Toussidé

Coordinates: 21°02′N 16°27′E / 21.03°N 16.45°E / 21.03; 16.45
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Toussidé
Ultra
Coordinates21°02′N 16°27′E / 21.03°N 16.45°E / 21.03; 16.45[1]
Geography
LocationTibesti Region, Chad
Parent rangeTibesti Mountains
Geology
Mountain typeStratovolcano
Last eruptionunknown

Toussidé (also known as Tarso Toussidé) is a potentially active stratovolcano in Chad. Toussidé lies in the Tibesti Mountains, the large Yirrigué caldera and the smaller Trou au Natron and Doon Kidimi craters are close to it. It has an elevation of 3,265 m (10,712 ft) above sea level. The volcano is the source of a number of lava flows, which have flowed westward away from Toussidé and east into the Yirrigué caldera.

Trou au Natron, the depression southeast of the volcano, measures approximately 8 by 6 kilometres (5.0 mi × 3.7 mi) in diameter and 700–1,000 metres (2,300–3,300 ft) in depth. During the last glacial maximum or the early-middle Holocene, it was filled with a lake. A number of volcanic cones have developed within Trou au Natron. Fumarolic activity on the peak of Toussidé and geothermal manifestations within Trou au Natron represent signs of volcanic activity at Toussidé.

Names

Toussidé is also known as Tarso Toussidé.[1] Another transliteration is "Tusside".[2] "Trou au Natron" refers to the springs which have deposited white trona in the caldera.[3] "Toussidé" translates as "Which killed the local people (Tou) with fire".[4][5]

Geography and geomorphology

Regional

Toussidé is part of the western

Zouar lie east-northeast and south of Toussidé, respectively,[3] and a road between the two passes just southeast from Trou au Natron.[9]

Another volcano in Tibesti is Emi Koussi,[3] which is the highest mountain of the Tibesti and of the entire Sahara region.[6] The volcano Tarso Toh lies northwest of Toussidé,[10] the Botoum and Botoudoma/Petit Botoum rhyolite extrusions are located 10 kilometres (6.2 mi) south of Trou au Natron.[11] The origin of volcanism in Tibesti is unclear; both a hotspot-related mechanism and tectonic effects of the collision between the African Plate and the Eurasian Plate have been proposed.[12]

Local

Toussidé is a symmetrical

parasitic vents.[24]

Toussidé itself lies in part within an even larger caldera, the 14-by-13-kilometre (8.7 mi × 8.1 mi) "pre-Toussidé" (also known as "Yirrigué"[25]) caldera which is in part filled by the lava flows from Toussidé and eruption products from the more recent explosion craters,[26] as well as debris that fell from the steep caldera margin.[27] Toussidé is located on the caldera's western side,[1] and the smaller Trou au Natron caldera cuts into the flanks of Yirrigué.[28] Yirrigué contains a small cinder cone and an associated 1 kilometre (0.62 mi) long lava flow,[29] as well as an alluvial plain.[27] The "Yirrigué" caldera is part of a large rhyolitic shield-shaped volcano[30] that developed on top of a tectonic horst, which in turn may have been formed by intrusion of magmas.[31] The ignimbrites have buried older terrain and filled valleys.[20]

See also: Trou au Natron

Southeast of Toussidé lies the 8-by-6-kilometre (5.0 mi × 3.7 mi) wide

ring fault of the "pre-Toussidé" caldera.[21] A salty swamp lies within Trou au Natron,[35] whose floor is in part covered by evaporites,[20] mainly sodium sulfate.[36]

Another 1,500-metre (4,900 ft) wide and 300-metre (980 ft) deep crater, Doon Kidimi (also known as Petit Trou[21] or Doon Kinimi[32]), lies northeast of Trou au Natron;[16][19] it is among the most pristine volcanic features in the region.[35] Additional volcanoes in the neighbourhood are the 3,040-metre (9,970 ft) high Ehi Timi northeast and the 2,515-metre (8,251 ft) high Ehi Sosso/Ehi Soso east of Toussidé,[9][1] the former of which features lava domes. The river Enneri Oudingueur originates closely in the area and becomes a tributary of the Enneri Bardagué,[20] which drains the Tibesti northward.[37]

