4Objectives14 – Describe the types of changes associated with metamorphic rocks.15 – Contrast regional and contact metamorphism.
5Metamorphic RocksPre-existing rocks changed by heat and pressure
6Different Types of Changes CompactionGrains move closer.Rock becomes more dense.Porosity reduced.Example: clay to shale to slateRecrystallization-Growth of new crystals.No changes in overall chemistry.New crystals grow from the minerals already presentFoliationMinerals separate into bandsNew minerals form from heat and pressure
7Types of Metamorphism: Contact Contact (thermal)Small scaleAssociated with igneous intrusions
8Types: Regional Metamorphism Regional (dynamic)Large scaleAssociated with mountain building
9Foliated vs. Non-foliated Foliated – has bands or layersNon-foliated -No bandingForm from rocks made up of single minerals
10RankThe degree of metamorphism required to change a rock