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In geology, felsic is a modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz. [1] It is contrasted with mafic rocks, which are richer in magnesium and iron. Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium ...
At continental arcs, fractional crystallisation is the dominant process in magma generation, and the melts formed are more evolved due to magmatic differentiation through the felsic continental crust. [37] Granitic plutons and granitic and rhyolitic melts are observed. [37] [31]
Igneous rock (igneous from Latin igneus 'fiery'), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet 's mantle or crust.
Magma (from Ancient Greek μάγμα (mágma) 'thick unguent') [1] is the molten or semi-molten natural material from which all igneous rocks are formed. [2] 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 ...
Felsic lavas (dacites or rhyolites) are highly viscous and are erupted as domes or short, stubby flows. [40] Lassen Peak in California is an example of a volcano formed from felsic lava and is actually a large lava dome. [41] Because felsic magmas are so viscous, they tend to trap volatiles (gases) that are present, which leads to explosive ...
Igneous differentiation. In geology, igneous differentiation, or magmatic differentiation, is an umbrella term for the various processes by which magmas undergo bulk chemical change during the partial melting process, cooling, emplacement, or eruption. The sequence of (usually increasingly silicic) magmas produced by igneous differentiation is ...
Felsic magmas are thought to form by addition of heat or water vapor to rock of the lower crust, rather than by decompression of mantle rock, as is the case with basaltic magmas. [19] It has also been suggested that some granites found at convergent boundaries between tectonic plates , where oceanic crust subducts below continental crust, were ...
Lava domes are formed by the extrusion of viscous felsic magma. They can form prominent rounded protuberances, such as at Valles Caldera. As a volcano extrudes silicic lava, it can form an inflation dome or endogenous dome, gradually building up a large, pillow-like structure which cracks, fissures, and may release cooled chunks of rock and rubble.