Phyllite—thickness of the foliation layers(bands of

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Unformatted text preview: Phyllite—thickness of the foliation layers (bands of parallel minerals) is greater than slate, but still not visible without magnification Schist—thickness of the foliation layers (bands of parallel minerals) is visible, characterized by flakes of mica arranged in parallel bands Gneiss—thickness of the foliation layers (bands of parallel minerals) is clearly visible (several cm’s) characterized by alternating bands of light and dark minerals The thicker the foliation layer, higher the grade (or degree) of metamorphism—higher pressures and temperatures that rocks have been exposed to Non-Foliated—ricks have been formed by higher pressures that are equivalent in all directions (not directed) or by higher temperatures, or by the passage of fluids Subdivided by composition Examples Quartzite—composed of mineral quartz (SiQ2) Marble—composed of mineral calcite (CaCO3) Amphibolite—composed of mineral amphibole (as hornblende) and plagioclase feldspar, with little or no quartz—weakly foliated or schistose structure. Hornfels—metamorphosed by heat formed plutons (igneous intrusions) Mylonite—metamorphosed by pressures along ductile fault zone Metaconglomerate—metamorphosed conglomerates Metamorphic rocks—metamorphic facies refer to different pressure and temperature conditions under which rocks are metamorphosed Zeolite facies—lowest temperatures and pressures Greenschist facies—lower to moderate temperatures, lower to moderate pressures. Amphibolite facies—higher moderate temperatures, moderate to higher pressures Granulite facies—highest temperatures, moderate to high pressures. Blueschist facies—lower to moderate temperatures, high pressures Eclogites facies—moderate temperatures high pressures 17:20 17:20...
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Phyllite—thickness of the foliation layers(bands of...

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