Principles of Geology

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Principles of Geology

• Chapter 8 Metamorphism and Metamorphic Rocks

Mian Liu 2007
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Figure 8.1
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Figure 8.1
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Metamorphic rocks formed from alteration of
other rocks due to changes of P, T, and reaction
with fluids
Metamorphism the processes of change one rock
into another
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Metamorphism

• Metamorphic settings
• Contact or thermal metamorphism driven by a
  rise in temperature within the host rock
• Hydrothermal metamorphism chemical alterations
  from hot, ion-rich water
• Regional metamorphism
• Occurs during mountain building
• Produces the greatest volume of metamorphic rock
• Rocks usually display zones of contact and/or
  hydrothermal metamorphism

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What causes metamorphism?
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Figure 8.3
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How metamorphism alters rocks

• Texture changes
• Foliation
• Rock (slaty) cleavage
• Schistosity
• Gneissic texture
• Nonfoliated texture
• Mineralogical changes

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Figure 8.8
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Figure 8.9
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Common Metamorphic Rocks

• Foliated
• Slate
• Phyllite
• Schist
• Gneiss
• Nonfoliated
• Marble
• quartzite

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Common Metamorphic Rocks

• Foliated
• Slate
• Phyllite
• Schist
• Gneiss
• Nonfoliated
• Marble
• quartzite

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Figure 8.12
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Metamorphic Environment

• Contact or Thermal metamorphism
• Associated with pluton intrusion
• Hydrothermal metamorphism
• Associated with hydrothermal fluids
• Regional metamorphism
• Associated with mountain building
• Cataclastic metamorphism
• Associated with faults

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Figure 8.19A,B
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Figure 8.19C
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Figure 8.20
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Figure 8.21
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Regional metamorphism often occurs during
mountain building at convergent plate boundaries
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Figure 8.23
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Figure 8.23
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Figure 8.A
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Figure 8.B
tektite
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Metamorphic zones
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Figure 8.24
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Index minerals and metamorphic grades
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metamorphic zones in New England
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Rock Cycles
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End of Ch8