READING QUESTIONS: Metamorphic Rocks
NAME________________________
GEOL 131
DUE: Tuesday, September 30th
Fall 2015
50 pts
All answers should be in your own words.
What is Metamorphism? (p. 102-103)
1. What is meant by the statement “Every metamorphic rock has a parent rock”? (2 pts) ______________
__________________________________________________________________________________
2. Which of the following are aspects of a rock that can change during metamorphism? (Circle all that
apply).
a. Mineral composition
b. Chemical composition
c. Texture
d. None of the above
3. Define metamorphic grade.(2 pts) ________________________________________________________
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What Drives Metamorphism? (p. 103-106)
4. List the four agents of metamorphism. (2 pts)
a. ___________________________________
b. ___________________________________
c. ___________________________________
d. ___________________________________
5. Why is heat the most important agent of metamorphism? (2 pts) _______________________________
_________________________________________________________________________________
_________________________________________________________________________________
6. How are confining pressure and differential stress different? (Mark one answer.)
a. Confining pressure is greater in one direction than others; differential stress is equal in all
directions
b. Differential stress is greater in one direction than others; confining pressure is equal in all
directions
c. Differential stress is produced in tectonic plate collisions; confining pressure is produced by
burial
d. Confining pressure is produced in tectonic plate collisions; differential stress is produced by
burial
e. A and C
f. B and D
g. B and C
h. A and D
i. These two kinds of pressure are essentially the same
7. What role do chemically active fluids play in metamorphism? (2 pts) ____________________________
___________________________________________________________________________________
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8. EXTRA CREDIT: List the three sources of water for chemically active fluids. (3 pts)
a. ___________________________________________________________________
b. ___________________________________________________________________
c. ___________________________________________________________________
Metamorphic Textures (p. 106-109)
9. Define foliation. (2 pts) _______________________________________________________________
___________________________________________________________________________________
10. Match each of the following foliations with the correct picture on the next page. Write the letter of your
answer on the line beneath the picture. (3 pts)
a. Slaty cleavage
b. Schistosity
c. Gneissic banding
_______
______
______
11. Name and describe the three ways in which the mineral grains in a rock develop preferred orientation.
(5 pts)
a. ____________________________________________________________________________
____________________________________________________________________________
b. ____________________________________________________________________________
____________________________________________________________________________
c. ____________________________________________________________________________
____________________________________________________________________________
12. Define nonfoliated texture. ____________________________________________________________
13. What type of environment does nonfoliated texture typically develop in? (2 pts) _________________
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Common Metamorphic Rocks (p. 109-112)
14. The rocks slate and phyllite are similar in appearance. How might you distinguish them from each other?
(2 pts)
____________________________________________________________________________________
____________________________________________________________________________________
15. In the rock mica schist, what does the word mica indicate, and what does the word schist indicate? (2 pts)
____________________________________________________________________________________
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16. Match the rocks slate, phyllite, schist, and gneiss to the correct descriptions of their textures and grain
sizes. (2 pts)
a. Slate
Coarse-grained; banded foliation
____
b. Phyllite
Very fine-grained; smooth flat surfaces
____
c. Schist
Medium- to coarse-grained; scaly foliation with abundant mica
____
d. Gneiss
Fine-grained; wavy foliation and glossy sheen
____
17. Name one way in which marble and quartzite are similar, and two ways they are different. (3 pts)
a. Same: ________________________________________________________________
b. Different: _____________________________________________________________
_____________________________________________________________________
Metamorphic Environments (p. 112-115)
18. In which type of metamorphism does compressional stress play a major role?
a. Subduction zone
b. Burial
c. Hydrothermal
d. Contact
e. None of the above
19. List three rocks that are produced by hydrothermal metamorphism. (3 pts)
a. ________________________________________
b. ________________________________________
c. ________________________________________
20. What is a metamorphic aureole? (2 pts) __________________________________________________
__________________________________________________________________________________
21. Besides heat, which of the other three metamorphic agents plays the most important role in
hydrothermal metamorphism? ________________________________________________
22. Which tectonic plate boundary is associated with regional metamorphism?
a. Subduction zone
b. Continental collision
c. Divergent
d. All of the above
23. List the five metamorphic rocks commonly produced by regional metamorphism. (3 pts)
a. _____________________________________
b. _____________________________________
c. _____________________________________
d. _____________________________________
e. _____________________________________
Metamorphic Zones (p. 116-117)
24. The Appalachian Mountains were created several hundred million years ago by the collision of other
continents with North America. These collisions not only uplifted the mountains, they also caused
regional metamorphism throughout the Appalachians. Today, as one moves through the Appalachians
east from Ohio, through Pennsylvania, and into Vermont and New Hampshire, does one find
metamorphic rocks of increasing grade or decreasing grade? (Circle one.)
25. What does your answer to the last question indicate about where the most intense heat and pressure
existed during the formation of the Appalachians? _______________________________________
________________________________________________________________________________
26. Using Figure 25, match each index mineral assemblage below with the correct metamorphic rock name.
(3 pts)
a. Chlorite, muscovite, and biotite
Gneiss
_____
b. Muscovite, biotite, garnet, and staurolite
Slate
_____
c. Sillimanite
Schist
_____
27. EXTRA CREDIT: In what country are the oldest known Earth rocks located, and how old are they? (2
pts)
a. Country: _______________________
b. Age: _________________________ years