The lower limit of metamorphic temperatures is 150 degrees Celsius. The upper limit is the melting temperature when magma forms. Typically destroys some or all of the original rock textures. Occurs along plate boundaries particularly convergent plate boundaries. Contact Metamorphism Occurs when hot magma comes into contact with country rock.
Temperature decreases with distance from the source.
The distance that the affected rock changes is a function of temperature of the intrusion, cooling rate, and fluid content. Zonation of a rock along a contact is common. Hydrothermal Metamorphism Chemical reactions as a result of circulation of fluids. Metamorphism Occurs along fault planes, places where rocks are grinding together. Typically fluids are involved in the reaction.