1.4 Metamorphic Rocks And Processes

Question 1

How do metamorphic rocks form?

Answer 1

Recrystallisation of a parent rock

Caused by temperature +/or pressure making the parent rocks composition +/or texture change

Question 2

What are the two types of metamorphism?

Answer 2

Contact and regional

Question 3

Explain contact metamorphism?

Answer 3

1. Crystalline texture
2. High temperature
3. Low pressure
4. Next to igneous bodies eg baked margin, metamorphic aureole
5. Random orientation
6. Minerals = meta quartzite, marble, hornfels, spotted rock

Question 4

Explain regional metamorphism?

Answer 4

1. Crystalline texture
2. High temperature
3. High pressure
4. Convergent plate boundaries eg subduction zone, orogenic belts (fold mountains)
5. Crystal becomes aligned perpendicular to pressure
6. Minerals = gneiss, slate, marble, meta quartzite, schist

Question 5

Explain how sandstone, limestone, clay metamorphose?

Answer 5

1. Sandstone only becomes metaquartzite (boring!)
2. Limestone only becomes marble (boring!)
3. Clay is chemically diverse (different elements) because many minerals break down by chemical weathering to form clays

Question 6

What is foliation?

Answer 6

The alignment of minerals in regional metamorphic rock
Has different foliation names in different rocks
Slate = slatey cleavage
Marble = foliation
Meta quartzite = foliation
Gneiss = gneissose banding
Schist =schistosity