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Somali Plate
The Somali Plate is a minor tectonic plate which straddles the Equator in the Eastern Hemisphere. It is currently in the process of separating from the African Plate along the East African Rift Valley. It is approximately centered on the island of Madagascar and includes about half of the east coast of Africa, from the Gulf of Aden in the north through the East African Rift Valley. The southern boundary with the Nubian-African Plate is a diffuse plate boundary consisting of the Lwandle Plate. Geology The Arabian Plate diverges to the north forming the Gulf of Aden. The Indian Plate, Australian Plate, and Antarctic Plate all diverge from the Somali Plate forming the eastern Indian Ocean. The Somali-Indian boundary spreading ridge is known as the Carlsberg Ridge. The Somali-Australian boundary spreading ridge is known as the Central Indian Ridge. The Somali-Antarctic boundary spreading ridge is known as the Southwest Indian Ridge. The western boundary with the African Plate is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Tectonic Plates
This is a list of tectonic plates on Earth's surface. Tectonic plates are pieces of Earth's crust and uppermost mantle, together referred to as the lithosphere. The plates are around thick and consist of two principal types of material: oceanic crust (also called ''sima'' from silicon and magnesium) and continental crust (''sial'' from silicon and aluminium). The composition of the two types of crust differs markedly, with mafic basaltic rocks dominating oceanic crust, while continental crust consists principally of lower-density felsic granitic rocks. Current plates Geologists generally agree that the following tectonic plates currently exist on Earth's surface with roughly definable boundaries. Tectonic plates are sometimes subdivided into three fairly arbitrary categories: ''major'' (or ''primary'') ''plates'', ''minor'' (or ''secondary'') ''plates'', and ''microplates'' (or ''tertiary plates''). Major plates These plates comprise the bulk of the continents and the P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Indian Ridge
The Central Indian Ridge (CIR) is a north–south-trending mid-ocean ridge in the western Indian Ocean. Geological setting The morphology of the CIR is characteristic of slow to intermediate ridges. The axial valley is 500–1000 m deep; 50–100 km-long ridge segments are separated by 30 km-long transform faults and 10 km-long non-transform discontinuities. Melt supply comes from axial volcanic ridges that are 15 km-long, 1–2 km wide, and reaches 100–200 m above the axial floor. With a spreading rate of 30 mm/yr near the Equator and 49 mm/yr near the Rodrigues Triple Junction (RTJ) at its southern end, the CIR is an intermediately fast spreading ridge characterised by moderate obliquity and few large offsets, the obvious exception being the almost 300 km-long Mary Celeste Fracture Zone at 18°S. Between 21°S and the Mary Celeste Fracture Zone (18°S) the CIR deviates westward. Along this section the larger offsets switc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tectonic Plates
Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large tectonic plates which have been slowly moving since about 3.4 billion years ago. The model builds on the concept of ''continental drift'', an idea developed during the first decades of the 20th century. Plate tectonics came to be generally accepted by geoscientists after seafloor spreading was validated in the mid to late 1960s. Earth's lithosphere, which is the rigid outermost shell of the planet (the crust and upper mantle), is broken into seven or eight major plates (depending on how they are defined) and many minor plates or "platelets". Where the plates meet, their relative motion determines the type of plate boundary: '' convergent'', '' divergent'', or ''transform''. Earthquakes, volcanic activity, mountain-building, and oceanic tren ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Victoria Microplate
The Victoria Microplate or Victoria Plate is a small tectonic plate in East Africa. It is bounded on all sides by parts of the active East African Rift System. It is currently rotating anticlockwise. Its boundaries are close to those of the mainly Archaean Tanzania Craton, with the two arms of the rift system having propagated along the surrounding Proterozoic shear belts. To the northwest, west and southwest it has a boundary with the Nubian Plate, to the northeast and east with the Somali Plate and to the southeast with the Rovuma Plate The Rovuma Plate or Rovuma microplate is one of the four tectonic microplates that, together with the larger Nubian Plate, form the African Plate. The other three are the Somali Plate, the Lwandle Plate The Lwandle Plate is one of three tectoni .... References {{Geology-stub Tectonic plates Geology of Africa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of African Earth Sciences
The ''Journal of African Earth Sciences'' is a peer-reviewed scientific journal published by Elsevier. It covers the earth sciences, primarily on issues that are relevant to Africa and the Middle East. The journal was established in 1983 and the editors-in-chief are P.G. Eriksson and R.B.M. Mapeo. See also *''GeoArabia'' *''South African Journal of Geology The ''South African Journal of Geology'' is a quarterly peer-reviewed scientific journal published by the Geological Society of South Africa that was established in March 1896 as the ''Transactions of the Geological Society of South Africa'', obta ...'' External links * Geology journals Geology of Africa Elsevier academic journals English-language journals Publications established in 1983 {{geology-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rift
In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben with normal faulting and rift-flank uplifts mainly on one side. Where rifts remain above sea level they form a rift valley, which may be filled by water forming a rift lake. The axis of the rift area may contain volcanic rocks, and active volcanism is a part of many, but not all, active rift systems. Major rifts occur along the central axis of most mid-ocean ridges, where new oceanic crust and lithosphere is created along a divergent boundary between two tectonic plates. ''Failed rifts'' are the result of continental rifting that failed to continue to the point of break-up. Typically the transition from rifting to spreading develops at a triple junction where three converging rifts meet over a hotspot. Two of these evolve to the poi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Craton
