Andean Volcanic Belt

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The andes mountains are one of the tallest.Map of the volcanic arcs in the Andes, and subducted structures affecting volcanism MAGMAARC1.jpg
The andes mountains are one of the tallest.Map of the volcanic arcs in the Andes, and subducted structures affecting volcanism

The Andean Volcanic Belt is a major volcanic belt along the Andean cordillera in Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru. It is 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 broad range of volcano-tectonic settings, as it has rift systems and extensional zones, transpressional faults, subduction of mid-ocean ridges and seamount chains as well as a large range of crustal thicknesses and magma ascent paths and different amounts of crustal assimilations.

Contents

Romeral in Colombia is the northernmost active member of the Andean Volcanic Belt. [1] South of latitude 49° S within the Austral Volcanic Zone volcanic activity decreases with the southernmost volcano Fueguino in Tierra del Fuego archipelago.

Volcanic zones

Map of major Colombian volcanoes.svg
MajorVolcanoesInEcuador-USGS.gif
Map of the major Colombian (left) and Ecuadorian (right) volcanoes

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 arc.

Northern Volcanic Zone

The Northern Volcanic Zone (NVZ) extends from Colombia to Ecuador and includes all volcanoes on the continental mainland of these countries. Of the volcanoes in this zone, 55 are located in Ecuador, while 19 are in Colombia. In Ecuador, the volcanoes are located in the Cordillera Occidental and the Cordillera Real while in Colombia they are located in the Western and Central Ranges. The Pliocene Iza-Paipa volcanic complex in Boyacá, in the Eastern Ranges is the northernmost manifestation of the Northern Andean Volcanic Belt. The volcanic arc has formed due to subduction of the Nazca Plate underneath 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 significant sources of hazards. It has been estimated that crustal thickness beneath this region varies from around 40 to perhaps more than 55 kilometres (34 mi). [2] Sangay is the southernmost volcano of the Northern Volcanic Zone.

The Geophysics Institute at the National Polytechnic School in Quito, Ecuador houses an international team of seismologists and volcanologists [3] whose responsibility is to monitor Ecuador's numerous active volcanoes in the Andean Volcanic Belt and the Galápagos Islands, all of which is part of the Ring of Fire.

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 Peru 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. [2] Within this zone, there are 44 major and 18 minor volcanic centers that are considered to be active. [2] 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. [2] [4] [5]

Southern Volcanic Zone

Map of the volcanoes of the Southern Volcanic Zone that erupted in the 1990–2010 period.

The South Volcanic Zone (SVZ) extends roughly from Central Chile's Andes at the latitude of Santiago, 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.

From north to south the Southern Volcanic Zone is divided into four segments according to the characteristics of the continental crust, volcanoes and volcanic rocks: [6]

In Central Southern Volcanic Zone and Southern Southern Volcanic Zone, magma ascent occur primarily by the Liquiñe-Ofqui Fault. [7]

The Principal Cordillera of Andes (east Santiago) rose in late Cenozoic and became extensively glaciated about one million years ago. This meant lavas from NSVZ volcanoes begun to be channeled along a network of glacial valleys ever since. [8] The Maipo caldera exploded about 450 thousand years ago, leaving behind copious amounts of ash and ignimbrite rock that can be observed today both in Chile and Argentina. [8]

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). [9] A reduction in the convergence rate of the Nazca and the South American Plate from 9 cm per year to 7.9 cm [9] per year 2–3 million years ago contributed to a narrowing of the southern SVZ that occurred possibly 1.6 million years ago. [10] The southern part of the SVZ retained vigorous activity only in the west, especially around the Liquiñe-Ofqui Fault Zone, [10] while eastern volcanoes such as Tronador and Cerro Pantoja became extinct. [9]

The magmas of modern (Holocene) volcanoes in the Transitional Southern Volcanic Zone are derived from heterogenous sources in the Earth's mantle. Lots of lesser parts of melts are derived from subducted oceanic crust and subducted sediments. Towards the east, in the backarc region, the degree of melting in the mantle that gave origin to volcanism is less as are the subducted crust influences. [11]

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), Cordón Caulle (2011) and Calbuco (2015).

Austral Volcanic Zone

The Austral Volcanic Zone (AVZ) is a volcanic arc 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. [12] 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 volcanoes under the Southern Patagonian Ice Field.

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. [13] 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 areas of flat slab (low angle) subduction 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. [14]

Peruvian gap

Between the latitudes of 3 °S–15 °S in Peru the last volcanic activity occurred 2.7 million years ago in Cordillera Blanca. [15] 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. [15]

Pampean gap

The Pampean gap or Norte Chico 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.

