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Danakil Depression

Coordinates: 14°14′30″N 40°18′00″E / 14.2417°N 40.3°E / 14.2417; 40.3
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Map of the Danakil Depression. Panel A shows the topography and the parts of the Depression situated below sea-level. Panel C show a satellite image showing the dark colours of the volcanic rocks in the south and the light colours of the salt plain and marine sediments in the north.

The Danakil Depression is a large valley of approximately 200 by 50 km (124 by 31 mi), across the north of the Afar Region of Ethiopia and Eritrea. It is about 125 m (410 ft) below sea level and is bordered to the west by the Ethiopian Plateau and to the east by the Danakil Alps, beyond which is the Red Sea.[1] It is the third lowest-lying location on the continent of Africa.

The Danakil Depression is a geological depression formed by rifting. It constitute the northern part of the Afar Triangle or Afar Depression.[2][3]

Geology

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Landscape of the Danakil Depression. The bright white coloured rocks are Pleistocene marine sediments. The Erta Ale range is visible in the background.
Lake Afrera, Danakil Depression, Ethiopia

The Danakil Depression is a large valley caused by the extension between the Nubian plate and the Danakil (or Arrata) microplate (on which lie the Danakil Alps)[4][5]. The velocity between these two plates is approximately 18 mm/yr in the south of the Depression and 8 mm/yr in the north of it.[5] The Danakil Depression is thus a rift, more precisely the northern tip of the Afar rift.[6]

The formation of this rift started approximately 11 million years ago with the counterclockwise rotation of the Danakil microplate.[7][6][8] Since then, tectonic extension caused the thinning of the crust and the subsidence of the basin where both sediments and volcanic rocks accumulated. In contrary to the neighbouring central Afar region which is closer to the Afar hotspot, the Danakil Depression only experienced a moderate volcanic activity during it first rifting phase.[6] However, this volcanic activity increased significantly since at least 0.6 Ma, forming the Erta Ale volcanic range.[6] This volcanic activity was probably triggered by the thinning of the crust and the adiabatic decompression of the underlying mantle, producing large quantities of magma.[9]

The southern part of the Depression is dominated by the Erta Ale volcanic range featuring multiple shield- and stratovolcanoes such as the Gada Ale, Alu, Dalafilla, Bora Ale, Erta Ale and Ale Bagu. These volcanoes mainly produced basaltic rocks.[10] The petrology and geochemistry of these rocks indicate an absence of continental crust under the volcanic range,[10][11][12][13][14] suggesting that the Nubian and Danakil plates are probably detached there. This indicates that the rift is at an advanced stage of evolution, close to continental breakup and oceanisation. However, the Erta Ale volcanic range does not represent a normal oceanic crust yet, but rather a transitional crust.[14] In this part of the Depression, most of the extension is accommodated by dike intrusions, and not by faulting.[15]

The northern part of the Depression is dominated by sedimentary rocks. The extension is accommodated by tectonic faulting.[16][17] The volcanic activity is less important than in the southern part of the depression, but two volcanoes can be found: Maraho and Dallol. The intrusion of dikes has also been measured.[18][19]. Close to the western margin of the depression, ephemeral rivers bring coarse sediments forming alluvial fans dominated by conglomerates. During Mid- and Late Pleistocene, the basin was flooded at least 4 times by the Red Sea during periods of high sea-level.[20][21] The last flooding happened approximately 130'000 years ago.[20][21] These flooding are testified by fossil coral reefs[20][21] and by thick (>500m) evaporite deposits (mainly halite, i.e. salt) found in the central part of the basin.[22][23] The lower part of the evaporites, featuring halite and potash minerals, deposited directly in evaporating seawater coming from the Red Sea during the last flooding.[23] The upper part of the evaporites deposited in continental waters forming salt lakes and salt pans. These continental waters became saline after dissolving older marine evaporites at the margins of the basin or at depth.[23] This process is still ongoing, in particular around Lake Karum.[24][23]

Dallol

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Landscape at Dallol, Afar Triangle, East Africa

