Waw an Namus

Coordinates: 24°55′03″N 17°45′46″E / 24.91750°N 17.76278°E / 24.91750; 17.76278
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Waw an Namus
Wau-en-Namus, Uau en Namus, Waw an Namous
A white hill within a black depression, with lakes and vegetation at its foot and desert elsewhere
The central cone of Waw an Namus
Highest point
Elevation547 m (1,795 ft) Edit this on Wikidata
Coordinates24°55′03″N 17°45′46″E / 24.91750°N 17.76278°E / 24.91750; 17.76278[1]
Naming
English translationOasis of mosquitoes
Geography
Waw an Namus is located in Libya
Waw an Namus
Waw an Namus
Geology
Age of rockPleistocene[1]
Mountain typeVolcano

Waw an Namus (also spelled Wau-en-Namus,

Arabic: واو الناموس) is a volcano in Libya. Of either Pleistocene or Holocene age, it is located within the eastern Fezzan region. The origin of the volcanism there and at Al Haruj farther north is not clear. Radiometric dating
has yielded an age of about 200,000 years, but other circumstantial evidence points to a formation of the volcano during Holocene or even historical times.

Waw an Namus is characterized by a

scoria cone
. Several small lakes and associated vegetation are located within the caldera.

Name

The volcano is also known as Uaw en Namus,[2] Uau en Namus, Wau-en-Namus[3] and Wau Sqair.[4] It means "Oasis of mosquitoes", a reference to the small lakes around it[1] and the numerous mosquitoes that exist at Waw an Namus,[4] nurtured by the lakes at the volcano.[5]

Geography and geomorphology

The volcano lies within the

Libyan Civil War make it difficult to access the area.[14]

Waw an Namus is a 100-metre-deep (330 ft), 4-kilometre-wide (2.5 mi) caldera, which has a small relief outwards[2] but a steep margin inwards.[8] During its formation, over 800,000,000 cubic metres (2.8×1010 cu ft) of rock were displaced.[15] Another crater lies 5 kilometres (3.1 mi) northwest from Waw an Namus.[16] That vent was formed by overlapping craters which feature no volcanic rocks and which have produced salty mud; this may have been a site of phreatic activity and of volcanic degassing.[11] The caldera contains ash deposits and some dunes, but also a humid zone with reeds.[17]

Within the caldera lies a 140-metre-high (460 ft),

gullies.[20]

Dark-coloured

megaripples formed by volcanic material occur both inside and outside of the caldera.[24]

Lakes

Also within the caldera are three small lakes[1] and additional smaller water bodies,[25] which together form a semicircle around the northern, eastern and southern flanks of the central cone. One of the lakes is north of the scoria cone, the second southeast and south and the third southwest.[19] These lakes cover a total surface of 0.3 square kilometres (0.12 sq mi)[25] and the largest lake has a surface area of 0.146 square kilometres (0.056 sq mi) with a depth of 12.5 metres (41 ft),[26] while the deepest of these waterbodies reaches depths of 15–16 metres (49–52 ft).[27] The water surface reaches 434 metres (1,424 ft) elevation above sea level, although seasonal variations[25] sometimes cause the lakebodies to dry up.[7] These lakes, some of which have red colours, give Waw an Namus a multicoloured appearance.[28]

The lakes are probably

isotope ratio analysis indicates that the water at Waw an Namus is recent water,[23] certainly more recent than 8,000 years.[30]

Geology

Waw an Namus is an isolated volcano.

lava flows of basaltic composition and the Haruj volcanic field,[1] of which Waw an Namus is sometimes considered to be a part. These in turn are only two out of several large but little known volcanic fields in the Sahara.[2] A number of theories have been proposed to explain the volcanism in the Sahara,[31] such as the activation of ancient crustal lineaments by the collision between Africa and Europe;[32] in the case of Waw an Namus the magmas originated in the mantle at about 130 kilometres (81 mi) depth,[33] and include both asthenosphere and lithosphere components[34] that underwent metasomatism before melting.[35] The processes at Haruj and Waw an Namus were probably different.[36]

The terrain surrounding Waw an Namus is covered by

crystalline, and is in turn covered by limestone, marl and the Nubian Sandstone.[19]

clinopyroxene, magnetite, nepheline and olivine, and occasionally melilite and sodalite. The rocks contain xenoliths of harzburgite, lherzolite[38] and peridotite.[2] Sulfur occurs within the crater of the scoria cone,[1] as well as white deposits that may be formed by alunite.[2]

  • Black hill rising from black terrain
    The central cone
  • Hole in the hill top
    The central crater
  • Black surface in the middle of a yellow expanse
    Waw an Namus seen from space; one notes the colour contrast and the lateral crater

Climate

Waw an Namus is part of the Sahara desert, one of the world's largest and driest deserts although parts of it were wetter in the past. In some parts of the Sahara it has only rained a few times during a whole century;[14] at Waw an Namus the little precipitation mostly occurs during winter.[39] Wind is the most important weather factor, forming ventifacts and dunes among other structures;[14] at Waw an Namus it mostly blows from the northeast[39] and is sometimes accompanied by dust devils south of the volcano.[40]

