EARTH121 Chapter Notes - Chapter 3: Basalt, Peridotite, Aphanite
9 Nov 2016
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Igneous rocks forms as molten rock cools and solidifies. Parent material of igneous rock is magma formed by a process called. Extrusive igneous rocks that form when magma solidifies at the surface. Intrusive/plutonic rocks that form at the depth. Earths crust and mantel are composed primarily of solid, not molten rock. Magma originates when essentially solid rock, located in the crust and upper mantel, melts. At subduction zones, friction generates heat as a huge slabs of lithosphere slide past one another. Crustal rocks are heated as they descend into the mantle during subduction. Hot mantle rocks can rise and intrude crustal rocks. Increase in confining pressure causes a rise in the rocks melting temperature. Reducing confining pressure lowers a rocks melting temperature. When confining pressure drops enough, decompression melting is triggered. Plays an important role in generating magma in regions where cool slabs of oceanic lithosphere descend into the mantle. Magma can be generated in 3 sets of conditions:
