Continental shelves/South east African

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South east African continental shelves are shown near Madagascar and Mauritius. Credit: Jasper Hamill.

"SCIENTISTS have discovered a gigantic “lost continent” called Mauritia hidden BENEATH the island of Mauritius."[1]

"It is believed this prehistoric landmass disappeared into the ocean when Madagascar and India split apart."[1]

"The lost continent is buried beneath Mauritius and was swallowed up [by] the ocean more than 80 million years ago."[1]

"Scientists were able to predict the presence of the submerged landmass by analysing ancient crystals of zircon which proved to be older than Mauritius itself."[1]

Mozambique and Tanzania continental shelves[edit | edit source]

The image shows portions of the Mozambique and Tanzania continental shelves. Credit: Futura Sciences.

The image on the right shows portions of the south east African continental shelves west and northwest of Madagascar. This includes a clearer view of the islands or seamounts between the north end of Madagascar and the African coast. Some of these are the Comoro Islands and to their north the Glorioso Islands.

Mauritius[edit | edit source]

The image shows pyramid number four of seven that occur on Mauritius. Credit: Rémy De Saint Simon & Selva Gunness.
Pyramid is situated south of road M2 between Plaine Magnien and New Grove. Credit: Uli sh.{{free media}}

Massive "walls, hydraulic systems and road systems on the island of Mauritius, [...] are connected with the pyramid complexes that have been rediscovered there in recent months."[2]

"Since all these structures are in the same general area of the seven pyramids that have been discovered on the island, it is reasonable to conclude that everything was probably built by the same civilisation – and that this was done a long time ago."[2]

"As for the structure of the pyramids on this island off the coast of Africa, they are platform pyramids made of volcanic rock with other stones worked into them, similar in design and size to the pyramids on Tenerife, in the Canary Islands."[2]

"In the vicinity of these seven pyramids, in a zone that is about two square kilometres in size, near the villages of Plaine Magnien, the cemetery and Mahebourg, there are massive rock walls, constructed with the same techniques and from the same material as the pyramids."[2]

"There are also paved roadways that connect the pyramids to other remarkable structures. The roads are perfectly flat and of such design that the trucks that use them every day cause little damage."[2]

"The long-held notion that the pyramids were built only in Egypt and Mexico had to change in the 20th century. It was discovered that stone and brick structures in the shape of the pyramid were built thousands of years ago from Bolivia and Peru through Central American countries of Mexico, El Salvador, Guatemala, Honduras and Belize as well as throughout the islands of the coasts of Africa such as Canary Islands and Mauritius, then Sudan, Southern European countries such as Italy, France and Greece and in the east in China, Korea and Pacific islands."[3]

"In Mauritius the stony soils form an integral part of the industry,5 though often stones are so numerous that they are piled into walls and pyramids, and in parts cultivation is possible only by muraille creole-one row of canes, one of stones- a system that has some advantages for moisture conservation in dry areas."[4]

"It goes without saying that the theory that these are merely heaps of stones is totally absurd, especially when you show them to geologists and engineers. For one thing the precision of the corner angles of these monuments [especially shown in the image on the right] seen from space is unmistakable, and there is no way this could be the work of slaves clearing useless stones from the fields and heaping them up, even artistically. The precision of the corners and bases, and the allowances made for the sometimes uneven ground, demand calculations and execution by experienced architects."[2]

Mascarene Plateau[edit | edit source]

Topographical map shows the Mascarene Plateau north and east of Madagascar. Credit: Sean.hoyland.

The Mascarene Plateau is an oceanic plateau (submarine plateau) in the Indian Ocean, north and east of Madagascar, that extends approximately 2,000 km (1,200 mi), from the Seychelles in the north to Réunion in the south, covering an area of over 115,000 km2 (44,000 sq mi) of shallow water, with depths ranging from 8–150 m (30–490 ft), plunging to 4,000 m (13,000 ft) to the abyssal plain at its edges, where depths of shallow water range from 8–150 m.[5]

The southern part of the Mascarene plateau, also known as the Southern Mascarene plateau (SMP), was formed by the Réunion volcanic hotspot along with the Chagos-Laccadive Ridge.[6]

South African continental shelves[edit | edit source]

Bathymetric features of the South African continental shelves are shown. Credit: David Barratt and Richard Tilzey.

