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Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. Molten felsic magma and lava is more viscous than molten mafic magma and lava. Felsic magmas and lavas have lower temperatures of melting and solidification than mafic magmas and lavas.
Cerro Mackay, a mountain in Coyhaique in Chile, made of columns of adakite [1] Closer view of the adakite columns of Cerro Mackay, Chile. Adakites are volcanic rocks of intermediate to felsic composition that have geochemical characteristics of magma originally thought to have formed by partial melting of altered basalt that is subducted below volcanic arcs. [2]
Pitchstone is a dark coloured, glassy volcanic rock formed when felsic lava or magma cools quickly. Since it is a volcanic glass, pitchstone may have a conchoidal fracture. Pitchstones may also contain phenocrysts, in which case it is a form of vitrophyre. Pitchstone has a resinous lustre, or silky in some cases, and a variable composition. Its ...
Extrusive igneous rock is made from lava released by volcanoes Sample of basalt (an extrusive igneous rock), found in Massachusetts. Extrusive igneous rock, also known as volcanic rock, is formed by the cooling of molten magma on the earth's surface. The magma, which is brought to the surface through fissures or volcanic eruptions, rapidly ...
The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic magma, which is high in magnesium and iron and produces basalt or gabbro, as it fractionally crystallizes to become a felsic magma, which is low in ...
It does so through magmatic activity or igneous activity, the production, intrusion and extrusion of magma or lava. Volcanism is the surface expression of magmatism. Magmatism is one of the main processes responsible for mountain formation. The nature of magmatism depends on the tectonic setting. [1]
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The oldest felsic rocks that are currently exposed intruded pre-existing, even older, mafic crustal rock and crystallized well beneath the Earth's surface. Later, these rocks were thermally metamorphosed, intruded by additional felsic magma, and partially melted during Eoarchean thermal events occurred about 3.85 to 3.72 Ga and 3.66 to 3.59 Ga.