Eruptive history

The central scoria cone may be only a few thousand years old,

arid climate may mislead as to its actual age,[1] as there is little erosion in the desert.[2] Early geological studies estimated an age of less than 800–1,000 years.[15] Salty muds and rocks erupted by the scoria cone and the crater northwest of the main Waw an Namus caldera must have been emplaced after the last pluvial.[16][11] The Waw an Namus caldera cuts a Holocene drainage system in the Sahara and there is no evidence of Neolithic artifacts at Waw an Namus, further supporting a recent origin of the volcano.[30]

lava bomb associated with the central cone,[41] and the Global Volcanism Program assigns a Pleistocene age to Waw an Namus.[1] Hot springs are active at Waw an Namus and produce sulfurous water.[22]

Biology

tamarisks (including Tamarix tetragyna[43]) grow within the caldera,[42] as well as swamp vegetation to varying degrees.[15] Part of the largest lake is covered with reeds[26] (including Phragmites australis[44]) up to 4 metres (13 ft) high; smaller reeds and tamarisks grow around the saline lake as well.[45]

Animal life includes

green algae are found in the lake waters.[a][26]

  • Brown lake surrounded by green vegetation in a black desert
    A lake at Waw an Namus
  • A green lake within a depression
    A green lake seen from the central cone
  • Blue lake surrounded by green-yellow vegetation, within a desert and at the foot of a hill
    Vegetation surrounding one of the lakes at Waw an Namus
  • A black surface with a brighter circle in the middle, which in turn contains blue lakes and green vegetation
    The caldera

See also

Notes

  1. Amphora coffeaeformis, Amphora duplex, Amphora ocellata, Amphora subtilissima, Amphora veneta, Anomoeoneis sphaerophora, Bacillaria paradoxa, Cocconeis placentula, Cymbella pusilla, Denticula sp., Mastogloia aquilegiae, Melosira goetzeana, Navicula interruptestriata, Nitschia amphibia, Nitzschia hybrida, Nitzschia sigma, Nitzscia iugiformis, Nitzscia richterae, Nitzscia sigma, Rhopalodia gibberula, Rhopalodia musculus, Stephanodiscus astraea and Synedra tabulata.[53][54]

References

  1. ^ a b c d e f g h i j k l "Waw an Namous". Global Volcanism Program. Smithsonian Institution.
  2. ^ a b c d e f g h i Bardintzeff et al. 2012, p. 1049.
  3. ^ "Waw an Namous". Global Volcanism Program. Smithsonian Institution., Synonyms & Subfeatures
  4. ^ a b Lautensach & Fischer 1957, p. 303.
  5. ^ Foroutan et al. 2019, p. 844.
  6. ^ Richter 1951, p. 16.
  7. ^
    IUCN
    . p. 38.
  8. ^ a b c Knctsch 1950, p. 49.
  9. S2CID 161077245
    .
  10. ISSN 2191-5784
    .
  11. ^ a b c Knctsch 1950, p. 50.
  12. ^ Klitzsch 1968, p. 587.
  13. ISSN 2414-6064
    .
  14. ^ a b c Foroutan et al. 2019, p. 841.
  15. ^ a b c d e Richter 1951, p. 20.
  16. ^ a b c Klitzsch 1968, p. 598.
  17. ^ Foroutan et al. 2019, p. 843.
  18. ^ a b c d e Miller et al. 2012, p. 11.
  19. ^ a b c Pachur & Altmann 2006, p. 128.
  20. ^ Lautensach & Fischer 1957, p. 307.
  21. ISSN 0016-7185
    .
  22. ^ a b Klitzsch 1968, p. 597.
  23. ^ a b Pachur & Altmann 2006, p. 129.
  24. ^ Foroutan et al. 2019, p. 850.
  25. ^ a b c d e Schwabe & Simonsen 1961, p. 255.
  26. ^ a b c Schwabe & Simonsen 1961, p. 256.
  27. ^ Kanter 1967, p. 20.
  28. ^ Lautensach & Fischer 1957, p. 308.
  29. JSTOR 40173401
    .
  30. ^ a b Pachur & Altmann 2006, p. 130.
  31. ^ Miller et al. 2012, p. 19.
  32. ^ Bardintzeff et al. 2012, p. 1060.
  33. ^ Miller et al. 2012, p. 23.
  34. ^ Ball et al. 2019, p. 3547.
  35. ^ Ball et al. 2019, p. 3543.
  36. ^ Ball et al. 2019, p. 3533.
  37. ^ Bardintzeff et al. 2012, p. 1052.
  38. ^ a b Miller et al. 2012, p. 13.
  39. ^ a b Foroutan et al. 2019, p. 842.
  40. ^ Foroutan et al. 2019, p. 845.
  41. ^ Bardintzeff et al. 2012, p. 1054.
  42. ^ a b Kanter 1967, p. 12.
  43. ^ Scholz & Gabriel 1973, p. 176.
  44. ^ Scholz & Gabriel 1973, p. 180.
  45. ^ Kanter 1967, p. 19.
  46. ^ Knctsch 1950, pp. 49–50.
  47. ^ Hering 2009, p. 20.
  48. ^ Hering 2009, p. 8.
  49. ^ Hering 2009, pp. 9–18.
  50. ^ Hering 2009, p. 9.
  51. ^ Schwabe & Simonsen 1961, p. 257.
  52. ^ Schwabe & Simonsen 1961, p. 259.
  53. ^ Schwabe & Simonsen 1961, pp. 263–268.
  54. ^ Schwabe & Simonsen 1961, p. 264.

Sources

External links

Media related to Waw an Namus at Wikimedia Commons

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