Andean Volcanic Belt
Encyclopedia
The Andean Volcanic Belt is a major volcanic belt
along the Andean cordillera
in Colombia
, Bolivia
, Peru
, Ecuador
, Chile
and Argentina
. It formed as a result of subduction
of the Nazca Plate
and Antarctic Plate
underneath the South American Plate
. The belt is subdivided into four main volcanic zones that are separated from each other by volcanic gaps. The volcanoes of the belt are diverse in terms of activity style, products and morphology. While some differences can be explained by which volcanic zone a volcano belongs to, there are significant differences within volcanic zones and even between neighboring volcanoes. Despite being a type location for calc-alkalic and subduction volcanism, the Andean Volcanic Belt has a large range of volcano-tectonic settings, such as rift systems and extensional zones, transpressional faults, subduction of mid-ocean ridge
s and seamount
chains apart from a large range on crustal thicknesses and magma
ascent paths, and different amount of crustal assimilations.
Nevado del Ruiz
in Colombia
is the northernmost member of the Andean Volcanic Belt. South of latitude 49° S within the Austral Volcanic Zone volcanic activity decreases with the southernmost volcano Fueguino
in Tierra del Fuego
archipelago.
.
to Ecuador
and includes all volcanoes on the continental mainland of these countries. Of the zone's volcanoes, 55 are located in Ecuador while 19 are in Colombia. In Ecuador the volcanoes are located in the Cordillera Occidental and Cordillera Real
while in Colombia they are located in Cordillera Central. The volcanic arc has formed due to subduction
of the Nazca Plate
under western South America. Some volcanoes of the Northern Volcanic Zone, such as Galeras
and Nevado del Ruiz
that lie in densely populated highland areas, are major sources of hazards. It has been estimated that crustal thickness beneath this region varies from around 40 to perhaps more than 55 km. Sangay
is the southernmost volcano of the Northern Volcanic Zone.
to Chile
and forms the western boundary of the Altiplano
plateau. The volcanic arc has formed due to subduction of the Nazca Plate under western South America along the Peru-Chile Trench
. To the south the CVZ is limited by the Pampean flat-slab segment or Norte Chico flat-slab segment, a region devoid of volcanism due to a lower subduction angle caused by the subduction of Juan Fernández Ridge
.
The CVZ is characterized by a continental crust
that reaches a thickness of approximately 70 km. Within this zone there are 44 major and 18 minor volcanic centers that are considered to be active. This volcanic zone also contains not less than six potentially active large silicic
volcanic systems, which include those of the Altiplano-Puna Volcanic Complex, as are Cerro Panizos, Pastos Grandes
, Cerro Guacha and La Pacana
. Other silicic systems are Los Frailes ignimbrite plateau in Bolivia
, and the caldera
complexes of Incapillo and Cerro Galán
in Argentina
.
, at ca. 33°S, to Cerro Arenales
in Aysén Region
at ca. 46°S, a distance of well over 870 mi (1,400 km). The arc has formed due to subduction of the Nazca Plate under the South American Plate along the Peru-Chile Trench
. The northern boundary of the SVZ is marked by the flat-slab subduction of the Juan Fernández Ridge
, which is believed to have produced a volcanic gap called the Pampean flat-slab segment in the Norte Chico
region since the late Miocene
. The southern end of the SVZ is marked by the Chile Triple Junction
where the Chile Rise
subducts under South America at the Taitao Peninsula
giving origin to the Patagonian Volcanic Gap. Further south lies the Austral Volcanic Zone.
During the Pliocene
the SVZ south of 38°S consisted of a broad volcanic arc. The area with volcanic activity 1 to 2 million years ago between 39°S-42°S was up to 300 km wide (if back-arc volcanism is included). A reduction in the convergence rate of the Nazca
and the South American Plate
from 9 cm per year to 7.9 cm per year 2-3 million years ago contributed to a narrowing of the southern SVZ that occurred possibly 1.6 million years ago. The southern part of the SVZ retained vigorous activity only in the west, especially around the Liquiñe-Ofqui Fault Zone, while eastern volcanoes such as Tronador
and Cerro Pantoja
became extinct.