Back-arc volcanism

Back-arc 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. [16] Notable back-arc volcanoes include Payun Matru, Agua Poca, 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 foothills of Ecuador's Cordillera Real, where a series of alkaline volcanoes like Sumaco develops. [2]

Geothermal activity

The Andean Volcanic Belt represents a large geothermal province, with numerous hot springs, solfataras and geysers associated with its volcanoes. Already in the pre-Columbian era, the indigenous peoples used the various hot springs as places of healing. The geothermal exploration in the Chilean Andes was pioneered in the 1960s, [17] although the site of El Tatio was investigated previously in the 1920s. Compared to neighboring Central America, the Andean region is poorly explored and exploited for geothermal resources.

See also

Related Research Articles

Subduction A geological process at convergent tectonic plate boundaries where one plate moves under the other

Subduction is a geological process that takes place at convergent boundaries of tectonic plates where one plate moves under another and is forced to sink due to high gravitational potential energy into the mantle. Regions where this process occurs are known as subduction zones. Rates of subduction are typically measured in centimeters per year, with the average rate of convergence being approximately two to eight centimeters per year along most plate boundaries.

Volcanic arc A chain of volcanoes formed above a subducting plate

A volcanic arc is a chain of volcanoes formed above a subducting plate, positioned in an arc shape as seen from above. Offshore volcanoes form islands, resulting in a volcanic island arc. Generally, volcanic arcs result from the subduction of an oceanic tectonic plate under another tectonic plate, and often parallel an oceanic trench. The oceanic plate is saturated with water, and volatiles such as water drastically lower the melting point of the mantle. As the oceanic plate is subducted, it is subjected to greater and greater pressures with increasing depth. This pressure squeezes water out of the plate and introduces it to the mantle. Here the mantle melts and forms magma at depth under the overriding plate. The magma ascends to form an arc of volcanoes parallel to the subduction zone.

Cerro Azul (Chile volcano) mountain in Curicó Province Chile

Cerro Azul, sometimes referred to as Quizapu, is an active stratovolcano in the Maule Region of central Chile, immediately south of Descabezado Grande. Part of the South Volcanic Zone of the Andes, its summit is 3,788 meters (12,428 ft) above sea level, and is capped by a summit crater that is 500 meters (1,600 ft) wide and opens to the north. Beneath the summit, the volcano features numerous scoria cones and flank vents.

Nevado de Longaví mountain in Chile

Nevado de Longaví is a volcano in the Andes of central Chile. The 3,242 m (10,636 ft) high volcano lies in the Linares Province, which is part of the Maule Region. It features a summit crater and several parasitic vents. The volcano is constructed principally from lava flows. Two collapses of the edifice have carved collapse scars into the volcano, one on the eastern slope known as Lomas Limpias and another on the southwestern slope known as Los Bueye. The volcano features a glacier and the Achibueno and Blanco rivers originate on the mountain.

Mentolat mountain in Aysén Province Chile

Mentolat is an ice-filled, 6 km (4 mi) wide caldera in the central portion of Magdalena Island, Aisén Province, Chilean Patagonia. This caldera sits on top of a stratovolcano which has generated lava flows and pyroclastic flows. The caldera is filled with a glacier.

Aguilera (volcano) stratovolcano in southern Chile

Aguilera is a stratovolcano in southern Chile, which rises above the edge of the Southern Patagonian Ice Field. It is a remote volcano that was identified as such in 1985, but the first ascent only occurred in 2014, making it the last unclimbed major Andean volcano.

Geology of Chile

The geology of Chile is a characterized by processes linked to subduction such as volcanism, earthquakes and orogeny. The buildings blocks of Chile's geology assembled during the Paleozoic Era. Chile was by then the southwestern margin of the supercontinent Gondwana. In the Jurassic Gondwana begun to split and the ongoing period of crustal deformation and mountain building known as the Andean orogeny begun. In the Late Cenozoic Chile definitely separated from Antarctica, the Andes expienced a great rise accomplained by a cooling climate and the onset of glaciations.

Juan Fernández Ridge A volcanic island and seamount chain on the Nazca Plate

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.

Los Patos mountain in Argentina

Los Patos is a mountain in the Andes mountain range of South America. The peak is located on the international border of the Catamarca Province of Argentina and the Atacama Region of Chile. It has a summit elevation of 6,239 metres (20,469 ft).

Andean orogeny Ongoing mountain-forming process in South America

The Andean orogeny is an ongoing process of orogeny that began in the Early Jurassic and is responsible for the rise of the Andes mountains. The orogeny is driven by a reactivation of a long-lived subduction system along the western margin of South America. On a continental scale the Cretaceous and Oligocene were periods of re-arrangements in the orogeny. Locally the details of the nature of the orogeny varies depending on the segment and the geological period considered.