Dallol is a very special volcano situated in the central part of the salt plain. Magmatic fluids interact at depth with the evaporites, dissolving them and causing their ascent to the surface, and forming a salt volcano. [24] The fluids escaping at the surface are extremely acidic, salty and hot. The oxidation of dissolved salts, the complexation of iron and chlorine sulfates, and evaporation create impressive coloured structures.[25] These extreme conditions are also studied by biologists looking at extremophiles, organisms living in conditions usually fatal to life.[26] They found microorganisms in most of Dallol's ponds, but not in the immediate proximity of the hot chimineas where the fluids reach the surface.[27][28]

Hot springs

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Around Dallol, several other hydrothermal spring are present, such as the Gaet'Ale Pond (also called Yellow Lake).[29][25][30]

Gaet'ale Pond is a small hypersaline lake located over a tectonic hot spring in the Danakil Depression (Afar, Ethiopia). With a salinity of 43%, Gaet'ale Pond is the saltiest water body on Earth.[30] The pond was created in January 2005 following an earthquake, according to residents of the Ahmed'ela village, which reactivated the hot spring.[31]

IUGS geological heritage site

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In respect of it demonstrating 'the ongoing birth of an ocean witnessed through tectonics and volcanism in an extreme evaporite arid environment', the International Union of Geological Sciences (IUGS) included 'The Danakil Rift depression and its volcanism' in its assemblage of 100 'geological heritage sites' around the world in a listing published in October 2022. The organisation defines an IUGS Geological Heritage Site as 'a key place with geological elements and/or processes of international scientific relevance, used as a reference, and/or with a substantial contribution to the development of geological sciences through history.'[32]

Features

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The Danakil Depression is the hottest place on Earth in terms of year-round average temperatures. It is also one of the lowest places on the planet at 100 metres (330 ft) below sea level,[33] and without rain for most of the year.

It features several endorheic and saline lakes, such as Lake Afdera, Lake Karum, and Lake Bakili that sit on volcano-tectonic depressions.[34]