Several volcanoes of the SVZ are being monitored by the Southern Andean Volcano Observatory
(OVDAS) based in Temuco
. The volcanoes monitored have varied over time but some like Villarrica
and Llaima
are monitored constantly. In recent years, there have been major eruptions at Chaitén
(2008–2010) and Cordón Caulle
(2011).
in the Andes of southwestern South America. It is one of the four volcanic zones of the Andes. The AVZ extends south of the Patagonian Volcanic Gap to Tierra del Fuego
archipelago, a distance of well over 600 mi (1,000 km). The arc has formed due to subduction of the Antarctic Plate
under the South American Plate. Eruption products consist chiefly of alkaline basalt
and basanite
. Volcanism in the Austral Volcanic Zone is less vigorous than in the Southern Volcanic Zone. Recorded eruptions are rare due to the area being unexplored well into the 19th century; the cloudy weather of its western coast might also have prevented sightings of eruptions. The Austral Volcanic Zone hosts both glaciated stratovolcanoes as well as subglacial volcano
es under the Southern Patagonian Ice Field
.
areas and therefore the lack of volcanism is believed to be caused by the shallow dip of the subducting Nazca Plate
in these places. The shallow dip has in turn been explained by the subduction of the Nazca Ridge
and the Juan Fernández Ridge
for the Peruvian and Pampean gaps respectively. Since the Nazca and Juan Fernández Ridge are created by volcanic activity in Pacific hotspots (Easter
and Juan Fernández
) it can be said that volcanic activity in the Pacific is responsible for the suppression of volcanism in parts of the Andes.
The Patagonian gap is different in nature as it is caused not by the subduction of an aseismic ridge but by the subduction of the Chile Rise
, the boundary ridge between the Nazca and the Antarctic Plate.
. The lack of volcanism in central and northern Peru is widely attributed to a side effect of the flat-slab (low angle) subduction
of the Nazca Plate
occurring there. While the subduction of the Nazca Ridge
has often been credited for causing this flat-slab and hence the lack of volcanism, many researchers find the gap too wide to be explained by this alone.
One hypothesis claims that the flat-slab is caused by the ongoing subduction of an oceanic plateau
. This hypothetical plateau named Inca Plateau would be a mirror image of the Marquesas Plateau
in the South Pacific.
separates the Andes Central and Southern volcanic zones. A low subduction
angle caused by the subduction of Juan Fernández Ridge
has been pointed out as causing or contributing to the suppression of volcanism.
volcanism is a significant phenomenon in Argentine Patagonia
and Mendoza Province
. Flat-slab subduction
along the Peru-Chile Trench
during the Miocene
has been pointed out as being responsible for back-arc volcanism in Mendoza and Neuquén Province
during the Quaternary
. Notable back-arc volcanoes include Payun Matru
, Payun Liso, Pali-Aike Volcanic Field
, Tromen
, Cochiquito Volcanic Group
and Puesto Cortaderas.
Other significant back-arc volcanism regions include the Argentine Northwest
where the Galán Caldera is located and the Andean foothils of Ecuador's Cordillera Real
, where a series of alkaline volcanoes like Sumaco develops.
province, with numerous hot springs
, solfataras and geysers associated with its volcanoes. The geothermal
exploration in the Andes was pioneered in Chile in the 1960s, although the site of El Tatio
was invistigated already in the 1920s. Compared to neighboring Central America
, the Andean region is poorly explored and exploited for geothermal resources.
Volcanic belt
A volcanic belt is a large volcanically active region. Other terms are used for smaller areas of activity, such as volcanic fields. Volcanic belts are found above zones of unusually high temperature where magma is created by partial melting of solid material in the Earth's crust and upper mantle....
along the Andean cordillera
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
in Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
, Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
, Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
, Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
, Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
and Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. It formed as a result of subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...
of the Nazca Plate
Nazca Plate
]The Nazca Plate, named after the Nazca region of southern Peru, is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction along the Peru-Chile Trench of the Nazca Plate under the South American Plate is largely responsible for the...
and Antarctic Plate
Antarctic Plate
The Antarctic Plate is a tectonic plate covering the continent of Antarctica and extending outward under the surrounding oceans. The Antarctic Plate has a boundary with the Nazca Plate, the South American Plate, the African Plate, the Indo-Australian Plate, the Scotia Plate and a divergent boundary...
underneath the South American Plate
South American Plate
The South American Plate is a continental tectonic plate which includes the continent of South America and also a sizeable region of the Atlantic Ocean seabed extending eastward to the Mid-Atlantic Ridge....
