EARTHSC 1108 Lecture Notes - Lecture 3: Corundum, Alluvium, Subduction
5 Apr 2016
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Document Summary
Plate tectonics creates metamorphic environments where rocks deform under high temps and pressures. *changes in density determine if a plate will subduct or plates will collide. Subduction zones: plates collide and one plate dives or subducts under another. Mountain building zones: plates collide and both plates buckled up forming mountains two types of metamorphic rocks: regional and contact metamorphism (diopside, lapis, emeralds) Some gems form in these conditions regional metamorphism. Affects large areas further away from the heat and pressure action zone gems growing in metamorphic rocks. Garnets growing in gneiss rock (garnets yellow and light green) contact metamorphism. Rocks melt and forms new crystals results in new minerals forming. Diopside, lapis lazuli, some emeralds form this way how are gems found mining. Diamonds, rubies, sapphires, etc. sifting through alluvial deposits. Diamonds, sapphires, emeralds, etc. collecting shells or skeletons of animals from the sea. Pearls, coral, shell, etc collecting from sedimentary deposits.
