Metamorphic Rocks Flashcards
How do metamorphic rocks form?
As a result of metamorphism
Metamorphism is…
a change in a rock, either in its mineral content, its texture, its chemistry, or its structure
What can metamorphism change about a rock?
its mineral continue, its texture, its chemistry, or its structure
_____ refers to changes of an existing rock
Metamorphism
What conditions can metamorphism occur?
- high temperatures (>150C <800C)
- high pressures
What can speed up metamorphism?
when pore fluids are present
The presence of _____ such as highly concentrated saltwater tend to speed up chemical reactions
fluids
Can metamorphism occur at 801C?
No because the rock would start melting into magma
As you decrease under the crust temperature _____ and pressure ______.
increases, increases
High pressure, and high temperature create _____ grade metamorphic rocks.
high
Are low grad metamorphic rocks formed under high temp and pressure?
No, they are formed under low temp and pressures.
Often when rocks are metamorphosed, they form a texture known as ….
foliation
How does foliation form?
When rocks are compressed in one direction.
Often the mineral grains themselves will align perpendicular to the force.
What are the four main types of foliated metamorphic rocks? (from low to high grade)
- Slate
- Phyllite
- Schist
- Gneiss
A rock is a _____ if it has undergone very high grade metamorphosis so that the minerals separate into light & dark bands
Gneiss