Solimana (volcano) volcano in Peru

Solimana is a volcanic massif in the Andes of Peru, South America, that is approximately 6,093 metres (19,990 ft) high. It is considered an extinct stratovolcano that is part of the Central Volcanic Zone, one of the volcanic belts of the Andes. It features a caldera as well as traces of a sector collapse and subsequent erosion. The volcano is glaciated.

Flat slab subduction is characterized by a low subduction angle beyond the seismogenic layer and a resumption of normal subduction far from the trench. A slab refers to the subducting lower plate. Although, some would characterize flat slab subduction as any shallowly dipping lower plate as in western Mexico. Flat slab subduction is associated with the pinching out of the asthenosphere, an inland migration of arc magmatism, and an eventual cessation of arc magmatism. The coupling of the flat slab to the upper plate is thought to change the style of deformation occurring on the upper plate's surface and form basement-cored uplifts like the Rocky Mountains. The flat slab also may hydrate the lower continental lithosphere and be involved in the formation of economically important ore deposits. During the subduction, a flat slab itself may be deformed, or buckling, causing sedimentary hiatus in marine sediments on the slab. The failure of a flat slab is associated with ignimbritic volcanism and the reverse migration of arc volcanism. Multiple working hypotheses about the cause of flat slabs are subduction of thick, buoyant oceanic crust (15–20 km) and trench rollback accompanying a rapidly overriding upper plate and enhanced trench suction. The west coast of South America has two of the largest flat slab subduction zones. Flat slab subduction is occurring at 10% of subduction zones.

Incapillo

Incapillo is a Pleistocene caldera, a depression formed by the collapse of a volcano, in the La Rioja province of Argentina. Part of the Argentine Andes, it is considered the southernmost volcanic centre in the Central Volcanic Zone of the Andes with Pleistocene activity. Incapillo is one of several ignimbritic or calderic systems that, along with 44 active stratovolcanoes, are part of the Central Volcanic Zone.

Irruputuncu mountain shared by Bolivia and Chile

Irruputuncu is a volcano in the commune of Pica, Tamarugal Province, Tarapacá Region, Chile, as well as San Pedro de Quemes Municipality, Nor Lípez Province, Potosí Department, Bolivia. The mountain's summit is 5,163 m (16,939 ft) high and has two summit craters—the southernmost 200 m (660 ft)-wide one has active fumaroles. The volcano also features lava flows, block and ash flows and several lava domes. The volcano is part of the Andean Central Volcanic Zone (CVZ).

Jotabeche is a Miocene-Pliocene caldera in the Atacama Region of Chile. It is part of the volcanic Andes, more specifically of the extreme southern end of the Central Volcanic Zone (CVZ). This sector of the Andean Volcanic Belt contains about 44 volcanic centres and numerous more minor volcanic systems, as well as some caldera and ignimbrite systems. Jotabeche is located in a now inactive segment of the CVZ, the Maricunga Belt.

Fueguino is a volcanic field in Chile. The southernmost volcano in the Andes, it lies on Tierra del Fuego's Cook Island and also extends over nearby Londonderry Island. The field is formed by lava domes, pyroclastic cones, and a crater lake.

Río Murta is a volcano in Chile.

Wheelwright caldera is a caldera in Chile. It is variously described as being between 11 kilometres (6.8 mi) and 22 kilometres (14 mi) wide and lies in the Central Volcanic Zone of the Andes. A lake lies within the caldera, which is among the largest of the Central Andes. The caldera lies in the region of Ojos del Salado, the world's tallest volcano.

Tata Sabaya mountain

Tata Sabaya is a 5,430-metre (17,810 ft) high volcano in Bolivia. It is part of the Central Volcanic Zone, one of several volcanic belts in the Andes which are separated by gaps without volcanic activity. This section of the Andes was volcanically active since the Jurassic, with an episode of strong ignimbritic volcanism occurring during the Miocene. Tata Sabaya lies in a thinly populated region north of the Salar de Coipasa salt pan.

Pampean flat-slab Geologic zone in Chile and Argentina

The Pampean flat-slab is the low angle subduction of oceanic lithosphere beneath northern Chile and Argentina. The Pampean flat-slab is one of three flat slabs in South America, the other being the Peruvian flat-slab and the Bucaramanga flat-slab.

