GEOL 101 Lecture Notes - Lecture 7: Acasta Gneiss, Mid-Ocean Ridge, Subduction
Document Summary
Define foliation and how it is formed. Compare and contrast foliated and nonfoliated metamorphic rocks. Compare and contrast regional and contact metamorphism. Produced from preexisting rock that undergoes a change as a result of change in chemical or physical environment. Every metamorphic rock once was a different rock. Parent rock/protolith: rock from which it was formed. Composition of protolith is one factor which controls what type of metamorphic rock will be formed. If protolith is one mineral, metamorphic rock will have a fairly simple composition. If protolith is many minerals, metamorphic rock will have a fairly complicated composition. Process that leads to changes in mineralogy, texture, and the chemical composition of rocks. In geology, metamorphism occurs when a rock is subjected to physical/chemical environment that is different from which it initially formed. Provide energy to drive chemical reactions which result in a the formation of new minerals. Confining pressure: forces applied equally in all directions.