African Plate

  The African plate, shown in pinkish-orange

The African Plate is a tectonic plate which includes the continent of Africa, as well as oceanic crust which lies between the continent and various surrounding ocean ridges.

Contents

Boundaries

The westerly side is a divergent boundary with the North American Plate to the north and the South American Plate to the south forming the central and southern part of the Mid-Atlantic Ridge. The African plate is bounded on the northeast by the Arabian Plate, the southeast by the Indo-Australian Plate, the north by the Eurasian Plate and the Anatolian Plate, and on the south by the Antarctic Plate. All of these are divergent or spreading boundaries with the exception of the northern boundary with the Eurasian Plate (except for a short segment near the Azores, the Terceira Rift).

Components

The African Plate includes several cratons, stable blocks of old crust with deep roots in the subcontinental lithospheric mantle, and less stable terranes, which came together to form the African continent during the assembly of the supercontinent Gondwana around 550 million years ago. The cratons are, from south to north, the Kalahari craton, Congo craton, Tanzania craton and West African craton. The cratons were widely separated in the past, but came together during the Pan-African orogeny and stayed together when Gondwana split up. The cratons are connected by orogenic belts, regions of highly deformed rock where the tectonic plates have engaged. The Saharan Metacraton has been tentatively identified as the remains of a craton that has become detached from the subcontinental lithospheric mantle, but alternatively may consist of a collection of unrelated crustal fragments swept together during the Pan-African orogeny.

In some areas, the cratons are covered by sedimentary basins, such as the Tindouf basin, Taoudeni basin and Congo basin, where the underlying archaic crust is overlaid by more recent Neoproterozoic sediments. The plate includes shear zones such as the Central African Shear Zone (CASZ) where, in the past, two sections of the crust were moving in opposite directions, and rifts such as the Anza trough where the crust was pulled apart, and the resulting depression filled with more modern sediment.

Modern movements

Map of East Africa showing some of the historically active volcanoes(red triangles) and the Afar Triangle (shaded, center) -- a triple junction where three plates are pulling away from one another: the Arabian Plate, and the two parts of the African Plate (the Nubian Plate and the Somali Plate) splitting along the East African Rift Zone (USGS).

The African Plate is rifting in the eastern interior along the East African Rift. This rift zone separates the Nubian Plate to the west from the Somali Plate to the east. One hypothesis proposes the existence of a mantle plume beneath the Afar region, while an opposing hypothesis asserts that the rifting is merely a zone of maximum weakness where the African Plate is deforming as plates to its east are moving rapidly northward.

The African Plate's speed is estimated at around 2.15 cm (0.85 in) per year. It has been moving over the past 100 million years or so in a general northeast direction. This is drawing it closer to the Eurasian Plate, causing subduction where oceanic crust is converging with continental crust (e.g. portions of the central and eastern Mediterranean). In the western Mediterranean, the relative motions of the Eurasian and African plates produce a combination of lateral and compressive forces, concentrated in a zone known as the Azores-Gibraltar Fault Zone. Along its northeast margin, the African Plate is bounded by the Red Sea Rift where the Arabian Plate is moving away from the African Plate.

The New England hotspot in the Atlantic Ocean has probably created a short line of mid to late-Tertiary age seamounts on the African Plate but appears to be currently inactive.[1]

References

External links


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • African Plate — Geol. a major tectonic division of the earth s crust, comprising the African continent as well as adjacent ocean basins (the Canary, Cape Verde, Angola, Cape Agulhas, Somali, Madagascar, and Natal Basins), and bounded on the north by the Eurasian …   Universalium

  • African Plate — /æfrɪkən ˈpleɪt/ (say afrikuhn playt) noun a major tectonic plate including the African continent and surrounding waters to the east, south, and west …   Australian English dictionary

  • African Plate — Geol. a major tectonic division of the earth s crust, comprising the African continent as well as adjacent ocean basins (the Canary, Cape Verde, Angola, Cape Agulhas, Somali, Madagascar, and Natal Basins), and bounded on the north by the Eurasian …   Useful english dictionary

  • Plate tectonics — The tectonic plates of the world were mapped in the second half of the 20th century …   Wikipedia

  • plate tectonics — /pleɪt tɛkˈtɒnɪks/ (say playt tek toniks) noun a theory concerning the movements of the earth s lithosphere that explains how tectonic plates ride on the moving asthenosphere; supporting the theory of continental drift and sea floor spreading.… …   Australian English dictionary

  • plate tectonics — plate tectonic, adj. Geol. a theory of global tectonics in which the lithosphere is divided into a number of crustal plates, each of which moves on the plastic asthenosphere more or less independently to collide with, slide under, or move past… …   Universalium

  • Plate-forme de correspondance aéroportuaire — Cet article concerne le transport aérien. Pour les autres homonymes de Hub, voir Hub (homonymie) et Plateforme. L aéroport international Hartsfield Jackson d Atlanta est la principale plate forme de correspond …   Wikipédia en Français

  • African Leopards — The African Leopards are an African rugby union representative team, organised by the Confederation of African Rugby (CAR). The side will play an important role in promoting rugby in Africa. The Leopards are the first ever Pan African… …   Wikipedia

  • African Silverbill — Taxobox name = African Silverbill status = LC | status system = IUCN3.1 regnum = Animalia phylum = Chordata classis = Aves ordo = Passeriformes familia = Estrildidae genus = Lonchura species = L. cantans binomial = Lonchura cantans binomial… …   Wikipedia

  • Arabian Plate — The Arabian Plate is one of three tectonic plates (the African, Arabian and Indian crustal plates) which have been moving northward over millions of years toward an inevitable collision with Eurasia. This is resulting in a mingling of plate… …   Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.