1. METAMORPHIC ROCKS

2. METAMORPHIC ROCKS META = CHANGE MORPH = FORM
Called the “Cinderella Rock”
Start with pre-existing rock and change to another rock – but these changes occur in the SOLID STATE
Change occurs because the rock is moved into an environment in which the minerals which make up the rock become unstable and out of equilibrium with the new environmental conditions
In most cases, this involves BURIAL which leads to a rise in temperature and pressure

3. Occurs in rocks due to the effects of
METAMORPHISM
Occurs in rocks due to the effects of
High temperature
High pressure

4. HEAT EFFECTS
Temperature increases with depth or contact with magma
Recrystallization – a process that forms new mineral crystals because the mineral is no longer stable at the new temperature
Changes to a new (high temperature) mineral

5. PRESSURE EFFECTS Mineral crystals grow larger
Pressure increases with depth – weight of overlying rock
Mineral crystals grow larger
Mineral crystals are more dense
Mineral crystals grow perpendicular to pressure
Mineral crystals are arranged in parallel layers – PRODUCES FOLIATION

6. FOLIATION
Pressure actually rearranges the minerals into parallel layers.
More pressure – minerals grow larger and recrystallize and separate into layers
Even more pressure – alternating layers of light and dark minerals called
Banding

8. Random arrangement of minerals
Organized arrangement of minerals - banding

9. METAMORPHIC ROCK MANTRA
INTERGROWN CRYSTALS IN AN ORGANIZED PATTERN

10. Granite
Intergrown crystals
random pattern
Gneiss
Intergrown crystals
Organized Pattern

11. 2 Types of Metamorphism
Regional Metamorphism – Occurs over large areas where there is active mountain building
Convergent plate boundaries
Contact Metamorphism – areas in contact with magma intrusions and/or lava extrusions

13. MOUNTAIN
BUILDING
Let’s start with regional metamorphism

14. FOLIATED METAMORPHIC ROCKS

16. GRADES OF METAMORPHISM
LOW GRADE – LESS HEAT AND PRESSURE – SLATE
HIGH GRADE – MORE HEAT AND PRESSURE - GNEISS

17. FOLIATED METAMORPHIC ROCKS

18. METAMORPHIC ROCKS WILL OFTEN BE DEFORMED BECAUSE OF INTENSE HEAT AND PRESSURE
LOOK AT ROCK SYMBOL FOR GNEISS

19. DEFORMED GNEISS

20. A metamorphic rock exposed to too much heat will melt and become ???
MAGMA

21. CONTACT METAMORPHISM

22. Contact Metamorphic Metamorphism means "changed form".
The Changes occur because of:
Heat from magma intruding on the surrounding rock
Very little pressure

23. Near magma chambers (plutons)
Rocks in “contact” with the magma are baked
New minerals are formed –recrystallization
Transition zone of contact metamorphism is usually relatively narrow baking the adjacent rocks

24. Contact Metamorphism – Baking the adjacent rocks

25. Symbol for Contact Metamorphism is a line with tick marks
When limestone undergoes contact metamorphism what rock will it metamorphose into? Marble!

26. PARENT ROCK IN THE COMMENTS

27. LIMESTONE METAMORPHOSES INTO MARBLE

28. SANDSTONE METAMORPHOSES INTO QUARTZITE