Physical Geology - Chapter 6 Test Bank

77. Oil companies rarely drill deeper than the _____ isotherm. A) 100˚C B) 150˚C C) 200˚C D) 250˚C

B) 150˚C

6. What is the average rate at which temperature increases with depth in Earth's crust? A) 10°C/km B) 30°C/km C) 100°C/km D) 300°C/km

B) 30°C/km

14. At what depth does low-grade metamorphism begin? A) 1 to 2 km B) 6 to 10 km C) 20 to 50 km D) 100 to 200 km

B) 6 to 10 km

22. Which of the following statements about the metamorphism of a shale is false? A) With increasing metamorphism, clay minerals break down to form micas. B) With increasing metamorphism, the grain size of the rock gets smaller. C) With increasing metamorphism, foliation develops. D) With increasing metamorphism, the amount of water in the rock decreases.

B) With increasing metamorphism, the grain size of the rock gets smaller.

44. Which metamorphic rock forms in the forearc of a subduction zone? A) amphibolite B) blueschist C) hornfels D) granulite

B) blueschist

73. Directed pressure is also sometimes called A) confining pressure. B) differential stress. C) differential pressure. D) confining stress.

B) differential stress.

17. The parallel alignment of mica in a metamorphic rock is an example of A) bedding. B) foliation. C) metasomatism. D) porphyroblasts.

B) foliation.

41. Which mineral is commonly used to determine a metamorphic P-T path? A) calcite B) garnet C) muscovite D) quartz

B) garnet

37. What metamorphic facies occurs at temperatures of 400°C and pressures of 6 kilobars? A) granulite B) greenschist C) hornfels D) zeolite

B) greenschist

27. Which of the following rocks has a granular texture? A) gneiss B) hornfels C) schist D) slate

B) hornfels

29. A nonfoliated contact metamorphic rock is called a A) gneiss. B) hornfels. C) phyllite. D) schist.

B) hornfels.

52. Different pressure-temperature zones within a belt of regionally metamorphosed rock are defined by the presence of A) porphyroblasts. B) index minerals. C) migmatite. D) sillimanite.

B) index minerals.

1. Marble is a metamorphic rock that forms from A) granite. B) limestone. C) sandstone. D) shale.

B) limestone.

31. Which of the following metamorphic rocks cannot form from a shale? A) hornfels B) marble C) schist D) slate

B) marble

32. What type of metamorphic rock has undergone partial melting? A) hornfels B) migmatite C) schist D) slate

B) migmatite

80. At temperatures of approximately 600˚C and pressure of approximately 5 kbar, the minerals muscovite and quartz react with each other and produce orthoclase feldspar, sillimanite, and water. Which mineral is the source of the water? A) orthoclase feldspar B) muscovite C) sillimanite D) quartz

B) muscovite

25. Which of the following metamorphic rocks is incorrectly paired with its parent rock? A) greenstone - basalt B) quartzite - granite C) marble - limestone D) schist - shale

B) quartzite - granite

8. During metamorphism, changes in the bulk composition of a rock occur primarily as a result of A) increases in pressure. B) reaction with hydrothermal fluids. C) increases in temperature. D) decreases in temperature.

B) reaction with hydrothermal fluids.

69. In a thickened lithosphere you expect to see A) thinner crust. B) shallower geothermal gradients. C) steeper geothermal gradients. D) constant temperature increase with depth.

B) shallower geothermal gradients.

23. Which of the following sequences describes the metamorphic changes in a shale with increasing metamorphic grade? A) schist, gneiss, slate B) slate, schist, gneiss C) gneiss, slate, schist D) gneiss, schist, slate

B) slate, schist, gneiss

2. Which of the following tectonic settings will be coolest at 30 km depth? A) regions of continental extension B) stable continental lithosphere C) volcanic arcs D) The temperature in all three tectonic settings above will be the same at 30 km depth.

