Kunlun Volcanic Group

Coordinates: 35°46′15″N 81°37′18″E / 35.77083°N 81.62167°E / 35.77083; 81.62167
Source: Wikipedia, the free encyclopedia.

Kunlun Volcanic Group
Kunlun Volcanic Group is located in China
Kunlun Volcanic Group
Kunlun Volcanic Group
Highest point
Pyroclastic cones
Last eruptionMay 1951

Kunlun Volcanic Group (Chinese: 昆仑火山群), also known as Ashikule Volcanic Field, is a volcanic field in northwestern Tibet. Eight other volcanic fields are also in the area. The field is within a basin that also contains three lakes.

Volcanism in the field has produced lavas and cones, with rocks having varying compositions dominated by trachyandesite. Volcanism in the field may be influenced by faults in the area.

The dates obtained from the field range from 5.0 ± 0.6 million years ago to 74,000 ± 4,000 years ago. An eruption of Ashi volcano was observed in 1951, making this one of China's youngest volcanoes.

Geological context

The

Asian Plate and the northward one of the Indian Plate have been found.[5] Mélange from these subducting plates forms the source material of the magmas of the volcanic fields in northwestern Tibet,[6] although isotope data suggest that the Ashikule magma may not derive from subduction.[7] Magma generation in Ashikule could have been affected by garnet or garnet-containing crustal layers.[8] More generally, the crust beneath northern and central Tibet is suspected to be partially molten between 55–60 kilometres (34–37 mi) of depth.[4]

Rocks younger than 350,000 years have been found in the Tengchong system in the southeast and the Ashikule plateau in the northwestern part of Tibet.[9] These are also the only volcanic systems with Holocene activity in Tibet.[10] The volcanic areas of northwestern Tibet for the most part are situated at over 4,500 metres (14,800 ft) altitude and are poorly accessible.[3]

The Ashikule volcanic field is one among nine in northwestern Tibet, other volcanic fields are

seismic velocity anomaly in southern Tarim may be associated with the volcanism at Ashikule,[13] and a seismically imaged gap between the Tarim block and the Indian Plate below the crust may be a pathway for mantle upwelling that feeds the Ashikule volcanoes.[14][15]

Geography

The Ashikule volcanic field is located in the

strike slip faults in the area could be involved too, whereas subduction of the Tarim Basin beneath the Kunlun is unlikely.[20] The Altyn Tagh fault crosses the field in east-northeast to south-southwest direction,[14] and several other fault zones such as the Kangxiwa fault pass north of the basin; they are involved in the genesis of the Ashikule basin.[21]

Geomorphology

There are 11

Spatter cones and volcanoes of Quaternary age are in the Ashikule area,[7] for a total amount of over 70 cones.[23] Over 20 volcanoes have been found in the eastern part of the field, they reach heights of several 100 metres (330 ft).[24] It features perfectly preserved cinder cones.[25] Silicic lava domes are also found.[4] The Ashikule basin is covered by 250 square kilometres (97 sq mi)[18]-200 square kilometres (77 sq mi) of lava from this field.[17] Various kinds of rock coatings have developed on these lavas, some of biogenic origin.[26] The entire field covers a surface of about 4,820 square kilometres (1,860 sq mi).[22]

Xi Shan is the westernmost volcano with a diameter of 500 metres (1,600 ft) and a height of 25–30 metres (82–98 ft)[19] With a summit height of 5,104.6 metres (16,747 ft) and a height of 400 metres (1,300 ft) above base, Dahei Shan volcano is the highest volcano at Ashikule and features a V-shaped crater.[27] 80 metres (260 ft) high Wuluke cone north of Wukule lake features a crater lake[28] and has sent out many lava flows, some of which entered Wuluke lake.[18] Migong Shan is east of Wuluke volcano. Yueya Shan has a 60 metres (200 ft) high secondary cone within its 300 metres (980 ft) wide crater; Maoniu Shan volcano is located nearby and they are surrounded by even smaller centres. Heilong Shan is a long volcanic ridge on the terraces of the Akesu River and to the east of it is the horseshoe-shaped Mati Shan and the 7–8 metres (23–26 ft) high Dong Shan.[29] Other volcanoes are known as Binhushan, Gaotaishan, Yinshan and Yizishan.[30]

The

Lava flows from Ashi extend both north and south and cover a surface area of 33 square kilometres (13 sq mi), reaching as far as lake Ashikule.[32]

There are three

Playas of the same name are found in the area and are a source of mineral dust.[36] The basin is in the area of the upper Keriya River.[23]

Composition

The field is dominated by trachyandesite and

orthopyroxene and phlogopite.[38] Xenoliths of gneiss are found in the rocks of Ashi volcano.[27]

Ashikule and Tengchong have high ratios of

ultramafic rocks.[42] The magma of Ashi volcano formed by the mixing of trachyandesitic magma with a more silicic component.[43]

The conditions in the magma chamber of Ashi volcano have been estimated. There are two populations of rocks, one formed at temperatures of 1,135–1,176 °C (2,075–2,149 °F) at a depth of 18–25 kilometres (11–16 mi), the other at temperatures of 1,104–1,143 °C (2,019–2,089 °F) at a depth of 13–18 kilometres (8.1–11.2 mi).[44]

Climate

The Ashikule basin is one of the driest areas of Tibet.[36]