. The belt is subdivided into four main volcanic zones that are separated from each other by volcanic gaps. The volcanoes of the belt are diverse in terms of activity style, products and morphology. While some differences can be explained by which volcanic zone a volcano belongs to, there are significant differences within volcanic zones and even between neighboring volcanoes. Despite being a type location for calc-alkalic and subduction volcanism, the Andean Volcanic Belt has a large range of volcano-tectonic settings, such as rift systems and extensional zones, transpressional faults, subduction of mid-ocean ridge
Mid-ocean ridge
A mid-ocean ridge is a general term for an underwater mountain system that consists of various mountain ranges , typically having a valley known as a rift running along its spine, formed by plate tectonics. This type of oceanic ridge is characteristic of what is known as an oceanic spreading...
s and seamount
Seamount
A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface , and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of depth. They are defined by oceanographers as...
chains apart from a large range on crustal thicknesses and magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
ascent paths, and different amount of crustal assimilations.
Nevado del Ruiz
Nevado del Ruiz
The Nevado del Ruiz, also known as La Mesa de Herveo or Kumanday in the language of the local pre-Columbian indigenous people, is a volcano located on the border of the departments of Caldas and Tolima in Colombia, about west of the capital city Bogotá. It is a stratovolcano, composed of many...
in Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
is the northernmost member of the Andean Volcanic Belt. South of latitude 49° S within the Austral Volcanic Zone volcanic activity decreases with the southernmost volcano Fueguino
Fueguino
Fueguino, also known as Cook, is a cluster of lava domes and pyroclastic cones located on Cook Island, Tierra del Fuego, Chile. This volcanic group lies south of the Magallanes-Fagnano Fault, on the Scotia Plate....
in Tierra del Fuego
Tierra del Fuego
Tierra del Fuego is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of a main island Isla Grande de Tierra del Fuego divided between Chile and Argentina with an area of , and a group of smaller islands including Cape...
archipelago.
Volcanic zones
The Andean Volcanic Belt is segmented into four main areas of active volcanism; the Northern, Central, Southern and Austral volcanic zones, each of which is a separate continental volcanic arcVolcanic arc
A volcanic arc is a chain of volcanoes positioned in an arc shape as seen from above. Offshore volcanoes form islands, resulting in a volcanic island arc. Generally they result from the subduction of an oceanic tectonic plate under another tectonic plate, and often parallel an oceanic trench...
.
Northern Volcanic Zone
The Northern Volcanic Zone (NVZ) extends from ColombiaColombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
to Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
and includes all volcanoes on the continental mainland of these countries. Of the zone's volcanoes, 55 are located in Ecuador while 19 are in Colombia. In Ecuador the volcanoes are located in the Cordillera Occidental and Cordillera Real
Cordillera Real (Ecuador)
The Cordillera Real is a chain of mountains in the Andes of Ecuador, the largest of them volcanic. They are continued by the Cordillera Central of Peru to the south and the Cordillera Central of Colombia to the north...
while in Colombia they are located in Cordillera Central. The volcanic arc has formed due to subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...
of the Nazca Plate
Nazca Plate
]The Nazca Plate, named after the Nazca region of southern Peru, is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction along the Peru-Chile Trench of the Nazca Plate under the South American Plate is largely responsible for the...
under western South America. Some volcanoes of the Northern Volcanic Zone, such as Galeras
Galeras
Galeras is an Andean stratovolcano in the Colombian department of Nariño, near the departmental capital Pasto. Its summit rises above sea level. It has erupted frequently since the Spanish conquest, with its first historical eruption being recorded on December 7, 1580...
and Nevado del Ruiz
Nevado del Ruiz
The Nevado del Ruiz, also known as La Mesa de Herveo or Kumanday in the language of the local pre-Columbian indigenous people, is a volcano located on the border of the departments of Caldas and Tolima in Colombia, about west of the capital city Bogotá. It is a stratovolcano, composed of many...
that lie in densely populated highland areas, are major sources of hazards. It has been estimated that crustal thickness beneath this region varies from around 40 to perhaps more than 55 km. Sangay
Sangay
Sangay is a constantly active stratovolcano in central Ecuador. It is the southernmost and most active volcano in the country, and is known for its explosive venting of thick ash clouds, which has built a dome since 1976.-See also:...
is the southernmost volcano of the Northern Volcanic Zone.
