Seychelles Microcontinent

Early Jurassic breakup of Gondwana (left) and A- Early Cretaceous, B- Late Cretaceous, C-Paleocene, D- Present Day (right)

The Seychelles Microcontinent is a microcontinent underlying Seychelles in the western Indian Ocean made of Late Precambrian rock.

The granite outcrops of the Seychelles Islands in the central Indian Ocean were amongst the earliest examples cited by Alfred Wegener as evidence for his continental drift theory.^[1] Ridge–plume interactions have been responsible for separating a thinned continental sliver from a large continent (i.e. India).^[2]

The granites of the Seychelles Microcontinent were emplaced 750 Ma, during the late Precambrian.^[3]^[4]^[5]^[6] Thermally-induced rifting in the Somali Basin and transform rifting along the Davie Fracture Zone began in the late Permian, 225 million years ago. The Gondwana supercontinent began to break up in the Middle Jurassic, about 167 million years ago. At that time, East Gondwana, comprising Antarctica, Madagascar, India, and Australia, began to separate from Africa. East Gondwana then began to separate about 115–120 million years ago when India began to move northward.^[5]

The Seychelles Islands then underwent two more stages of rifting to isolate it from Madagascar and India. Between 84–95 million years ago, rifting separated Seychelles/India from Madagascar. An initial period of transform rifting moved the Seychelles/India block northward.^[5] Around 84 million years ago, oceanic crust started to form in the Mascarene Basin,^[7] causing a rotation of the Seychelles/India land mass. This continued until 66 million years ago when new rifting severed the Seychelles from India, forming the currently active Carlsberg Ridge. The rift jump coincided with the maximum output of the Deccan Traps,^[8] and volcanics found on the Seychelles Plateau have also been linked with this event.^[5] This has led to suggestions that the initiation of the Reunion plume caused rifting to jump to its current location.^[9]

References

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Duncan, R. A.; Pyle, D. G. (1988). "Rapid eruption of the Deccan flood basalts at the Cretaceous/Tertiary boundary" (PDF). Nature. 333 (6176): 841–843. Bibcode:1988Natur.333..841D. doi:10.1038/333841a0. S2CID 4351454.
Gaina, C.; Müller, R. D.; Brown, B. J.; Ishihara, T. (2003). "Microcontinent formation around Australia". Evolution and Dynamics of the Australian Plate. Geological Society of America. doi:10.1130/0-8137-2372-8.405. ISBN 9780813723723.
Miller, J. A.; Mudie, J. D. (1961). "Potassium-argon age determinations on granite from the island of Mahé in the Seychelles Archipelago". Nature. 192 (4808): 1174–1175. Bibcode:1961Natur.192.1174M. doi:10.1038/1921174a0. S2CID 42032857.
Müller, R. D.; Gaina, C.; Roest, W. R.; Hansen, D. L. (2001). "A recipe for microcontinent formation". Geology. 29 (3): 203–206. Bibcode:2001Geo....29..203D. doi:10.1130/0091-7613(2001)029<0203:ARFMF>2.0.CO;2.
Plummer, P. S.; Belle, E. R. (1995). "Mesozoic tectono-stratigraphic evolution of the Seychelles microcontinent". Sedimentary Geology. 96 (1): 73–91. Bibcode:1995SedG...96...73P. doi:10.1016/0037-0738(94)00127-G.
Schlich, R. (1982). "The Indian Ocean: aseismic ridges, spreading centres and basins". The Ocean Basins and Margins. Vol. 6. New York: Plenum. pp. 51–147. doi:10.1007/978-1-4615-8038-6_2. ISBN 978-1-4615-8040-9.
Tucker, R. D.; Ashwal, L. D.; Torsvik, T. H. (2001). "U–Pb geochronology of Seychelles granitoids: a Neoproterozoic continental arc fragment". Earth and Planetary Science Letters. 187 (1): 27–38. Bibcode:2001E&PSL.187...27T. doi:10.1016/S0012-821X(01)00282-5.
Wasserburg, G. J.; Craig, H.; Menard, H. W.; Engel, A. E. J.; Engel, C. J. (1963). "Age and composition of a Bounty Islands granite and age of a Seychelles Islands granite". J. Geol. 71 (6): 785–789. Bibcode:1963JG.....71..785W. doi:10.1086/626954. JSTOR 30062225. S2CID 128550824.
Wegener, A. (1924). The Origin of Continents and Oceans. New York: Methuen. ISBN 978-0-486-61708-4.

