Rocks
The Geologic Dictionary
Metamorphic Rocks
Rocks Under Stress
Metamorphism
• Recrystalization• Solid-State Chemical
Reactions• No Melting
• Parent Rock Composition
• Temperature• Pressure• Fluids
Factors that affect Metamorphism
• Parent Rock Composition
• Temperature• Pressure• Fluids
Factors that affect Metamorphism
• Parent Rock Composition
• Temperature• Pressure• Fluids
Factors that affect Metamorphism
Lithostaticpressure
DirectionalPressure
Directed Pressure Results in:
Foliation
Foliation Under a Microscope
• Parent Rock Composition
• Temperature• Pressure• Fluids
Factors that affect Metamorphism
Metamorphic Rocks - Identification
Metamorphic Textures(All Crystalline)
Foliated
Nonfoliated
Composition - Index Minerals
Composition - Index Minerals
Mineral Composition - Geothermometers
Rock Forms:500-550°C
Staurolite - Forms 500-750°C
Garnet - Forms 450-700°C
Muscovite - Forms 300-550°C
Foliated Metamorphic Rocks
Parent Rock - Shale
Slate (Low Grade)
Schist (Medium Grade)
Foliated Rocks (cont.)
Felsic Parent Rock
Gneiss (High Grade)
Migmatite (Very High Grade)
NonFoliated Rocks
Parent RockLimestone
Marble(Low to High Grade)
Nonfoliated Rocks (cont.)
Quartzite
Metacoglomerate
Parent Rocks
Sandstone
Conglomerate
Metamorphic Rocks - Interpretation
Metamorphic Environments=
Metamorphic Facies
Metamorphic Rock “Translations”
• Chemical Composition
• Mineral Composition
• Foliation
• Parent Rock (Protolith)
• T & P of Formation(Depth / Facies)
• T & P of Formation (Depth / Facies)