Metamorphic Rocks - Sacramento State rocks.pdf · 3 Metamorphic Rocks Metamorphism – The...
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1 Metamorphic Rocks Metamorphic Rocks Metamorphism – The transformation of pre-existing rocks into new types by the action of heat and pressure changes. Photos by C.C. Plummer
Transcript of Metamorphic Rocks - Sacramento State rocks.pdf · 3 Metamorphic Rocks Metamorphism – The...
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Metamorphic Rocks
Metamorphic Rocks
Metamorphism – The transformation of pre-existing rocks into new types by the action of heat and pressure changes.
Photos by C.C. Plummer
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Metamorphic Rocks
Metamorphism – The transformation of pre-existing rocks into new types by the action of heat and pressure changes.
Heat – from magma intrusion, compression, or decay of radioactive elements. Generally, at depths of about 35 km, temps are high enough to begin melting rocks.
Metamorphic Rocks
Metamorphism – The transformation of pre-existing rocks into new types by the action of heat and pressure changes.
Pressure – generates heat, and along points of contact can melt rocks. Also generates the development of banded and foliated textures. Increasing pr4essure conditions force grains closer together and eliminates pore space.
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Metamorphic Rocks
Metamorphism – The transformation of pre-existing rocks into new types by the action of heat and pressure changes.
Chemically active fluids – chemical exchange of elements generate different mineral compositions.
Metamorphic Rocks
Two different types of metamorphism:
1. Contact metamorphism –occurs upon contact of hot igneous rocks and surrounding country rocks. As distance from intrusion increases degree of metamorphism decreases.
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Metamorphic Rocks
Two different types of metamorphism:
1. Regional metamorphism –occurs upon contact of hot igneous rocks and surrounding country rocks. As distance from intrusion increases degree of metamorphism decreases.
Metamorphic Rocks
Identifying metamorphic rocks using texture.
Foliation – parallel arrangement of minerals
Photos by C.C. Plummer
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Metamorphic Rocks
Identifying metamorphic rocks using texture.
Foliated rocks:
Slate – metamorphosed clayey rocks (shale). Sheety appearance
Photo by C.C. Plummer Photo by P.D. Rowley, USGS
Metamorphic Rocks
Identifying metamorphic rocks using texture.
Foliated rocks:
Schist
Photo by C.C. Plummer
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Metamorphic Rocks
Identifying metamorphic rocks using texture.
Foliated rocks:
Gneiss
Metamorphic Rocks
Identifying metamorphic rocks using texture.
Foliated rocks:
Gneiss
Photo by C.C. Plummer
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Metamorphic Rocks
Identifying metamorphic rocks using texture.
Nonfoliated rocks:
Marble
Quartzite
Photo by C.C. Plummer