A craton (, , or ; from grc-gre, κράτος "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the crust and the uppermost mantle. Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates; the exceptions occur where geologically recent rifting events have separated cratons and created passive margins along their edges. Cratons are characteristically composed of ancient crystalline basement rock, which may be covered by younger sedimentary rock. They have a thick crust and deep lithospheric roots that extend as much as several hundred kilometres into Earth's mantle. Terminology The term ''craton'' is used to distinguish the stable portion of the continental crust from regions that are more geologically active and unstable. Cratons are composed of two layers: A continental ''shield'', in which the basement rock crops out at the surface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orogeny
Orogeny is a mountain building process. An orogeny is an event that takes place at a convergent plate margin when plate motion compresses the margin. An ''orogenic belt'' or ''orogen'' develops as the compressed plate crumples and is uplifted to form one or more mountain ranges. This involves a series of geological processes collectively called orogenesis. These include both structural deformation of existing continental crust and the creation of new continental crust through volcanism. Magma rising in the orogen carries less dense material upwards while leaving more dense material behind, resulting in compositional differentiation of Earth's lithosphere ( crust and uppermost mantle). A synorogenic process or event is one that occurs during an orogeny. The word "orogeny" () comes from Ancient Greek (, , + , , ). Although it was used before him, the term was employed by the American geologist G. K. Gilbert in 1890 to describe the process of mountain-building as distinguished f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gondwana
Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages of break-up, involving the separation of Antarctica from South America (forming the Drake Passage) and Australia, occurred during the Paleogene. Gondwana was not considered a supercontinent by the earliest definition, since the landmasses of Baltica, Laurentia, and Siberia were separated from it. To differentiate it from the Indian region of the same name (see ), it is also commonly called Gondwanaland. Gondwana was formed by the accretion of several cratons. Eventually, Gondwana became the largest piece of continental crust of the Palaeozoic Era, covering an area of about , about one-fifth of the Earth's surface. During the Carboniferous Period, it merged with Laurasia to form a larger supercontinent called Pangaea. Gondwana (and Pan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kibaran Orogeny
The Kibaran orogeny is a term that has been used for a series of orogenic events, in what is now Africa, that began in the Mesoproterozoic, around 1400 Ma and continued until around 1000 Ma when the supercontinent Rodinia was assembled. The term "Kibaran" has often been used for any orogenic rocks formed during this very extended period. Recently, it has been proposed that the term should be used in a much narrower sense for an event around 1375 Ma and a region in the southeast of the Democratic Republic of the Congo (DRC). These orogenic events are also known as the Grenville orogeny in North America and the Dalslandian orogeny in Western Europe. Broad sense Regions that contain relics of Kibaran age include the Kibara Mountains of the eastern DRC and Namaqua-Natal belt in southern Africa. Rocks of this age have been found in the Hoggar Mountains, in northwest and southwest Nigeria and in Cameroon to the north of the Congo Craton. The orogeny in northwest Nigeria was a major t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mascarene Plateau
The Mascarene Plateau is a submarine plateau in the Indian Ocean, north and east of Madagascar. The plateau extends approximately , from Seychelles in the north to Réunion in the south. The plateau covers an area of over of shallow water, with depths ranging from , plunging to to the abyssal plain at its edges. It is the second-largest oceanic plateau in the Indian Ocean after the Kerguelen Plateau. Geography The northern part of the Mascarene Plateau includes the Agaléga Islands and the Seychelles Islands. The southern part of the Mascarene Plateau includes Hawkins Bank, the Mascarene Islands, Nazareth Bank, the Saya de Malha Bank, and the Soudan Banks. The Mascarene Islands are the mountainous islands of the Cargados Carajos Shoals, Mauritius, Réunion, and Rodrigues. Geology The Indian subcontinent was at one time next to the east coast of Seychelles, but seafloor spreading has moved the landmass to its current position, where it has collided and fused with the co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seychelles
Seychelles (, ; ), officially the Republic of Seychelles (french: link=no, République des Seychelles; Creole: ''La Repiblik Sesel''), is an archipelagic state consisting of 115 islands in the Indian Ocean. Its capital and largest city, Victoria, is east of mainland Africa. Nearby island countries and territories include the Comoros, Madagascar, Mauritius, and the French overseas departments of Mayotte and Réunion to the south; and Maldives and the Chagos Archipelago (administered by the United Kingdom as the British Indian Ocean Territory) to the east. It is the least populated sovereign African country, with an estimated 2020 population of 98,462. Seychelles was uninhabited prior to being encountered by Europeans in the 16th century. It faced competing French and British interests until coming under full British control in the late 18th century. Since proclaiming independence from the United Kingdom in 1976, it has developed from a largely agricultural society to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
