Physics Chapter 8 Life changes the physical and chemical properties of

Earth: An Introduction to Physical Geology, 11e (Tarbuck)

Chapter 8 Metamorphism and Metamorphic Rocks

8.1 Multiple-Choice Questions

1) ________ is the process where a rock changes form or mineral content as a result of

environmental changes such as heat and pressure.

A) Rifting

B) Precipitation

C) Metamorphism

D) Foliation

2) What is the definition of a parent rock?

A) The rock that was altered by metamorphism

B) The resulting precipitate when water dissolves mineral matter

C) The rock produced by metamorphism

D) The igneous rock forming through solidification of magma

3) Which of the following is the parent rock for quartzite?

A) Limestone

B) Conglomerate

C) Granite

D) Sandstone

4) If clay minerals were buried at a depth where subsurface temperatures exceed 200°C, which

mineral are they likely to become?

A) Quartz

B) Muscovite

C) Amphibole

D) Plagioclase

5) Which low-grade metamorphic rock will display fine rock cleavage and contains very fine

grains of mica?

A) Schist

B) Gneiss

C) Anthracite

D) Slate

6) Which of the following lists of metamorphic rocks places the rocks in order from lowest

metamorphic grade to highest?

A) Gneiss, Slate, Phyllite, Schist

B) Anthracite, Hornfels, Quartzite, Marble

C) Slate, Phyllite, Schist, Gneiss

D) Ironstone, Sandstone, Slate, Gneiss

7) Which of the following rocks represents the highest grade of metamorphism?

A) Biotite Schist

B) Quartzite

C) Phyllite

D) Gneiss

8) ________ is when new mineral grains form as a result of metamorphic heat that are larger

than the original mineral grains.

A) Recrystallization

B) Foliation

C) Dissolution

D) Metasomatism

9) What is the definition of metasomatism?

A) The rearrangement of ions already present due to changes in heat

B) The lengthening of mineral crystals due to directed pressure

C) The change in chemical composition because hot fluids are bringing or removing ions

D) The more compact organization of mineral crystals due to confining pressure

10) Generally speaking, how is the chemical composition of most metamorphic rocks going to

compare to that of the parent rock?

A) Chemical compositions will be nearly the same

B) In order to be a metamorphic rock, the chemical composition must change by 50%

C) There will be a complete compositional change

D) Chemical composition is not necessary to understand metamorphic rocks

11) What kind of force will create foliation in metamorphic rocks?

A) Tension

B) Compression

C) Shear

D) Brittle

12) What is foliation?

A) Intergrown mineral crystals formed from cooling magma

B) Randomly oriented mineral crystals placed due to confining pressure

C) Thin, parallel layers of clay sediments that have been compressed

D) Roughly parallel layers of mineral crystals aligned perpendicular to the direction of pressure

13) Which of the following is not an example of foliation?

A) Parallel alignment of flattened mineral grains or pebbles

B) Compositional banding in which the separation of light and dark minerals creates a layered

appearance

C) Rock cleavage where rocks can be easily split into tabular slabs

D) Recrystallization of elongated minerals parallel to the direction of greatest stress

14) Physical rotation of platy minerals will contribute most to the development of foliation

________ grade metamorphism.

A) Low

B) Medium

C) Medium-High

D) High

15) Metamorphic rocks can sometimes contain unusually large grains surrounded by a fine-

grained matrix of other minerals. These large crystals are called ________.

A) Vesicles

B) Phenocrysts

C) Inclusions

D) Porphyroblasts

16) Which of the following is not an environment of metamorphism?

A) Metamorphism from contact with a hot magma body

B) Metamorphism as the result of hot fluids coming off a diapir

C) Metamorphism as the result of slow cooling of magma

D) Metamorphism in a subduction zone

17) Which of the following scenarios best describes the formation of hornfels?

A) Mudstones are metamorphosed by directed pressure

B) Granite is melted and recrystallized

C) Shales and mudstones are baked during contact metamorphism

D) Phyllite is altered by contact with hydrothermal fluids

18) Which style of metamorphism will be generated by a mantle plume?

