Week 7

Question 1

Parent rock (protolith)

Answer 1

The rock before metamorphism

Question 2

Metamorphic grade

Answer 2

The degree to which a parent rock changes during metamorphism. It varies from low grade (temperature and pressure) to high

Question 3

Recrystallization

Answer 3

The formation of new mineral crystals in a rock that tend to be larger than the original

Change in shape and size of grains without changing ID of mineral

Question 4

Noecrystallization

Answer 4

Brand new minerals formed from protolith

Question 5

Confining pressure

Answer 5

Stress that is applied in all directions

Question 6

Differential stress

Answer 6

Forces that are unequal in all directions

CONVERGENT PB

Question 7

Compressional stress

Answer 7

Differential stress that shortens a rock body

Question 8

Shear stress

Answer 8

J

Question 9

3 types of stress

Answer 9

Differential
Compressional
Shear

Question 10

Texture (foliation)

Answer 10

Refers to any planar( flat) arrangement of mineral grains or crystals within a rock. Driven by compressional stress. Includes banding/ cleavage

Layers

Question 11

Non foliation

Answer 11

Tends to be one type. No layers

Where deformation is minimal
Hydrothermal

Question 12

Contact metamorphism

Answer 12

Changes in rock caused by the heat from a nearby magma body

Question 13

Hydrothermal metamorphism

Answer 13

Chemical alterations that occur as hot iron rich water circulates through fractures in rock

Enhances recrystallization

Question 14

Subduction zone (burial) metamorphism

Answer 14

High pressure low temperatures metamorphism that occurs where sediments are carried to great depths by a subducting plate

Question 15

Types of metamorphic environments

Answer 15

Hydrothermal: low pressure, low to mid temp

Contact: low pressure, low to high temp

Regional: low to high temperature and pressure

Subd zone; high pressure low temp

Question 16

4 agents that drive metamorphism

Answer 16

Heat
Pressure
Directional stress
Chemically active fluids

Question 17

How is confining pressure different from differential stress

Answer 17

Confining pressure squeezes rock equally in all directions, differential is greater in one direction than others.

Question 18

Define foliation

Answer 18

Refers to any planar( flat) arrangement of mineral grains or crystals within a rock. Driven by compressional stress. Includes banding/ cleavage

Question 19

How does a slate change to a phylite and so on

Answer 19

Goes through regional metamorphism. Low to high grade metamorphism

Slate phylite schist gneiss

Question 20

What is the agent of hydrothermal metamorphism

Answer 20

Hot iron fluids / water

Question 21

What type of plate boundary is associated with regional metamorphism

Answer 21

Convergent plate boundary

Question 22

How does contact metamorphism work

Answer 22

Rocks surrounding a molten igneous body are baked. Alters rock adjacent to the heat source called an aureole.

Question 23

Regional metamorphism

Answer 23

Metamorphism associated with large scale mountain building

Folding and faulting

Question 24

Phase change

Answer 24

Transforms one mineral into another. Same composition different structure

Question 25

Metamorphic rocks

Answer 25

Meta= change from one rock type team another

Altering of any pre existing rock through a solid state Change

Question 26

Temperatures of metamorphism

Answer 26

200-700 degrees

Question 27

Causes of metamorphism 4

Answer 27

Heat- subducting lithosphere leads to recrystallization/ne

Pressure: confining/ differential stress. Leads to phase change/ neo

Water- hot water will accelerate processes

Importance of parent rock

Question 28

Is ductile high or low pressure?

Answer 28

(No fractures) high confining pressure

Fractures- low confining pressure

Question 29

Read figure 8.3

Answer 29

J

Question 30

Metamorphism

Answer 30

Transforms one rock type into another

Process that changes the mineralogy, texture, and sometimes chemical composition that of a rock