Apacheta-Aguilucho volcanic complex

Edit links
Coordinates: 21°50′S 68°10′W / 21.833°S 68.167°W / -21.833; -68.167
This is a good article. Click here for more information.
Source: Wikipedia, the free encyclopedia.

Apacheta-Aguilucho volcanic complex
Highest point
Elevation5,557 m (18,232 ft)[1]
Coordinates21°50′S 68°10′W / 21.833°S 68.167°W / -21.833; -68.167[1]
Geography
Apacheta-Aguilucho volcanic complex is located in Chile
Apacheta-Aguilucho volcanic complex
Apacheta-Aguilucho volcanic complex

Apacheta-Aguilucho volcanic complex (also known as Cerro Pabellón

lava flows and surrounded by outcrops of lava. A sector collapse and its landslide deposit are located on Apacheta's eastern flank. Two lava domes
are associated with the volcanic complex, Chac-Inca and Pabellón.

The volcanic complex was active from the

fumarolic activity has been observed and a geothermal system is present. A geothermal power
plant was being built in 2015 and became active in late 2017, with another unit coming into service in 2022. It is the first geothermal power plant in Chile.

Geography and geomorphology

The Apacheta-Aguilucho volcanic complex lies in northern Chile, close to the border with

arid climate.[5] Vegetation, if present, consists mainly of grasses and shrubs.[6]

The volcanic complex is part of the

South America Plate.[10] Aside from volcanic activity, crustal shortening has resulted in a thickened crust since about 35 million years ago.[8]

The volcanic complex

Apacheta-Aguilucho is a volcanic complex formed by two volcanoes,

dacitic lavas. An andesitic lahar and pyroclastic flow crops out south and east of Apacheta,[12] which as the oldest part of the edifice is heavily eroded.[3] North and east of the complex, the two lava domes Chac-Inca and Cerro Pabellón[12] (also known as Apacheta or Pabellóncito[13]) form the youngest part of the volcanic complex.[3]

last glacial maximum.[15]

Geothermal manifestations

The volcanic complex as seen from Bolivia.

Apacheta volcano is

mud pools and vents.[19]

Apacheta-Aguilucho has a geothermal system and the chemistry of fumarole gases suggests that Apacheta-Aguilucho features an active

hydrothermal alteration of many parts of the volcanic complex;[1] this activity has generated a sulfur deposit on the west flank of Aguilucho.[11] The mine Mina Aguilucho is located on Aguilucho's western flank.[16]

The Pabellón geothermal system was discovered in 1999,

drill holes presumably seal the geothermal system.[26] The water remains in the system for a long time and undergoes prolonged interaction with the country rock.[21] The source of heat is unclear; the last eruptions of Apacheta-Aguilucho are too long ago and the more recent lava domes are unlikely to be associated with significant heat reserves.[27] Another geothermal area is found in the Cordón de Inacaliri range southeast from Apacheta-Aguilucho.[28]

Sector collapse

A landslide deposit extends 4.5 kilometres (2.8 mi) away from the volcanic complex on its eastern flank. The landslide deposit covers a surface of about 3 square kilometres (1.2 sq mi),

hydrothermally altered material. The landslide deposit is confined between two older lava flows.[1]

Sector collapses like the one at the Apacheta-Aguilucho volcanic complex have been observed on other volcanoes (such as

Mount St Helens during its 1980 eruption), and they result in characteristic landslide deposits known as debris avalanche deposits; these feature hummock-like hills and often levees. Such collapses occur for different reasons for each event and are fairly common; in the Central Andes alone 14 volcanoes feature deposits of such collapses.[32] Such deposits commonly feature a stratigraphy that resembles that of the source edifice, as well as jigsaw-like cracks in rocks that form when rocks disintegrate during the collapse and sliding.[33]

In the case of Apacheta-Aguilucho, it is likely that the sector collapse was triggered by hydrothermal alteration of the edifice that weakened its structure until it failed, and its path was likely influenced by regional tectonics.[34] After the edifice had failed, the landslide moved eastward until it was deflected by older topography; the material became increasingly fragmented.[35]

Geology

Off the west coast of South America, the

Peru-Chile Trench. This subduction process is responsible for volcanism in the Central Andes, which occurs at distances of 250–300 kilometres (160–190 mi) from the trench.[1] There are about 200 volcanoes, including a dozen giant calderas.[9]