Several features apparently could have substantial portions at or above sea level due to the previous ice age during the last 50 kyrs. These include the Madagascar Ridge, the Mozambique Plateau, the Southwest Indian Ridge, and the Del Cano Rise. The Kerguelen Plateau is closer to and likely an extension of the Antarctic continental shelves.

Agulhas Bank[edit | edit source]

Map shows the Agulhas Bank centered on the Outeniqua Basin. Credit: Fama Clamosa.{{free media}}

The Agulhas Bank stretches approximately 800 km (500 mi) along the African coast,[7] from off Cape Peninsula (18°E) to Port Alfred (26°E),[8] and up to 250 km (160 mi) from it. The bank is 50 m (160 ft) deep near the coast and reaches 200 m (660 ft) before dropping steeply to 1,000 m (3,300 ft) on its southern edge.[7]

The shelf spans an area of 116,000 km2 (45,000 sq mi) with a mean depth slightly over 100 m (330 ft).[9]

Agulhas Plateau[edit | edit source]

NOAA map shows the Agulhas Plateau. Credit: NOAA.{{free media}}

The Agulhas Plateau, in the image on the right, is limited by the Agulhas Passage to the north; by the Agulhas Basin to the west; and by the Transkei Basin to the north-east.[10]

The Agulhas Plateau is an oceanic plateau located in the south-western Indian Ocean about 500 km (310 mi) south of South Africa,[11] a remainder of a large igneous province (LIP), the Southeast African LIP, that formed 140 to 95 million years ago (Ma) at or near the triple junction where Gondwana broke-up into Antarctica, South America, and Africa. The plateau formed 100 to 94 Ma together with Northeast Georgia Rise and Maud Rise (now located near the Falkland Island and Antarctica respectively) when the region passed over the Bouvet Island, Bouvet hotspot.[12][13]

The Agulhas Plateau is the remaining core of a large-scale volcanism that started in the Lazarev Sea (today off Antarctica) with the emplacement of the Karoo Supergroup (Karoo basalts) 184 Ma.[14] This process continued with the formation of the Mozambique Ridge (MOZR)-Agulhas Plateau LIP which was active in phases between 140-95 Ma coinciding with the formation of the Kerguelen Plateau, or Kerguelen-Heard Plateau.[15] The MOZR formed 140-122 Ma and must have reached its maximum extent about 120 Ma while the spreading zone between Africa and Antarctica was located under its eastern flank.[13]

The South Atlantic Ocean started to open-up 130 Ma when the Falkland Plateau moved westwards along what was becoming the Agulhas-Falkland Fracture Zone (AFFZ). In the wake of the Falkland Plateau, during the Geomagnetic reversal Superchrons, Cretaceous quiet interval, first the Natal Valley formed, then the Transkei Basin, a process completed 90 Ma.[16]

The process continued with the formation of the Agulhas Plateau—Northeast Georgia Rise—Maud Rise LIP (AP-NEGR-MR LIP or Southeast African LIP) at the end of the Early Cretaceous (100 Ma).[17] The AP-NEGR-MR LIP formed when the region passed over the Bouvet hotspot. About 94 Ma the main eruption ended and seafloor spreading detached the NEGR and MR from the AP. Before this separation the AP-NEGR-MR LIP consisted of 1.2×10^6 km2 (0.46×10^6 sq mi) of oceanic plateau.[13]

