Los Frailes ignimbrite plateau

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Los Frailes ignimbrite plateau
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Los Frailes ignimbrite plateau
Highest point
Coordinates 19°30′S66°18′W / 19.5°S 66.3°W / -19.5; -66.3 Coordinates: 19°30′S66°18′W / 19.5°S 66.3°W / -19.5; -66.3 [1]

Los Frailes is an ignimbrite plateau in Bolivia, between the city of Potosi and the Lake Poopo. It belongs to a group of ignimbrites that exist in the Central Andes and which includes the Altiplano–Puna volcanic complex. The plateau covers a surface of 7,500 square kilometres (2,900 sq mi)8,500 square kilometres (3,300 sq mi) with about 2,000 cubic kilometres (480 cu mi) of ignimbrite. [2] [3]

Contents

The plateau features several putative vents, including Cerro Condor Nasa, Cerro Livicucho, Cerro Pascual Canaviri, Cerro Villacollo and Nuevo Mundo. The plateau was emplaced starting from 25 million years ago to the Holocene, when the Nuevo Mundo vent was active.

Geography and geomorphology

Los Frailes lies in the Eastern Cordillera of Bolivia, [4] between the southeastern shores of Lake Poopo and the city of Potosi. [5] It is a little-studied volcanic system. [3]

Los Frailes belongs to the Central Andean ignimbrites, [6] which cover parts of southern Peru, southwestern Bolivia, northwestern Argentina and northeastern Chile [7] and which contains the Altiplano–Puna volcanic complex. [8] Ignimbrites do not cover all of the terrain there, however, and in some places there is more than one ignimbrite. [9] Where ignimbrites get emplaced is controlled by crustal fractures and lineaments, which are not always visible on the surface. [10] Some better studied volcanic centres are Galán and Cerro Guacha. [11]

The Los Frailes ignimbrite plateau covers a heart-shaped [5] area of about 7,500 square kilometres (2,900 sq mi) [12] or 8,500 square kilometres (3,300 sq mi), which makes it one of the largest such plateaus in the world. [13] The plateau has an average elevation of 4,000 metres (13,000 ft) [12] -4,500 metres (14,800 ft). [14] It was emplaced over a pre-existent topography, which resulted in the ignimbrites having irregular thicknesses; [4] they reach maxima of 1 kilometre (0.62 mi) but on average the thickness is about 100 metres (330 ft). They consist of mostly welded tuffs with column-like joint structures; [13] a total volume of 2,000 cubic kilometres (480 cu mi) has been estimated for the plateau, which is a large size. [2] [3]

Several potential vents have been identified, such as Cerro Condor Nasa and Cerro Livicucho (both of which appear to be circular structures with post-ignimbrite extrusions) in the northern part of the field, [13] the Huanapampa lava dome complex in the central part of the field [14] and Cerro Pascual Canaviri, Cerro Villacollo and Nuevo Mundo in its southern part. [15] Cerro Villacollo in the western sector of the plateau [5] is am eroded composite volcano [14] with a 200–600 metres (660–1,970 ft) deep and 3 kilometres (1.9 mi) wide collapse structure, and is accompanied by dacitic lava flows, [4] whereas Cerro Pascual Canaviri and Nuevo Mundo are complexes of lava domes, the latter of which also contains ash deposits that have been in part transported away by wind. [15] [16] Lava domes and lava flows are widespread on their surface, [13] and some volcanic necks contain mineral deposits. [4]

Geology

At least since the Jurassic, the Nazca Plate has been subducting beneath the South America Plate at a rate of about 80 millimetres per year (3.1 in/year). [17] Volcanism does not occur along the entire length of the subduction zone; where the subducting plate descends into the mantle at a shallow angle volcanism is absent. [18] There are thus three volcanic zones in South America, the Northern Volcanic Zone, the Central Volcanic Zone and the Southern Volcanic Zone. An additional volcanic belt, the Austral Volcanic Zone, is controlled by the subduction of the Antarctic Plate beneath the South America Plate. [8]

The remoteness of many volcanic formations of the Central Andes and the often hostile weather conditions mean that many volcanic formations are poorly investigated. [6]

The basement beneath Los Frailes is of PaleozoicMesozoic age and covered by Miocene andesitic-dacitic volcanics; some of these have been dated to 11.6 and 20 million years ago. [4] The terrain was heavily dissected when eruptive activity began. [14] Pre-existent cracks in this basement may have formed the pathways for the magma that eventually gave rise to the Los Frailes ignimbrite to ascend. [19] The onset of volcanic activity may ultimately be due to changes in the regional tectonic regime, such as the delamination of part of the lower crust and a change in the inclination of the subducting slab. [20]

