Tectonic plate

See also: Plate

The lithospheric tectonic plates or plates are fragments of the Lithosphère which result from its cutting to the manner of a puzzle by a system of Faille S, of dorsal, Rift S and pits of subduction. The plates lithospheric, pulled by the currents of Convection which animate the coat, move few centimetres per annum in directions different, which involves the formation of zones of divergence, from Subduction and collision.

The tectonic adjective comes from the Greek “τέκτων” or “tektōn” which means manufacturer or mason .

Cutting in plates affecting only the lithosphere, they measure approximately hundred kilometers thickness. Largest peaceful plate is the . It is also it which moves most quickly (approximately 18 centimetres per annum).

There exist two structural types of plates:

• oceanic plates made up almost exclusively of oceanic Crust (plate of the Coconuts, plate of Nazca, etc);
• continental plates made up of continental and oceanic Crust (Eurasian plate, Indian plate, etc).

One can also differentiate two types of plates according to their size:

• major plates fourteen (Australian plate, Eurasian plate, North-American plate, etc);
• minor or microplaques plates with the number of forty (plate of Mariannes, plate Scotia, plate of the sea of Moluques, etc).

There exist also plates subjected to a process of Orogenèse, i.e. their surface and their borders are in evolution (disappearance, welding with another plate, etc). It is about the plate of the Adriatic, the plate Explorer and the plate Gorda.

The limit between two plates can be very clear like in the case of the dorsals or of the pits of subduction but it can be also very fuzzy when the limit corresponds to a zone of more or less extended deformation of the lithosphere as it is the case between the Eurasian plate and the African plate on the level of the Atlantic Ocean or of the the Western Mediterranean.

Other phenomena, like the hot spots, imply the tectonic plates. The hot spots explain the existence of Volcan S apart from the zones of contact between plates.

See too

Related articles

• Plate tectonics List of tectonic plates