262:, 2.05 km uplift has occurred within the last 30 million years. Baker et al. (1972) also suggest that the uplift of this area is sporadic and divided by long periods of stability and erosion. Some periods of uplift are recorded at the end of the Cretaceous that resulted in 400 metres (1,300 ft) of uplift and the end of the Neogene with a staggering 1,500 metres (4,900 ft) in magnitude. The Ethiopian dome experienced its largest uplift coinciding with the end of the Neogene uplift associated with the Kenyan dome. It has been argued that the current Ethiopian plateau is a result of the most recent uplift of 500 metres (1,600 ft) estimated to be an Oligocene–early Miocene event. But the most accepted argument of the plateau is the result of the
315:
1020:
306:, which contain lakes and sediments. The lakes in this area (e.g. Lake Tanganyika and Lake Rukwa) are located in highly rifted basins and have an inter-fingering relationship with faults. Many of the lakes are bounded by normal or strike-slip faults. The extension rate for this rift starts at about 6 millimetres per year (0.24 in/year) in the north, and declines to the south.
458:(failed arm) together with two successful rifting arms. Some geologists have proposed that the East African Rift System will be the aulacogen in the future, failing to produce an ocean basin, but as of present-day there seems to be no aulacogen and the EARS does not show any evidence of slower rifting.
478:
Evidence shows the East
African Rift System is a typical complex continental-continental rifting event beginning in the Paleogene. It was caused by the far-field stress from the subduction of the Arabian plate under the Eurasian plate, and by mantle upwelling powered by multiple hot spots around the
382:
is a geological depression that ranges in height from 1,000 to −120 m (3,280 to −390 ft) The area has experienced many domal uplifts, including the Afar dome beginning 40 Mya. This uplift caused massive crustal extension leading to horst and graben structures associated with normal,
482:
This crustal uplift has created extension and horst-and-graben structures, and even listric faults suggesting a pre-oceanic basin. If current tectonics continue without change it is thought that an ocean basin with a mid-oceanic ridge will eventually separate the Nubian, Somali and
Arabian plates.
208:
219:
epoch to the
Paleogene period. At that time the African plate was experiencing far-field stresses caused by portions of the northern boundary of the African plate subducting under the Eurasian plate. Today, the Arabian plate is experiencing a crustal down pull, or
465:
forming along the eastern side of the Somali plate, caused by the spreading of the EARS and the Mid-Indian
Oceanic ridge. To accommodate the compression of the Somali plate due to two extensional edges, the oceanic plate might begin to subduct below the
257:
Gani et al. (2007) propose that episodic increase of incision of the
Ethiopian Plateau suggests episodic growth rates within the plateau, since the incision rates have no correlation to the past climate events. As an effect of Archimedes' principle of
391:
There are many active volcanic areas centralized in the East
African Rift System in comparison to the other areas in the Afro-Arabian rift system. Many protruding horsts show successive layers of flood basalts, which can be approximately dated using
383:
extensional, faults. The uplift ended in collapse around 25 Mya into the Afar depression covering more than 200,000 km (77,000 sq mi) and spreading at a rate of 6 to 17 millimetres per year (0.24 to 0.67 in/year).
450:
produce the correct model for this sufficient crustal extension. These faults have been documented by
Chorowicz (2005) and aid in further verification of the future of this region and the potential for continued extension and subsidence.
370:
According to McKenzie and Morgan's 1969 classification, the Afar Triple
Junction is of ridge-ridge-ridge (RRR) type, describing the movement of the three plates with respect to each other. The Arabian, Somali, and Nubian plates are all
411:
compiles P-wave and S-wave data from movements within the earth to create a 3D velocity model of the Earth's subsurface. The models distinguish between fast velocity, high anomaly, and slow velocity, slow anomaly, time measurements.
366:
Before the initial rifting began, Africa was one plate, but as rifting proceeded the plate it began to tear into the
Arabian, Somali, and Nubian plates (with the Nubian still sometimes called the African plate).
396:. It is found to be approximately 30 million years old. The trap series is dated to a time soon before the major rifting events began. Chorowicz (2005) illustrated the trap series surrounding the newer
375:, or ridges, with respect to the adjacent plates. Following Mackenzie and Morgan's stability model, RRR geometry will continue stably through time until there is a change in the tectonic movement.
20:
419:. Grand et al. (1997) model the large anomaly to extend from the base of the mantle to approximately 1,000 kilometres (620 mi) depth. This slow anomaly is considered to be a
266:. The uplift associated with both domes has resulted in major structural features due to the swelling and warped crustal extension. The two areas of swelling resulted in a large
274:
and subsidence along the coastal regions. The uplift caused by the
Ethiopian dome resulted in a massive faulting area of 1,000 metres (3,300 ft) in the Afar region.