Composition

Los Frailes has erupted rocks ranging from andesite to rhyolite. The main ignimbrite is of rhyodacitic composition [21] and contains phenocrysts consisting of apatite containing monazite and zircon, biotite, ilmenite, orthoclase, plagioclase and quartz. [22] Silver-tin deposits occur in the volcanic field, including the Cerro Rico stock that was a principal source of silver to the Spanish Empire. [14] The magmas appear to be partially derived from the mantle and partially as crustal melts, similar to other Central Andean ignimbrites. [3]

Eruption history

The Los Frailes ignimbrites were erupted between about 25 [14] or 13 and 2 million years ago, [12] but volcanism associated with the plateau goes back 25 million years, whereas the youngest ignimbrite is dated to 1.52–1.522 million years ago. [3] Several different stages of volcanic activity have been distinguished. [23]

After the emplacement of the ignimbrites, lava domes [25] and resurgent domes continued the volcanic activity in Los Frailes. [28] Nuevo Mundo is the youngest eruptive system of the Los Frailes plateau; [15] based on the position of its lavas with respect to moraines it must have been active within the last 11,000 years in the Holocene, [29] perhaps even in prehistoric time. [30] Surface exposure dating has yielded an age of about 11,700 for the northern Nuevo Mundo dome. [31]

Related Research Articles

Nuevo Mundo volcano

Nuevo Mundo also known as Jatun Mundo Quri Warani, is a stratovolcano, lava dome and a lava flow complex between Potosí and Uyuni, Bolivia, in the Andes rising to a peak at 5,438 m (17,841 ft). It is located in the Potosí Department, Antonio Quijarro Province, Tomave Municipality. It lies northeast of the peaks of Uyuni, Kuntur Chukuña and Chuqi Warani and south of Sirk'i.

Galán

Cerro Galán is a caldera in the Catamarca Province of Argentina. It is one of the largest exposed calderas in the world and forms part of the Central Volcanic Zone of the Andes, one of the three volcanic belts found in South America. One of several major caldera systems in the Central Volcanic Zone, the mountain is grouped into the Altiplano–Puna volcanic complex.

Linzor

Volcán Linzor is a stratovolcano on the border between Bolivia and Chile. In its vicinity lie Laguna Colorada and Cerro del León.

La Pacana

La Pacana is a Miocene age caldera in northern Chile's Antofagasta Region. Part of the Central Volcanic Zone of the Andes, it is part of the Altiplano-Puna volcanic complex, a major caldera and silicic ignimbrite volcanic field. This volcanic field is located in remote regions at the Zapaleri tripoint between Chile, Bolivia and Argentina.

Tunupa

Tunupa is a dormant volcano in the Potosí Department of southwestern Bolivia.

Aguas Calientes caldera

Aguas Calientes is a major Quaternary caldera in Salta Province, Argentina. It is in the Central Volcanic Zone of the Andes, a zone of volcanism covering southern Peru, Bolivia, northwest Argentina and northern Chile. This zone contains stratovolcanoes and calderas.

Abra Granada is a volcanic complex in the Puna de Atacama in Bolivia. It is located approximately 45 kilometres (28 mi) north of Pirquitas and is composed from a lava dome, lavas and dacitic ignimbrites centering on Cerro Granada and are dated 9.8-7.8 Ma. Deposits erupted 7.9-5.0 mya by this volcano overlie the older Granada ignimbrite. Individual volcanic centres are known as Cerro Caucani, Cerro Granada and Cerro Solterío. The Pirquitas mine is part of the volcanic complex.

Cerro Blanco (volcano)

Cerro Blanco is a caldera in the Andes of the Catamarca Province in Argentina. Part of the Central Volcanic Zone of the Andes, it is a volcano collapse structure located at an altitude of 4,670 metres (15,320 ft) in a depression. The caldera is associated with a less well defined caldera to the south and several lava domes.

Cerro Guacha

Cerro Guacha is a Miocene caldera in southwestern Bolivia's Sur Lípez Province. Part of the volcanic system of the Andes, it is considered to be part of the Central Volcanic Zone (CVZ), one of the three volcanic arcs of the Andes, and its associated Altiplano-Puna volcanic complex (APVC). A number of volcanic calderas occur within the latter.

Cerro Chascon-Runtu Jarita is a complex of lava domes located inside, but probably unrelated to, the Pastos Grandes caldera. It is part of the more recent phase of activity of the Altiplano-Puna volcanic complex.

Cerro Panizos

Panizos is a Late Miocene era caldera in the Potosí Department of Bolivia and the Jujuy Province of Argentina. It is part of the Altiplano-Puna volcanic complex of the Central Volcanic Zone in the Andes. 50 volcanoes active in recent times are found in the Central Volcanic Zone, and several major caldera complexes are situated in the area. The caldera is located in a logistically difficult area of the Andes.

Coranzuli is a back-arc caldera in the Andes, related to the Altiplano-Puna volcanic complex.

Kari-Kari is a Miocene caldera in the Potosi department, Bolivia. It is part of the El Fraile ignimbrite field of the Central Volcanic Zone of the Andes. Volcanic activity in the Central Volcanic Zone has generated 44 volcanic centres with postglacial activity and a number of calderas, including the Altiplano-Puna volcanic complex.

