Metamorphic Rocks

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Metamorphic Rocks
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Metamorphic
Metamorphic means Change!
Biochemical Limestone
Marble
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Metamorphic Rock Sources
Metamorphic rocks are formed when 1.Igneous 2.
Sedimentary or 3. Pre-existing Metamorphic rocks
are
changed
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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
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Common Metamorphic Rocks
Rock Name Parent Rock
Slate Shale or Mud
Mica Shale or Mud
Gneiss Granite
Quartzite Sandstone
Marble Limestone
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Temp C Temp F Coal Limestone Sandstone Basalt Shale Index 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 1100 Gneiss Kyanite
1200 Sillimanite
700 Melting Begins
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Slate
8
Mica
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Gneiss
10
Quartzite
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Marble
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Schist
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What Causes Metamorphic Rocks to Form?
Metamorphic Rocks are formed when preexisting
rocks are changed by
Heat
Pressure
And
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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

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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)

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Effects of Metamorphism on Rocks

• Impurities such as holes and fossils destroyed.

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Effects of Metamorphism on Rocks

• Pore Space between grains is lost due to
  Compression.
• Rock density increases.

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Effects of Metamorphism on Rocks

• Mineral Grains are flattened, enlarged and
  elongated.

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Types of Metamorphism
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Regional Metamorphism
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Regional Metamorphism

• Occurs in large areas.
• Occurs in response to deep burial by large areas
  of rock.
• Occurs with Mountain Building (Collision
  Boundary).

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Regional Metamorphism
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Regional Metamorphism
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Foliated Metamorphic Rocks
Increasing metamorphic grade
Increasing foliation
gneiss
phyllite
schist
migmatite
slate
(partially melted)
(high grade)
(low grade)
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Dynamic Metamorphism

• Occurs between moving plates (very localized and
  happens quickly).

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Thermal or Contact Metamorphism

• Occurs when rock comes into contact with Magma or
  hot Pore Fluids (Geysers and Hot Springs).

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Thermal or Contact Metamorphism