escarpment, which rises about 300 to 400 feet (90 to 100 m) above the Rio Grande valley about a mile (1.6 km) west of the river. The Rio Grande passes through White Rock Canyon to the southeast, and the Caja del Rio (Cerros del Rio) across the river is sometimes regarded as part of the plateau. The plateau is occupied by several notable entities, including Bandelier National Monument, the town of Los Alamos and its remote suburb White Rock, and Los Alamos National Laboratory. Elevations range from about 5,600 feet (1,700 meters) at the river to about 7,800 feet (2,400 meters) where the plateau merges into the mountain range.

The Pajarito Plateau is primarily composed of Bandelier Tuff, a voluminous deposit of volcanic tuff laid down in an explosive eruption — in this case, a pair of eruptions from the nearby Valles Caldera. The two ignimbrite-forming eruptions occurred about 1.6 million and 1.2 million years ago and ejected about 300 cubic kilometers of rock each. The orange-pink rock formations constituting the resulting ignimbrites are known as the Otowi and Tshirege Members of the Bandelier tuff. The tuff lies on top of a volcanic field, exposed to the east, which used to be continuous with the Caja del Rio (now across the Rio Grande).

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Volcanic field in the context of Gegham mountains

The Gegham mountains (or Gegham Ridge; Armenian: Գեղամա լեռնաշղթա, romanizedGeġama lernasheghta) are a range of mountains in Armenia. The range is a tableland-type watershed basin of Sevan Lake from east, inflows of rivers Araks and Hrazdan from north and west, Azat and Vedi rivers from south-west and Arpachai river from south. The average elevation of the Gegham mountain range is near 2500m. The range is of volcanic origin including many extinct volcanoes. The range is 70 km length and 48 km width, and stretch between Lake Sevan and the Ararat plain. The highest peak of the Gegham mountains is the Azhdahak, at 3597m. They are formed by a volcanic field, containing Pleistocene-to-Holocene lava domes and cinder cones. The highland reaches a height of 1800–2000m up to 3000m in the dividing ridge.

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Volcanic field in the context of Volcanic belt

A volcanic belt is a large volcanically active region. Other terms are used for smaller areas of activity, such as volcanic fields or volcanic systems. Volcanic belts are found above zones of unusually high temperature (700 to 1,400 °C (1,292 to 2,552 °F)) where magma is created by partial melting of solid material in the Earth's crust and upper mantle. These areas usually form along tectonic plate boundaries at depths of 10 to 50 kilometres (6.2 to 31.1 mi). For example, volcanoes in Mexico and western North America are mostly in volcanic belts, such as the Trans-Mexican Volcanic Belt that extends 900 kilometres (560 mi) from west to east across central-southern Mexico and the Northern Cordilleran Volcanic Province in western Canada. In the case of Iceland, the geologist G.G. Bárdarson in 1929 identified clusters of volcanic belts while studying the Reykjanes Peninsula.

The deeply deformed and eroded remnants of ancient volcanic belts are found in volcanically inactive regions such as the Canadian Shield. It contains over 150 volcanic belts (now deformed and eroded down to nearly flat plains) that range from 600 to 1,200 million years old. These are zones of variably metamorphosed mafic to ultramafic volcanic sequences with associated sedimentary rocks that form what are known as greenstone belts. They are thought to have formed at ancient oceanic spreading centers and island arc terranes. The Abitibi greenstone belt in Ontario and Quebec, Canada is one of the world's largest greenstone belts.

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Volcanic field in the context of Monogenetic volcanic field

A monogenetic volcanic field is a type of volcanic field consisting of a group of small monogenetic volcanoes, each of which erupts only once, as opposed to polygenetic volcanoes, which erupt repeatedly over a period of time. The small monogenetic volcanoes of these fields are the most common subaerial volcanic landform.

Many monogenetic volcanoes are cinder cones, often with lava flows, such as Parícutin in the Michoacán-Guanajuato volcanic field, which erupted from 1943 to 1952. Some monogenetic volcanoes are small lava shields, such as Rangitoto Island in the Auckland volcanic field. Other monogenetic volcanoes are tuff rings or maars. A monogenetic field typically contains between ten and a hundred volcanoes. The Michoacán-Guanajuato field in Mexico contains more than a thousand volcanoes and is exceptionally large.

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Volcanic field in the context of Volcanic Eifel

The Volcanic Eifel or Vulkan Eifel (German: Vulkaneifel) consists of three areas of volcanic activity, known as the West Eifel, High Eifel, and East Eifel volcanic fields. Volcanic Eifel is a region in the Eifel Mountains in Germany that is defined to a large extent by its volcanic geological history. Characteristic of the volcanic fields are their typical explosion crater lakes or maars, and numerous other signs of volcanic activity such as volcanic tuffs, lava streams and volcanic craters, for example the Laacher See. The Volcanic Eifel is still volcanically active today. One sign of this activity is the escaping gases in the Laacher See.

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Volcanic field in the context of Volcanic group

A volcanic group, depending on context, is either (1) a group of related volcanoes in the form of volcanic fields, volcanic complexes and cone clusters, or (2) a stratigraphic group consisting of volcanic strata.

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Volcanic field in the context of Chaîne des Puys

The Chaîne des Puys (French: [ʃɛːn de pɥi]; lit.'Chain of the Puys') is a north-south oriented chain of cinder cones, lava domes, and maars in the Massif Central of France. The chain is about 40 km (25 mi) long, and the identified volcanic features, which constitute a volcanic field, include 48 cinder cones, eight lava domes, and 15 maars and explosion craters. Its highest point is the lava dome of Puy de Dôme, located near the middle of the chain, which is 1,465 m (4,806 ft) high. The name of the range comes from a French term, puy, which refers to a volcanic mountain with a rounded profile. A date of 4040 BC is usually given for the last eruption of a Chaîne des Puys volcano.

An outstanding example of plate tectonics in action and continental rifting, the Chaîne des Puys region became a UNESCO World Heritage Site in 2018.

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