  • Trou au Natron (centre down) and Doon Kidimi (upper right corner)
    Trou au Natron (centre down) and Doon Kidimi (upper right corner)
  • Trou au Natron seen from northeast; Toussidé lava flows upper right corner and Doon Kidimi lower right corner
    Trou au Natron seen from northeast; Toussidé lava flows upper right corner and Doon Kidimi lower right corner

Paleolake

Trou Au Natron was once filled by a

stromatoliths lived in the lake.[41] Ferns and mosses colonized the margins of the crater.[40]

The lake reached maximum depths of at a minimum 300–350 metres (980–1,150 ft),

subtropical jet stream.[39]

Geology

The Tibesti mountains are part of a volcanic province that reaches from Libya into Chad and covers a total surface area of about 100,000 square kilometres (39,000 sq mi).[45] The Tibesti Mountains have been volcanically active since the late Cenozoic, with one old volcanic unit being dated to 17 million years ago.[7] While all the higher peaks are volcanoes, not all of Tibesti is formed by volcanic material; the volcanoes have developed on top of a basement uplift.[45]

The terrain beneath Toussidé is formed by Precambrian schists and sandstones, including the Nubian Sandstone. A thick layer of ash has covered much of the terrain and with the exception of the younger volcanoes only few parts of the terrain crop out.[46] Several of these outcrops can be found east of Trou au Natron.[47] The volcanism of the Tibesti has been subdivided into several series.[48]

The volcano has erupted rhyolite,

peralkaline rhyolite,[30] while Ehi Timi erupted rhyolite and trachyte and Ehi Sosso only rhyolite.[20] The formation of Trou au Natron has been accompanied by the eruption of bedrock material.[35]

Climate and vegetation

Annual temperatures at Trou au Natron fluctuate between 27 – −8 °C (81–18 °F), with a daily temperature variation of 8.8 °C (15.8 °F); this is less than in the lowlands.[49] At higher altitudes frost can be expected.[47] Precipitation amounts to 93.3 millimetres per year (3.67 in/year) at Trou au Natron. Most of it falls as frontal precipitation during summer,[50] and it is more copious than in the lowlands; the Tibesti mountains are the sources for wadis.[47] Other, more indirect estimates yield precipitation of 150–250 millimetres (5.9–9.8 in) per year at Toussidé.[51]

A characteristic vegetation has been discovered on the

Sahelian species.[56]

Eruption history

Volcanic activity at Toussidé appears to be of Quaternary age.[57] The "pre-Toussidé" caldera is considered to be the source of numerous local ignimbrites,[26] including the 430,000 ± 110,000 year old Yirrigué ignimbrite. This ignimbrite covers a surface area of 3,200 square kilometres (1,200 sq mi) with about 150 cubic kilometres (36 cu mi) of rock.[30] The eruption that generated this ignimbrite also led to the formation of the Yirrigué caldera.[31]

Trou au Natron probably formed through two or three separate

Neolithic Subpluvial,[59] and after Trou au Natron.[16]

Toussidé is among the youngest volcanoes in Tibesti,

water vapour[22] at temperatures of 40–60 °C (104–140 °F);[17] thus it is considered to be the only active Tibesti volcano.[21] Likewise, the volcanic cones in Trou au Natron are considered to be recent,[3] lake deposits underneath the cones have been radiocarbon-dated to be between 15,000 and 12,500 years old.[60] Finally, in Trou au Natron there are hot springs that deposit trona[35] and fumarolic activity has been reported there.[20]