References

  1. "Romeral". Volcano.si.edu. 29 March 2012. Global Volcanism Program
  2. 1 2 3 4 5 Stern, Charles R (December 2004). "Active Andean volcanism: its geologic and tectonic setting". Revista Geológica de Chile . 31 (2): 161–206. doi:10.4067/S0716-02082004000200001. ISSN   0716-0208.
  3. "Home – Instituto Geofísico – EPN". igepn.edu.ec. Retrieved 11 September 2015.
  4. Ort, M.H. (1993). "Eruptive processes and caldera formation in a nested downsag collapse caldera: Cerro Panizos, central Andes mountains". J. Volcanol. Geotherm. Res. 56 (3): 221–252. Bibcode:1993JVGR...56..221O. doi:10.1016/0377-0273(93)90018-M.
  5. de Silva, S.L.; Francis, P.W. (1991). Volcanoes of the Central Andes. Berlin Heildelberg New York: Springer. p. 216.
  6. López-Escobar, Leopoldo; Kilian, Rolf; Kempton, Pamela D.; Tagiri, Michio (1993). "Petrography and geochemistry of Quaternary rocks from the Southern Volcanic Zone of the Andes between 41 30'and 46 00'S, Chile". Revista Geológica de Chile . 20 (1): 33–55.
  7. Hickey-Vargas, Rosemary; Holbik, Sven; Tormey, Daniel; Frey, Federick A.; Moreno-Roa, Hugo (2016). "Basaltic rocks from the Andean Southern Volcanic Zone: Insights from the comparison of along-strike and small-scale geochemical variations and their sources". Lithos . 258–259: 115–132. doi:10.1016/j.lithos.2016.04.014.
  8. 1 2 Charrier, Reynaldo; Iturrizaga, Lafasam; Charretier, Sebastién; Regard, Vincent (2019). "Geomorphologic and Glacial Evolution of the Cachapoal and southern Maipo catchments in the Andean Principal Cordillera, Central Chile (34°-35º S)". Andean Geology . 46 (2): 240–278. doi:10.5027/andgeoV46n2-3108 (inactive 22 January 2020). Retrieved 9 June 2019.
  9. 1 2 3 Lara, L.; Rodríguez, C.; Moreno, H.; Pérez de Arce, C. (2001). "Geocronología K-Ar y geoquímica del volcanismo plioceno superior-pleistoceno de los Andes del sur (39–42°S)" [K-Ar geochronology and geochemistry of Upper Pleistocene to Pliocene volcanism of the southern Andes (39-42°S)]. Revista Geológica de Chile (in Spanish). 28 (1): 67–90. doi:10.4067/S0716-02082001000100004.
  10. 1 2 Lara, L. E.; Folguera, A. (2006). The Pliocene to Quaternary narrowing of the Southern Andean volcanic arc between 37° and 41°S latitude. GSA Special Papers. 407. pp. 299–315. doi:10.1130/2006.2407(14). ISBN   978-0-8137-2407-2.
  11. Jaques, G.; Hoernle, K.; Gill, J.; Hauff, F.; Wehrmann, H.; Garbe-Schönbeg, D.; Van den Bogaard, P.; Bindeman, I.; Lara, L.E. (2013). "Across-arc geochemical variations in the Southern Volcanic Zone, Chile (34.5–38.0°S): Constraints on mantle wedge and slab input compositions". Geochimica et Cosmochimica Acta . 123: 218–243. doi:10.1016/j.gca.2013.05.016.
  12. D'Orazio, M.; Agostini, S.; Mazzarini, F.; Innocenti, F.; Manetti, P.; Haller, M. J.; Lahsen, A. (2000). "The Pali Aike Volcanic Field, Patagonia: slab-window magmatism near the tip of South America". Tectonophysics. 321 (4): 407–427. Bibcode:2000Tectp.321..407D. doi:10.1016/S0040-1951(00)00082-2.
  13. Nur, A.; Ben-Avraham, Z. (1983). "Volcanic gaps due to oblique consumption of aseismic ridges". Tectonophysics. 99 (2–4): 355–362. Bibcode:1983Tectp..99..355N. doi:10.1016/0040-1951(83)90112-9.
  14. Russo, R. M.; Vandecar, J. C.; Comte, D.; Mocanu, V. I.; Gallego, A.; Murdie, R. E. (2010). "Subduction of the Chile Ridge: Upper mantle structure and flow". GSA Today. 20 (9): 4–10. doi:10.1130/GSATG61A.1.
  15. 1 2 Gutscher, M.-A.; Olivet, J.-L.; Aslanian, D.; Eissen, J.-P.; Maury, R. (1999). "The "lost inca plateau": cause of flat subduction beneath peru?" (PDF). Earth and Planetary Science Letters. 171 (3): 335–341. Bibcode:1999E&PSL.171..335G. doi:10.1016/S0012-821X(99)00153-3.
  16. Germa, A.; Quidelleur, X.; Gillot, P. Y.; Tchilinguirian, P. (2010). "Volcanic evolution of the back-arc Pleistocene Payun Matru volcanic field (Argentina)". Journal of South American Earth Sciences. 29 (3): 717–730. Bibcode:2010JSAES..29..717G. doi:10.1016/j.jsames.2010.01.002.
  17. "Andean Volcanic Belt". 5 November 1997. Retrieved 19 July 2009.