Rocks

The Geologic Dictionary

Rock Cycle

Magma

Igneous Rocks

Sedimentary Rocks

Metamorphic Rocks

Sediment

Crystallization Melting

Metamorphism

Lithification

Weathering

Erosion

Transport

Deposition

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

Metamorphic Grade

• Parent Rock Composition

• Temperature• Pressure• Fluids

Factors that affect Metamorphism

Metamorphic Rocks - Identification

Rock Identification is based on:

• Composition

What minerals make up the rock?

• Texture

What is the shape, size and orientation of the mineral grains that make up the rock?

Metamorphic Textures(All Crystalline)

Foliated

Nonfoliated

Foliation

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)