Central Volcanic Zone
The Central Volcanic Zone (CVZ) is a volcanic arc in western South America. It is one of the four volcanic zones of the Andes. The Central Volcanic Zone extends from PeruPeru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
to Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
and forms the western boundary of the Altiplano
Altiplano
The Altiplano , in west-central South America, where the Andes are at their widest, is the most extensive area of high plateau on Earth outside of Tibet...
plateau. The volcanic arc has formed due to subduction of the Nazca Plate under western South America along the Peru-Chile Trench
Peru-Chile Trench
The Peru-Chile Trench, also known as the Atacama Trench, is an oceanic trench in the eastern Pacific Ocean, about 160 kilometres off the coast of Peru and Chile...
. To the south the CVZ is limited by the Pampean flat-slab segment or Norte Chico flat-slab segment, a region devoid of volcanism due to a lower subduction angle caused by the subduction of Juan Fernández Ridge
Juan Fernández Ridge
The Juan Fernández Ridge is a volcanic island and seamount chain on the Nazca Plate. It runs in a west-east direction from the Juan Fernández hotspot to the Peru-Chile Trench at a latitude of 33° S near Valparaíso. The Juan Fernández Islands are the only seamounts that reach the surface....
.
The CVZ is characterized by a continental crust
Continental crust
The continental crust is the layer of igneous, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial due to more felsic, or granitic, bulk composition, which lies in...
that reaches a thickness of approximately 70 km. Within this zone there are 44 major and 18 minor volcanic centers that are considered to be active. This volcanic zone also contains not less than six potentially active large silicic
Silicic
Silicic is a term used to describe magma or igneous rock rich in silica. The amount of silica that constitutes a silicic rock is usually put at at least 65 percent. Granite and rhyolite are typical silicic rocks....
volcanic systems, which include those of the Altiplano-Puna Volcanic Complex, as are Cerro Panizos, Pastos Grandes
Pastos Grandes Caldera
Pastos Grandes Caldera or Cerro Pastos Grandes is an old caldera in the Potosí Department, Bolivia, which belongs to the Altiplano-Puna Volcanic Complex. Lagunas Pastos Grandes, Khara and Cachi may be remnants of a greater caldera lake. Size of the caldera: 50 km x 40 km. A large ...
, Cerro Guacha and La Pacana
Pacana Caldera
La Pacana Caldera is the most important caldera of the La Pacana Complex in the Antofagasta Region, northern of Chile, East of the Salar de Atacama. The La Pacana Complex belongs to the Altiplano-Puna Volcanic Complex...
. Other silicic systems are Los Frailes ignimbrite plateau in Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
, and the caldera
Caldera
A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...
complexes of Incapillo and Cerro Galán
Galán
Cerro Galán is a caldera in Catamarca Province, Argentina, considered to be the best exposed large caldera in the world. It was formed 2.2 million years ago when 1,050 km3 of material was erupted, producing ignimbrite deposits stretching up to 100 km away...
in Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
.
Southern Volcanic Zone
The South Volcanic Zone (SVZ) extends roughly from Central Chile's Andes at the latitude of SantiagoSantiago, Chile
Santiago , also known as Santiago de Chile, is the capital and largest city of Chile, and the center of its largest conurbation . It is located in the country's central valley, at an elevation of above mean sea level...
, at ca. 33°S, to Cerro Arenales
Cerro Arenales
Cerro Arenales is a heavily ice-covered stratovolcano located in the Aisén Region of Chile, within Laguna San Rafael National Park. It towers over the southern part of the Northern Patagonian Ice Field....
in Aysén Region
Aysen Region
The XI Aisén Region of General Carlos Ibáñez del Campo , also spelled Aysén, is one of Chile's 15 first order administrative divisions. Although the third largest in area, the region is Chile's most sparsely populated region with a population of 105,000. The capital of the region is Coihaique, the...
at ca. 46°S, a distance of well over 870 mi (1,400 km). The arc has formed due to subduction of the Nazca Plate under the South American Plate along the Peru-Chile Trench
Peru-Chile Trench
The Peru-Chile Trench, also known as the Atacama Trench, is an oceanic trench in the eastern Pacific Ocean, about 160 kilometres off the coast of Peru and Chile...
. The northern boundary of the SVZ is marked by the flat-slab subduction of the Juan Fernández Ridge
Juan Fernández Ridge
The Juan Fernández Ridge is a volcanic island and seamount chain on the Nazca Plate. It runs in a west-east direction from the Juan Fernández hotspot to the Peru-Chile Trench at a latitude of 33° S near Valparaíso. The Juan Fernández Islands are the only seamounts that reach the surface....
