Final

Question 1

What sedimentary, igneous, and metamorphic processes occur at convergent margins?

Answer 1

Convergent- subduction

Sedimentary- accretionary wedge (subducting plate sediments scraped onto upper plate), forearc basin (shale/sandstone?), trench (pelagic sediment), subducted sediments

Igneous- flux partial melting of the overlying mantle wedge

Metamorphic- High P/T (steep pressure increase/ slow, low temperatures), blueschist facies, dehydration/decarbonation, subduction metamorphism

Question 2

What sedimentary, igneous, and metamorphic processes occur at divergent margins?

Answer 2

Divergent: mid-ocean ridges

Sedimentary: siliceous/carbonate ooze

Igneous: Decompression Melting, tholeitic basalt magma, pillow basalts and gabbro (4km?)

Metamorphic: Low P/T (high T, low P), contact metamorphism

Question 3

What does thermal evolution mean?

Answer 3

changes in temperature and heat flow in geological settings over time
*influenced by plate tectonics and subduction

Question 4

What is the thermal evolution of a convergent margin?

Question 5

What is the thermal evolution of a divergent margin?

Question 6

What does surface heat flow mean?

Question 7

What is the surface heat flow of a convergent margin?

Question 8

What is the surface heat flow of a divergent margin?

Question 9

What does schematic isotherm mean?

Question 10

What are the schematic isotherms of The Drawing?

Question 11

Where do magmas form in convergent margins?

Question 12

Where do magmas form in divergent margins?

Question 13

How do magmas form in convergent margins?

Question 14

How do magmas form in divergent margins?

Question 15

What is the composition of a convergent margin magma?

Question 16

What is the composition of a divergent margin magma?

Question 17

What types of sediment are involved in convergent margin settings? What is their source?

Question 18

What types of sediment are involved in divergent margin settings? What is their source?

Question 19

What kinds of metamorphic rocks are formed in convergent margin settings?

Question 20

What kinds of metamorphic rocks are formed in divergent margin settings?

Question 21

List the differences in expected generalized metamorphic P-T paths.

Question 22

What are the depositional environments of the Philadelphia Wissahickon Schist?

Question 23

What is the tectonic evolution of the Philadelphia Wissahickon Schist?

Question 24

What is the timing of formation for the Philadelphia Wissahickon Schist?

Question 25

What process produced the Philadelphia Wissahickon Schist?

Answer 25

Continental collisional

Question 26

What metamorphism occurs in collisional processes like the Philadelphia Wissahickon Schist?

Answer 26

medium-P/T Barrovian

Question 27

What is a prograde metamorphic history?

Answer 27

- Subjecting a rock to increasing *temperature* and pressure - burial and heating - irreversible mineral assemblage changes

Question 28

What is a retrograde metamorphic history?

Answer 28

- decreasing *temperature* and pressure - decompression and cool - reversible mineral assemblage changes

Question 29

When do we hit maximum P and T in a P-T loop? When do we experience peak metamorphism?

Answer 29

Maximum P is reached first Peak metamorphism occurs at maximum T

Question 30

What is a P-T loop?

Answer 30

- A graphical representation of the pressure and temperature conditions experienced by a rock during its metamorphic history - The loop is traced to increasing temperatures and pressure and turn back to its origins as it is exhumed

Question 31

What information do we get from P-T loops?

Answer 31

1. maximum conditions 2. metamorphism duration 3. path 4. shape processing evolution

Question 32

What factors govern the thermal evolution of contact metamorphic aureoles?

Question 33

What factors govern the thermal evolution of subduction zones?

Question 34

What does metamorphism mean?

Question 35

What is a metamorphic facies?

Question 36

What processes lead to the formation of igneous rocks?

Answer 36

cooled/crystallized magma/molten rock

Question 37

What processes lead to the formation of metamorphic rocks?

Answer 37

solid-state changes in texture and mineralogy

Question 38

What are the major general types of metamorphic reactions?

Answer 38

1. solid-solid (polymorphic and multi-phase) 2. Devolatilization (dehydration, decarbonation) 3. Redox 4. Exchange reactions

Question 39

Explain the solid-solid polymorphic and multi-phase metamorphic reaction.

Question 40

Explain the devolatilization, dehydration, and decarbonation metamorphic reactions.

Question 41

Explain metamorphic redox.

Question 42

Explain metamorphic exchange reactions.

Question 43

What is the Barrovian metamorphic zone sequence?

Question 44

In what type of tectonic setting does Barrovian-style metamorphism generally occur?

Question 45

What generalized P/T prograde trajectory is expected of subduction zones?

Answer 45

high P/T

Question 46

What generalized P/T prograde trajectory is expected of contact metamorphic settings?

Answer 46

Low P/T

Question 47

What generalized P/T prograde trajectory is expected of collisional orogenic belts?

Answer 47

Medium P/T

Question 48

What are some settings in which ore deposits are formed?

Question 49

What are some examples of processes that lead to the production of an ore deposit?

Question 50

Describe contact metamorphism.

Answer 50

- occurs next to igneous intrusions over a wide range of pressures - metasomatic effects take place because of hot magma intrusion of cool, shallow rocks - produces aureoles

Question 51

What does metasomatic mean?

Answer 51

rock composition changes because of chemical exchanges

Question 52

What are aureoles?

Answer 52

metamorphic zone surrounding igneous intrusion