how is graniteformed
Answers
Answer:
It forms from the slow crystallization of magma below Earth's surface.Granite is composed mainly of quartz and feldspar with minor amounts of mica, amphiboles, and other minerals
Answer:
Explanation:
Granite is formed within the crust of the Earth when Felsic magma, that is magma that is rich in Silica, cools down without reaching the surface. Because it remains beneath the surface as it is cooling it forms large crystals.
It has a minimum of 20% Quartz with up to 65% of the rock being Feldspar. Other minerals such as Mica or Amphibole are usually present and can make up to 25% of the total volume.
Granites tend to form in Subduction zones, where water-rich crust gets assimilated into the Asthenosphere and undergoes partial melting. The melt rises, reaches the base of the crust, partially assimilates the base of the crust (increasing silica content), and continues to rise until it reaches a point where the majority of the melt stops moving. The melt stops moving when the internal pressure is equal to the surrounding pressure (if the melt has a greater internal pressure then the rocks surrounding it, then it will continue to rise all the way to the surface). But because gases (volatiles) can escape quicker than the molten rock, the melt loses volatiles as it rises and the internal pressure drops. Some of the melt may reach the surface as a Rhyolite, but the majority (some 95%) remains below ground and cools slowly to form a granite.