Desert Eagle Colors Gold

c) Magmas as composition

genres magmas on Earth are due to the existence of convective currents in the mantle and the relative movements of lithospheric plates.

magmatism in the ocean is dominated by the generation of basalt. Small amounts of felsic or silicic magmas formed in the ridges, are linked to long with the basalts by processes of differentiation. On the continents, the magmatism is much more complex and diverse.
to describe this type of magmatism may be considered three main categories within the continental volcanism:

• FLOOD BASALT

Certain volcanic provinces are characterized by the formation of a large number of lava flows, with large volumes of hundreds of cubic miles. The basalts are

toleíca composition suggesting an extensive partial melting in the mantle. Large amounts of melt can be interpreted as the consequence of decompression in the mantle.

• alkaline magmatism

There is a wide and bewildering variety of igneous alkaline silica-deficient, incluyenfo alkali basalts, basanites and nephelinite, can also be grouped carbonalitas and kimberlites. but these rock types do not lead to the same origin.

There is sufficient evidence to believe that parts of the continental lithospheric mantle are very aniguas and in some places have been invaded by volatile components, mainly water and carbon dioxide.

• MAGMATISM SILICEA

The most important category within the continental volcanism, as it involves the development of large volumes of intermediate and silicic magmas, which often predominate over basaltic products. In the plutonic environment rocs form as diorite, tonalite, and granite ganodiorita whereas in volcanic environments range formaanrocas andesite-dacite-rhyolite. There

Two main hypotheses on the origin of siliceous amgmas. First is the idea that, since the continental crust is made up of granitic materials, these magmas are the result of a simple remelting of the crust. Second, siliceous magmas are formed by differentiation of basaltic magmas generated in the mantle.

siliceous magmas have much higher viscosities than basaltic magmas. These viscosities as high have important implications for the mechanisms of segregation and ascent of magma. This implies that the siliceous magmas must rise as masses rather than through narrow cracks.

crystallization along the margins of the chamber is a possible mechanism for differentiation and zonation of siliceous magmas.