Rift (geology) in the context of "Divergent plate boundary"

The African plate, also known as the Nubian plate, is a major tectonic plate that includes most of the continent of Africa (except for its easternmost part) and the adjacent oceanic crust to the west and south. It also includes a narrow strip of Western Asia along the Mediterranean Sea, including much of Israel and Lebanon. It is bounded by the North American plate and South American plate to the west (separated by the Mid-Atlantic Ridge); the Arabian plate and Somali plate to the east; the Eurasian plate, Aegean Sea plate and Anatolian plate to the north; and the Antarctic plate to the south.

Between 60 million years ago and 10 million years ago, the Somali plate began rifting from the African plate along the East African Rift. Since the continent of Africa consists of crust from both the African and the Somali plates, some literature refers to the African plate as the Nubian plate to distinguish it from the continent as a whole.

Magma (from Ancient Greek μάγμα (mágma) 'thick unguent') is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as lava) is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural satellites. Besides molten rock, magma may also contain suspended crystals and gas bubbles.

Magma is produced by melting of the mantle or the crust in various tectonic settings, which on Earth include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Mantle and crustal melts migrate upwards through the crust where they are thought to be stored in magma chambers or trans-crustal crystal-rich mush zones. During magma's storage in the crust, its composition may be modified by fractional crystallization, contamination with crustal melts, magma mixing, and degassing. Following its ascent through the crust, magma may feed a volcano and be extruded as lava, or it may solidify underground to form an intrusion, such as a dike, a sill, a laccolith, a pluton, or a batholith.

In plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other. Divergent boundaries within continents initially produce rifts, which eventually become rift valleys. Most active divergent plate boundaries occur between oceanic plates and exist as mid-oceanic ridges.

Current research indicates that complex convection within the Earth's mantle allows material to rise to the base of the lithosphere beneath each divergent plate boundary.This supplies the area with huge amounts of heat and a reduction in pressure that melts rock from the asthenosphere (or upper mantle) beneath the rift area, forming large flood basalt or lava flows. Each eruption occurs in only a part of the plate boundary at any one time, but when it does occur, it fills in the opening gap as the two opposing plates move away from each other.