Transcript Diapositiva 1 - IES La Madraza

TYPES OF ROCKS
Tectonics and Metamorphism
Regional metamorphism
Zone of burial metamorphism
Granitic magma rises and causes
contact metamorphism
Figure 10.13
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Blueschist and eclogite
metamorphism
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.
Where does it occur?
Underground, very deep but specially
where there are stress forces
Factors in metamorphism?
Temperature and pressure.
Types of metamorphism
Figure 10.2
© 2008, John Wiley and Sons, Inc.
Metamorphism is a complex process including:
•Loss of water
•Orientation of minerals.
•Recrystallization.
•New minerals formation.
Second process: orientation.
Extreme pressure produces foliation, a planar
arrangement of mineral grains giving a layered
texture. (Esquistosidad)
See animation: http://www.bioygeo.info/Animaciones/Foliation1.swf
Third process: recrystallization.
Increasing the size of some minerals.
Shale
Sedimentary
Rock
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Slate
Fine
grained, low grade
metamorphic rock with
slaty cleavage.
Phyllite
Fine grained, high grade
metamorphic rock with
foliation.
From shale to gneiss
Figure 10.3
Diagenesis
Shale
Low-Grade
Slate
Medium-Grade
Phyllite
* Sillmanite and Kyanite
Al2O3 with different
crystal structures
© 2008, John Wiley and Sons, Inc.
High-Grade
Gneiss
There are some metamorphic rocks
without foliation. Why?
If the previous rock hasn’t got planar components
foliation is impossible
Sandstone
Dominantly quartz minerals
Quartzite
Very little foliation due to low diversity of
minerals.
Video sobre recristalización: http://www.youtube.com/watch?v=J_2FdkRqmCA&feature=related
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
A collection of metamorphic rocks