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Flashcards in Week 7 Deck (30):
1

Parent rock (protolith)

The rock before metamorphism

2

Metamorphic grade

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

3

Recrystallization

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

4

Noecrystallization

Brand new minerals formed from protolith

5

Confining pressure

Stress that is applied in all directions

6

Differential stress

Forces that are unequal in all directions

CONVERGENT PB

7

Compressional stress

Differential stress that shortens a rock body

8

Shear stress

J

9

3 types of stress

Differential
Compressional
Shear

10

Texture (foliation)

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

Layers

11

Non foliation

Tends to be one type. No layers

Where deformation is minimal
Hydrothermal

12

Contact metamorphism

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

13

Hydrothermal metamorphism

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

Enhances recrystallization

14

Subduction zone (burial) metamorphism

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

15

Types of metamorphic environments

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

16

4 agents that drive metamorphism

Heat
Pressure
Directional stress
Chemically active fluids

17

How is confining pressure different from differential stress

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

18

Define foliation

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

19

How does a slate change to a phylite and so on

Goes through regional metamorphism. Low to high grade metamorphism

Slate phylite schist gneiss

20

What is the agent of hydrothermal metamorphism

Hot iron fluids / water

21

What type of plate boundary is associated with regional metamorphism

Convergent plate boundary

22

How does contact metamorphism work

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

23

Regional metamorphism

Metamorphism associated with large scale mountain building

Folding and faulting

24

Phase change

Transforms one mineral into another. Same composition different structure

25

Metamorphic rocks

Meta= change from one rock type team another

Altering of any pre existing rock through a solid state Change

26

Temperatures of metamorphism

200-700 degrees

27

Causes of metamorphism 4

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

28

Is ductile high or low pressure?

(No fractures) high confining pressure
Fractures- low confining pressure

29

Read figure 8.3

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30

Metamorphism

Transforms one rock type into another

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