, which is believed to have produced a volcanic gap called the Pampean flat-slab segment in the Norte Chico
Norte Chico, Chile
The Norte Chico is one of the five natural regions on which CORFO divided continental Chile in 1950. Its northern border is formed by the limit with the Far North, on west lies the Pacific Ocean, by the east the Andes mountains and Argentina, and by the south the Zona Central natural region...
region since the late Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
. The southern end of the SVZ is marked by the Chile Triple Junction
Chile Triple Junction
The Chile Triple Junction is a geologic triple junction located on the seafloor of the Pacific Ocean off Taitao and Tres Montes Peninsula on the southern coast of Chile. Here three tectonic plates meet: the South American Plate, the Nazca Plate, and the Antarctic Plate...
where the Chile Rise
Chile Rise
The Chile Rise or Chile Ridge is an oceanic ridge, a tectonic divergent plate boundary between the Nazca and Antarctic Plates. Its eastern end is the Chile Triple Junction where the Chile Rise is being subducted below the South American Plate in the Peru-Chile Trench...
subducts under South America at the Taitao Peninsula
Taitao Peninsula
The Taitao Peninsula is a westward projection of the mainland of Chile, with which it is connected by the narrow Isthmus of Ofqui, over which the natives and early missionaries were accustomed to carry their boats between the Moraleda Channel and Gulf of Penas...
giving origin to the Patagonian Volcanic Gap. Further south lies the Austral Volcanic Zone.
During the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
the SVZ south of 38°S consisted of a broad volcanic arc. The area with volcanic activity 1 to 2 million years ago between 39°S-42°S was up to 300 km wide (if back-arc volcanism is included). A reduction in the convergence rate of the Nazca
Nazca Plate
]The Nazca Plate, named after the Nazca region of southern Peru, is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction along the Peru-Chile Trench of the Nazca Plate under the South American Plate is largely responsible for the...
and the South American Plate
South American Plate
The South American Plate is a continental tectonic plate which includes the continent of South America and also a sizeable region of the Atlantic Ocean seabed extending eastward to the Mid-Atlantic Ridge....
from 9 cm per year to 7.9 cm per year 2-3 million years ago contributed to a narrowing of the southern SVZ that occurred possibly 1.6 million years ago. The southern part of the SVZ retained vigorous activity only in the west, especially around the Liquiñe-Ofqui Fault Zone, while eastern volcanoes such as Tronador
Tronador
Tronador is an extinct stratovolcano in the southern Andes, located along the border between Argentina and Chile near the city of Bariloche. The mountain was named Tronador by locals in reference to the sound of falling seracs...
and Cerro Pantoja
Cerro Pantoja
Cerro Pantoja, also spelled as Cerro Pantojo, is an extint stratovolcano on the border of Argentina and Chile. It lies immediately south of Cardenal Antonio Samoré Pass and its characteristic spire-shaped summit is an eroded volcanic plug....
became extinct.
Several volcanoes of the SVZ are being monitored by the Southern Andean Volcano Observatory
Southern Andean Volcano Observatory
200px|thumb|right|[[Llaima]]'s 2008 eruption as viewed from [[Temuco]]The Southern Andean Volcano Observatory , also known by its acronyms as OVDAS, is a program of the Chilean National Geology and Mining Service to watch the most dangerous volcanoes of the Southern Volcanic Zone in Zona Sur and...
(OVDAS) based in Temuco
Temuco
Temuco is a city and commune, capital of the Cautín Province and of the Araucanía Region in southern Chile. The name comes from the Mapudungun language, meaning "temu water"; "temu" is a tree used by Mapuches for medicinal purposes. The city is located 670 km south of Santiago...
. The volcanoes monitored have varied over time but some like Villarrica
Villarrica (volcano)
Villarrica is one of Chile's most active volcanoes, rising above the lake and town of the same name. The volcano is also known as Rucapillán, a Mapuche word meaning "House of the Pillán". It is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain along the...
and Llaima
Llaima
Llaima Volcano is one of the largest and most active volcanoes in Chile. It is situated 82 km northeast of Temuco and 663 km southeast of Santiago, within the borders of Conguillío National Park.-Geography:...
are monitored constantly. In recent years, there have been major eruptions at Chaitén
Chaitén (volcano)
|290px|thumb|right|Image of the [[rhyolitic]] [[lava dome]] of Chaitén Volcano during its 2008-2010 eruption.Chaitén is a volcanic caldera in diameter, west of the elongated ice-capped Michinmahuida volcano and northeast of the town of Chaitén, near the Gulf of Corcovado in southern Chile. The...
