What Does magma Mean
The notion of magma comes from a word in the Greek language that can be translated as “pasta” . The term allows to refer to the molten rock mass that is inside the planet Earth .
Magma is a mixture of solid, volatile, and liquid materials . As it cools, it crystallizes and consolidates, giving rise to igneous rocks . When crystallization occurs inside the Earth , it is intrusive or plutonic rocks ; On the other hand, if the magma rises to the surface, it becomes lava and only then cools down, it generates effusive or volcanic rocks .
Another name by which igneous and volcanic rocks are known is magmatic rocks . It is important to note that both types are formed from magma and that the main difference between them is the medium in which they are formed. Volcanic ones, on the other hand, tend to form after an eruption and the process is much faster than those that arise below the surface.
Of the more than 700 classes of igneous rocks that have been documented, most formed below the surface of the Earth. Among the most common we can mention diorite, andesite, rhyolite, granite, basalt, gabbro and porphyry.
The magmatism is the process of formation of magma. It usually takes place on the edges of tectonic plates, below the oceanic ridges, although it can also take place in areas located inside the plates and in subduction areas.
When high temperatures are combined with high levels of pressure , the rocks coalesce and become magma. This substance can only be found underground since, when it reaches the outside, it receives the name of lava .
Magma is usually concentrated in underground chambers (so-called magma chambers ). There the molten mass is kept, which includes a liquid part, fragments of crystals and rocks and different dissolved gases. Magma chambers feed volcanoes .
Volcanic eruptions often occur when the vapor pressure of the gases becomes greater than the pressure exerted by solid rocks that keep magma confined. This generates the appearance of multiple bubbles that try to "escape" until the eruption takes place and the magma is expelled as lava.
Broadly speaking, we can describe three types of magmas, which are granitic, andesitic and basaltic. The granitic magmas have the lowest melting point of the three and can generate large pluton (plutons are masses of plutonic rocks that are embedded in the crust of the earth). Its origin takes place in orogenic areas such as the andesitic ones, although it starts from some of the other two magmas when they penetrate and melt sedimentary or metamorphosed igneous rocks whose composition is altered when the magma is incorporated.
The andesite magmas , on the other hand, have a lower percentage of silica to sixty a series of hydrated minerals, among which are several belonging to groups biotite and amphibole . These types of magma occur in any subduction zone, both in the oceanic and continental crust .
With regard to basaltic magmas , the most common of the three, we know that they can be of two types: alkaline, with a high level of potassium and sodium, generated in internal areas of the tectonic plates; toleitic, with a silica content of less than fifty percent and arising in the mid- ocean ridges (the submarine elevations that are in the middle of the oceans).