The MOZR and AP are today connected by a crustal corridor, the Transkei Rise, which rises 500–1,000 m (1,600–3,300 ft) above the surrounding ocean floor. This rise is thought to be the product of continuous but reduced volcanism during the 20 Ma period between the formation of the MOZR-AP LIP and AP-NEGR-MR LIP.[13]

Volcanic layers on the southern Agulhas Plateau where later overlaid by sediments in which traces of either sub-areal or shallow marine erosions indicate that the plateau was near sea-level.[18]

Southern Africa experienced two periods of erosion and denudation during the Early and Mid-late Cretaceous. The driving forces behind these events is poorly understood, but both periods coincide with LIP formation: the first period (130-120 Ma) coincides with the initial stages of the Gondwana break-up and the second period (100-90 Ma) with the formation of the Agulhas LIP. Somehow, these two events led to the Mesozoic uplift of southern Africa.[19]

Crozet Plateau[edit | edit source]

"Shallow thermal processes contribute to the present topography of the Crozet Bank, emplaced further away from the Southeast Indian Ridge on older crust."[20]

Del Cano Rise[edit | edit source]

"The Del Cano Rise appears to have been formed near the active Southwest Indian Ridge before Early Eocene and is locally supported by a thickened crust."[20]

Madagascar Ridge[edit | edit source]

"The Madagascar Ridge is an elongated aseismic plateau in the southwest Indian Ocean, which separates two ocean basins of mid- to late Cretaceous age. From interpretations of a reversed refraction line on the ridge and a continuous gravity profile across it we conclude that it formed during the Cretaceous as thickened oceanic crust, at a mid-ocean ridge which possibly overlay a mantle hot-spot."[21]

Mozambique Plateau[edit | edit source]

"The origin of the Mozambique Plateau (Southwest Indian Ocean), remains unclear from present geological and geophysical studies. [The] plateau is locally compensated at depth of 27–31 km. From these results, which are consistent with the structure having a continental upper crust, it is proposed that oceanic crust and lithosphere was created underneath the initial plateau. The continental origin [is] thus inferred for the Mozambique Plateau".[22]

Southwest Indian Ridge[edit | edit source]

"The southwest Indian ridge is a particularly intriguing region, as it is both the slowest-spreading of the main ridges1 and the sole modern migration pathway between the diverse vent fauna of the Atlantic and Pacific oceans2. [...] hydrothermal plumes [occur] at six locations within two 200-km-long sections of the southwest Indian ridge indicating a higher frequency of venting than expected."[23]

See also[edit | edit source]

References[edit | edit source]