See also

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References

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  1. ^ J.L. Melvin (1991). Evaporites, Petroleum and Mineral Resources. Elsevier. pp. 44–45. ISBN 978-0-08-086964-3.
  2. ^ Beyene, Alebachew & Abdelsalam, Mohamed G. (2005). "Tectonics of the Afar Depression: A review and synthesis". Journal of African Earth Sciences. 41 (1–2): 41–59. Bibcode:2005JAfES..41...41B. doi:10.1016/j.jafrearsci.2005.03.003.
  3. ^ Yee, Amy (30 January 2017). "Gazing into Danakil Depression's Mirror, and Seeing Mars Stare Back". The New York Times. Retrieved 31 January 2017.
  4. ^ Varet, Jacques (2018). Geology of Afar (East Africa). Regional Geology Reviews. Bibcode:2018geaf.book.....V. doi:10.1007/978-3-319-60865-5. ISBN 978-3-319-60863-1. ISSN 2364-6438.
  5. ^ a b Viltres, Renier; Jónsson, Sigurjón; Ruch, Joël; Doubre, Cécile; Reilinger, Robert; Floyd, Michael; Ogubazghi, Ghebrebrhan (1 June 2020). "Kinematics and deformation of the southern Red Sea region from GPS observations". Geophysical Journal International. 221 (3): 2143–2154. doi:10.1093/gji/ggaa109. ISSN 0956-540X.
  6. ^ a b c d Rime, Valentin; Foubert, Anneleen; Ruch, Joël; Kidane, Tesfaye (1 September 2023). "Tectonostratigraphic evolution and significance of the Afar Depression". Earth-Science Reviews. 244: 104519. Bibcode:2023ESRv..24404519R. doi:10.1016/j.earscirev.2023.104519. ISSN 0012-8252.
  7. ^ McClusky, Simon; Reilinger, Robert; Ogubazghi, Ghebrebrhan; Amleson, Aman; Healeb, Biniam; Vernant, Philippe; Sholan, Jamal; Fisseha, Shimelles; Asfaw, Laike; Bendick, Rebecca; Kogan, Lewis (2010). "Kinematics of the southern Red Sea–Afar Triple Junction and implications for plate dynamics". Geophysical Research Letters. 37 (5). Bibcode:2010GeoRL..37.5301M. doi:10.1029/2009GL041127. ISSN 1944-8007.
  8. ^ Eagles, Graeme; Gloaguen, Richard; Ebinger, Cynthia (30 October 2002). "Kinematics of the Danakil microplate". Earth and Planetary Science Letters. 203 (2): 607–620. Bibcode:2002E&PSL.203..607E. doi:10.1016/S0012-821X(02)00916-0. ISSN 0012-821X.
  9. ^ Bastow, Ian D.; Keir, Derek (April 2011). "The protracted development of the continent–ocean transition in Afar". Nature Geoscience. 4 (4): 248–250. Bibcode:2011NatGe...4..248B. doi:10.1038/ngeo1095. hdl:2158/1110138. ISSN 1752-0908.
  10. ^ a b Barberi, F.; Varet, J. (1 December 1970). "The Erta Ale volcanic range (Danakil depression, northern afar, ethiopia)". Bulletin Volcanologique. 34 (4): 848–917. Bibcode:1970BVol...34..848B. doi:10.1007/BF02596805. ISSN 1432-0819.
  11. ^ Watts, Emma J.; Gernon, Thomas M.; Taylor, Rex N.; Keir, Derek; Siegburg, Melanie; Jarman, Jasmin; Pagli, Carolina; Gioncada, Anna (15 December 2020). "Evolution of the Alu-Dalafilla and Borale volcanoes, Afar, Ethiopia". Journal of Volcanology and Geothermal Research. 408: 107094. Bibcode:2020JVGR..40807094W. doi:10.1016/j.jvolgeores.2020.107094. hdl:2158/1233436. ISSN 0377-0273.
  12. ^ Hutchison, William; Mather, Tamsin A.; Pyle, David M.; Boyce, Adrian J.; Gleeson, Matthew L. M.; Yirgu, Gezahegn; Blundy, Jon D.; Ferguson, David J.; Vye-Brown, Charlotte; Millar, Ian L.; Sims, Kenneth W. W.; Finch, Adrian A. (1 May 2018). "The evolution of magma during continental rifting: New constraints from the isotopic and trace element signatures of silicic magmas from Ethiopian volcanoes". Earth and Planetary Science Letters. 489: 203–218. Bibcode:2018E&PSL.489..203H. doi:10.1016/j.epsl.2018.02.027. ISSN 0012-821X.
  13. ^ Barrat, J. A.; Fourcade, S.; Jahn, B. M.; Cheminée, J. L.; Capdevila, R. (1 January 1998). "Isotope (Sr, Nd, Pb, O) and trace-element geochemistry of volcanics from the Erta'Ale range (Ethiopia)". Journal of Volcanology and Geothermal Research. 80 (1): 85–100. Bibcode:1998JVGR...80...85B. doi:10.1016/S0377-0273(97)00016-4. ISSN 0377-0273.
