GEOL 1425 1st Edition Lecture 12 Outline of Last Lecture I. MetamorphismII. Metamorphism and the earth systemIII. Causes of metamorphismIV. Types of metamorphismV. What you should know about Sedimentary RocksOutline of Current Lecture I. Metamorphic texturesII. Regional metamorphism and metamorphic gradeIII. Plate tectonics and metamorphismIV. What you should know for the testCurrent LectureI. Metamorphic textures—determined by heat and pressure. The more heat and pressure, the larger the crystal size. Very little heat and pressure produces small bands that are small and sometimes unable to seeA. Nomenclature of foliated rocks:i. Slates- lowest grade of foliation, commonly produced from metamorphism ofshales (which are produced from mudstone). Can’t see the banding. Has a flatand dull appearanceii. Phyllites- generally won’t see foliation with naked eye but might see bedding layers. Created from even further metamorphosed slate. More lustrous and shiny because of the greater heat and pressureiii. Schist- foliation is closely spaced but you can see the layers of foliation. Parallel arrangement of sheet minerals. Mica schist is flaky.iv. Gneiss- even coarser fraction, with light and dark minerals in the foliation.Poor foliation and little tendency to split—compressed so much and is so dense so its hard to split. v. Migmatite—high temps melting the country rock. vi. Granoblastic (nonfoliated)—high temperature but not as much pressure compressing it. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.II. Regional metamorphism and metamorphic grade-- As rocks metamorphize, they go from low-grade to high-gradeIII. Plate tectonics and metamorphismA. We know that certain rocks react with certain temperatures and pressures, so when a certain type of rock is produced we can assume the temperature and pressure of the earth at that location.IV. What you need to know about metamorphic rocks for the test:1. The terms: pore pressure, directed pressure, confining pressure2. The terms: metasomatism, prograde metamorphism, exhumation3. The terms blueschist facies minerals, hornfels, melanges4. Contact metamorphism5. Shock metamorphism6. Metamorphic grade7. Foliation8. The terms marble, phyllite, slate9. The terms phenocryst, prophyroblasts, vesicles10. Metamorphic facies11. The terms phyllitic, granoblastic,
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