Taftan (volcano)

Coordinates: 28°36′00″N 61°07′57″E / 28.60000°N 61.13250°E / 28.60000; 61.13250
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Taftan
Koh-i-Taftan ("Mountain of Taftan"),
Ultra
Coordinates28°36′00″N 61°07′57″E / 28.60000°N 61.13250°E / 28.60000; 61.13250[6]
Naming
English translationThe place of heat[7]
Geography
Location
Last eruption
Uncertain
Shelter on Taftan

Taftan (

Khash
.

Taftan has two main summits, Narkuh and Madehkuh, and various heights have been reported for both summits. The northwestern Narkuh has two

lava flows and has at least three craters. The principal rock at Taftan is andesite
.

Reports of historical volcanic activity are unclear and the youngest radiometric dates are 6,950 ± 20 years before present. Currently, the volcano features vigorous fumarolic activity that is visible from a great distance and involves numerous vents on Materkuh. Taftan appears to be part of a geothermal area; there are a number of hot springs around the volcano.

Taftan is part of a

Arabian Plate beneath Iran at the Makran trench
.

Geography and geology

Taftan in Iran

Taftan is in Iran's

Sistan and Balochistan province. Closest cities are Khash 45 kilometres (28 mi) south and Zahedan c. 100 kilometres (62 mi) north north-west.[8][9] In 1844, Abdul-Nabi reported of the existence of the mountain, as well as its volcanic activity.[10] In 1971, it was reported that some Beluch tribes camp on Taftan's slopes outside of winter.[11]

Regional setting

Volcanic activity has occurred in parts of Iran since the Cretaceous

epochs, volcanic activity reached its maximum, with thick pyroclastic layers being deposited in central Iran and the Alborz mountains.[13] The area around Taftan volcano belongs to a tectonic zone which is variously referred to as the Sistan suture or the Zabul-Baloch zone. There, after a previous episode of rifting and subsequent formation of an ocean, the Neh and Lut tectonic blocks collided during the Eocene epoch after a subduction episode that commenced in the Maastrichtian age.[14]

Volcanic activity at Taftan itself appears to relate to the subduction of the

Arabian Plate beneath the Central Iran Plate,[14] occurring at a pace of 2.5–3.0 centimetres per year (0.98–1.18 in/year)[15] or 3.5–4.2 centimetres per year (1.4–1.7 in/year) at the Makran trench.[16] This subduction is also responsible for volcanism at Bazman in Iran and Koh-i-Sultan in Pakistan;[8][17] this chain is known as the Baluchistan volcanic arc.[8][16] The volcanism appears to not align with pre-existent structural trends in the basement.[13] This subduction has also created an accretionary wedge that forms the Makran region.[18]

The convergence of the two blocks continued even after their collision, generating

strike-slip faults. The Saravan fault east of Taftan is one such fault;[14] the 2013 Saravan earthquake occurred on this fault.[19] From some of these faults it has been inferred that the mass load from the Taftan edifice has measurable effects on tectonic stress within the region.[20]

Local setting

Taftan is the highest mountain in southeast Iran.[7] The topography is overall steep.[21] Deep valleys with U and V shapes have developed on Taftan, and the volcano has a strongly eroded appearance.[17] One of these valleys, Tamindan, may be the Damindan valley in the Avesta religious texts.[22] One series of ignimbrites surrounding Taftan which reaches thicknesses of 50 metres (160 ft) and reaches distances of 15 kilometres (9.3 mi) from the edifice[23] may be 2 million years old.[24]

The basement of Taftan is formed by various

pluton may be associated with Taftan;[29] it could be the remnant of a Miocene volcano.[30] Volcanic rocks of Quaternary age are widespread in the area.[31]

