Magma

"Magma"

What is Magma?

Magma is a mixture of molten or semi-molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets and some natural satellites.Besides molten rock, magma may also contain suspended crystals, dissolved gas and sometimes gas bubbles. Magma often collects in magma chambers that may feed a volcano or solidify underground to form an intrusion. Magma is capable of intruding into adjacent rocks (forming igneous dikes and sills), extrusion onto the surface as lava, and explosive ejection as tephra, or fragmented rock, to form pyroclastic rock.

Molten rock usually located deep within the mantle of the Earth that occasionally comes to the surface through cracks in the mantle or through the eruption of volcanoes.

Note: When magma cools and solidifies, it forms igneous rock, of which lava is one.

Description of Magma:

Magma is a complex high-temperature fluid substance. Temperatures of most magmas are in the range 700 °C to 1300 °C (or 1300 °F to 2400 °F), but very rare carbonatite magmas may be as cool as 600 °C, and komatiite magmas may have been as hot as 1600 °C. Most magmas are silicatemixtures.

Environments of magma formation and compositions are commonly correlated. Environments include subduction zones, continental rift zones,mid-ocean ridges and hotspots. Despite being found in such widespread locales, the bulk of the Earth's crust and mantle is not molten. Except for the liquid outer core, most of the Earth takes the form of a rheid, a form of solid that can move or deform under pressure. Magma, as liquid, typically forms in high-temperature, low-pressure environments within several kilometers of the Earth's surface.

After formation, magma compositions may be changed by fractional crystallization, contamination, or magma mixing. Rock formed of solidified magma is called igneous rock.

While the study of magma has historically relied on observing magma in the form of lava outflows, magma has been encountered in situ three times during geothermal drilling projects—twice in Iceland (see Magma usage for energy production below), and once in Hawaii.

Magma Composition

Magma is primarily a very hot liquid, which is called a 'melt.' It is formed from the melting of rocks in the earth's lithosphere, which is the outermost shell of the earth made of the earth's crust and upper part of the mantle, and the asthenosphere, which is the layer below the lithosphere.