Metamorphism can be defined as the solid state recrystallisation of pre-existing
rocks due to changes in heat and/or pressure and/or introduction of fluids i.e without melting. There will be
mineralogical, chemical and
crystallographic changes.Metamorphism produced with increasing pressure and temperature conditions is known as prograde metamorphism. Conversely, decreasing temperatures and pressure characterize retrograde metamorphism.
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