High Strain Textures
In the upper crust the pressure is less and brittle shear zone prevails whereas in the lower part pressure is enough to go for ductile shearing. Development of Textures
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METAMORPHIC PETROLOGY ARTICLES
High Strained Rocks
The shear zones is a region in the Earth’s crust where rocks are highly strained than the surroundings. These highly strained rocks can be found in the highly structural deformed terrains. These highly strained rocks can be cohesive or they can loose cohesion. These high strained rocks are classified on the basis of Cohesion, Foliation
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Replacement reactions (reaction rim/ corona)
In metamorphic petrology the reactions generally involves the replacement of minerals by their polymorphs and often the reactions may not complete. In many reactions, a pseudomorph may develop in which the new mineral retain the older minerals shape. “Some reactions produce intimate, typically wormy-looking intergrowths of two or more minerals called symplectite texture. Pseudomorphs may
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Metamorphic facies series
A metamorphic facies series is a sequence of facies that occurs across a metamorphic terrane due to differences in pressure and temperature (P/T) conditions. Each facies series is characterized by the development of a particular sequence of individual facies, with each facies stable at a specific range of temperature and pressure conditions High P/T series
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Specific Metamorphic Rocks
The commonly used names that specify a particular rock type are listed below. As a rule, these names take precedence over the textural names –
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Partial melting of rocks
Separation of a liquid from the partially melted solid residue is a form of diversification because it involves partitioning and separation of chemical constituents, and it can produce a variety of melt compositions from a single source. When the interfacial energy (surface tension) of the melt is similar to that of the minerals, the dihedral
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Metamorphic facies assemblages
Facies Pelitic Calcareous Mafic Zeolite (100-2000C) interlayered smectite/chlorite calcite calcite Laumonite, thompsonite, calcite, interlayered smectite/chlorite Prehnite- Pumpellyite(150-3000C) Prehnite, Pumpellyite, calcite, chlorite, albite Calcite Prehnite, Pumpellyite, calcite, chlorite, albite Greenschist(300-4500C) Muscovite, chlorite, Quartz, albite, biotite, garnet Calcite, dolomite, Quartz, epidote, tremolite Albite, epidote, chlorite, quartz, actinolite, sphene Epidote-Amphibolite(450-5500C) Muscovite, biotite, Garnet, albite, quartz calcite, quartz, tremolite,
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