Taftan is a volcano with several summits; the highest two are separated by a saddle and are named Narkuh or Narkooh and Materkuh or Madekooh,[3] which are 2 kilometres (1.2 mi) apart.[32] Narkuh is 4,100 metres (13,500 ft) high and Materkuh 3,950 metres (12,960 ft).[33] There are different heights reported for the summits, some of them placing Materkuh as the higher of the two:[3] for example more recent Iranian maps cited in 2004 show Narkuh with a height of 3,840 metres (12,600 ft) and Materkuh with a height of 3,940 metres (12,930 ft), while Gansser in 1964 indicated a summit height of 4,050 metres (13,290 ft).[8][34] Another report from 1931 claimed a summit height of 3,973 metres (13,034 ft),[35] a report in 1976 stated 4,032 metres (13,228 ft),[36] and a map in 2004 claimed a measurement of 4,061 metres (13,323 ft).[37] These summits rise 2,000 metres (6,600 ft) above the surrounding plains.[14]

Narkuh has two craters, the northern of which is lower and is the source of more lava flows than the southern.

solfataric activity.[3][17] Materkuh has three principal craters,[38] although the eastern side of the eastern crater has also been affected by erosion.[32] Alternatively, an explosive eruption removed the eastern side and generated a steep ravine. The northern crater has been the source of lava flows, some of which are well preserved and reach lengths of 12 kilometres (7.5 mi).[38] In general, thick andesitic lava flows cover Materkuh.[39] In 1893 and 1914, Percy Sykes described a summit plateau with a surface of 370 metres (400 yd), at the side of which lay the two summits Ziaret Kuh ("Hill of Sacrifice", where pilgrims sacrificed goats) and Madar Kuh ("Mother Hill", containing fumaroles according to the 1893 report).[2][5] Fumarolic alteration of the summit area has generated sulfur and clay deposits which resemble snowcap.[34] One report in 1893 indicated that the summit area of the volcano was covered with ash from 3,400 metres (11,000 ft) upwards.[5]

Sistan and Baluchestan province, Iran

The bulk of the volcano is formed by lava flows, along with

nuee ardentes and tuffs.[33] Volcanic rocks cover a surface of 1,050 square kilometres (410 sq mi).[27] There is also evidence of southeastern migration of the craters of Taftan, with Anjerk and Sardarya being more westerly vents.[42][8] These preceding centres have left andesitic lava flows that are partially dissected and agglomerates.[32] The existence of a caldera at Taftan has been inferred.[28] The table mountain Takht-i-Rostam 25 kilometres (16 mi) south of Taftan may be the remnant of a basalt extrusion, but it doesn't appear to be related to Taftan.[43] A magma chamber may lie beneath the volcano.[44]

Composition

Taftan has erupted lavas ranging from basaltic andesite to dacite. The dominant rock is andesite, with SiO
2 content ranging from 49.8 to 63.5%.[45] Grey andesites form the youngest rocks on the main summit and contain chlorite schist and biotite gneiss inclusions.[41] The andesites are vesicular.[10] The magma of Taftan volcano is very oxidized, as can be inferred from the composition of the surrounding ignimbrite and fumarole gases.[46]

The lavas of Taftan are porphyritic. Mineral components include biotite,

calc-alkaline,[47][33] of sub–alkaline affinity.[45] The magma that formed these rocks was influenced by crystal fractionation and mixing processes.[33] Its composition has characteristics of volcanic arc magmas.[48] Crustal materials were involved in the formation of the magma,[17] with strontium isotope data indicating crustal assimilation.[25]

Fumarolic activity affects surrounding rocks and pyroclastics.

epithermal mineralizations have been identified around Taftan.[48] Other secondary factors at Taftan include lahars.[33]

Eruptive history

About five different active eruption periods have been discovered at Taftan volcano.

rhyodacitic composition. Later, upper Pliocene lavas were erupted along with agglomerates. These can be found up to 10 kilometres (6.2 mi) away from the cone.[14] Three phases have been dated at 6.95 ± 0.72, 6.01 ± 0.15 and 0.71 ± 0.03 million years ago;[33] an even older phase west-northwest of the current volcano occurred 8 million years ago,[26] while a Quaternary ignimbrite has produced an age of 404,000 ± 82,000 years before present.[51] The youngest dates have been obtained on lava flows and indicate ages of 6,950 ± 20 years ago, by radiometric dating.[52] Research published in 1897 indicated the absence of very fresh lava flows but the authors inferred from the fresh ash that volcanic activity had occurred during the present geological epoch.[5] That the name "Taftan" may be derived from an ancient Iranian word "taft" for "semi solid liquid material" could indicate that effusive activity was witnessed by the people of that time period around the volcano.[12]