243:. Based on the environmental correlations and current topographic locations of the Jurassic Upper Limestone and Cretaceous Upper Sandstone, the net rock uplift of the
290:
and the Afar region. Trending NNE to SSW, the East African Rift is composed of a western and an eastern branch. The eastern branch (sometimes called the
767:
Grand, Stephen; van der Hilst, Rob D.; Widiyantoro, Sri (April 1997). "Global Seismic Tomography: A Snapshot of Convection in the Earth".
350:
is a divergent plate boundary that divides the African (or Somali) and Arabian Plate. It extends from the triple junction eastward to the
804:
129:
and connects to the Mid-Indian Ocean ridge further to the east. Both of these rifting arms are below sea level and are similar to a
263:
54:, inside the Afar Triangle (at center shaded red). Fault lines are in black, and red triangles show historically active volcanoes.
680:; et al. (2010). "Length and Timescales of Rift Faulting and Magma Intrusion: The Afar Rifting Cycle from 2005 to Present".
725:
Leroy, Sylvie; d'Acremont, Elia; Tiberi, Christel; Basuyau, Clémence; Autin, Julia; Lucazeau, Francis; Sloane, Heather (2010).
483:
However, the rifting is studied by a diverse body of research with conflicting hypothetical models, and its future is unknown.
358:
plates. The spreading rate for Aden Ridge is about 17 millimetres per year (0.67 in/year) near the Afar Triple Junction.
286:
is an active rift between the Nubian and Somali protoplates. This rift is caused by elevated heat flow from the mantle under
852:
607:
Beyene, Alebachew; Abdelsalam, Mohamed G. (1 January 2005). "Tectonics of the Afar Depression: A review and synthesis".
330:
is between the African (or Nubian) and Arabian Plates. The rift runs along the length of the Red Sea, starting from the
947:
26:
400:
volcanics. This helps quantify the amount of crustal extension and gives a model of pre-rifting crustal connection.
989:
892:
797:
588:
338:. The extension rate for this rift varies from about 7 to 17 millimetres per year (0.28 to 0.67 in/year).
254:. The thinned Ethiopian lithosphere could have resulted in ponding from mantle plume and subsequent uplift.
548:"Blue Nile incision on the Ethiopian Plateau: Pulsed plateau growth, Pliocene uplift, and hominin evolution"
136:
The third rifting arm runs south extending around 4,000 kilometres (2,500 mi) through the countries of
1046:
867:
145:
915:
334:
to the Afar triple junction. Within the rift, in the Red Sea, there are many volcanoes, including the
446:
to form, there needs to be extension that can accommodate for the extensive down fall of the grabens.
1051:
1024:
973:
957:
897:
887:
872:
834:
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726:
727:"Recent off-axis volcanism in the eastern Gulf of Aden; implications for plume-ridge interaction"
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420:
355:
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354:, where it meets the Aden-Owen-Carlsberg triple junction between the African, Arabian, and
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throughout the East African Rift System. The Kenyan dome has been studied extensively.
228:
in the north, there was mantle upwelling causing the crust to down warp and swell into
87:
663:
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628:
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283:
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are very well documented throughout this region. Although they do show and produce
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114:
67:
19:
1005:
753:
299:
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Gani, Nahid D. S.; Gani, M. Royhan; Abdelsalam, Mohamed G. (September 2007).
447:
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103:
91:
79:
71:
41:
28:
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Multiple tomography models show a slow anomaly structure beneath southern
314:
102:. The latter extends a total of 6,500 kilometers (4,000 mi) from the
564:
547:
443:
193:
710:
347:
225:
169:
107:
455:
236:
224:, that has separated from the African plate. At the same time as the
221:
782:
331:
240:
204:
magma rises up into the colder lithosphere to stretch and thin it.
157:
122:
642:
Waltham, Tony (2005). "Extension tectonics in the Afar Triangle".
511:
Chorowicz, Jean (1 October 2005). "The East African rift system".
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153:
118:
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or the East African Rift System (EARS), when it includes the
137:
189:
117:. The northernmost branching arm extends north through the
82:
plates. This area is considered a present-day example of
579:
Baker, B. H.; Mohr, P. A.; Williams, L. A. J. (1972).
426:
318:
Manda-Hararo rift in the Afar region of Ethiopia with
298:
activity and the western branch (sometimes called the
583:. Boulder, Colorado: Geological Society of America.
16:
Place where three tectonic rifts meet in East Africa
454:Some past rifting events have been seen to have an
172:. This southern rifting arm is better known as the
545:
578:
1038:
606:
215:The triple rift is thought to have begun in the
506:
504:
502:
500:
498:
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192:is the result of pulling apart or extension of
798:
682:Annual Review of Earth and Planetary Sciences
602:
600:
581:Geology of the eastern rift system of Africa
493:
386:
125:, while the eastern arm extends through the
805:
791:
200:, caused by mantle upwelling where hotter
709:
597:
563:
510:
247:would be 2.2 km (1.4 mi) since
235:The plume is thought to have begun under
313:
206:
18:
676:
641:
211:The internal dynamics of a rift system.