(2008–2010) and Cordón Caulle
Puyehue-Cordón Caulle
Puyehue and Cordón Caulle are two coalesced volcanic edifices that form a major mountain massif in Puyehue National Park in the Andes of Ranco Province, Chile. In volcanology this group is known as the Puyehue-Cordón Caulle Volcanic Complex...
(2011).
Austral Volcanic Zone
The Austral Volcanic Zone (AVZ) is a volcanic arcVolcanic arc
A volcanic arc is a chain of volcanoes positioned in an arc shape as seen from above. Offshore volcanoes form islands, resulting in a volcanic island arc. Generally they result from the subduction of an oceanic tectonic plate under another tectonic plate, and often parallel an oceanic trench...
in the Andes of southwestern South America. It is one of the four volcanic zones of the Andes. The AVZ extends south of the Patagonian Volcanic Gap to Tierra del Fuego
Tierra del Fuego
Tierra del Fuego is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of a main island Isla Grande de Tierra del Fuego divided between Chile and Argentina with an area of , and a group of smaller islands including Cape...
archipelago, a distance of well over 600 mi (1,000 km). The arc has formed due to subduction of the Antarctic Plate
Antarctic Plate
The Antarctic Plate is a tectonic plate covering the continent of Antarctica and extending outward under the surrounding oceans. The Antarctic Plate has a boundary with the Nazca Plate, the South American Plate, the African Plate, the Indo-Australian Plate, the Scotia Plate and a divergent boundary...
under the South American Plate. Eruption products consist chiefly of alkaline basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
and basanite
Basanite
Basanite is an igneous, volcanic rock with aphanitic to porphyritic texture.The mineral assembly is usually abundant feldspathoids , plagioclase, and augite, together with olivine and lesser iron-titanium oxides such as ilmenite and magnetite-ulvospinel; minor alkali feldspar may be present, as...
. Volcanism in the Austral Volcanic Zone is less vigorous than in the Southern Volcanic Zone. Recorded eruptions are rare due to the area being unexplored well into the 19th century; the cloudy weather of its western coast might also have prevented sightings of eruptions. The Austral Volcanic Zone hosts both glaciated stratovolcanoes as well as subglacial volcano
Subglacial volcano
A subglacial volcano, also known as a glaciovolcano, is a volcanic form produced by subglacial eruptions or eruptions beneath the surface of a glacier or ice sheet which is then melted into a lake by the rising lava...
es under the Southern Patagonian Ice Field
Southern Patagonian Ice Field
The Southern Patagonian Ice Field , located at the Southern Patagonic Andes between Argentina and Chile, is the second largest contiguous extrapolar extent of ice in the world...
.
Volcanic gaps
The different volcanic zones are intercalated by volcanic gaps, zones that, despite lying at the right distance from an oceanic trench, lack volcanic activity. The Andes has three major volcanic gaps the Peruvian flat-slab segment (3 °S—15 °S), the Pampean flat-slab segment (27 °S—33 °S) and the Patagonian Volcanic Gap (46 °S—49 °S). The first one separates the Northern from the Central Volcanic Zone, the second the Central from the Southern and the last separates the Southern from the Austral Volcanic Zone. The Peruvian and Pampean gaps coincide with "flat slab" (low angle) subductionSubduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...
areas and therefore the lack of volcanism is believed to be caused by the shallow dip of the subducting Nazca Plate
Nazca Plate
]The Nazca Plate, named after the Nazca region of southern Peru, is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction along the Peru-Chile Trench of the Nazca Plate under the South American Plate is largely responsible for the...
in these places. The shallow dip has in turn been explained by the subduction of the Nazca Ridge
Nazca Ridge
The Nazca Ridge is an ocean ridge in the southern Pacific Ocean. It lies on the Nazca Plate and is being subducted in the Peru-Chile Trench under the South American Plate by ongoing plate motion....
and the Juan Fernández Ridge
Juan Fernández Ridge
The Juan Fernández Ridge is a volcanic island and seamount chain on the Nazca Plate. It runs in a west-east direction from the Juan Fernández hotspot to the Peru-Chile Trench at a latitude of 33° S near Valparaíso. The Juan Fernández Islands are the only seamounts that reach the surface....
