Earth Science Chapter 3 Section 4 Metamorphic Rocks Earth Science Chapter 3 Section 4

Introduction Metamorphism is the transformation of preexisting rock. Rocks that undergo metamorphism tend to be different from the parent rock. Parent rocks are the original rocks that the new rocks came from.

Types of Metamorphism Metamorphism most often occurs in rocks that are buried deep below the earth’s surface. There are 2 types of metamorphism: Contact Magma changes rock that it is in contact with Small areas, Minor changes Regional Occurs when plates collide which increases temperature and pressure Large areas, Major changes

Agents of Metamorphism The major agents of metamorphism are heat and pressure.

Heat Most important agent of metamorphism Provides the energy needed to drive the reactions Comes from magma and deeper layers of earth When the temperature increases the minerals in rock become unstable. The minerals will change into new minerals that are stable at the higher temperatures.

Pressure Two types: confining and directed Confining Associated with burial all directions increases with depth Directed Associated with plate movement greater in one direction associated with mountain building

Fluids Fluids around minerals can make it easier for metamorphism to occur because the minerals can move easier. If the temperature of the fluid increases, then reactions can occur faster.

Classification of Metamorphic Rocks Foliated Metamorphic Rock Layered or banded appearance. The bands contain different minerals Slate, schist, and gneiss (shale) Nonfoliated Metamorphic Rock No layers or bands Only one mineral Marble (limestone) and quartzite (sandstone)

Foliated Nonfoliated