Metamorphic Rocks 30 Flashcards
What are metamorphic rocks made up of
Sedimentary or igneous rocks
How are meta metamorphic rocks changed
By great heat or pressure or both
They change physically and chemically
Give an example of 4 metamorphic rocks
Quartzite from sandstone (thermal)
Marble from limestone or chalk (thermal)
Slate from shale (dynamic)
Gneiss from granite (regional)
Name the 3 types of metamorphism
Thermal
Dynamic
Regional
How does thermal metamorphism work
Intrusion of molten magma into crust
Comes into contact with rock and bakes it
What happens when a rock is ‘baked’
It causes recrystallisation of the rock minerals
Where does thermal metamorphism take place
Along edges of dykes and batholiths
What is an aureole
It is the surrounding band of rock that is cooked because thermal metamorphism is localised
Give an irish example of quartzite
Sugar load Wicklow
Give an example of gneiss
Bulmullet, Mayo
What was quartzite changed from
Sandstone (sedimentary)
What was marble changed from
Limestone or chalk
Where can marble be found in Ireland
White marble of rathlin island, Antrim
At what temp does metamorphism take place at
250-850
What is dynamic metamorphism
From great pressure
What causes pressure dynamic
Plate movement and along fault lines
Is metamorphic rocks harder or softer
Harder
What is slate made from
Shale
What can slate be used for
Good building material
Why is slate good for building
It can be split easily
Slate is a purple-grey foliated rock
What is regional metamorphism
Rocks changed from heat and pressure over a large area
Where does regional metamorphism take place
Zones of fold mountain building and subduction zones
How does regional metamorphism happen
> Plate movement puts pressure on rock forcing it deep into earths crust
here they are heated up to 1000 degrees
Example of a regional metamorphic rock
Gneiss from granite
What is foliation
A process that occurs when pressure is greater on one side causing the mineral crystals in a rock to line up in parallel bands
In what two rocks can foliation be seen
Gneiss
Slate - layers are very thin (flattened and hardened)
What can damage marble
Acid rain
What is marble
A course grained rock made from limestone or chalk
It is used in tiles and headstones
Can be damaged by acid rain
White marble used to build Taj Mahal in India
What is a protolith
The older rock that existed before metamorphism
