EES-1000 Lecture 15: Lecture Notes 3
7 Oct 2016
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Fluids: hot water with dissolved ions and volatiles (co2), they facilitate metamorphism. Metamorphic textures: two major subdivisions of metamorphic rocks, nonfoliated- no planar fabric evident. Forms from a limestone or dolostone parent rock. Original textures and fossils are obliterated: quartzite! Like quartz, it is hard, glassy, and resistant: hornfels- alteration by heating! Finely crystalline: two major subdivisions of metamorphic rocks, foliated- has a through-going planar fabric. Classi ed by composition, grain size, and classi cation type. Foliated metamorphic rocks: slate- very ne, low-grade metamorphic shale. Foliation develops by parallel alignment of platy clay minerals. Orientation is perpendicular to compression: phyllite- fine mica-rich rock. Micas re ect a satiny luster: schist- fine or coarse rock with larger micas. Parallel alignment of large mica crystals: gneiss- has a distice banded of foliation. Light bands of felsic minerals (quartz and feldspars). Dark bands of magic minerals (biotite or amphibole): migmatite- a partially melted gneiss, mineralogy controls behavior!
