Regional Metamorphism

• Corresponds to progressive changes, increases, in Temperature & Pressure, due to burial.
• Commonly this type of metamorphism is associated with orogenic events and processes.
• Regionally metamorphosed rocks occur in very large belts, 10 - 100's km wide by 100 - 1000's km long.
• Within each belt will be preserved at least one thermal axis, representing the maximum temperature of metamorphism within the belt
.
• Temperatures will increase towards the thermal axis.
• Associated granitic and/or ultramafic masses intruded into the terranes generally, but not always near the thermal axis.

Contact Metamorphism

• Recrystallization, production of metamorphic mineral assemblages, within the contact aureole surrounding an intrusive body
• Generally held that P remains constant and metamorphism results from temperature increase, due to conduction of heat away from intrusive.

Pyro Metamorphism

• Recrystallization at high temperature of xenolith fragments in volcanic rocks or small intrusions
;
• Melting of the xenolith may occur.

Hydrothermal Metamorphism

• Recrystallization associated with and influenced by a hydrothermal solution.

Cataclastic Metamorphism

• Crushing or grinding of rocks as a result of fault movement
.