Danakil Alps
| Danakil Alps | |
|---|---|
| Highest point | |
| Listing | List of mountain ranges |
| Dimensions | |
| Width | 40–70 km (25–43 mi) |
| Naming | |
| Native name | Arrata (Afar) |
| Geography | |
| Countries | Etiopia and Eritrea |
| Geology | |
| Rock age | Miocene |
| Rock type | 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]
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
[edit]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
[edit]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
[edit]References
[edit]- ^ "Ethiopian (Danakhil) Potash Project, Afar, Ethiopia". mining-technology.com. Retrieved 11 January 2017.
- ^ a b c d Varet, Jacques (2017). Geology of Afar (East Africa). Regional Geology Reviews. Springer. p. 68. ISBN 9783319608655.
- ^ "Curiosities of the Danakil Depression". NASA. 27 August 2014.
- ^ a b 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.
- ^ 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.
- ^ 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.
- ^ Elaine Morgan (2012). The Scars of Evolution: What our bodies tell us about human origins. Souvenir Press. ISBN 9780285641327.
- ^ 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.
- ^ 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.
- ^ a b "Geology of the Danakil and Ali-Sabieh Blocks". Afar Rift Consortium. Retrieved 17 January 2017.
- ^ a b 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.
- ^ a b 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.
- ^ 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: The Indian Ocean. Vol. 6. Springer Science & Business Media. p. 292. ISBN 9781461580386.