NATS 1750 Lecture Notes - Lecture 3: Lithification, Gneiss, Metamorphic Rock
24 Feb 2015
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Document Summary
Chapters 1, 3, 6, 7: rocks are mixtures of minerals, 3 main types. Metamorphic (chp 7: they can be formed a number of different ways, we place these different pathways in the rock cycle. Also important how fast or slow it solidifies. Rate of cooling produces texture very rapid cooling glassy or frothy texture. As rate of cooling slows, grains in rock tend to become larger: igneous rock mainly silicates, but exact mixture varies, two major groups. Dark silicates includes olivine, pyroxene, amphibole etc are richer iron or magnesium. Light silicates higher silica content quartz & feldspars. Also makes up the larger part of oceanic crust. (this sometimes gives rise to name basement rock") This results in compaction into denser material: water can also transport material into spaces and cement materials together. Sedimentary environments: sedimentary rock very much an indication of surface processes, this includes life as many sediments have fossils or some evidence of life trapped in them.
