Metdesc - the textural relations VI- Protolith VII- Rock...

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Hand-Specimen Description of Metamorphic Rocks Mineralogy: (a) Essential minerals (b) Accessory minerals (c) Secondary minerals (d) Index minerals Textures: (a) Grain size (b) General texture (c) Special textures Facies (metamorphic grade): Protolith: Rock Name:
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Thin Section Description I- Mineralogy: List the minerals (preferably in order of abundance), and, whenever possible, list the modal percentage of each mineral. II- Mineral description: (a) Modal content, (b) Grain size + grain size variation, (c) Shape, (d) Texture: Relations to other minerals, small scale textures, reaction textures, inclusions, zoning, exsolution, alteration, preferred orientation, relict textures, . .. etc. III- General Texture : schistose, gneissic, . .. etc. IV- Special Textures that need to be emphasized and their significance. V- Order of crystallization from the first mineral to crystallize, to the last one, based on
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Unformatted text preview: the textural relations VI- Protolith VII- Rock Name: list the essential minerals in the "reverse" order of abundance, and attach a "textural" term (e.g. "sillimanite garnet biotite gneiss" indicates that the modal content of biotite is greater than that garnet, which in turn is greater than that of sillimanite. VII- Chemographic representation of the phase relations: Plot the mineral assemblage(s) on the appropriate projection. Identify the "equilibrium" or "peak" assemblage. VIII- Inferred reactions IX- Facies and Metamorphic Grade : in addition to any information on the P-T conditions of formation of the studied sample and its P-T history (inferred from the textural relations, metamorphic reactions, . ..etc.). X- Mode of formation, relationship to other samples,. .. etc....
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Metdesc - the textural relations VI- Protolith VII- Rock...

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