GSCI 1050 Lecture Notes - Lecture 3: Phanerite, Metamorphism, Igneous Rock
28 Jan 2018
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Intrusive and extrusive: classifications, thin sections, small crystals mean rocks were cooled quickly, big crystals with different colors means the rocks cooled slowly, aphanitic fine grain, paneritic coarse grain. What is the main factor in controlling crystal size: how quickly the rock cools determines the rocks crystal size. Mafic composition: darker minerals, low silica composition. Felsic composition: more silica composition, lighter color than mafic. How to identify these rocks: mafic minerals are darker, as we get more felsic the rocks will become lighter in color, texture and composition used to classify igneous rocks, texture is all about the cooling rate. Which rocks are representative of continental and oceanic crust: continental is granite, oceanic is basalt. Protoliths: these are the rocks in the original form before they are weathered or changed into other rocks/minerals. Foliation: parallel planar fabric common to many metamorphic rocks. It is all made of one composition, it is just calcite so it will not develop these bands.