Two major fault systems are found close to Apacheta-Aguilucho. The first is the major regional Calama-Olacapato-El Toro fault, the second fault system runs from neighbouring Inacaliri volcano northwest of Apacheta-Aguilucho towards the southeast, where it forms the Pabellóncito graben;[1] the volcanic complex is built within that graben[4] and the eruption of Pabellón was influenced by the graben faults, which allowed magma to reach the surface. The Pabellóncito fault system was active during the Pliocene[23] until present-day, with seismic activity recorded in 2017 and 2020.[36] The activity of these regional fault systems appears to be a consequence of tectonic regime changes during the early Pleistocene, which drove extensional tectonics in the area,[15] or of gravitational spreading of the crust under the weight of volcanoes in the area.[37] Northwest of Apacheta-Aguilucho, the axis of the graben is buried beneath other volcanoes starting with Cerro del Azufre[38] which form a northwest–southeast alignment[22] known as Inacaliri lineament.[39]

The basement beneath Apacheta-Aguilucho is of Eocene to Miocene age. It consists of various volcanic and sedimentary formations[38][1] including eroded volcanoes,[4] and it is in part covered by 7.5 million years old ignimbrites.[1]

Composition

Apacheta-Aguilucho has principally erupted

hydrothermally altered rocks on the eastern flank[23] and in the summit fumarole field. At the fumarole field, minerals like chlorite, gypsum, halloysite, hematite, mica and quartz formed through supergene and acid leaching processes.[19] The magmas appear to derive from the Altiplano-Puna magmatic complex volcanic body and underwent fractional crystallization and other geochemical processes before erupting.[41]

Eruption history

The volcanic complex is of Pliocene to Pleistocene age[11] and developed over several different stages. In the first stage, the so-called Aguilucho ignimbrite consisting of moderately welded, white-to-pink pyroclastic flows was emplaced 7.5 ± 0.6 million years ago and andesitic lava flows 6.7 ± 0.3 million years ago. Subsequently, more lava flows were emplaced, consisting of blocky dacite.[17]

The Apacheta and Aguilucho volcanoes were constructed consecutively. Apacheta consists of lava flows and pyroclastic material made out of andesite, and its crater is covered by pyroclastic flows and a 2.5 kilometres (1.6 mi) long rhyolitic lava flow. Aguilucho is constructed by lava flows. Finally, several lava flow fields were emplaced together with the lava domes Pabellón and Chac-Inca.[17] 1,204,000 ± 33,000 years ago an ignimbrite named Aguilucho ignimbrite was erupted[42] from the Apacheta volcano.[8]

Apacheta grew between about 1.024 and 0.9 million years ago and Aguilucho between 0.7 and 0.6 million years ago.

Lava flows on Apacheta-Aguilucho have been dated to 910,000 ± 140,000 and 700,000 ± 200,000 years before present,[1] with one lava flow being dated to 652,000 ± 12,000 years ago.[42] The date of the sector collapse is not known with certainty but was probably after the last lava flow was emplaced on Apacheta-Aguilucho.[34]

Dating of Chac-Inca has produced an age of 140,000 ± 80,000 years before present. Different dates have been obtained on Cerro Pabellón:

argon-argon dating has yielded an age of 50,000 ± 10,000 years before present.[17] After the cessation of volcanic activity at Apacheta-Aguilucho, it appears to have migrated to the neighbouring Azufre volcano.[43] Future eruptions may consist of small explosions with local impact, of perhaps phreatic nature.[39] A local subsidence of the ground began in 2017 and ended in 2020 appears to be related to the beginning geothermal power extraction.[44]

Geothermal power production

The discovery of steam during the drilling of a freshwater well in the 1990s led to investigations by

CODELCO obtained the permission to explore the area, but while a geothermal system was discovered political questions about ENAP's involvement derailed the project.[3]

Another joint enterprise this time including the Italian

MW each started, to be completed in 2017–2018.[45] The plant on Pampa Apacheta[23] 3.5 kilometres (2.2 mi) east of Apacheta-Aguilucho[5] was inaugurated by the Chilean president Michelle Bachelet on 12 September 2017, becoming the first[a] geothermal power station in South America[47] and as of 2021 the only operating one.[48] Situated at an elevation of over 4,500 metres (14,800 ft), it is the highest large-scale geothermal plant in the world.[49]

