The notion of magma it comes from a word of the Greek language that can be translated as "pasta" . The term allows reference to the molten rock mass that is inside the planet land .
Magma is a mixture of solid, volatile and liquid materials . When it cools it crystallizes and consolidates, giving rise to igneous rocks . When crystallization occurs inside the land , is about intrusive or plutonic rocks ; instead, if magma rises to the surface, it becomes wash and only then it cools, generates effusive or volcanic rocks .
Another name by which igneous and volcanic rocks are known is magmatic rocks . It is important to highlight that both types are formed from magma and that the main difference between them is the medium in which they are formed. Volcanics, on the other hand, usually form after an eruption and the process It is much faster than those that arise beneath the surface.
Of the more than seven hundred igneous rock classes that have been documented, most were formed under the surface from the earth. Among the most common we can mention diorite, andesite, rhyolite, granite, basalt, gabbro and porphyry.
He magmatism It is the magma formation process. It is usually carried out at the edges of the tectonic plates, below the ocean ridges, although it can also be specified in areas located inside the plates and in the subduction areas.
When high temperatures are combined with high levels of Pressure , the rocks merge and become magma. That substance can only be found underground because, upon reaching the outside, it is called wash .
Magma usually concentrates in underground chambers (the so-called magma cameras ). There, the melt is maintained, which includes a liquid part, fragments of crystals and rocks and different dissolved gases. Magma chambers allow feeding volcanoes .
Many times volcanic eruptions occur when the vapor pressure of gases becomes greater than the pressure exerted by solid rocks that keep magma confined. This generates the appearance of multiple bubbles that try "escape" until the eruption and magma is expelled as lava.
In broad strokes, we can describe three types of magmas, which are granitic, andesitic and basaltic. The granitic magmas they have the least melting point of the three and can generate large plutons (plutons are masses of plutonic rocks that fit into the Earth's crust). Its origin takes place in orogenic areas such as the andesitic, although part of one of the other two magmas when they penetrate and melt sedimentary rocks or metamorphosed igneous whose composition is altered when the magma is incorporated.
The andesitic magmas , on the other hand, they have a percentage of silica less than sixty and a series of hydrated minerals, among which are several belonging to the groups biotite and amphiboles . These types of magma occur in any subduction zone, both in those of Cortex Oceanic as continental.
With respect 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; tolerative, with a silica content of less than fifty percent and arising in the mid-ocean ridges (the elevations submarines found in the middle zone of the oceans).