Metamorphic Rocks

“Metamorphic” means Change!

“Metamorphic”

Biochemical Limestone Marble

Metamorphic Rock SourcesMetamorphic rocks are formed when:

1.Igneous

2. Sedimentary or

3. Pre-existing Metamorphic rocks are

Metamorphic Rock Classification

Metamorphic Rocks are classified based on:

1. Formation Conditions (where formed)

2. Texture

3. Parent Rock (what rock, or rock type, it came from)

Quartzite- Fine Grained

Gneiss- Foliated

Common Metamorphic Rocks

Rock Name Parent Rock

Slate Shale or Mud

Mica Shale or Mud

Gneiss Granite

Quartzite Sandstone

Marble Limestone

Temp C Temp F Coal Limestone Sandstone Basalt ShaleIndex Minerals

Lignite Bituminous

500 Anthracite

300 600 Graphite Marble Slate Chlorite

700 Greenstone

800 Quartzite Phyllite Biotite

500 900 Schist Garnet

1000 Amphibolite Staurolite

600 1100Gneiss

Kyanite

1200 Sillimanite

700Melting Begins

Slate

Mica

Gneiss

Quartzite

Marble

Schist

What Causes Metamorphic Rocks to Form?

Metamorphic Rocks are formed when preexisting rocks are changed by:

And

Sources of Heat

•Increase in Temperature due to Deep Burial (20-30 degrees Celsius per kilometer below the surface). Due to radioactive decay.----Regional- Metamorphism

•Increase in Temperature due to Plate Friction (100-300 degree Celsius per km below the surface). -----Dynamic Metamorphism

•Intrusion by hot Magma. ----Contact Metamorphism

Sources of Pressure• Weight of Overlying Rocks (1 cubic foot of granite weighs 167 pounds)

•Created by converging plates (Converging- Boundaries) or those

•Transform Boundaries (side-by-side movement)

Effects of Metamorphism on Rocks

• Impurities such as holes and fossils destroyed.

Effects of Metamorphism on Rocks

• Pore Space between grains is lost due to Compression.

• Rock density increases.

Effects of Metamorphism on Rocks

•Mineral Grains are flattened, enlarged and elongated.

Types of Metamorphism

Regional Metamorphism

Regional Metamorphism

•Occurs in large areas.

•Occurs in response to deep burial by large areas of rock.

•Occurs with Mountain Building (Collision Boundary).

Regional Metamorphism

Regional Metamorphism

Increasing metamorphic grade

Increasing foliation

Foliated Metamorphic Rocks

slate phyllite schist gneiss migmatite

(low grade) (high grade)

(partially melted)

Dynamic Metamorphism• Occurs between moving plates (very localized and happens quickly).

Thermal or Contact Metamorphism

•Occurs when rock comes into contact with Magma or hot Pore Fluids (Geysers and Hot Springs).

Thermal or Contact Metamorphism