It is not certain that there were any

dormant volcano.[39] Satellite imagery indicates, however, that ground deformation occurs at Taftan.[56][57] Unofficial volcano hazard maps have been developed.[58]

Fumarolic and geothermal activity

Taftan displays vigorous

fumarolic activity, with high temperature vents found around the crater.[46] Fumaroles are found chiefly in the eastern and at the edge of the western crater, with minor fumaroles within the western crater, along some minor craters and along the major lava flow.[38] These gas exhalations are known as "Dood" by local peoples and they appear as yellow-white clouds with a strong smell. The vents they come from have the shape of fissures, cracks and crevices.[3] The larger fumaroles can reach diameters of 1 metre (3 ft 3 in).[41] The occurrence of hydrothermal explosions has been inferred from the presence of breccia made up by volcanic rocks.[28]

Reportedly in 1897 the smell of the fumaroles was so strong as to be unbearable when one was close to the vents.[5] One report mentioned in a magazine of 1899 indicated the presence of seven steam vents at an altitude of 3,700 metres (12,000 ft), produced audible noise. Their steam plumes were visible at distances of 16–24 kilometres (10–15 mi);[1] later reporting indicated visibility to distances of 100 kilometres (62 mi).[11] Another report in 1999 found a 1.5 by 5 metres (4 ft 11 in × 16 ft 5 in) solfatara surrounded by clay and sulfur deposits that looked like a snowcap.[59] A fumarole field was described on the west side of the southeast cone, the venting clearly visible from a refuge farther down the mountain and covering a surface area of c. 10 square metres (110 sq ft).[34] The name "Taftan" is derived from these exhalations, which make the mountain appear to be burning.[3]

The overall gas composition found at Taftan includes CO
2, H
2S, SO
2 and water.[3] Sulfur is present in high quantities in fumarolic gases, which also contain arsenic. These gases are hence extremely acidic.[46] The fumaroles have altered rocks, forming highly colourful exposures especially on Taftan's eastern flank.[41] Ammonium chloride (salmiak) and sulfur has been collected around fumaroles.[1] The thick sulfur layers on the southeastern summit were formerly extracted for use in Iran and Pakistan. Sulfur and sulfate deposits are also found lower on the volcano, from hot springs around Gooshe, at Sangān and Torshāb.[3]

Hot springs are also found at Taftan, especially at over 3,000 metres (9,800 ft) altitude.

Mud pools are also found at Taftan.[68] Probably due to decreased precipitation, before 2002 a trend to increased steam and decreased water release has been observed, especially in the upper part of the geothermal system.[69]

Hot springs and other geothermal manifestations are widespread in Iran and using them to gain geothermal energy has been studied; according to a report of 2002 hot springs at that time were mainly used for therapeutic purposes and bathing.[31] A report in 2002 indicated that Taftan may be a feasible place to install a binary cycle power plant.[70]

Climate and vegetation

The climate at Taftan features cold winters accompanied by

arid locale but has more precipitation than the surrounding area, thus providing water to the surrounding terrain.[63] Average precipitation is 150 millimetres (5.9 in) per year.[21]

Owing to the height of the mountain, there are distinct vegetation belts at Taftan. The lowlands around the mountain are covered with Artemisia steppe and occasional shrubland. Open scrubs occur in a higher altitude belt of 1,800–2,500 metres (5,900–8,200 ft) where the terrain is rocky, and thorn-cushion vegetation at elevations of 2,600–3,700 metres (8,500–12,100 ft); there is little vegetation in the summit area.[71] The summit of Taftan and several other Iranian volcanoes were deemed national natural monuments in 2002.[72]