  14. ^ a b Pin, Juliette; Chazot, Gilles; France, Lydéric; Abily, Bénédicte; Gurenko, Andrey; Bertrand, Hervé; Loppin, Alexandra (1 December 2024). "Protracted Magma Evolution and Transcrustal Magmatic Plumbing System Architecture at Erta Ale Volcano (Afar, Ethiopia)". Journal of Petrology. 65 (12): egae118. doi:10.1093/petrology/egae118. ISSN 0022-3530.
  15. ^ Illsley-Kemp, Finnigan; Keir, Derek; Bull, Jonathan M.; Gernon, Thomas M.; Ebinger, Cynthia; Ayele, Atalay; Hammond, James O. S.; Kendall, J.-Michael; Goitom, Berhe; Belachew, Manahloh (2018). "Seismicity During Continental Breakup in the Red Sea Rift of Northern Afar". Journal of Geophysical Research: Solid Earth. 123 (3): 2345–2362. Bibcode:2018JGRB..123.2345I. doi:10.1002/2017JB014902. hdl:2158/1136575. ISSN 2169-9356.
  16. ^ Bastow, Ian D.; Booth, Adam D.; Corti, Giacomo; Keir, Derek; Magee, Craig; Jackson, Christopher A.-L.; Warren, John; Wilkinson, Jason; Lascialfari, Matteo (2018). "The Development of Late-Stage Continental Breakup: Seismic Reflection and Borehole Evidence from the Danakil Depression, Ethiopia". Tectonics. 37 (9): 2848–2862. Bibcode:2018Tecto..37.2848B. doi:10.1029/2017TC004798. hdl:2158/1136583. ISSN 1944-9194.
  17. ^ Hurman, Gareth L.; Keir, Derek; Bull, Jonathan M.; McNeill, Lisa C.; Booth, Adam D.; Bastow, Ian D. (2023). "Quantitative Analysis of Faulting in the Danakil Depression Rift of Afar: The Importance of Faulting in the Final Stages of Magma-Rich Rifting". Tectonics. 42 (6): e2022TC007607. Bibcode:2023Tecto..4207607H. doi:10.1029/2022TC007607. hdl:10044/1/104631. ISSN 1944-9194.
  18. ^ Nobile, Adriano; Pagli, Carolina; Keir, Derek; Wright, Tim J.; Ayele, Atalay; Ruch, Joel; Acocella, Valerio (2012). "Dike-fault interaction during the 2004 Dallol intrusion at the northern edge of the Erta Ale Ridge (Afar, Ethiopia)". Geophysical Research Letters. 39 (19). Bibcode:2012GeoRL..3919305N. doi:10.1029/2012GL053152. hdl:11568/500305. ISSN 1944-8007.
  19. ^ Ruch, Joël; Keir, Derek; Passarelli, Luigi; Di Giacomo, Domenico; Ogubazghi, Ghebrebrhan; Jónsson, Sigurjón (16 August 2021). "Revealing 60 years of Earthquake Swarms in the Southern Red Sea, Afar and the Gulf of Aden". Frontiers in Earth Science. 9. Bibcode:2021FrEaS...9..690R. doi:10.3389/feart.2021.664673. hdl:10754/672011. ISSN 2296-6463.
  20. ^ a b c Jaramillo-Vogel, David; Foubert, Anneleen; Braga, Juan Carlos; Schaegis, Jean-Charles; Atnafu, Balemwal; Grobety, Bernard; Kidane, Tesfaye (2019). "Pleistocene sea-floor fibrous crusts and spherulites in the Danakil Depression (Afar, Ethiopia)". Sedimentology. 66 (2): 480–512. Bibcode:2019Sedim..66..480J. doi:10.1111/sed.12484. ISSN 1365-3091.
  21. ^ a b c Foubert, Anneleen; Keir, Derek; Atnafu, Balemwal; Kidane, Tesfaye; the ADD-ON Workshop Consortium (30 August 2024). "Workshop report: Afar Dallol Drilling – ONset of sedimentary processes in an active rift basin (ADD-ON)". Scientific Drilling. 33 (2): 207–218. Bibcode:2024SciDr..33..207F. doi:10.5194/sd-33-207-2024. hdl:2158/1394234. ISSN 1816-8957.
  22. ^ Holwerda, James G.; Hutchinson, Richard W. (1 March 1968). "Potash-bearing evaporites in the Danakil area, Ethiopia". Economic Geology. 63 (2): 124–150. Bibcode:1968EcGeo..63..124H. doi:10.2113/gsecongeo.63.2.124. ISSN 1554-0774.
  23. ^ a b c d Rime, Valentin; Negga, Haileyesus; Fentimen, Robin; Rüggeberg, Andres; El Korh, Afifé; Pirkenseer, Claudius; Schaegis, Jean-Charles; Hajdas, Irka; Adatte, Thierry; Atnafu, Balemwal; Kidane, Tesfaye; Foubert, Anneleen (2025). "Nature and significance of Late Pleistocene to Holocene thick evaporite deposits of the Danakil Depression, Afar, Ethiopia". Sedimentology. 72 (2): 475–506. Bibcode:2025Sedim..72..475R. doi:10.1111/sed.13237. ISSN 1365-3091.
