1. TYPES OF ROCKS

2. Tectonics and Metamorphism
Regional metamorphism
Zone of burial metamorphism
Granitic magma rises and causes contact metamorphism
Blueschist and eclogite metamorphism
Figure 10.13
© 2008, John Wiley and Sons, Inc.

3. What’s metamorphism?
The set of changes that occur in rocks as a result of elevated temperatures and pressures. It takes place in solid state, without melting.

4. Underground, very deep but specially where there are stress forces
Where does it occur?
Squeeze
Underground, very deep but specially where there are stress forces

5. Factors in metamorphism?
Temperature and pressure.

6. Types of metamorphism
Figure 10.2
© 2008, John Wiley and Sons, Inc.

7. Metamorphism is a complex process including:
Loss of water
Orientation of minerals.
Recrystallization.
New minerals formation.

8. Second process: orientation.
Extreme pressure produces foliation, a planar arrangement of mineral grains giving a layered texture. (Esquistosidad)
See animation:

9. Third process: recrystallization.
Increasing the size of some minerals.
Shale
Slate
Phyllite
Sedimentary
Rock
Fine grained, low grade metamorphic rock with slaty cleavage.
Fine grained, high grade metamorphic rock with foliation.
© 2008, John Wiley and Sons, Inc.

10. From shale to gneiss Figure 10.3 Diagenesis Low-Grade Medium-Grade
Slate
Medium-Grade
Phyllite
* Sillmanite and Kyanite
Al2O3 with different
crystal structures
High-Grade
© 2008, John Wiley and Sons, Inc.
Gneiss

11. There are some metamorphic rocks without foliation. Why?

12. If the previous rock hasn’t got planar components foliation is impossible
Sandstone
Quartzite
Very little foliation due to low diversity of minerals.
Dominantly quartz minerals
Video sobre recristalización:

13. Quarzite and marble are metamorphic rocks without foliation
Made of cacite Made of quartz
From limestones From sandstones
Soft, it reacts with acid Hard, it doesn’t react

14. A collection of metamorphic rocks