Ojos de Maricunga is a volcano in the Maricunga Belt of Chile, in the Cordillera Domeyko.(Muñoz 1894, p. 51)

Pairique volcanic complex is a volcanic complex in the Jujuy Province, Argentina.

Pastos Grandes

Pastos Grandes is the name of a caldera and its crater lake in Bolivia. The caldera is part of the Altiplano-Puna volcanic complex, a large ignimbrite province that is part of the Central Volcanic Zone of the Andes. Pastos Grandes has erupted a number of ignimbrites through its history, some of which exceeded a volume of 1,000 cubic kilometres (240 cu mi). After the ignimbrite phase, the lava domes of the Cerro Chascon-Runtu Jarita complex were erupted close to the caldera and along faults.

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.

Vilama (caldera)

Vilama is a Miocene caldera in Bolivia and Argentina. Straddling the border between the two countries, it is part of the Central Volcanic Zone, one of the four volcanic belts in the Andes. Vilama is remote and forms part of the Altiplano-Puna volcanic complex, a province of large calderas and associated ignimbrites that were active since about 8 million years ago, sometimes in the form of supervolcanoes.

Cerro Tuzgle

Cerro Tuzgle is a dormant stratovolcano in the Susques Department of Jujuy Province in Argentina. Tuzgle is a prominent volcano of the back-arc of the Andes and lies about 280 kilometres (170 mi) east of the main volcanic arc. Part of the Central Volcanic Zone of the Andes, it is 5,486 metres (17,999 ft) high above sea level and was constructed during different stages over a caldera and lava domes. Some major lava flows emanate from the summit crater, and one confirmed and one possible flank collapse unit as well as an ignimbrite sheet are associated with this volcano.

Tocorpuri

Tocorpuri is a volcano in Chile, close to the border with Bolivia. Its peak height is most commonly given as 5,808 metres (19,055 ft) and it features a 1.3 kilometres (0.81 mi) wide summit crater. The volcano consists mainly of lava flows and pyroclastic deposits and is subdivided into two separate edifices. Just west of Tocorpuri, the La Torta lava dome is a 200 metres (660 ft) high flat-topped structure. The volcanoes are formed by andesitic, dacitic and rhyolitic rocks.

References

  1. Barke, Lamb & MacNiocaill 2007, p. 3.
  2. 1 2 Kay, S. M.; Keller, C. B.; Coira, B.; Jiménez, N.; Caffe, P. J. (1 December 2010). "Chemistry of Post 12 Ma Los Frailes Volcanic Complex Ignimbrites in Bolivia and the Role of Magmatism in the Uplift of the Central Andean Altiplano Plateau". AGU Fall Meeting Abstracts. 13: T13D–08. Bibcode:2010AGUFM.T13D..08K.
  3. 1 2 3 4 5 Kato et al. 2014, p. 1.
  4. 1 2 3 4 5 Baker 1981, p. 303.
  5. 1 2 3 Baker 1981, p. 304.
  6. 1 2 Baker 1981, p. 293.
  7. Baker 1981, p. 294.
  8. 1 2 Stern, Charles R. (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.
  9. Baker 1981, p. 295.
  10. Baker 1981, pp. 296, 297.
  11. Baker 1981, p. 298.
  12. 1 2 3 Barke, Lamb & MacNiocaill 2007, p. 4.
  13. 1 2 3 4 Crown et al. 1989, p. 206.
  14. 1 2 3 4 5 6 De Silva & Francis, p. 160.
  15. 1 2 3 Crown et al. 1989, p. 207.
  16. De Silva & Francis, p. 162.
  17. Barke, Lamb & MacNiocaill 2007, p. 2.
  18. Coira, Kay & Viramonte 1993, p. 677.
  19. Baker 1981, p. 313.
  20. Jacobi, Robert D.; Mitchell, Charles. Aseismic ridge subduction as a driver for the Ordovician Taconic orogeny and Utica foreland basin in New England and New York State. p. 648.
  21. Leroy & George-Aniel 1992, p. 270.
  22. Leroy & George-Aniel 1992, p. 257.
  23. Jiménez & López-Velásquez 2008, p. 94.
  24. Coira, Kay & Viramonte 1993, p. 690.
  25. 1 2 3 Leroy & George-Aniel 1992, p. 250.
  26. Coira, Kay & Viramonte 1993, p. 694.
  27. Kato et al. 2014, p. 2.
  28. Coira, Kay & Viramonte 1993, p. 700.
  29. Jiménez & López-Velásquez 2008, p. 95.
  30. Jiménez & López-Velásquez 2008, p. 96.
  31. Jimenez, Nestor (2019). "Eruption of the Nuevo Mundo dacitic domes in the Los Frailes volcanic region (Eastern Bolivian Altiplano) triggered by glacier unloading at the end of the LGM". Geophysical Research Abstracts. 21.

Sources