GEOL107 Lecture Notes - Lecture 4: Diorite, Pyroxene, Biotite
6 Sep 2018
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Document Summary
Beneath surface - rock is very slow conductor of heat - magma is slowly cooled. Pluton lies along layers of pre-existing rocks. Result of experiments conducted in lab of n. l. Examined ways minerals crystallized from magma by taking intermediate composition igneous rock (diorite) and under pressure melting it to produce magma and allowing magma to cool. Bowen observed 2 major types of processed taking place as magma in lab cooled: Distinct minerals being formed within distinct temperature ranges - as temperatures decreased, different minerals formed. At distinct temperatures, distinct minerals formed (high to low) At highest temperatures (where initial crystallization (solidification) occurred), mineral formed was olivine. As temperatures dropped, olivine stopped forming and next pyroxene formed. Pyroxene = more complex, single chain structure. As temperatures dropped further, pyroxene stopped forming and amphibole formed. Amphibole = more complex, double chain structure. As temperatures dropped further, amphibole stopped forming and biotite mica formed. Biotite mica = more complex, sheet structure.
