Sillajhuay

Coordinates: 19°44′32″S 68°41′26″W / 19.74222°S 68.69056°W / -19.74222; -68.69056
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Sillajhuay
Alto Toroni, Sillajguay
Ultra,
Coordinates19°44′32″S 68°41′26″W / 19.74222°S 68.69056°W / -19.74222; -68.69056[3]
Geography
Location
Central Volcanic Zone
Climbing
First ascentpre columbian but first recorded ascent 1926 - Friedrich Adolf Ernest Ahlfeld (Germany)[4]
Sillajhuay seen from ISS

Sillajhuay (also known as Sillajguay or Alto Toroni) is a

mountain massif that is in part covered by ice; whether this ice should be considered a glacier
is debatable but it has been retreating in recent decades.

The volcano has developed on top of older ignimbrites. The volcano was active within the last one million years, but not within recent times considering the heavy glacial erosion of the mountain and the widespread periglacial modifications. Non-eruptive activity however occurs in the form of surface deformation and earthquake activity.

Geography and geomorphology

Sillajhuay is located in the

Tarapaca Region[6]) although only a small easterly sector of the mountain is located in Bolivia.[7][8] The volcano lies in a thinly inhabited region;[9] the towns of Cancosa and Villa Blanca lie 16 kilometres (9.9 mi) southeast and 18 kilometres (11 mi) northeast of Sillajhuay, respectively,[7] and a road runs west of the volcano.[10] The volcano is also known as Alto Toroni,[11] Sillajguay,[3] or sometimes Candelaria.[12] The name "Sillajhuay" means "devil's chair" in Aymara[13] but the part silla may also refer to sila which means llama.[14]

About 50 different volcanoes and geothermal features have been active in the Central Andes during the

Northern Volcanic Zone (NVZ).[20]

The mountain is most commonly stated to be maximally 5,995 metres (19,669 ft) high,

lava flows that reached lengths of about 14–5 kilometres (8.7–3.1 mi)[29] and valleys occur all around it.[8] Farther west lie the Cerros de Quimsachata which form a volcanic chain with Sillajhuay.[10][30][8]

Glaciation

Firn including penitentes occurs on the mountain at elevations of over 5,750 metres (18,860 ft)[31] and is visible over large distances[32] but there are no presently active, moving glaciers[31] unless they are buried beneath a snow cover.[8] Some sources consider Sillajhuay's firn a glacier however, in which case it would be considered to be the southernmost glacier north of the Arid Diagonal of the Andes.[33] Between 1989 and 2011 the firn lost over half of its surface, interrupted by some small advances,[34] and further retreat is likely.[35] Ice loss between 2000 and 2003 amounted to about 0.03 square kilometres (0.012 sq mi).[36]

In the past during the

glacial valleys and various types of moraines.[38] The lowest moraines are found on the eastern flank, with the northern flanks having the highest moraines and the southern flank moraines reaching intermediate elevations.[40] Some ancient tills have been overrun by porphyries.[41] The extent of glacial erosion suggests that at least two stages of glaciation occurred at Sillajhuay.[42]

Some

periglacial processes are common on the southern and northern-northwestern flanks of the massif.[45]

Hydrography

Erosion has cut steep valleys into the massif; these include clockwise the Rio Blanco southeast, Ricon Tacurma south, Quebrada Mina Chucha southwest, Quebrada Seca northwest and Quebrada Quisimachiri north-northwest of the volcano.[1] These valleys reach up to the summit plateau[46] and contain perennial rivers; additional valleys contain ephemeral streams,[47] and they are often linked to alluvial fans down where eroded material has been deposited.[48] Sulfurous springs are active on the massif.[49]

The valleys descending the volcano have steep slopes, the Rio Blanco valley for example has a 1.1 kilometres (0.68 mi) drop over 2 kilometres (1.2 mi).

formation was deposited.[55] Farther west, away from Sillajhuay,[30] drainages conversely descend to the Pampa del Tamarugal.[52]

Geology

The

Austral Volcanic Zone (AVZ) (49°S-55°S).[18][20][57] Between them they contain about 60 active volcanoes and 118 volcanoes which appear to have been active during the Holocene, not including potentially active very large silicic volcanic systems or very small monogenetic ones.[18] These belts of active volcanism occur where the Nazca Plate subducts beneath the South America Plate at a steep angle, while in the volcanically inactive gaps between them the subduction is much shallower;[58] thus there is no asthenosphere between the slab of the subducting plate and the overriding plate in the gaps.[18]

Among the oldest volcanics in the region are

glaciation.[54]

Local

The regional geography is characterized by north–south trending mountain chains which are separated by relatively flat plains covered by

sedimentary and volcanic rocks of Paleozoic to Mesozoic age.[61] Some of these ignimbrites have been identified as the 19.38 million years old Oxaya Ignimbrite, the much younger Ujina Tsu ignimbrite and finally the Pastillos Ignimbrite.[62]

