Formation of metamorphic rocks

Formation of Metamorphic Rocks - Most changes occur at high temperatures and pressures a few km below the Earth’s surface... Contact Metamorphism – hot magma moves into rock.. Regional

3.4 Metamorphic Rocks

Metamorphism – “to change form”

I Formation of Metamorphic Rocks

- Most changes occur at high temperatures and pressures a

few km below the Earth’s surface

Gneiss Rock

A Contact Metamorphism –

hot magma moves into rock.

B Regional Metamorphism –

results in large-scale

deformation and high-grade metamorphism.

II Agents of Metamorphism

* A Heat – The most important agent Provides the energy needed to drive

chemical reactions.

- The heat comes from magma and the change in temperature with depth.

*B Pressure (Stress) –

Causes a more compact

rock with greater density

Origin of Pressure in Metamorphism

III Classification of Metamorphic

Rocks

• Can be classified by texture and

composition.

A Foliated Metamorphic Rocks - rock has a layered or banded

appearance.

Ex: Gneiss & Schist.

Gneiss Typically Displays a

Banded Appearance

B Nonfoliated Metamorphic Rocks –

- Does not have a banded texture

- Most only contain one mineral Ex: Marble (calcite)

parent rock = limestone & Quartzite

Marble

Marble - A Nonfoliated

Metamorphic Rock

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