EAPS 11100 Study Guide - Midterm Guide: Divergent Boundary, Intermediate Composition, Phase Diagram
4 Dec 2018
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Increasing temperature vibrates atoms and can break bonds. Temperature increases with depth, pressure increases downward within the earth: understand what could happen (melting/freezing) of rock in pressure-temperature plots along different pathways. Phase diagram where all of the three aspects add up and are the same. If magma were generated by complete melting of the source region, it would have a composition identical to that of the source. Magma cools and solidifies from the outside in. As magma cools mafic minerals crystallize first, which makes the composition of the remaining magma less mafic (more felsic). Magmatism is caused by decompression melting as the asthenosphere rises in response to stretching and thinning of the overlying plate. Understand their names, the relative silica content, relative melting/freezing points and viscosities of these rock and magma types. Mafic: relatively low silica, rich in iron and magnesium, melt at high temperature, lower viscosity (lava spreads out), form in high temp igneous environments.