B) stable continental lithosphere

43. Mélanges and blueschists are characteristic of which tectonic setting? A) continent collisions B) subduction zones C) mid-ocean ridges D) transform faults

B) subduction zones

48. Eclogite rocks form during ___________ metamorphism. A) high-pressure B) ultra-high-pressure C) burial D) seafloor

B) ultra-high-pressure

65. One might expect shock metamorphism to be more common on the lunar than terrestrial surface because the Moon has __________ than Earth. A) a thicker atmosphere B) a denser atmosphere C) a less dense atmosphere D) higher atmospheric pressures

C) a less dense atmosphere

5. A geothermometer is A) a device that measures current rock temperatures. B) a device that measures temperature when lowered into deep drill holes. C) a mineral assemblage that reveals the maximum temperature attained by a rock. D) the range of temperatures encountered by a rock in its geologic history.

C) a mineral assemblage that reveals the maximum temperature attained by a rock.

35. What is a porphyroblast? A) a common type of copper ore deposit B) an igneous rock with two distinct crystal sizes C) a relatively large metamorphic mineral D) a strongly foliated metamorphic rock

C) a relatively large metamorphic mineral

53. Epidote is a common metamorphic mineral found in metamorphosed A) shale. B) limestone. C) basalt. D) sandstone.

C) basalt.

42. The prograde part of a metamorphic P-T path occurs during A) burial and cooling. B) exhumation and cooling. C) burial and heating. D) exhumation and heating.

C) burial and heating.

66. Geologists have recently linked rapid rates of uplift and exhumantion to A) tectonic setting. B) rock type. C) climate. D) isograds.

C) climate.

13. What type of metamorphism is caused by igneous intrusions? A) burial metamorphism B) regional metamorphism C) contact metamorphism D) shock metamorphism

C) contact metamorphism

15. Where does seafloor metamorphism take place? A) continent collision zones B) subduction zones C) divergent plate boundaries D) transform plate boundaries

C) divergent plate boundaries

30. Granoblastic metamorphic rocks generally contain minerals that are _______ in shape. A) linear B) platy C) equant D) bladed

C) equant

72. During metamorphism pressure will ____ the rocks in the direction a force is applied and ____ in the direction perpendicular to that same force. A) elongate; flatten B) elongate; elongate C) flatten; elongate D) flatten; flatten

C) flatten; elongate

46. Metamorphic mineral assemblages that can be used as pressure gauges are referred to as A) kilobarometers. B) geothermometers. C) geobarometers. D) kilothermometers.

C) geobarometers.

39. Which of the following metamorphic facies represents the highest temperature? A) amphibolite B) blueschist C) granulite D) greenschist

C) granulite

51. A metamorphic rock that is described as porphyroblastic has A) original igneous rock textures. B) abundant equant minerals. C) large crystals in a fine-grained matrix. D) no preferred alignment of minerals.

C) large crystals in a fine-grained matrix.

84. For any given depth along the P-T path of a metamorphic rock the retrograde path is always at a A) lower pressure. B) higher pressure. C) lower temperature. D) higher temperature.

C) lower temperature.

60. Which of the following metamorphic rocks is most likely to contain visible fossils? A) gneiss B) hornfels C) marble D) quartzite

C) marble

33. Which of the following rocks can be considered gradational between an igneous and a metamorphic rock? A) amphibolite B) gneiss C) migmatite D) zeolite

C) migmatite

82. Metamorphic geologists often refer to the "P-T path" of a particular rock. What does the "P-T" stand for? A) plate-tectonic B) phorphyroblastic-texture C) pressure-temperature D) part-time

C) pressure-temperature

12. What type of metamorphism is caused by high temperature and high pressure imposed over a large volume of crust? A) burial B) contact C) regional D) shock

C) regional

11. What is the primary source of the carbon dioxide in metamorphic fluids? A) atmospheric carbon B) carbon dioxide released from Earth's core C) sedimentary carbonates D) weathered cement and other man-made materials

C) sedimentary carbonates

3. Which of the following minerals is diagnostic of metamorphism? A) calcite B) feldspar C) staurolite D) quartz

C) staurolite

85. Differences in the P-T paths experienced by metamorphic rocks in ocean-continent collision zones versus continent-continent collision zones are mainly due to differences in A) pressure. B) rock composition. C) temperature gradients. D) plate subduction rates.