South view panorama in winter

See also

References

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  6. ^ a b c "Iran - 54 Mountain Summits with Prominence of 1,500 meters or greater". Peaklist.org. Retrieved 2013-02-10.
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  8. ^ a b c d e Richards et al. 2018, p.3
  9. ^ a b c d Biabangard, H.A.; Moradian, Abas (2009). "VOLCANOSTRATIGHRAPHY AND DIFFERENT STAGES OF EXPLOSIVE OF TAFTAN VOLCANO". Geosciences. 18 (72): 73–82. Retrieved 13 July 2016.
  10. ^ a b c Reclus, Elisée (1906). Les volcans de la terre (in French). Société belge d 'astronomie, de météorologie et de physique du globe. pp. 23–24. Retrieved 2 August 2016.
  11. ^ a b Gansser, 1971, p.320
  12. ^ a b Gansser, 1971, p.321
  13. ^ a b Gansser, 1971, p.322
  14. ^ a b c d e f Sadeghi et al., 2015, p.2
  15. ^ Richards et al. 2018, p.5
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  20. ^ Sadeghi et al., 2015, p.5
  21. ^ a b c Shakeri et al., 2015, p.50
  22. ^ Skrine, 1931, p.322
  23. ^ Richards et al. 2018, p.7
  24. ^ Saadat, S.; Karimpour, M.H.; Stern, Ch. (2010). "Petrochemical Characteristics of Neogene and Quaternary Alkali Olivine Basalts from the Western Margin of the Lut Block, Eastern Iran" (PDF). Iranian Journal of Earth Sciences. 2: 89. Retrieved 13 July 2016.
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  26. ^ a b c Richards et al. 2018, p.6
  27. ^ a b Gansser, 1971, p.324
  28. ^ a b c d Ghazban, 2002, p.810
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  38. ^ a b c Gansser, 1971, p.326
  39. ^ a b Biabangard and Moradian, 2008, p.357
  40. ^ Ghazban, 2004, p.45
  41. ^ a b c d Gansser, 1971, p.328
  42. ^ Biabangard and Moradian, 2008, p.368. Note, the map clearly indicates southeastward migration.
  43. ^ a b Gansser, 1971, p.329
  44. ^ a b Shakeri et al., 2008, p.835
  45. ^ a b Biabangard and Moradian, 2008, p.360
  46. ^ a b c d e f Mokhtari, Zahra; Ahmadi, Ali. "INVESTIGATION OF CHEMICAL COMPOSITION OF GAS EXHALATION AND POST VOLCANIC ACTIVITIES OF TAFTAN VOLCANO, SE IRAN". ResearchGate. Geochemistry. Retrieved 13 July 2016.
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  51. ^ Richards et al. 2018, p.11
  52. ^ Khaiatzadeh, Abbasnejad, Ranjbar 2016, p.7
  53. ^ a b "Taftan". Global Volcanism Program. Smithsonian Institution.
  54. ^ Rezaeinahal, Bahar; Zare, Mehdi; Ghorashi, Manoochehr; Nozaiiem, Reza (2014). "REVIEW THE SEISMIC ACTIVITY AND THE SIGNS INDICATE THE VOLCANIC ACTIVITY IN TAFTAN VOLCANIC REGION". Geography and Development. 11 (33): 131–138. Retrieved 13 July 2016.
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  63. ^ a b Biabangard, H.; Moradian, A.; Bavali, Y. (2009). "STUDY OF THE HYDROGEOCHEMISTRY OF TAFTAN VOLCANO'S MINERAL SPRINGS AND THEIR RELATION TO HARD-ROCK MASSES OF REGION". Geosciences. 19 (73): 99–108. Retrieved 13 July 2016.
  64. ^ Shakeri et al., 2008, p.834
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  67. ^ Yousefi, Hossein; Ehara, Sachio; Noorollahi, Younes (January 2007). "GEOTHERMAL POTENTIAL SITE SELECTION USING GIS IN IRAN" (PDF). pangea.stanford.edu. Thirty-Second Workshop on Geothermal Reservoir Engineering. Retrieved 13 July 2016.
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