  1. 1.0 1.1 1.2 1.3 Jasper Hamill (1 February 2017). Mysterious ‘lost continent’ discovered underneath island of Mauritius. United Kingdom: The Sun. Retrieved 2017-05-09. 
  2. 2.0 2.1 2.2 2.3 2.4 2.5 Antoine Gigal (2013). Megalithic walls and hydraulic systems linked with Mauritius pyramids. United Kingdom: Gigal Research. Retrieved 2017-05-10. 
  3. Semir Sam Osmanagich (25 August 2008). BOSNIAN VALLEY OF THE PYRAMIDS Discovery and Road to Recognition, In: The First International Scientific Conference Bosnian Valley of the Pyramids. Sarajevo, Bosnia-Herzegovina: the “Archaeological Park: Bosnian Pyramid of the Sun” Foundation. pp. 1-55. Retrieved 2017-05-10. 
  4. H. C. Brookfield (1959). "Problems of monoculture and diversification in a sugar island: Mauritius". Economic Geography 35 (1): 25-40. doi:10.2307/142076?journalCode=recg20. Retrieved 2017-05-10. 
  5. Encyclopædia Britannica (2010). Seychelles-Mauritius Plateau. Encyclopædia Britannica Online. Retrieved 27 June 2010. 
  6. Ashalatha, B.; Subrahmanyam, C.; Singh, R. N. (1991). "Origin and compensation of Chagos-Laccadive ridge, Indian ocean, from admittance analysis of gravity and bathymetry data". Earth and Planetary Science Letters 105 (1–3): 47–54. doi:10.1016/0012-821X(91)90119-3. 
  7. 7.0 7.1 "Sea Atlas - Agulhas Bank". Bayworld Centre For Research & Education. Retrieved 12 November 2016.
  8. Blanke, B.; Penven, P.; Roy, C.; Chang, N.; Kokoszka, F. (2009). "Ocean variability over the Agulhas Bank and its dynamical connection with the southern Benguela upwelling system". Journal of Geophysical Research 114 (C12028): C12028. doi:10.1029/2009JC005358. Retrieved 2 January 2015. 
  9. Whittle, C. P. (2012). "Characterization of Agulhas Bank upwelling variability from satellite-derived sea surface temperature and ocean colour products" (PDF). American Geophysical Union Chapman Conference. Retrieved 2 January 2015.
  10. Parsiegla, N.; Gohl, K.; Uenzelmann-Neben, G. (2008). "The Agulhas PLateau: structure and evolution of a Large Igneous Province". Geophysical Journal International 174 (1): 336–350. doi:10.1111/j.1365-246X.2008.03808.x. 
  11. Gohl, K.; Uenzelmann-Neben, G. (2001). "The crustal role of the Agulhas Plateau, southwest Indian Ocean: evidence for seismic profiling". Geophysical Journal International 144 (3): 632–646. doi:10.1046/j.1365-246x.2001.01368.x. Retrieved 13 November 2016. 
  12. Gohl, K.; Uenzelmann-Neben, G. (2001). "The crustal role of the Agulhas Plateau, southwest Indian Ocean: evidence for seismic profiling". Geophysical Journal International 144 (3): 632–646. doi:10.1046/j.1365-246x.2001.01368.x. Retrieved 13 November 2016. 
  13. 13.0 13.1 13.2 13.3 Gohl, K.; Uenzelmann-Neben, G.; Grobys, N. (2011). "Growth and dispersal of a southeast African Large Igenous Province". South African Journal of Geology 114 (3–4): 379–386. doi:10.2113/gssajg.114.3-4.379. Retrieved 13 November 2016. 
  14. König & Jokat 2010, Fig. 16; Conclusion, pp. 177-178
  15. Gohl, Uenzelmann-Neben & Grobys 2011, Abstract
  16. Uenzelmann-Neben & Huhn 2009, Geological background pp. 65-66
  17. Parsiegla, Gohl & Uenzelmann-Neben 2008, Fig. 12
  18. Uenzelmann-Neben, Gohl & Ehrhardt 1999, Conclusions, pp. 1943-1944
  19. Tinker, de Wit & Brown 2008, Regional implications and discussion, p. 90
  20. 20.0 20.1 J. Goslin and M. Diament (July 1987). "Mechanical and thermal isostatic response of the Del Cano Rise and Crozet Bank (southern Indian Ocean) from altimetry data". Earth and Planetary Science Letters 84 (2-3): 285-94. Retrieved 5 March 2020. 
  21. Martin C. Sinha, Keith E. Louden, and Barry Parsons (1 August 1981). "The crustal structure of the Madagascar Ridge". Geophysical Journal International 66 (2): 351-377. doi:10.1111/j.1365-246X.1981.tb05960.x. Retrieved 5 March 2020. 
  22. C.M. Doucouré and H.W.Bergh (October-November 1992). "Continental origin of the Mozambique Plateau: a gravity data analysis". Journal of African Earth Sciences (and the Middle East) 15 (3-4): 311-9. doi:10.1016/0899-5362(92)90017-7. Retrieved 5 March 2020. 
  23. C. R. German, E. T. Baker, C. Mevel, K. Tamaki & the FUJI Science Team (1 October 1998). "Hydrothermal activity along the southwest Indian ridge". Nature 395: 490-3. doi:10.1038/26730. Retrieved 5 March 2020. 

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