Transcript metamorphic

Metamorphic Rocks
Metamorphic Rocks
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Both pressure and
temperature increase with
depth.
When pressure and
temperature become high
enough, rocks completely
melt to form magma .
But… if pressure and
temperature become high
enough to alter the texture,
mineralogy, or chemical
composition of the rocks
WITHOUT completely
melting them, we get
metamorphic rocks.
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In Greek the word meta
means change while
morphe` means form .
Types of Metamorphism
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Regional Metamorphism: When high
temperature and pressure affect large regions
of Earth’s crust, large belts of Regional
Metamorphism are produced.
Types of Metamorphism
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Contact Metamorphism: When molten rock
(magma) come in contact with existing rock,
Contact Metamorphism can occur.
Types of Metamorphism
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Hydrothermal Metamorphism: When very hot
water comes in contact with rock and alters
its chemistry and mineralogy.
Metamorphic Texture
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Foliated: Metamorphic Rocks that
contain wavy layers and bands of
minerals (caused by high
pressure).
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Nonfoliated: Minerals that contain
no bands or layers (heat plays the
larger role).
An Exception to the Rule
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Porphyroblasts: A condition where new
metamorphic minerals can grow, while
surrounding minerals stay small.
Metamorphic Rocks in N. America