Minerals - Web viewDifferential stress is produced in tectonic plate collisions; confining...
Transcript of Minerals - Web viewDifferential stress is produced in tectonic plate collisions; confining...
Minerals
READING QUESTIONS: Metamorphic RocksGEOL 131Winter 2017
NAME________________________DUE: Tuesday, February 7th 47 pts
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) ________________________________________________________
__________________________________________________________________________________
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) ____________________________
___________________________________________________________________________________
___________________________________________________________________________________
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 the three ways in which the mineral grains in a rock develop preferred orientation. (3 pts)
a. ____________________________________________________________________________
b. ____________________________________________________________________________
c. ____________________________________________________________________________
12. Define nonfoliated texture. ____________________________________________________________
13. What type of environment does nonfoliated texture typically develop in? (2 pts) _________________
__________________________________________________________________________________
_________________________________________________________________________________
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. Match the rocks slate, phyllite, schist, and gneiss to the correct descriptions of their textures and grain sizes. (2 pts)
a. SlateCoarse-grained; banded foliation____
b. PhylliteVery fine-grained; smooth flat surfaces____
c. SchistMedium- to coarse-grained; scaly foliation with abundant mica____
d. GneissFine-grained; wavy foliation and glossy sheen____
16. 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)
17. In which type of metamorphism does differential stress play a major role?
a. Subduction zone
b. Burial
c. Hydrothermal
d. Contact
e. None of the above
18. List two metamorphic rocks that are produced by hydrothermal metamorphism. (2 pts)
a. ________________________________________
b. ________________________________________
19. What is a metamorphic aureole? (2 pts) __________________________________________________
__________________________________________________________________________________
20. Besides heat, which of the other four metamorphic agents plays the most important role in
hydrothermal metamorphism? ________________________________________________
21. Which tectonic plate boundary is associated with regional metamorphism?
a. Subduction zone
b. Continental collision
c. Divergent
d. All of the above
22. List five metamorphic rocks commonly produced by regional metamorphism. (5 pts)
a. _____________________________________
b. _____________________________________
c. _____________________________________
d. _____________________________________
e. _____________________________________
Metamorphic Zones (p. 116-117)
23. 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.)
24. What does your answer to the last question indicate about where the most intense heat and pressure
existed during the formation of the Appalachians? Give a state name from those mentioned in the last
question. ________________________________________________________________________
25. Using Figure 25, match each index mineral assemblage below with the correct metamorphic rock name. (3 pts)
a. Chlorite, muscovite, and biotiteGneiss_____
b. Muscovite, biotite, garnet, and stauroliteSlate_____
c. Sillimanite Schist_____
26. EXTRA CREDIT: In what country are the oldest known Earth rocks located, and how old are they? (2 pts)
a. Country: _______________________
b. Age: _________________________ years