C) temperature gradients.

70. Which of the following factors remains constant and does not vary depending on tectonic setting? A) the geothermal gradient B) the thickness of the lithosphere C) the rate of pressure increase with depth D) the depth to the 1300˚C isotherm

C) the rate of pressure increase with depth

74. During metamorphism, hydrothermal fluids can remove all _____ from an affected rock. A) solids B) minerals C) water-soluble chemical elements D) chemical elements

C) water-soluble chemical elements

71. In which of the following tectonic settings is the depth to the 1300˚C isotherm greatest? A) volcanic mountain belt B) subduction zone C) zone of plate extension D) stable continental lithosphere

C) zone of plate extension

10. What is metasomatism? A) a change in the bulk composition of a rock during metamorphism B) metamorphism caused by nearby magmatic intrusions C) metamorphism caused by tectonic movements along faults D) the parallel alignment of minerals in a metamorphic rock

A) a change in the bulk composition of a rock during metamorphism

57. What type of metamorphic rock is granofels? A) a granulite B) a schist C) a gneiss D) a marble

A) a granulite

9. Which of the following is a general pressure in all directions, such as the pressure that the atmosphere exerts? A) confining pressure B) pore pressure C) directional pressure D) stress pressure

A) confining pressure

21. Which of the following tectonic settings may be characterized by regional, high-pressure, and ultra-high-pressure metamorphism? A) convergent plate boundaries B) plate interiors C) divergent plate boundaries D) transform plate boundaries

A) convergent plate boundaries

56. The flow of metamorphic rocks back to Earth's surface is controlled by tectonics and A) erosion. B) hydrothermal circulation. C) magmatism. D) retrograde metamorphism.

A) erosion.

55. The process whereby metamorphic rocks rise to Earth's surface is called A) exhumation. B) orogeny. C) subduction. D) progradation.

A) exhumation.

19. Which of the following rocks represents the highest metamorphic grade? A) gneiss B) phyllite C) schist D) slate

A) gneiss

24. Light-colored rocks with coarse bands of segregated light and dark minerals are called A) gneisses. B) quartzites. C) schists. D) slates.

A) gneisses.

28. Which of the following metamorphic rocks forms from mafic volcanic rocks? A) greenstone B) marble C) quartzite D) all of the above

A) greenstone

64. Under what P and T conditions does zeolite-facies metamorphism occur? A) less than 5 kbars and 200°C B) 5 to 10 kbars and 200 to 400°C C) less than 5 kbars and greater than 400°C D) greater than 5 kbars and less than 400°C

A) less than 5 kbars and 200°C

68. During metamorphism a rock will not A) loose its solid form. B) change shape. C) change its texture. D) experience metasomatism.

A) loose its solid form.

61. Metamorphism happens when rocks are subjected to A) new temperatures and pressures. B) fluids. C) whole-scale melting. D) atmospheric gases.

A) new temperatures and pressures.

40. Under what conditions does zeolite-facies metamorphism occur? A) relatively low pressure and low temperature B) relatively low pressure and high temperature C) relatively high pressure and low temperature D) relatively high pressure and high temperature

A) relatively low pressure and low temperature

47. What kind of metamorphism would you expect to see in the rocks at a meteorite impact site? A) shock B) burial C) regional D) contact

A) shock

4. Approximately what is the pressure on a rock at 15 km depth in Earth's crust? (Note: 1 bar is approximately 1 atmosphere and 1000 bars equals 1 kbar.) A) 4 bars B) 40 bars C) 400 bars D) 4 kbars

D) 4 kbars

16. What is the relationship between metamorphic foliation and sedimentary bedding? A) Sedimentary bedding is generally perpendicular to metamorphic foliation. B) Sedimentary bedding is generally at a 45° angle to metamorphic foliation. C) Sedimentary bedding is generally parallel to metamorphic foliation. D) There is no general angular relationship between sedimentary bedding and metamorphic foliation.

