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Metamorphic Rock SourcesMetamorphic 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 ShaleIndex Minerals
Lignite Bituminous
500 Anthracite
300 600 Graphite Marble Slate Chlorite
700 Greenstone
800 Quartzite Phyllite Biotite
500 900 Schist Garnet
1000 Amphibolite Staurolite
600 1100Gneiss
Kyanite
1200 Sillimanite
700Melting Begins
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 (20-30 degrees Celsius per kilometer below the surface). Due to radioactive decay.----Regional- Metamorphism
•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 (Converging- Boundaries) or those
•Transform Boundaries (side-by-side movement)
Effects of Metamorphism on Rocks
• Pore Space between grains is lost due to Compression.
• Rock density increases.
Regional Metamorphism
•Occurs in large areas.
•Occurs in response to deep burial by large areas of rock.
•Occurs with Mountain Building (Collision Boundary).
Increasing metamorphic grade
Increasing foliation
Foliated Metamorphic Rocks
slate phyllite schist gneiss migmatite
(low grade) (high grade)
(partially melted)
Thermal or Contact Metamorphism
•Occurs when rock comes into contact with Magma or hot Pore Fluids (Geysers and Hot Springs).