Metamorphic

Question 1

How do metamorphic rocks form?

Answer 1

when a pre-existing undergoes a solid-state change in response to the modification of its environment at depth

Question 2

What are in meta rocks?

Answer 2

meta minerals, these are new minerals that grow in place under metamorphic conditions

Question 3

What are groups of minerals called?

Answer 3

Mineral assemblies

Question 4

How are meta textures defined?

Answer 4

alignment of mineral grains

Question 5

how do meta minerals and textures form?

Answer 5

Recrystallization

Question 6

What is phase change?

Answer 6

transform one mineral to another with the same chemical composition but different atomic structure (polymorphs)

Question 7

Define Neocrystallization

Answer 7

growth of a new mineral

Question 8

How does neocrystallization happen?

Answer 8

pressure solution, wet rocks get squeezed, parts dissolve, new minerals precip out

Question 9

How does plastic deformation work?

Answer 9

rocks get squeezed or sheared at elevated temps or pressures causing mineral grains to align and develop foliation

Question 10

What causes metamorphism?

Answer 10

heat

Question 11

What happens when you go deeper into Earth?

Answer 11

Temps and pressure rises

Question 12

What happens if you subject rocks to pressure?

Answer 12

causes atoms to get tighter

Question 13

how do Earth’s temps increase

Answer 13

~25 degrees celcius/km, at 20km ~500 celsius

Question 14

What is the most formed temperature?

Answer 14

~250-800 degrees

Question 15

how is pressure measured?

Answer 15

0.3 kbar/km, 1 kbar=14,000 psi

Question 16

What kbar measurement forms the most rocks?

Answer 16

3-12 bars

Question 17

what is it called when a material is squeezed or sheered unevenly from different directions?

Answer 17

differential stress

Question 18

Describe normal stress vs sheer stress

Answer 18

normal: push or pull, perpendicular to surface, smash of pizza dough
sheer stress: push or pull, parallel to surface, making a pb&j

Question 19

List 4 foliated and non foliated rocks

Answer 19

Foliated:slate, phyllite, schist, gneiss
Non foliated: Hornfels, marble, quartzite, amphibolite (can be foliated)

Question 20

Is all metamorphism the same?

Answer 20

no

Question 21

How is the metamorphic grade measured? (Low, intermediate, High)

Answer 21

low-200-400 degrees celsius
Int-400-600 degrees Celsius
High-over 600 degrees

Question 22

What is it called when we get groups of minerals under different metamorphic conditions?

Answer 22

mineral assemblies

Question 23

What is a particular mineral whose pressure and temp conditions are well known?

Answer 23

Index mineral

Question 24

where does metamorphism occur?

Answer 24

contact metamorphism, adjacent to igneous intrusions

Question 25

Describe regional metamorphism

Answer 25

occurs over large areas, results in continental collusion, produces foliated meta rocks