for the Peruvian and Pampean gaps respectively. Since the Nazca and Juan Fernández Ridge are created by volcanic activity in Pacific hotspots (Easter
Easter hotspot
The Easter hotspot is a volcanic hotspot located in the southeastern Pacific Ocean. The hotspot created the Sala y Gómez Ridge which includes Easter Island and the Pukao Seamount which is at the ridge's young western edge....
and Juan Fernández
Juan Fernández hotspot
The Juan Fernández hotspot is a volcanic hotspot located in the southeastern Pacific Ocean. The hotspot created the Juan Fernández Ridge which includes the Juan Fernández Archipelago and a long seamount chain that is being subducted in the Peru-Chile Trench at the site of Papudo giving origin to...
) it can be said that volcanic activity in the Pacific is responsible for the suppression of volcanism in parts of the Andes.
The Patagonian gap is different in nature as it is caused not by the subduction of an aseismic ridge but by the subduction of the Chile Rise
Chile Rise
The Chile Rise or Chile Ridge is an oceanic ridge, a tectonic divergent plate boundary between the Nazca and Antarctic Plates. Its eastern end is the Chile Triple Junction where the Chile Rise is being subducted below the South American Plate in the Peru-Chile Trench...
, the boundary ridge between the Nazca and the Antarctic Plate.
Peruvian gap
Between the latitudes of 3 °S—15 °S in Peru the last volcanic activity occurred 2.7 million years ago in Cordillera BlancaCordillera Blanca
The Cordillera Blanca is a mountain range in the Ancash Region of Peru. Part of the larger Andes range, it includes 33 major peaks over high in an area wide and long.-Overview:...
. The lack of volcanism in central and northern Peru is widely attributed to a side effect of the flat-slab (low angle) subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...
of the Nazca Plate
Nazca Plate
]The Nazca Plate, named after the Nazca region of southern Peru, is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction along the Peru-Chile Trench of the Nazca Plate under the South American Plate is largely responsible for the...
occurring there. While the subduction of the Nazca Ridge
Nazca Ridge
The Nazca Ridge is an ocean ridge in the southern Pacific Ocean. It lies on the Nazca Plate and is being subducted in the Peru-Chile Trench under the South American Plate by ongoing plate motion....
has often been credited for causing this flat-slab and hence the lack of volcanism, many researchers find the gap too wide to be explained by this alone.
One hypothesis claims that the flat-slab is caused by the ongoing subduction of an oceanic plateau
Oceanic plateau
An oceanic plateau is a large, relatively flat submarine region that rises well above the level of the ambient seabed. While many oceanic plateaus are composed of continental crust, and often form a step interrupting the continental slope, some plateaus are undersea remnants of large igneous...
. This hypothetical plateau named Inca Plateau would be a mirror image of the Marquesas Plateau
Marquesas Islands
The Marquesas Islands enana and Te Fenua `Enata , both meaning "The Land of Men") are a group of volcanic islands in French Polynesia, an overseas collectivity of France in the southern Pacific Ocean. The Marquesas are located at 9° 00S, 139° 30W...
in the South Pacific.
Pampean gap
The Pampean gap or Norte ChicoNorte Chico, Chile
The Norte Chico is one of the five natural regions on which CORFO divided continental Chile in 1950. Its northern border is formed by the limit with the Far North, on west lies the Pacific Ocean, by the east the Andes mountains and Argentina, and by the south the Zona Central natural region...
separates the Andes Central and Southern volcanic zones. A low subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...
angle caused by the subduction of Juan Fernández Ridge
Juan Fernández Ridge
The Juan Fernández Ridge is a volcanic island and seamount chain on the Nazca Plate. It runs in a west-east direction from the Juan Fernández hotspot to the Peru-Chile Trench at a latitude of 33° S near Valparaíso. The Juan Fernández Islands are the only seamounts that reach the surface....
has been pointed out as causing or contributing to the suppression of volcanism.