1039:
473:
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183:
812:
277:
734:Earth and Planetary Science Letters
702:10.1146/annurev-earth-040809-152333
461:There is also the possibility of a
427:Potential opening of an ocean basin
13:
361:
14:
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609:Journal of African Earth Sciences
513:Journal of African Earth Sciences
113:The connecting three arms form a
1019:
1018:
656:10.1111/j.1365-2451.2005.00510.x
629:10.1016/j.jafrearsci.2005.03.003
533:10.1016/j.jafrearsci.2005.07.019
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1:
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302:) is characterized by deeper
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98:meets the Aden Ridge and the
868:Fifteen-Twenty Fracture Zone
146:Democratic Republic of Congo
7:
294:) is characterized by high
10:
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754:10.1016/j.epsl.2010.02.036
23:The triple junction is at
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843:
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387:Implications of volcanism
64:Afro-Arabian Rift System
746:2010E&PSL.293..140L
264:Paleogene flood-basalts
323:
212:
70:boundary dividing the
55:
317:
210:
66:) is located along a
22:
565:10.1130/GSAT01709A.1
394:Ar/Ar-isotope dating
60:Afar Triple Junction
1047:Geology of Ethiopia
925:Trench Trench Ridge
853:Aden-Owen-Carlsberg
694:2010AREPS..38..439E
621:2005JAfES..41...41B
525:2005JAfES..43..379C
474:Summary and problem
442:, for a sufficient
252: 150 Mya
84:continental rifting
38: /
983:Ridge Trench Fault
948:Kamchatka-Aleutian
941:Fault Fault Trench
409:Seismic tomography
352:Owen Fracture Zone
324:
213:
184:Doming and rifting
88:seafloor spreading
56:
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967:Ridge Fault Fault
468:continental plate
440:crustal extension
373:divergent margins
322:in the background
284:East African Rift
278:East African Rift
260:isostatic rebound
245:Ethiopian Plateau
174:East African Rift
100:East African Rift
90:and producing an
62:(also called the
42:11.500°N 43.000°E
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1052:Triple junctions
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814:Triple junctions
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740:(1–2): 140–153.
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678:Ebinger, Cynthia
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519:(1–3): 379–410.
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270:between the two
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380:Afar Depression
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362:Afar Depression
356:Indo-Australian
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320:Dabbahu Volcano
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217:Late Cretaceous
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131:mid-ocean ridge
115:triple junction
68:divergent plate
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688:(1): 439–466.
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650:(3): 101–107.
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615:(1–2): 41–59.
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448:Listric faults
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300:Albertine Rift
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168:and, finally,
47:11.500; 43.000
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202:asthenosphere
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178:Afar Triangle
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121:and into the
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104:Afar Triangle
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92:oceanic basin
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908:Triple Fault
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845:Triple Ridge
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711:2158/1110108
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328:Red Sea Rift
325:
310:Red Sea Rift
292:Gregory Rift
281:
256:
234:
214:
187:
135:
127:Gulf of Aden
112:
96:Red Sea Rift
94:. Here, the
63:
59:
57:
444:ocean basin
423:upwelling.
194:lithosphere
86:leading to
45: /
1041:Categories
1006:Mount Fuji
590:0813721369
487:References
404:Tomography
348:Aden Ridge
342:Aden Ridge
268:depression
226:subduction
170:Mozambique
108:Mozambique
974:Macquarie
958:Mendocino
898:Tongareva
888:Rodrigues
873:Galapagos
835:Banda Sea
769:GSA Today
664:128970545
552:GSA Today
456:aulacogen
237:Lake Tana
222:slab pull
1025:Category
999:See also
916:Karlıova
558:(9): 4.
332:Dead Sea
296:volcanic
241:Ethiopia
158:Tanzania
123:Dead Sea
775:(4): 1.
742:Bibcode
690:Bibcode
617:Bibcode
521:Bibcode
436:grabens
398:Neogene
154:Burundi
119:Red Sea
80:Arabian
33:43°00′E
30:11°30′N
883:Rivera
878:Bouvet
863:Azores
662:
587:
479:EARS.
432:Horsts
417:Africa
304:basins
166:Malawi
162:Zambia
150:Rwanda
144:, the
142:Uganda
78:, and
76:Somali
72:Nubian
953:Maraş
932:Chile
730:(PDF)
660:S2CID
421:plume
288:Kenya
272:domes
230:domes
198:crust
138:Kenya
858:Afar
830:Boso
585:ISBN
434:and
378:The
346:The
326:The
282:The
190:rift
58:The
750:doi
738:293
706:hdl
698:doi
652:doi
625:doi
560:doi
529:doi
239:in
106:to
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686:38
684:.
658:.
648:21
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623:.
613:41
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599:^
556:17
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527:.
517:43
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495:^
470:.
249:c.
188:A
180:.
164:,
160:,
156:,
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148:,
140:,
133:.
110:.
74:,
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799:t
792:v
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708::
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631:.
627::
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535:.
531::
523::
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