Tectonic stress during the subduction process has led to the development of a

Salar de Coipasa from the Salar de Uyuni and lacks recent volcanic activity.[64] Another isolated volcano Cerro Cariquima rises north of Sillajhuay,[7] the volcanic centres of Churullo northwest and the volcanic chain Pumiri northeast of Sillajhuay form the rest of the neighbouring centres.[65]

The volcano is formed by

Isotope ratios of volcanic rocks indicate a strong crustal influence on the magmas that were erupted at Sillajhuay.[67]

Climate and vegetation

The mountain lies in an

Grasses and shrubs with rare trees form the vegetation,[51] mostly on the eastern flank and sometimes reaching high elevations. Among the plant species that grow in the area are yareta plants.[68]

The dry climate is caused by the South East Pacific High and compounded by the Humboldt Current off the coast, which cools the atmosphere and reduces evaporation. Only during the summer months does convection on the Bolivian Altiplano lead to the arrival of moisture, leading to a predominant summer precipitation. The climate becomes even drier farther south.[69] Cut-off lows can sometimes reach Sillajhuay in winter but are uncommon.[70] In the past, such as 28,000, 8,000 and 3,700 - 1,500 years ago the climate was more humid[71] and this led frequently to glacier advances when it was also cold enough.[72] In return, glaciers on Sillajhuay may have enhanced the moisture supply to other mountains in the area such as Chuquiananta, allowing them to develop glaciers as well.[8]

The strong

freeze-thaw cycles.[51] The warming also leads to the development of mountain breeze and valley breeze, convective clouds as well as occasional landspouts.[74]

Human activity

The summit of Sillajhuay can be climbed and features

Inca ruins on the summit; there are a number of such high altitude ruins in the Andes such as at Llullaillaco. This site was discovered in 2013 by the Scottish mountaineer John Biggar.[12] Mining takes place east of Sillajhuay,[27] including sulfur mines;[75] estimated deposits are 3,200,000 tonnes (3,100,000 long tons; 3,500,000 short tons) of ore with 47% sulfur.[76] The area has also been prospected for the possibility of obtaining geothermal power.[77]The first recorded climb was by Friedrich Adolf Ernest Ahlfeld (Germany) in 1926.[78]

Eruptive history

The whole volcano is considered to be of

potassium-argon dating yielding an age of 890,000 ± 500,000 years ago.[79] Very young activity may have formed some gravel plains in the river valleys, when the heat from the eruption melted the permafrost of the summit region.[80]

However, between 2007 and 2010 a ground uplift of about 6 centimetres (2.4 in) was observed as Sillajhuay over an area 30 kilometres (19 mi) wide. In addition

seismic activity was recorded at the volcano, and hot springs can be observed close to Sillajhuay,[77] including the Pampa Lirima field 25 kilometres (16 mi) southwest of Sillajhuay.[81] These patterns indicate that magma may still exist below the volcano[82] and that it should be classified as a potentially active volcano.[83]

See also

Notes

  1. ALOS 5,966 metres (19,573 ft)[24] and TanDEM-X 6,023 metres (19,760 ft).[25]
  2. parent peak is Sajama and the Topographic isolation is 183.8 kilometres (114.2 mi).[21]

