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| Description: Changed form” rocks Produced from preexisting Igneous rocks Sedimentary rocks Other metamorphic rocks Metamorphism Takes place where preexisting rock is subjected to temperatures and pressures unlike those in which it formed Degrees of metamorphism Exhibited by rock texture and mineralogy Low-grade (e.g., shale becomes slate) High-grade (obliteration of original features) Metamorphic settings Contact, or thermal, metamorphism Occurs near a body of magma Changes are driven by a rise in temperature Regional metamorphism Directed pressures and high temperatures during mountain building Produces the greatest volume of metamorphic rock Metamorphic agents Heat Pressure (stress) Confining pressure – from burial Differential stress – occurs during mountain building Chemically active fluids Mainly water and other volatiles Promote recrystallization by enhancing ion migration Picture Stats: Views: 331 Filesize: 203.32kB Height: 921 Width: 886 Source: https://biology-forums.com/index.php?action=gallery;sa=view;id=39388 |