Metamorphic Rocks
“Metamorphic”
“Metamorphic” means Change!
Biochemical Limestone
Marble
Metamorphic Rock Sources
Metamorphic rocks are formed when:
1.Igneous
2. Sedimentary or
3. Pre-existing Metamorphic rocks are
Metamorphic Rock Classification
Metamorphic Rocks are classified based on:
1. Formation Conditions (where formed)
2. Texture
3. Parent Rock (what rock, or rock type, it came from)
Quartzite- Fine Grained
Gneiss- Foliated
Common Metamorphic Rocks
Rock Name
Parent Rock
Slate
Shale or Mud
Mica
Shale or Mud
Gneiss
Granite
Quartzite
Sandstone
Marble
Limestone
Temp C
Temp F
Coal
Limestone
Sandstone
Basalt
Shale
Index
Minerals
Slate
Chlorite
Phyllite
Biotite
Schist
Garnet
Lignite
Bituminous
300
500
Anthracite
600
Graphite
Marble
700
800
500
1100
1200
700
Quartzite
900
1000
600
Greenstone
Amphibolite
Staurolite
Gneiss
Kyanite
Sillimanite
Melting
Begins
Slate
Mica
Gneiss
Quartzite
Marble
Schist
What Causes Metamorphic
Rocks to Form?
Metamorphic Rocks are formed when preexisting
rocks are changed by:
And
Sources of Heat
•Increase in Temperature due to Deep Burial (2030 degrees Celsius per kilometer below the
surface). Due to radioactive decay.----RegionalMetamorphism
•Increase in Temperature due to Plate Friction
(100-300 degree Celsius per km below the
surface). -----Dynamic Metamorphism
•Intrusion by hot Magma. ----Contact
Metamorphism
Sources of Pressure
• Weight of Overlying Rocks (1 cubic foot of
granite weighs 167 pounds)
•Created by converging plates (ConvergingBoundaries) or those
•Transform Boundaries (side-by-side movement)
Effects of Metamorphism on
Rocks
• Impurities such as holes and fossils
destroyed.
Effects of Metamorphism on
Rocks
• Pore Space between grains is lost due to
Compression.
• Rock density increases.
Effects of Metamorphism on
Rocks
•Mineral Grains are flattened, enlarged and
elongated.
Types of Metamorphism
Regional Metamorphism
Regional Metamorphism
•Occurs in large areas.
•Occurs in response to deep burial by large
areas of rock.
•Occurs with Mountain Building (Collision
Boundary).
Regional Metamorphism
Regional Metamorphism
Foliated Metamorphic Rocks
Increasing metamorphic grade
Increasing foliation
slate
phyllite
schist
gneiss
migmatite
(partially melted)
(low grade)
(high grade)
Dynamic Metamorphism
• Occurs between moving plates (very localized
and happens quickly).
Thermal or Contact
Metamorphism
•Occurs when rock comes into contact with Magma or
hot Pore Fluids (Geysers and Hot Springs).
Thermal or Contact
Metamorphism