Danakil Alps

Last updated
Danakil Alps
Highest point
Listing List of mountain ranges
Dimensions
Width40–70 km (25–43 mi)
Naming
Native nameArrata (Afar)
Geography
Countries
Geology
Age of rock Miocene
Type of rock Limestone

The Danakil Alps are a highland region in Ethiopia and Eritrea with peaks over 1000 metres in height and a width varying between 40 and 70 kilometres. [1] The area is known in the Afar language as Arrata. The alps lie along the southern Red Sea [2] to the east of the Danakil Depression [3] and separate it from the sea. [4] The alps are asymmetric in cross-section with a comparatively gentle rift escarpment facing the Red Sea and intense normal faulting on the inland side. [2]

Contents

In the northern part of the alps the basement rock is less elevated and there are many volcanic edifices, [2] such as those forming the Nabro Volcanic Range. The largest of the Nabro Volcanic Range edifices are the Mallahle, Nabro, and Dubbi. The volcanic range extends northwestward to the Red Sea, ending with the Kod Ali volcano offshore. [5]

The Danakil Alps have been cut off from the sea since the late Pleistocene. [6]

Composition

Geologically these highlands are described as a horst [7] and are sometimes referred to as the Danakil Horst or Danakil Block. They were formed by geological faulting which has occurred since the Miocene epoch. [4] There is Precambrian basement rock underlying the region and in coastal Eritrea Precambrian and Mesozoic rocks are exposed. [8] The Antalo Limestone in the Danakil Alps is unusually thick for the Horn of Africa, being at least 1,000 metres (3,300 ft) in depth, [9] implying that the area acted as a drainage basin before the uplift and break up of the Afro-Arabian continent. [2] The basement rock of the alps has become overlaid with flood basalt since the Oligocene epoch. [10] The pre-rift stratigraphic section in the Danakil Alps exceeds 4,000 metres (13,000 ft), greater than that to the north, reflecting the development of the Indian Ocean margin during the Mesozoic. [11]

Development

About 20 million years ago the Afar rift zone opened up. This resulted in the alps breaking away from the Ethiopian plateau to which they had previously been attached and drifting to the east/northeast. [10] Paleomagnetic measurements indicate that, beginning in the early Miocene, the alps rotated counterclockwise by 20–30 degrees [12] from their original position over a period of 11 million years [13] as a result of the opening of the Red Sea. [12] During the last million years, spreading has continued to propagate west from the Gulf of Aden into the Gulf of Tadjoura and into the Afar Region via the subaerially exposed Asal–Ghoubbet rift. This active plate boundary continues along the west side of the Danakil Block, and links to the Red Sea at the Gulf of Zula. Stretching factors of the continental crust in the Danakil Alps are estimated to be up to β = ~2.5. [11]

See also

Related Research Articles

<span class="mw-page-title-main">Rift</span> Geological linear zone where the lithosphere is being pulled apart

In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben with normal faulting and rift-flank uplifts mainly on one side. Where rifts remain above sea level they form a rift valley, which may be filled by water forming a rift lake. The axis of the rift area may contain volcanic rocks, and active volcanism is a part of many, but not all, active rift systems.

<span class="mw-page-title-main">Afar Triangle</span> Geological depression caused by the Afar Triple Junction

The Afar Triangle is a geological depression caused by the Afar Triple Junction, which is part of the Great Rift Valley in East Africa. The region has disclosed fossil specimens of the very earliest hominins; that is, the earliest of the human clade, and it is thought by some paleontologists to be the cradle of the evolution of humans. The Depression overlaps the borders of Eritrea, Djibouti and the entire Afar Region of Ethiopia; and it contains the lowest point in Africa, Lake Assal, Djibouti, at 155 m (509 ft) below sea level.

<span class="mw-page-title-main">Danakil Desert</span> Desert in northeast Ethiopia

The Danakil Desert is a desert in northeast Ethiopia, southern Eritrea, and northwestern Djibouti. Situated in the Afar Triangle, it stretches across 136,956 square kilometres (52,879 sq mi) of arid terrain. It is inhabited by a few Afar, who engage in salt mining. The area is known for its volcanoes and extreme heat, with daytime temperatures surpassing 50 °C (122 °F). Less than 25 mm (1 in) of rainfall occurs each year. The Danakil Desert is one of the lowest and hottest places on Earth.

