1. Metamorophic Rock
Chapter 6
Section 3

2. Recognizing Metamorphic Rock
Metamorphosed rocks have been changed
Heat and pressure turn rocks to magma
Rocks that don’t reach their melting point
Texture changes
Mineral composition changes
Chemical composition changes

3. Recognizing Metamorphic Rock
During Metamorphism rocks change while they are still solid
Heat required for metamorphic rock to form
Deep within Earth
Near intrusions
Pressure also needed
Deep burial
Compression during mountain building

4. Metamorphic Minerals Foliated Nonfoliated Layers and bands
High pressure during metamorphism causes flat or needlelike crystals
Perpendicular to pressure
Parallel alignment of minerals creates the layers in foliated metamorphic rocks.
Form in blocky shapes
Examples:
Quartzite and marble

5. Grades of Metamorphism
Different combinations of heat and pressure result in different grades.
Low grade
Low temperature and low pressures
High grade
High temperature and high pressure
Intermediate grade
In between high and low grade metamorphism

6. Types of metamorphism Regional Metamorphism
High temperatures and pressure affect large regions
Range in grade from low to high
Results include
Changes in minerals
Changes in rock type
Folding and deforming of rock layers

7. Types of metamorphism Contact Metamorphism
Molten material (an intrusion) come in contact with solid rock
Local effect
High temperature to moderate/low pressure
Temperature decreases with distance from an intrusion, metamorphic effects decrease with distance.

8. Types of Metamorphism Hydrothermal Metamorphism
Very hot water reacts with rock
Alters chemical and mineral composition
Hot fluids migrate in and out of roc changing the mineral composition and texture.
Valuable ore formed this way
Gold, copper, zinc, tungsten and lead

9. Economic importance
Salt
Gold, silver, copper and lead
Fossil fuels

10. Metallic mineral resources
Occur mostly as metal ores
Many are precipitated from hydrothermal solutions
In veins- gold
Spread through the rock mass
In intrusions or in contact metamorphic zones

11. Non-metallic mineral resources
Metamorphism of ultrabasic igneous rocks
Talc and asbestos

12. Rock cycle
The continuous changing and remaking of rocks.