Metamorphic Rock Formation
Ever wonder how rocks change without melting? That's metamorphism! A protolith (original rock) transforms into a metamorphic rock through pressure, temperature, and fluids - with no melting involved.
Pressure increases with depth due to the weight of overlying rocks (up to 300 MPA). Similarly, temperature rises with depth from geothermal heat. Fluids come from water trapped in cracks or contained within minerals. When a protolith experiences some partial melting, it becomes a migmatite.
During metamorphism, rocks undergo several changes. Compaction eliminates air spaces, creating denser rock. Recrystallization rearranges elements to form more stable minerals. Minerals develop a preferred orientation as they realign during compaction. Metasomatic processes involve water and heat bringing additional elements.
Remember This! Metamorphic rocks form in two main settings: regional metamorphism (affecting large areas at convergent plate boundaries) and contact metamorphism (where magma heats adjacent rock).