The Cerro Pabellón project is expected to produce 340

Gigawatt-hours per year, enough to cover the electricity consumption of 165,000 families.[50] The plant is expected to reduce Chile's carbon dioxide emissions by about 166,000,000 kilograms per year (166,000 t/a)[2] and is owned by the companies Geotérmica del Norte S.A.(GDN) and Empresa Nacional de Geotermia; the latter is a joint venture between ENAP and ENEL.[5] A further expansion began in 2019[49] and was completed in 2022, aiming at increasing output by about 33 MW[9] to 81 MW.[49] The plant uses hydrogen for energy storage.[51]

Notes

  1. ^ An earlier pilot plant operated in Copahue between 1988 and 1997.[46][10]

See also

References

  1. ^ a b c d e f g h i j k l m Godoy et al. 2017, p. 137.
  2. ^ a b c Morata et al. 2020, p. 1.
  3. ^ a b c d e f Bona & Coviello 2016, p. 51.
  4. ^ a b c d e f Mercado et al. 2009, p. 1.
  5. ^ a b c d Taussi et al. 2019, p. 2.
  6. ^ Taussi et al. 2019, p. 7.
  7. ^ a b Taussi et al. 2019, p. 179.
  8. ^ a b c Taussi et al. 2019, p. 181.
  9. ^ a b c Lobos Lillo et al. 2023, p. 2.
  10. ^ a b c Maza et al. 2018, p. 4.
  11. ^ a b c Urzua et al. 2002, p. 1.
  12. ^ a b c Godoy et al. 2017, p. 138.
  13. ^
    S2CID 133979654
    .
  14. ^ a b Godoy et al. 2017, p. 141.
  15. ^ a b Mercado et al. 2009, p. 3.
  16. ^ a b c Urzua et al. 2002, p. 4.
  17. ^ a b c d Mercado et al. 2009, p. 2.
  18. ^ Maza et al. 2018, p. 6.
  19. ^ a b c Morata et al. 2020, p. 4.
  20. ^ Maza et al. 2021, p. 5.
  21. ^ a b Godoy et al. 2022, p. 2.
  22. ^ a b Morata et al. 2020, p. 2.
  23. ^ a b c d Morata et al. 2020, p. 3.
  24. ^ Taussi et al. 2019, p. 9.
  25. ^ Taussi et al. 2019, p. 3.
  26. ^ Morata et al. 2020, p. 6.
  27. ^ Taussi et al. 2019, p. 12.
  28. ^ Taussi et al. 2021, p. 2.
  29. ^ Godoy et al. 2017, p. 140.
  30. ^ Godoy et al. 2017, p. 139.
  31. ^ Godoy et al. 2017, p. 138,139.
  32. ^ Godoy et al. 2017, p. 136.
  33. ^ Godoy et al. 2017, p. 142.
  34. ^ a b Godoy et al. 2017, p. 144.
  35. ^ Godoy et al. 2017, p. 145.
  36. ^ Lobos Lillo et al. 2023, p. 6.
  37. ^ Taussi et al. 2021, p. 4.
  38. ^ a b Urzua et al. 2002, p. 3.
  39. ^
    ISSN 0717-7305. Archived from the original
    (PDF) on June 29, 2021. Retrieved 20 August 2021.
  40. ^ Taussi et al. 2019, p. 186.
  41. ^ Taussi et al. 2019, p. 195.
  42. ^ a b Taussi et al. 2019, p. 180.
  43. ^ Godoy et al. 2022, p. 17.
  44. ^ Lobos Lillo et al. 2023, p. 9.
  45. ^ Bona & Coviello 2016, p. 52.
  46. ^ Bona & Coviello 2016, p. 30.
  47. ^ "Cerro Pabellón, la planta geotérmica chilena pionera en Sudamérica y a mayor altura del mundo" (in Spanish). Santiago: Emol. 17 September 2017. Retrieved 13 December 2017.
  48. ^ Maza et al. 2021, p. 1.
  49. ^
    S2CID 224860830
    .
  50. ISBN 9789567052479 – via ResearchGate
    .
  51. ISBN 9780323886680
    .

Sources

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=Apacheta-Aguilucho_volcanic_complex&oldid=1214107357"