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The Nabro Volcano is an active stratovolcano in the Southern Red Sea Region of Eritrea. It is located at the south-east end of the Danakil Alps in the Danakil Depression. Before its 2011 eruption, the volcano was widely believed to be extinct.

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Lake Afrera is a hypersaline lake in northern Ethiopia. Located in Kilbet Rasu, Afar Region, it is one of the lakes of the Danakil Depression. According to its entry in Lakenet, it has a surface area of 100 km2 (39 sq mi), although another source states the area is 125 km2 (48 sq mi). An unconfirmed report gives its depth as 160 m (525 ft); the lake is fed by underground streams.

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References

  1. ↑ "Ethiopian (Danakhil) Potash Project, Afar, Ethiopia". mining-technology.com. Retrieved 11 January 2017.
  2. 1 2 3 4 Varet, Jacques (2017). Geology of Afar (East Africa). Regional Geology Reviews. Springer. p. 68. ISBN   9783319608655.
  3. ↑ "Curiosities of the Danakil Depression". Nasa. 27 August 2014.
  4. 1 2 Handford, C. Roberson (1991). "Chapter 1 – Marginal Marine Halite: Sabkhas and Salinas". In J.L.; Melvin (eds.). Evaporites, Petroleum and Mineral Resources. Elsevier. p. 44. ISBN   9780080869643.
  5. ↑ Pierre Wiart; Clive Oppenheimer (2005). "Final desiccation of the Afar Rift, Ethiopia". Science. 67 (2): 99–115. doi:10.1007/s00445-004-0362-x. S2CID   129124049.
  6. ↑ Enrico Bonatti; Cesare Emiliani; Göte Ostlund; Harold Rydell (1971). "Final desiccation of the Afar Rift, Ethiopia". Science. 172 (3982): 468–469. doi:10.1126/science.172.3982.468. PMID   17758081. S2CID   34061051.
  7. ↑ Elaine Morgan (2012). The Scars of Evolution: What our bodies tell us about human origins. Souvenir Press. ISBN   9780285641327.
  8. ↑ R. W. Hutchinson; G. G. Engels (29 October 1970). "Tectonic Significance of Regional Geology and Evaporite Lithofacies in Northeastern Ethiopia". Phil. Trans. R. Soc. Lond. A. 267 (1181): 313–329. doi:10.1098/rsta.1970.0038.
  9. ↑ Abbate, Ernesto; Billi, Paolo (2022). "Chapter 2: Geology and Geomorphological Landscapes of Eritrea". In Billi, Paolo (ed.). Landscapes and Landforms of the Horn of Africa: Eritrea, Djibouti, Somalia. World Geomorphological Landscapes. Springer Nature. ISBN   9783031054877.
  10. 1 2 "Geology of the Danakil and Ali-Sabieh Blocks". Afar Rift Consortium. Retrieved 17 January 2017.
  11. 1 2 Bosworth, William; Huchon, Philippe; McClay, Ken (2012). "Chapter 4 – The Red Sea and Gulf of Aden basins (4.7 Conclusions)". In Roberts, D.G.; Bally, A.W. (eds.). Regional Geology and Tectonics: Phanerozoic Passive Margins, Cratonic Basins and Global Tectonic Maps. Elsevier. pp. 62–139. doi:10.1016/C2010-0-67672-3. ISBN   978-0-444-56357-6 – via Science Direct.
  12. 1 2 Wood, Charles A. (1979). "Marda Fault Zone and the Opening of the Red Sea". In El-Baz, Farouk; Warner, D.M. (eds.). Apollo-Soyuz Test Project: Earth observations and photography. Vol. II. NASA Lyndon B. Johnson Space Center. pp. 29–31.
  13. ↑ Beydoun, Z.R. (2013). "Chapter 6: The Gulf of Aden and N.W. Arabian Sea". In Nairn, Alan E.M.; Stehli, Francis G. (eds.). The Ocean Basins and Margins. Vol. 6: The Indian Ocean. Springer Science & Business Media. p. 292. ISBN   9781461580386.
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