Back-arc volcanism
Back-arcBack-arc basin
Back-arc basins are geologic features, submarine basins associated with island arcs and subduction zones.They are found at some convergent plate boundaries, presently concentrated in the Western Pacific ocean. Most of them result from tensional forces caused by oceanic trench rollback and the...
volcanism is a significant phenomenon in Argentine Patagonia
Patagonia
Patagonia is a region located in Argentina and Chile, integrating the southernmost section of the Andes mountains to the southwest towards the Pacific ocean and from the east of the cordillera to the valleys it follows south through Colorado River towards Carmen de Patagones in the Atlantic Ocean...
and Mendoza Province
Mendoza Province
The Province of Mendoza is a province of Argentina, located in the western central part of the country in the Cuyo region. It borders to the north with San Juan, the south with La Pampa and Neuquén, the east with San Luis, and to the west with the republic of Chile; the international limit is...
. Flat-slab subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...
along the Peru-Chile Trench
Peru-Chile Trench
The Peru-Chile Trench, also known as the Atacama Trench, is an oceanic trench in the eastern Pacific Ocean, about 160 kilometres off the coast of Peru and Chile...
during the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
has been pointed out as being responsible for back-arc volcanism in Mendoza and Neuquén Province
Neuquén Province
Neuquén is a province of Argentina, located in the west of the country, at the northern end of Patagonia. It borders Mendoza Province to the north, Rio Negro Province to the southeast, and Chile to the west...
during the Quaternary
Quaternary
The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...
. Notable back-arc volcanoes include Payun Matru
Payun Matru
Payun Matru is a shield volcano in Argentina, located in the Reserva Provincial La Payunia of the Malargüe Department, to the south of the Mendoza Province....
, Payun Liso, Pali-Aike Volcanic Field
Pali-Aike Volcanic Field
Pali-Aike Volcanic Field is a Pleistocene-to-Holocene volcanic field in Patagonia on the Argentina–Chile border, located north of the Straits of Magellan about 150 km northeast of Punta Arenas, Chile. The volcanic field contains lake-filled maars, along with basaltic scoria cones and spatter...
, Tromen
Tromen
Tromen is a stratovolcano in western Argentina. It rises above the older caldera of the Volcán Negro del Tromen.-References:*...
, Cochiquito Volcanic Group
Cochiquito Volcanic Group
The Cochiquito Volcanic Group is a small volcanic group of volcanoes north of the town of Buta Ranquil in Argentina. The main peak is Volcán Cochiquito, a stratovolcano of estimated Pleistocene–Holocene age. There are eight satellite cones in the volcanic field, including Volcán Sillanegra and...
and Puesto Cortaderas.
Other significant back-arc volcanism regions include the Argentine Northwest
Argentine Northwest
The Argentine Northwest is a region of Argentina composed by the provinces of Catamarca, Jujuy, Salta, Santiago del Estero and Tucumán.-Geography:The region had 5 different biomes:* Sub-Andean humid Sierras of the east...
where the Galán Caldera is located and the Andean foothils of Ecuador's Cordillera Real
Cordillera Real (Ecuador)
The Cordillera Real is a chain of mountains in the Andes of Ecuador, the largest of them volcanic. They are continued by the Cordillera Central of Peru to the south and the Cordillera Central of Colombia to the north...
, where a series of alkaline volcanoes like Sumaco develops.
Geothermal activity
The Andean Volcanic Belt represents a large geothermalGeothermal
Geothermal is related to energy and may refer to:* The geothermal gradient and associated heat flows from within the Earth- Renewable technology :...
province, with numerous hot springs
Hot Springs
Hot Springs may refer to:* Hot Springs, Arkansas** Hot Springs National Park, Arkansas*Hot Springs, California**Hot Springs, Lassen County, California**Hot Springs, Modoc County, California**Hot Springs, Placer County, California...
, solfataras and geysers associated with its volcanoes. The geothermal
Geothermal
Geothermal is related to energy and may refer to:* The geothermal gradient and associated heat flows from within the Earth- Renewable technology :...
exploration in the Andes was pioneered in Chile in the 1960s, although the site of El Tatio
El Tatio
thumb|A geyser bubbling at El Tatio geyser fieldEl Tatio is a geyser field located within the Andes Mountains of northern Chile at 4,200 meters above mean sea level. Contrary to some reports, it is not the highest-elevation geyser field in the world. Puchuldiza Geyser Field, Chile, and possibly...
was invistigated already in the 1920s. Compared to neighboring Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
, the Andean region is poorly explored and exploited for geothermal resources.
See also
- List of volcanoes in Argentina
- List of volcanoes in Bolivia
- List of volcanoes in Chile
- List of volcanoes in Colombia
- List of volcanoes in Ecuador
- List of volcanoes in Peru