D) There is no general angular relationship between sedimentary bedding and metamorphic foliation.

7. Which of the following processes will cause metamorphism? D) all of the above

D) all of the above: A) an increase in pressure B) interaction with hydrothermal fluids C) an increase in temperature

54. What kind of metamorphism(s) would you expect to find at a convergent plate margin? A) regional B) high-pressure C) contact D) all of the above

D) all of the above: regional high-pressure contact

59. Metamorphic rocks may form from A) igneous rocks. B) sedimentary rocks. C) other metamorphic rocks. D) any of the major rock types.

D) any of the major rock types.

76. Carbon dioxide is one of the fluids consumed during metasomatism. What is the likely source of this fluid? A) silicate minerals B) the atmosphere C) the core D) carbonate rocks

D) carbonate rocks

81. In which plate tectonic setting is evidence of shock metamorphism most likely to be preserved? A) convergent plate boundaries B) transform faults C) divergent plate boundaries D) continental interiors

D) continental interiors

34. Which metamorphic mineral commonly forms porphyroblasts? A) amphibole B) calcite C) chlorite D) garnet

D) garnet

79. Which of the following metamorphic rocks can be either foliated or phorphyroblatstic, but not granoblastic? A) hornfels B) marble C) granulite D) gneiss

D) gneiss

36. Which of the following rocks represents the highest grade of metamorphosed mafic volcanic rocks? A) amphibolite B) blueschist C) greenschist D) granulite

D) granulite

67. Which metamorphic facies would be highly unlikely to occur in a subduction zone? A) zeolite B) blueschist C) eclogite D) granulite

D) granulite

83. For any given depth along the P-T path of a metamorphic rock the prograde path is always at a A) lower pressure. B) higher pressure. C) lower temperature. D) higher temperature

D) higher temperature.

45. What metamorphic rock could also be considered a transitional rock between igneous and metamorphic? A) schist B) hornfels C) gneiss D) migmatite

D) migmatite

62. Metasomatism does not involve a change in A) bulk rock chemistry. B) mineral composition. C) fluid composition. D) rock texture.

D) rock texture.

49. The parent rock of quartzite is A) granite. B) limestone. C) shale. D) sandstone.

D) sandstone.

26. Which of the following metamorphic rocks is always foliated? A) hornfels B) marbles C) quartzites D) schists

D) schists

38. What is the most likely parent rock of a metamorphic rock containing muscovite, biotite, garnet, and quartz? A) basalt B) limestone C) sandstone D) shale

D) shale

50. The parent rock(s) of granofels is(are) A) shale. B) impure sandstone. C) granite. D) shale, impure sandstone, and granite.

D) shale, impure sandstone, and granite.

63. What kind of metamorphism would you expect to be pervasive on the lunar surface? A) regional metamorphism B) burial metamorphism C) contact metamorphism D) shock metamorphism

D) shock metamorphism

18. What type of metamorphic rock was once used to make blackboards because of its ability to split easily into thin sheets along smooth, parallel surfaces? A) hornfels B) quartzite C) schist D) slate

D) slate

58. Which mineral is commonly found as a porphyroblast? A) quartz B) biotite C) mica D) staurolite

D) staurolite

75. During metamorphism, the process called metasomatism does not change the ______ of the affected rock. A) chemical composition B) mineral chemistry C) mineral content D) texture

D) texture

20. Which of the following is not used to classify foliated rocks? A) the metamorphic grade B) the size of the crystals C) the nature of the foliation D) the texture of the parent rock

D) the texture of the parent rock

78. One would expect shock metamorphism to be less common on Earth than on the Moon. This is because the moon has A) a smaller diameter. B) lower gravity. C) softer crust. D) virtually no atmosphere.

D) virtually no atmosphere.