This document defines metamorphic rocks as rocks that have changed from their original form due to heat, pressure, and fluid activity. It discusses the different types of metamorphism including contact metamorphism caused by igneous intrusions, dynamic metamorphism associated with fault zones, and regional metamorphism caused by plate tectonics over large areas. Metamorphic rocks can have foliated textures with layering or non-foliated massive textures depending on the direction of pressure during metamorphism.

2. DefinitionsDefinitions
• Metamorphic Rock
- "Meta"= Change (Grk)
- "Morph"= form (Grk)
• Metamorphic Rock
- "Meta"= Change (Grk)
- "Morph"= form (Grk)
- a rock that has been changed
from its original form ( parent ) by
heat , pressure , and fluid activity
into a new rock ( daughter ).
- a rock that has been changed
from its original form ( parent ) by
heat , pressure , and fluid activity
into a new rock ( daughter ).
Metamorphic RocksMetamorphic Rocks

3. HeatHeat
• Magma
- temperature of magma
- composition of magma
• Magma
- temperature of magma
- composition of magma
• Geothermal gradient
- temperature increases with depth of burial
- core of Earth is warmer than outer crust
• Geothermal gradient
- temperature increases with depth of burial
- core of Earth is warmer than outer crust
Sources Include.....Sources Include.....

4. Uniform PressureUniform Pressure vs Directed Pressure
• Lithostatic
- "Lithos"= rock, static= unchanged (pressure)
- uniform (aka non-directed)
- equal intensity from all directions by rocks
• Lithostatic
- "Lithos"= rock, static= unchanged (pressure)
- uniform (aka non-directed)
- equal intensity from all directions by rocks

5. Directed Pressure
one direction of squeezing is much stronger
than the others
Minerals align themselves to reduce stress.

6. Types of MetamorphismTypes of Metamorphism
• Contact
- caused by igneous activity
• Dynamic
- aka cataclastic
- associated with faults & earthquake zones
• Regional
- caused by tremendous pressures
associated with tectonic plate activity
• Contact
- caused by igneous activity
• Dynamic
- aka cataclastic
- associated with faults & earthquake zones
• Regional
- caused by tremendous pressures
associated with tectonic plate activity

7. Contact MetamorphismContact Metamorphism
• Igneous Intrusions
- size and type of magma important
> mafic magma hotter than felsic
- heat decreases away from magma
> forms a zone of altered country rocks called Aureoles
• Igneous Intrusions
- size and type of magma important
> mafic magma hotter than felsic
- heat decreases away from magma
> forms a zone of altered country rocks called Aureoles
Sometimes creates a metamorphic rock called a
hornfels -in essence a “cooked” rock

9. Dynamic MetamorphismDynamic Metamorphism
• aka Cataclastic Metamorphism
• associated with Fault Zones
- Places where the Earth's crust ruptured
- Rock pulverized
> heat and pressure come from movement along the
Fault
• resultant rock is known as a Mylonite
• aka Cataclastic Metamorphism
• associated with Fault Zones
- Places where the Earth's crust ruptured
- Rock pulverized
> heat and pressure come from movement along the
Fault
• resultant rock is known as a Mylonite

10. Regional MetamorphismRegional Metamorphism
• Most common form of metamorphism
• caused by large scale forces
- lithospheric plate collision
• covers very large areas
- metamorphic belts or zones
- Zones are characterized by Index Minerals
> form under specific temperatures and pressures
> metamorphic facies
• commonly associated with
- shields: stable areas of crystalline rocks
• Most common form of metamorphism
• caused by large scale forces
- lithospheric plate collision
• covers very large areas
- metamorphic belts or zones
- Zones are characterized by Index Minerals
> form under specific temperatures and pressures
> metamorphic facies
• commonly associated with
-
Shields and Mountains: areas of crystalline rocks

11. Shields of the WorldShields of the World

12. Metamorphic TexturesMetamorphic Textures
• Foliated
- Folios = page or leaf-like
- rock has distinct banding or layering
> often not smooth like in sedimentary rocks
- formed under directed pressure
• Non-foliated
- no distinct layering character
- often a massive crystalline texture
- formed under uniform pressures
• Foliated
- Folios = page or leaf-like
- rock has distinct banding or layering
> often not smooth like in sedimentary rocks
- formed under directed pressure
• Non-foliated
- no distinct layering character
- often a massive crystalline texture
- formed under uniform pressures

13. Foliated TextureFoliated Texture

14. Foliated TexturesFoliated Textures
• Slatey
- looks like blackboard
> dull surface
- smooth, thin layering
- breaks into flat slabs
> referred to as slatey cleavage
- no mineral grains visible
• Phyllitic
- looks like waxed surface
> has a "sheen" to it
- may have little "waves" on
surface
> referred to as crenulations
- some small grains visible
• Slatey
- looks like blackboard
> dull surface
- smooth, thin layering
- breaks into flat slabs
> referred to as slatey cleavage
- no mineral grains visible
• Phyllitic
- looks like waxed surface
> has a "sheen" to it
- may have little "waves" on
surface
> referred to as crenulations
- some small grains visible
• Schistose
-
- visible grains
> garnets, staurolites
- may have shiny
> due to mica minerals
• Gneissic
- larger grains
- may look like igneous rock
- may have crude banding
> intensely distorted
- different minerals than
schistose
• Schistose
- distinct bands of minerals
- visible mineral grains
> garnets, staurolites
- may have shiny
appearance
> due to mica minerals
• Gneissic
- larger grains
- may look like igneous rock
- may have crude banding
> intensely distorted
- different minerals than
schistose

15. Foliated MM RocksFoliated MM Rocks
slateslate
schistschist gneissgneiss
phyllitephyllite
MM Rocks that could form as a shale (sedimentary) parent rock isMM Rocks that could form as a shale (sedimentary) parent rock is
exposed to increasing directed pressure and temperature

16. • Marble:
- metamorphosed
limestone
• Quartzite:
- metamorphosed
quartz sandstone
• Quartzite:
- metamorphosed
quartz sandstone
Non-foliated RocksNon-foliated Rocks

17. Environment of Formation- EOF
look for specific minerals
Map out where those minerals are found
reconstruct T & P for given minerals
Find a modern setting that has similar T & P
using Uniformitarianism

18. Metamorphic ZonesMetamorphic Zones

19. Metamorphic Zones-MapMetamorphic Zones-Map

20. Metamorphic FaciesMetamorphic Facies
• distinctive metamorphic lithologies that occur in well
defined areas and named after the key rocks found
• distinctive metamorphic lithologies that occur in well
defined areas and named after the key rocks found

21. • Metamorphism is common along most plate boundaries like this.
Metamorphic ZonesMetamorphic Zones