v t e Major African geological formations
Plates	Major plates: African Plate Minor plates: Somali Plate Microplates: Lwandle Plate Madagascar Plate Rovuma Plate Seychelles Plate Victoria Microplate
Cratons and shields	Arabian-Nubian Shield Congo Craton Kaapvaal Craton Kalahari Craton Saharan Metacraton Tanzania Craton Tuareg Shield West African Craton Zimbabwe Craton
Shear zones	Aswa Dislocation Broodkop Shear Zone Central African Shear Zone Chuan Shear Zones Foumban Shear Zone Kandi Fault Zone Mwembeshi Shear Zone Todi Shear Zone Western Meseta Shear Zone
Orogens	Alpine Orogen Cape Fold Belt Damara Orogen East African Orogen Eburnean Orogen Gondwanide Orogen Kibaran Orogen Kuunga Orogen Mauritanide Belt Pan-African orogens Terra Australis Orogen
Rifts	Afar Triangle Anza trough Bahr el Arab rift Benue Trough Blue Nile rift East African Rift Gulf of Suez Rift Lamu Embayment Melut Basin Muglad Basin Red Sea Rift Sangha Aulacogen Atbara rift Urema Valley West and Central African Rift System White Nile rift
Sedimentary basins	Angola Basin Aoukar Blue Nile Basin Chad Basin Congo Basin Douala Basin El Djouf Karoo Basin Gabon Basin Iullemmeden Basin Kufra Basin Murzuq Basin Niger Delta Basin Ogaden Basin Orange River Basin Ouled Abdoun Basin Owambo Basin Reggane Basin Rio del Rey Basin Sirte Basin Somali Coastal Basin Taoudeni Basin Tanzania Coastal Basin Tindouf Basin Turkana Basin
Mountain ranges	Aïr Mountains Atlas Mountains Aurès Mountains Bambouk Mountains Blue Mountains Cameroon line Central Pangean Mountains Chaillu Mountains Drakensberg Eastern Arc Mountains Eastern Rift mountains Ethiopian Highlands Great Escarpment Great Karas Mountains Guinea Highlands Hoggar Mountains Imatong Mountains Jebel Uweinat Loma Mountains Mandara Mountains Marrah Mountains Mitumba Mountains Nuba Mountains Rif Mountains Rwenzori Mountains Sankwala Mountains Serra da Leba Serra da Chela Teffedest Mountains Tibesti Mountains
Inselbergs (aka koppie)	Anti-Atlas Mount Gorongosa Jugurtha Tableland Mount Mabu Mulanje Massif Mont Niénokoué Wase Rock Zuma Rock List of inselbergs

v t e Tectonic plates
Major plates	African Antarctic Eurasian Indo-Australian Australian Indian North American Pacific South American
Minor plates	Amurian Arabian Burma Caribbean Caroline Cocos Indian Nazca New Hebrides Okhotsk Philippine Scotia Somali Sunda Yangtze
Microplates	Adriatic Aegean Sea Anatolian Balmoral Reef Banda Sea Bird's Head Capricorn Coiba Conway Reef Easter Explorer Futuna Galápagos Gonâve Gorda Greenland Halmahera Iberian Iranian Juan de Fuca Juan Fernández Kerguelen Kermadec Lwandle Madagascar Malpelo Manus Maoke Mariana Molucca Sea Niuafo’ou North Andes North Bismarck North Galápagos Okinawa Panama Pelso Philippine Mobile Belt Rivera Rovuma Sangihe Seychelles Shetland Solomon Sea South Bismarck South Sandwich Timor Tisza Tonga Trobriand Victoria Woodlark
Ancient plates	Baltic Bellingshausen Charcot Cimmeria Farallon Insular Intermontane Izanagi Kula Lhasa Malvinas Moa Phoenix
Oceanic ridges	Aden Ridge Carlsberg Ridge Central Indian Ridge Chile Ridge Cocos Ridge East Pacific Rise Explorer Ridge Gakkel Ridge Galápagos Spreading Center Gorda Ridge Juan de Fuca Ridge Mid-Atlantic Ridge Knipovich Ridge Kolbeinsey Ridge Mohns Ridge Reykjanes Ridge Pacific-Antarctic Ridge South American–Antarctic Ridge Southeast Indian Ridge Southwest Indian Ridge
Ancient oceanic ridges	Aegir Ridge Alpha Ridge Kula-Farallon Ridge Mid-Labrador Ridge Pacific-Farallon Ridge Pacific-Kula Ridge Phoenix Ridge
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