See also

References

  1. ^ a b c d e f "Tarso Toussidé". Global Volcanism Program. Smithsonian Institution.
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  3. ^ a b c d e f g h i j Soulié-Märsche et al. 2010, p. 335.
  4. ^ Beauvilain 1996, p. 20.
  5. ^ Deniel et al. 2015, p. 19.
  6. ^ a b Gèze et al. 1959, p. 136.
  7. ^ a b c d e Soulié-Märsche et al. 2010, p. 334.
  8. ^ Schwarz 1976, p. 139.
  9. ^ a b Stäblein et al. 1976, p. 8.
  10. ^ Gèze et al. 1959, p. 154.
  11. ^ Gèze et al. 1959, p. 156.
  12. ^ Deniel et al. 2015, pp. 2–3.
  13. ^ Bruneau de Miré & Quézel 1959, p. 126.
  14. ^ a b c Louis 1960, p. 89.
  15. ^
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  16. ^ a b c d Gèze et al. 1959, p. 159.
  17. ^ a b c d e f Gèze et al. 1959, p. 160.
  18. ^ Louis 1960, p. 90.
  19. ^ a b c d Grove 1960, p. 25.
  20. ^ a b c d e f g Pachur & Altmann 2006, p. 99.
  21. ^ a b c d e Deniel et al. 2015, p. 9.
  22. ^ a b c d e Bruneau de Miré & Quézel 1959, p. 127.
  23. ^ a b c d Stäblein et al. 1976, p. 12.
  24. ^ Stäblein et al. 1976, p. 13.
  25. S2CID 129658074
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  26. ^ a b c Gèze et al. 1959, p. 157.
  27. ^ a b Louis 1960, p. 93.
  28. ^ a b Roland 1974, p. 690.
  29. ^ Roland 1974, p. 698.
  30. ^ a b c Deniel et al. 2015, p. 8.
  31. ^ a b Deniel et al. 2015, p. 16.
  32. ^ a b Pachur & Altmann 2006, p. 98.
  33. ^ a b Gèze et al. 1959, p. 158.
  34. ^ a b Louis 1960, p. 94.
  35. ^ a b c d Pachur & Altmann 2006, p. 100.
  36. ^ Scholz 1966, p. 185.
  37. ^ Pachur & Altmann 2006, p. 132.
  38. ^ Soulié-Märsche et al. 2010, pp. 335–336.
  39. ^ a b Soulié-Märsche et al. 2010, p. 339.
  40. ^ a b c Soulié-Märsche et al. 2010, p. 337.
  41. ^ a b Soulié-Märsche et al. 2010, p. 338.
  42. ^ a b Hoelzmann, Philipp (1 January 2016). "Crater palaeolakes in the Tibesti mountains (Central Sahara, North Chad) – New insights into past Saharan climates". ResearchGate. EGU2016.
  43. ^ Soulié-Märsche et al. 2010, p. 336.
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  45. ^ a b Deniel et al. 2015, p. 1.
  46. ^ Gèze et al. 1959, p. 155.
  47. ^ a b c Grove 1960, p. 21.
  48. ^ Stäblein et al. 1976, p. 9,11.
  49. ^ Schwarz 1976, p. 142.
  50. ^ Schwarz 1976, p. 141.
  51. JSTOR 1550163
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  52. ISBN 978-94-011-7596-8
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  53. ^ Bruneau de Miré & Quézel 1959, p. 128.
  54. ^ Duché, Grégoire; Picard, Marie (2010). "Aperçu sur la Taxonomie, l'Ecologie et la phylogénie du genre Erodium dans le bassin méditerranéen" [Overview on taxonomy, tcology and thylogeny of the genus Erodium in the Mediterranean Basin]. Tela Botanica (in French): 13. Retrieved 13 April 2018.
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  56. ^ Scholz 1966, p. 200.
  57. ^ Gèze et al. 1959, p. 163.
  58. ^ Roland 1974, p. 705.
  59. ^ Paylore, Patricia (September 1970). Desert Research, 2: Selected References 1966-1970 (Report). Defense Technical Information Center. p. 49.
  60. ^ Stäblein et al. 1976, p. 15.

Sources

Other sources
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