References

  1. ^ a b c d e f Kamp, Bolch & Olsenholler 2002, p. 2.
  2. ^ "Alto Toroni / Sillajguay/ Candelaria". Andes Specialists. Retrieved 2020-04-12.
  3. ^ a b "Cordillera de Sillajhuay". GEOnet Names Server. Retrieved 16 June 2018.
  4. ^ Pietro Meciani. Le Ande. p. 72.
  5. ^ Lobos 2013, p. 77.
  6. ^ Lobos 2013, p. 78.
  7. ^ a b c Schröder & Bolch 2001, p. 8.
  8. ^ a b c d e Jenny & Kammer 1996, p. 47.
  9. ^ a b Schröder, Kröber & Bolch 1998, p. 5.
  10. ^ a b Gardeweg, Moyra P.; Delcorto, Luis A. (October 2015). Glaciares de roca en la Alta Cordillera de Iquique – Región de Tarapacá, Chile (PDF). 14th Chilean Geological Congress. biblioteca.sernageomin (in Spanish). La Serena. p. 726. Archived from the original (PDF) on June 22, 2018. Retrieved 22 June 2018.
  11. doi:10.3112/erdkunde.1999.02.03
    .
  12. ^ a b c Griffin, Lindsay (21 October 2013). "British climber discovers high altitude Inca ruins". British Mountaineering Council. Retrieved 22 June 2018.
  13. ISSN 2411-1236
    .
  14. ^ Uhle, Max (1919). "Fundamentos étnicos de la región de Arica y Tacna" (PDF). Boletin de la Sociedad Ecuatoriana de Estudios Historicos Americans. p. 28. Retrieved 5 March 2019.
  15. ^ Pritchard et al. 2014, p. 90.
  16. ^ Pritchard et al. 2014, p. 92.
  17. doi:10.1016/j.geomorph.2011.10.010
    .
  18. ^
    doi:10.4067/S0716-02082004000200001
    .
  19. ^ Wörner et al. 1988, p. 288.
  20. ^
    S2CID 54181266
    .
  21. ^ a b "Alto Toroni / Sillajguay/ Candelaria". Andes Specialists. Retrieved 12 April 2020.
  22. ^ USGS, EROS Archive. "USGS EROS Archive - Digital Elevation - SRTM Coverage Maps". Retrieved 12 April 2020.
  23. ^ a b "ASTER GDEM Project". ssl.jspacesystems.or.jp. Retrieved 14 April 2020.
  24. ^ "ALOS GDEM Project". Retrieved 14 April 2020.
  25. ^ TanDEM-X, TerraSAR-X. "Copernicus Space Component Data Access". Archived from the original on 12 April 2020. Retrieved 12 April 2020.
  26. ^ "Andean Mountains - All above 5000m". Andes Specialists. Retrieved 12 April 2020.
  27. ^ a b c d Schröder & Bolch 2001, p. 9.
  28. Defense Mapping Agency (1995). "Salinas de Garci-Mendoza Bolivia; Chile"
    (Map). Latin America, Joint Operations Graphic (2 ed.). 1:250000.
  29. ^ a b Selles, Gardeweg & Garibaldi 2018, p. 45.
  30. ^ a b c Schröder, Kröber & Bolch 1998, p. 9.
  31. ^ a b Kamp, Bolch & Olsenholler 2002, p. 53.
  32. ^ Schröder, Kröber & Bolch 1998, p. 39.
  33. ^ Barcaza et al. 2017, p. 174.
  34. ^ Lobos 2013, p. 82.
  35. ^ Lobos 2013, p. 81.
  36. ^ Barcaza et al. 2017, p. 177.
  37. ^ Jenny & Kammer 1996, p. 48.
  38. ^ a b Kamp, Bolch & Olsenholler 2002, p. 54.
  39. ^ Kamp, Bolch & Olsenholler 2002, p. 55.
  40. ISSN 0031-0182
    .
  41. ^ Kamp, Bolch & Olsenholler 2002, p. 56.
  42. ^ Schröder, Kröber & Bolch 1998, p. 15.
  43. ^ a b Kamp, Bolch & Olsenholler 2002, p. 45.
  44. ^ Schröder, Kröber & Bolch 1998, p. 31.
  45. ^ Kamp, Bolch & Olsenholler 2002, pp. 5–6.
  46. ^ Schröder, Kröber & Bolch 1998, p. 41.
  47. ^ Kamp, Bolch & Olsenholler 2002, p. 19.
  48. ^ Kamp, Bolch & Olsenholler 2002, p. 37.
  49. ^ Kamp, Bolch & Olsenholler 2002, p. 39.
  50. ^ Schröder, Kröber & Bolch 1998, p. 10.
  51. ^ a b c d Kamp, Bolch & Olsenholler 2002, p. 3.
  52. ^ a b c Schröder & Bolch 2001, p. 6.
  53. ^ Schröder, Bolch & Kröber 1999, p. 221.
  54. ^ a b Sellés, Gardeweg & Garibaldi 2015, p. 79.
  55. ^ Selles, Gardeweg & Garibaldi 2018, p. 44.
  56. ^ Tassi et al. 2010, p. 1.
  57. ^ Wörner et al. 1988, p. 287,288.
  58. ^ Wörner et al. 1988, p. 289.
  59. ^ Sellés, Gardeweg & Garibaldi 2015, p. 78.
  60. ^ Sellés, Gardeweg & Garibaldi 2015, p. 77.
  61. ^ a b c d Kamp, Bolch & Olsenholler 2002, p. 16.
  62. ^ a b Kamp, Bolch & Olsenholler 2002, p. 66.
  63. ^ a b Schröder & Bolch 2001, p. 16.
  64. ISSN 1941-8264
    .
  65. ISBN 978-956-202-054-1
    .
  66. ISBN 978-0-8137-2265-8
    .
  67. ^ Schröder & Bolch 2001, p. 18.
  68. ^ Kamp, Bolch & Olsenholler 2002, p. 21.
  69. ^ Schröder & Bolch 2001, p. 12.
  70. ^ Schröder, Kröber & Bolch 1998, p. 14.
  71. ^ Kamp, Bolch & Olsenholler 2002, p. 67.
  72. ^ Schröder, Bolch & Kröber 1999, p. 220.
  73. ^ Schröder & Bolch 2001, pp. 13–14.
  74. ^ Kamp, Bolch & Olsenholler 2002, p. 15.
  75. S2CID 128436981
    .
  76. ^ Selles, Gardeweg & Garibaldi 2018, p. 66.
  77. ^ a b c Pritchard et al. 2014, p. 96.
  78. OCLC 7594407
    .
  79. ^ Selles, Gardeweg & Garibaldi 2018, p. 46.
  80. ^ Schröder, Kröber & Bolch 1998, p. 43.
  81. ^ Tassi et al. 2010, p. 2.
  82. ^ Pritchard et al. 2014, p. 102.
  83. hdl:1983/cf804ce1-dcfa-4abf-b2e3-0f267f7feed1
    .

Sources

Further reading
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