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African plate

earth science Maturity 7-9 Next article →

The African plate is a massive tectonic plate that makes up much of the Earth's outer shell.

Motion of Nubia Plate
Motion of Nubia Plate

It carries most of the African continent, though it excludes the easternmost part. The plate also includes oceanic crust to the west and south. A narrow strip of Western Asia is also part of this plate. This includes parts of Lebanon and Palestine. Because the continent itself includes parts of two different plates, scientists sometimes call this the Nubian plate. This specific name helps researchers distinguish the plate from the entire continent of Africa.

The plate is composed of several different types of crustal structures. It contains several cratons, which are very old and stable blocks of crust. These cratons have deep roots in the subcontinental lithospheric mantle. From south to north, these include the Kalahari, Congo, Tanzania, and West African cratons. These blocks were once widely separated. They came together during the Pan-African orogeny, a period of mountain building. They remained together even when the supercontinent Gondwana split apart.

Tectonical map of East Africa
Tectonical map of East Africa

These stable cratons are connected by orogenic belts. These are regions where the rock has been highly deformed by tectonic activity. The plate also contains less stable terranes. These are pieces of crust that joined together to form Africa during the assembly of Pangea. This assembly happened about 250 million years ago. Some areas have sedimentary basins, like the Congo Basin. In these basins, recent Neoproterozoic sediments cover the older, archaic crust. The plate also features shear zones like the Central African Shear Zone. In this zone, two sections of the crust once moved in opposite directions.

The boundaries of the African plate involve many different types of movement. To the west, the plate meets the North American and South American plates. This boundary is a divergent boundary, meaning the plates move apart. This happens at the Mid-Atlantic Ridge. To the south, the plate meets the Antarctic plate at the Southwest Indian Ridge. To the northeast, it meets the Arabian plate. The Red Sea Rift marks where the Arabian plate moves away from the African plate.

Tectonical map of East Africa
Tectonical map of East Africa

Other boundaries in the north are more complex. The African plate meets the Eurasian, Aegean Sea, and Anatolian plates. Most of these are divergent or spreading boundaries. However, the northern boundary is different. There is also a short segment near the Azores known as the Terceira Rift. In the western Mediterranean, the motion between the African and Eurasian plates creates lateral and compressive forces. These forces are concentrated in the Azores–Gibraltar Fault Zone. In the Adriatic Sea, the Eurasian plate pushes the land eastward. This causes the Adriatic basin to narrow by about 40 mm per year.

One of the most active processes is rifting in the eastern interior. This is known as the East African Rift. This rift zone is separating the African plate from the Somali plate.

Tectonical map of East Africa
Tectonical map of East Africa

Scientists have different ideas about why this is happening. One hypothesis suggests a mantle plume is rising beneath the Afar region. This plume would push the crust outward. Another hypothesis suggests the rifting is caused by crustal dynamics. It may be a break along a line of weakness as plates to the east move north rapidly.

We can measure the movement of the African plate quite precisely. It moves over the Earth's surface at a speed of 32.51 km per million years. For about 100 million years, it has generally moved in a northeast direction. This movement causes the plate to push closer to the Eurasian plate. This results in subduction in the central and eastern Mediterranean. Subduction occurs when oceanic crust converges with continental crust and sinks.

Italia Interazione placche tettoniche
Italia Interazione placche tettoniche

This constant movement shows how the Earth's surface is always being reshaped by tectonic forces.

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🖼️ Images & Media (3)
File:Italia_Interazione_placche_tettoniche.JPG
Italia_Interazione_placche_tettoniche.JPG
File:Motion of Nubia Plate.gif
Motion of Nubia Plate.gif
File:Tectonical map of East Africa.png
Tectonical map of East Africa.png
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