Discrepancies between dates obtained by

potassium-argon dating on some rocks have been interpreted as being due to lava flows being covered by snow and ice in the past. From this it has been inferred that the Ashikule field was covered by glaciers during the Last Glacial Maximum, when temperatures decreased by 6–9 °C (11–16 °F).[45]

Geochronology

Some ages are 5.0 ± 0.6 and 2.7 ± 1.8 million years ago and were obtained by

argon-argon dating.[46] Xi Shan volcano formed 2.8 million years ago. Mati Shan and a volcanic episode 120 kilometres (75 mi) north of Ashikule occurred 1.63-1.21 million years ago. Most volcanoes formed 670,000 - 500,000 years ago, two other minor episodes occurred 440,000 - 280,000 and 200,000 - 120,000 years ago.[29] Gaotaishan volcano is one million years and Binhushan volcano 370,000 years old.[17] A burst of volcanic activity took place 270,000 years ago, forming several volcanoes,[18] and Ashi and Wuluke cone erupted around 113,000 years ago.[47] Most of the lava flows around Ashi were erupted 66,000 years ago.[18] Sediments underlying volcanic rocks have ages of 9,700-6,700 years, indicating that eruptions took place during the Holocene.[48]

The latest eruption was on 27 May 1951,[24] at Ashi volcano as was reported by the newspaper Xinjiang Daily.[17] The report claimed that soldiers building a road heard roaring and saw a column of smoke, which continued for several days.[19] A volcanic ash layer from this eruption has been found in the Changce Ice Cap,[49] whereas the occurrence of lava flows at that time is unclear[18] and no rocks in the field itself have been conclusively linked to the eruption.[50]

Another unconfirmed report claims an eruption took place in the 19th century.

Fumarolic activity has been observed in the northern side of the crater of Ashi volcano.[32] It is one of the few active volcanic regions in China.[17]

The magnitude 7.2 2008 Yutian earthquake took place 30 kilometres (19 mi) south of the volcanic field, at the intersection of two major faults, the Karakax fault and the Altyn-Tagh fault.[52] Other earthquakes occurred in 2012 and 2014.[53] Volcanic activity may also be related to the Longmu-Gozha fault system;[54] conversely some volcanic landforms have been deformed by faulting.[55]

References

  1. ^ a b c d "Kunlun Volcanic Group". Global Volcanism Program. Smithsonian Institution.
  2. ^ a b Yu et al. 2014, p. 530.
  3. ^ a b Guo et al. 2014, p. 184.
  4. ^ a b c d Cooper et al. 2002, p. 2.
  5. ^ Guo et al. 2014, p. 185.
  6. ^ Guo et al. 2014, p. 193.
  7. ^ a b c d Furuya & Yasuda 2011, p. 126.
  8. ^ Jiandong 2014, p. 594.
  9. doi:10.1016/j.lithos.2010.05.001
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  10. ^ Zou et al. 2014, p. 132.
  11. ^ Guo et al. 2014, pp. 185–186.
  12. doi:10.1016/j.earscirev.2003.08.001
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  13. doi:10.1002/cjg2.234
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  14. ^ a b Wei et al. 2017, p. 176.
  15. S2CID 210625629
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  16. S2CID 129824878
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  17. ^ a b c d e Yu et al. 2014, p. 531.
  18. ^ a b c d e f g Zou, Vazquez & Fan 2020, p. 3.
  19. ^ a b c d e f Liu & Maimaiti 1989, p. 187.
  20. ^ Cooper et al. 2002, pp. 15–16.
  21. ^ Yu et al. 2020, p. 2.
  22. ^
    ISSN 0012-8252
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  23. ^
    ISBN 978-90-6764-265-1
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  24. ^
    doi:10.1029/2002JB001877
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  25. doi:10.1016/j.jseaes.2007.06.003
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  26. ISBN 978-1-4020-5719-9
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  27. ^ a b c Liu & Maimaiti 1989, p. 188.
  28. ^ Liu & Maimaiti 1989, pp. 188–189.
  29. ^ a b Liu & Maimaiti 1989, p. 189.
  30. ^ Yu et al. 2020, p. 3.
  31. ^ Krinsley, Dorn & DiGregorio 2009, pp. 552–53.
  32. ^ a b c Yu et al. 2014, p. 532.
  33. ^ Krinsley, Dorn & DiGregorio 2009, p. 553.
  34. ISBN 978-94-011-5458-1
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  35. S2CID 195306306
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  36. ^ a b Krinsley, Dorn & DiGregorio 2009, p. 552.
  37. S2CID 130129698
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  38. ^ Jiandong 2014, p. 556.
  39. ^ Zou et al. 2014, p. 138.
  40. ^ Zou et al. 2014, p. 137.
  41. ^ Cooper et al. 2002, p. 14.
  42. ^ Cooper et al. 2002, p. 15.
  43. ^ Yu et al. 2014, p. 539.
  44. ^ Yu et al. 2014, p. 538.
  45. Bibcode:2003AGUFMPP32B0284K
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  46. ^ Jiandong 2014, p. 558.
  47. ^ Zou, Vazquez & Fan 2020, p. 7.
  48. S2CID 234432724
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  49. ISBN 978-3-642-75112-7
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  50. ^ Xu et al. 2021, p. 2.
  51. S2CID 230539539
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  52. ^ Furuya & Yasuda 2011, p. 125.
  53. ^ Wei et al. 2017, p. 177.
  54. doi:10.1016/j.gr.2015.03.008
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  55. ^ Xu et al. 2021, p. 3.

Sources

External links
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