GEOL 1 Lecture Notes - Lecture 9: Volcanic Glass, Plagioclase, Phanerite
2 Dec 2020
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Crystallization take liquid and freeze it into crystals that become igneous rock. Partial freezing like melting, there is not one single freezing point, mixture of crystal and liquid. Equilibrium crystallization the composition doesn"t change, same components when liquid and solid. Fractional crystallization something is added or subtracted, different compositions at start and endpoint. Minerals from in a specific order as magma cools, each has their own freezing point. Bowens reaction series shows order in which minerals will form as magma cools. Discontinuous branch each mineral is formed one at a time, process is started and discontinued separately for each mineral. Continuous branch : plagioclase forms over a high range of temperature, results in different chemical compositions; higher temperature = more calcium, lower temperature = more sodium. One body of magma can have continuous and discontinuous reactions at the same time.
