Meta Rocks - iii.The loss of volatiles is important III)...

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I) Meta Rocks a. Formed by the alteration of rocks i. Changes result in the restoration of equilibrium under new environmental conditions ii.The kind of rock being metamorphosed (i.e. parent rock) is the most important factor in determining what meta rock will be formed. 1. Changes occur solid to solid b. Scales of metamorphism i. Batholith contacting host rock ii.Produces broad bands of meta (several km wide) c. Contact metamorphism i. Dike intrudes host rock ii.Forms a metamorphosed aureole (“baked zone”) around intrusion. II) Metamorphic processes a. Temperature i. Measurement of kinetic energy of molecules. ii.Chemical reactions take place more easily at higher temperatures. iii.Water drive off b. Pressure i. Force/unit area 1. Changes rock texture ii.Higher pressure can be achieved by 1. Deep burial 2. Stress [directional pressure] c. Metasomatism i. Chemical action of pore fluids. ii.Rextallization is accompanied by some chemical change.
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Unformatted text preview: iii.The loss of volatiles is important III) Effects of metamorphism a. Recrystallization i. Pre-metamorphic minerals are transformed into larger crystals. b. Foliation i. The parallel alignment of platy minerals c. Chemical recombination i. Two or more minerals in the host rock recombine to form a new mineral without the addition of any new material. d. Chemical replacement i. New material is combined with host rock minerals to produce a new mineral. e. Index minerals i. Minerals that define specific temperatures and pressure of formation. IV) Metamorphic textures\ a. Foliation i. Slate 1. Very fine cleavage 2. Fissile a. Break easily along cleavage plane ii.Phyllite 1. Waxy/greasy look on the surface. iii.Schist 1. Coarse foliation a. Visible micas iv.Gneiss 1. Very coarse foliation 2. Light and dark bands in rock v.Marble 1. Metamorphosed limestone vi.Quartzite 1. Metamorphosed sandstone...
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Meta Rocks - iii.The loss of volatiles is important III)...

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