READING QUESTIONS: Metamorphic Rocks GEOL 131 18/WI 47 pts NAME DUE: Tuesday, February 6 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. 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 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 biotite Gneiss b. Muscovite, biotite, garnet, and staurolite Slate 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