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CHAPTER 8 Metamorphism and Metamorphic Rocks
1. Metamorphic rocks result from the transformation of other rocks, usually beneath the Earth's
surface, as a consequence of one or a combination of three agents: heat, pressure, and active fluids (mostly
water with ions of other substances in solution).
2. What are metamorphic rocks, and how do they form?
3. The metamorphic rock formed from limestone is:
a. quartzite; b. hornfels; c. marble; d. slate; e. greenstone.
4. From which of the following rock groups can metamorphic rocks form?
a. plutonic; b. sedimentary; c. metamorphic; d. volcanic;
e. all of these.
5. Metamorphic rocks form a significant proportion of:
a. shields; b. the cores of mountain ranges; c. oceanic crust;
d. answers (a) and (b); e. answers (b) and (c).
6. Most of the heat for metamorphism comes from intrusive magmas. Pressure is either lithostatic
(confining) or differential (directional). Fluids in rocks or emanating from intruding magmas and or country
rock can enhance recrystallization and also chemical change with the formation of new minerals.
7. Name the three agents of metamorphism, and explain how each contributes to metamorphism.
8. Which of the following is not an agent of metamorphism?
a. gravity; b. heat; c. pressure; d. fluid activity; e. none of these.
9. What are the two types of pressure? What type of metamorphic textures does each produce?
10. Pressure exerted equally in all directions on an object is:
a. differential; b. directional; c. lithostatic; d. shear; e. none of these.
11. Metamorphic rocks resulting from pure dynamic metamorphism are:
a. fault breccias; b. quartzites; c. greenstones; d. mylonites; e. hornfels.
12. The three major types of metamorphism are contact, dynamic, and regional.
13. Where does contact metamorphism occur, and what type of changes does it produce?
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14. In which type of change are active fluids the primary agents?
a. contact; b. dynamic; c. regional; d. local; e. metosomatic.
15. What are aureoles? How can they be used to determine the effects of metamorphism?
16. Concentric zones surrounding an igneous Intrusion are:
a. metamorphic layers; b. thermodynamic rings; c. aureoles; d. hydrothermal regions;
e. none of these.
17. What is regional metamorphism, and under what conditions does it occur?
18. Which type of metamorphism produces the majority of metamorphic rocks?
a. contact; b. dynamic; c. regional; d) impact;
e. none of these.
19. Metamorphic rocks are classified primarily according to their texture. In a foliated texture,
platy minerals have a preferred orientation. A nonfoliated texture does not exhibit any
discernible preferred orientation of the mineral grains.
20. Describe the two types of metamorphic texture, and explain how they may be produced.
21. Which of the following metamorphic rocks displays a foliated texture?
a. marble; b. quartzite; c. greenstone; d. schist; e. hornfels.
22. Foliated metamorphic rocks can be arranged in order of grain size and/or perfection of their
foliation. Slate is very fine grained, followed by phyllite and schist; gneiss displays segregated
bands of minerals. Another fairly common foliated metamorphic rock is amphibolite.
23. Starting with a shale, what metamorphic rocks would be produced by increasing
heat and directed pressure?
24. What is the correct rock sequence of increasing metamorphic grade?
a. phyllite -> slate -> gneiss -> schist;
b. slate -> phyllite -> schist -> gneiss;
c. gneiss -> phyllite -> slate -> schist;
d. schist -> gneiss -> phyllite -> slate;
e. slate -> schist -> gneiss -> phyllite.
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25. Common nonfoliated metamorphic rocks are marble, quartzite, greenstone, and hornfels.
26. Name the three common nonfoliated rocks, and describe their characteristics.
27. Metamorphic rocks can be arranged into:
C
metamorphic zones based on the temperature of metamorphism
C
metamorphic facies characterized by a particular rock or mineral(s) that formed under certain
metamorphic conditions.
28. What is the difference between a metamorphic zone and a metamorphic facies?
29. Metamorphism can occur along all three kinds of plate boundaries. Most, however, occurs at
convergent plate margins.
30. Along what type of plate boundary is metamorphism most common?
a. convergent; b. divergent; c. transform; d. mantle plume; e. static.
31. Metamorphic rocks formed near the Earth's surface along an oceanic-continental plate
boundary result from low-temperature, high-pressure conditions. As a subducted oceanic plate
descends, it is subjected to increasingly higher temperatures and pressures that result in higher
grade metamorphism.
32. What types of metamorphic rocks and facies are produced in and are associated with convergent
plate margins?
33. To which metamorphic facies do metamorphic rocks formed under low-temperature,
low-pressure conditions belong?
a. granulite; b. greenschist; c. amphibolite; d. blueschist; e. eclogite.
34. Mixed rocks that originated with both igneous and high-grade metamorphic rock components
together are:
a. mylonites; b. migmatites; c. amphibolites; d. hornfels; e. greenstones.
35. Metamorphic zones:
a. are characterized by distinctive mineral assemblages;
b. are separated from each other by isograds;
c. reflect a metamorphic grade;
d. all of these; e. none of these.
36. Many metamorphic rocks, for example, marble, slate, and minerals, for example, graphite and talc, are
valuable natural resources.
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37. Name some common metamorphic rocks and minerals that are economically valuable,
and describe their uses.
38. An excellent rock for billiard table tops, floor and roofing tiles, and blackboards is:
a. marble; b. gneiss; c. phyllite; d. hornfels; e. slate.
39. Which of the following is not a metamorphic mineral?
a. graphite; b. asbestos; c. talc; d. garnet; e. gypsum.
40. Which of the following is known to be a cancer causing variety of asbestos?
a. chrysotile; b. crocidolite; c. tremolite; d. actinolite; e. anthophyllite.
amphibolite
lithostatic pressure
anthracite
marble
aureole
metamorphic facies
contact metamorphism
metamorphic grade
differential pressure
metamorphic rock
dynamic metamorphism
metamorphic zone
fluid
migmatite
foliated texture
mylonite
gneiss
nonfoliated texture
greenstone
phyllite
heat
quartzite
hornfels
regional metamorphism
index minerals
schist
isograd
slate