  24. ^ a b López-García, José M.; Moreira, David; Benzerara, Karim; Grunewald, Olivier; López-García, Purificación (17 January 2020). "Origin and Evolution of the Halo-Volcanic Complex of Dallol: Proto-Volcanism in Northern Afar (Ethiopia)". Frontiers in Earth Science. 7. doi:10.3389/feart.2019.00351. ISSN 2296-6463.
  25. ^ a b Kotopoulou, Electra; Delgado Huertas, Antonio; Garcia-Ruiz, Juan Manuel; Dominguez-Vera, Jose M.; Lopez-Garcia, Jose Maria; Guerra-Tschuschke, Isabel; Rull, Fernando (17 January 2019). "A Polyextreme Hydrothermal System Controlled by Iron: The Case of Dallol at the Afar Triangle". ACS Earth and Space Chemistry. 3 (1): 90–99. Bibcode:2019ESC.....3...90K. doi:10.1021/acsearthspacechem.8b00141. PMC 6380227. PMID 30801049.
  26. ^ Cavalazzi, B.; Barbieri, R.; Gómez, F.; Capaccioni, B.; Olsson-Francis, K.; Pondrelli, M.; Rossi, A.P.; Hickman-Lewis, K.; Agangi, A.; Gasparotto, G.; Glamoclija, M.; Ori, G.G.; Rodriguez, N.; Hagos, M. (April 2019). "The Dallol Geothermal Area, Northern Afar (Ethiopia)—An Exceptional Planetary Field Analog on Earth". Astrobiology. 19 (4): 553–578. Bibcode:2019AsBio..19..553C. doi:10.1089/ast.2018.1926. ISSN 1531-1074. PMC 6459281. PMID 30653331.
  27. ^ Sanz, Jose L.; Rodríguez, Nuria; Escudero, Cristina; Carrizo, Daniel; Amils, Ricardo; Gómez, Felipe (6 June 2021). "Methanogenesis at High Temperature, High Ionic Strength and Low pH in the Volcanic Area of Dallol, Ethiopia". Microorganisms. 9 (6): 1231. doi:10.3390/microorganisms9061231. ISSN 2076-2607. PMC 8228321. PMID 34204110.
  28. ^ Belilla, Jodie; Moreira, David; Jardillier, Ludwig; Reboul, Guillaume; Benzerara, Karim; López-García, José M.; Bertolino, Paola; López-Archilla, Ana I.; López-García, Purificación (September 2019). "Hyperdiverse archaea near life limits at the polyextreme geothermal Dallol area". Nature Ecology & Evolution. 3 (11): 1552–1561. Bibcode:2019NatEE...3.1552B. doi:10.1038/s41559-019-1005-0. ISSN 2397-334X. PMC 6837875. PMID 31666740.
  29. ^ "Yellow lake is located in the Danakil Depression". Independent Travellers. independent-travellers.com. Retrieved 13 June 2017.
  30. ^ a b Perez, Eduardo; Chebude, Yonas (April 2017). "Chemical Analysis of Gaet'ale, a Hypersaline Pond in Danakil Depression (Ethiopia): New Record for the Most Saline Water Body on Earth". Aquatic Geochemistry. 23 (2): 109–117. Bibcode:2017AqGeo..23..109P. doi:10.1007/s10498-017-9312-z. S2CID 132715553.
  31. ^ Master, Sharad (2016). "Gaet'ale – a reactivated thermal spring and potential tourist hazard in the Asale salt flats, Danakil Depression, Ethiopia". Journal of Applied Volcanology. 5 (1): 1–9. Bibcode:2016JApV....5....1M. doi:10.1186/s13617-015-0042-x.
  32. ^ "The First 100 IUGS Geological Heritage Sites" (PDF). IUGS International Commission on Geoheritage. IUGS. Retrieved 13 November 2022.
  33. ^ "Hydrothermal Systems Show Spectrum of Extreme Life on Earth". Europlanet. Astrobiology Web. 26 April 2016. Retrieved 1 May 2016.
  34. ^ Schaegis, Jean-Charles; Rime, Valentin; Kidane, Tesfaye; Mosar, Jon; Gebru, Ermias Filfilu; Atnafu, Balemwal; Foubert, Anneleen (1 July 2021). "Novel Bathymetry of Lake Afdera Reveals Fault Structures and Volcano-Tectonic Features of an Incipient Transform Zone (Afar, Ethiopia)". Frontiers in Earth Science. 9. Bibcode:2021FrEaS...9..530S. doi:10.3389/feart.2021.706643. ISSN 2296-6463.
[edit]
Wikivoyage has a travel guide for Danakil Depression.

14°14′30″N 40°18′00″E / 14.2417°N 40.3°E / 14.2417; 40.3

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