A) Contact

B) Hydrothermal

C) Burial

D) Regional

19) ________ metamorphism tends to occur in regions where massive amounts of sedimentary

or volcanic materials accumulate in a subsiding basin.

A) Contact

B) Hydrothermal

C) Burial

D) Regional

20) In which geologic setting is the most widespread occurrence of hydrothermal

metamorphism?

A) Subduction zones between oceanic and continental plates

B) Along the axis of a mid-ocean ridge system

C) Along transform plate boundaries

D) Where mantle plumes burn through the bottom of continental plates

21) ________ is a widespread type of metamorphism typically associated with mountain

building.

A) Pyrometamorphism

B) Burial metamorphism

C) Shock metamorphism

D) Regional metamorphism

22) Which of the following materials is not associated with shock metamorphism and meteorite

impact sites?

A) Coesite

B) Blueschist

C) Diamonds

D) Tektites

23) Which tectonic boundary is associated with regional metamorphism?

A) Convergent

B) Divergent

C) Dip-Slip

D) Transform

24) ________ are materials that are good indicators of the metamorphic environment in which

they formed and can be used to distinguish between various zones of metamorphism.

A) Index fossils

B) Index minerals

C) Blueschists

D) Aureoles

25) What is a metamorphic facies?

A) A mineral that forms at specific metamorphic conditions and can be used to determine the

metamorphic grade

B) Textural transitions based on the direction and amount of pressure

C) Zones of contact metamorphism along an intrusive igneous rock

D) An assemblage of minerals that form in very similar metamorphic environments

26) Which of the following is not a metamorphic facies?

A) Greenschist

B) Staurolite

C) Eclogite

D) Granulite

27) Which of the mineral assemblages are characteristic of a greenschist?

A) Amphibole, Biotite, and Quartz

B) Chlorite, Epidote, and Serpentine

C) Hornblende

D) Quartz, Plagioclase, and Muscovite

28) A(n) ________ facies is associated with a high pressure, low temperature environment.

A) Zeolite

B) Granulite

C) Blueschist

D) Eclogite

29) Along which type of tectonic boundary will greenschists and blueschists form?

A) Transform

B) Convergent

C) Divergent

D) Failed rift zone

8.2 True/False Questions

1) Sedimentary rocks are always the parent rocks for metamorphic rocks.

2) Metamorphism ends when the rock begins to melt.

3) Low-grade metamorphism will destroy parent rock features such as fossils.

4) The most important factor driving metamorphism is pressure.

5) The geothermal gradient represents a decrease in interior temperature with decreasing distance

from the surface.

6) Olivine can be converted to spinel through confining pressure.

7) Confining pressure produces folded rocks.

8) Foliated textures are primarily the result of heat. Nonfoliated textures are primarily the result

of directed pressure.

9) One possible parent rock for gneiss is granite.

10) Metamorphic rocks found in a contact metamorphism aureole will not be foliated.

11) Hydrothermal metamorphism is responsible for the emplacement of metallic ore veins.

12) Water for hydrothermal metamorphism can be groundwater that has percolated down from

the surface, which gets heated and circulated to assist metamorphism in high depth, high

temperature environments.

13) Fault zone metamorphism will occur where two fault blocks are grinding against each other

near the surface.

14) Pennti Eskola based his metamorphic facies work on the metamorphism of basalts.

15) Quartz is useful in determining metamorphic environments.

8.3 Short Answer Questions

1) Define metamorphic grade.

2) What are the agents of metamorphism?

3) What is the average increase in temperature along the geothermal gradient in the Upper Crust?

4) What fluid is generally responsible for metasomatism?

5) What are the two main categories of metamorphic texture?

6) Slate and Phyllite are similar in appearance. How can one distinguish between the two?

7) Marble and Quartzite can be similar in appearance. Name two simple ID techniques that can

be used to differentiate between the two?

8) Most metamorphic rocks near the Earth’s surface are derived from three common sedimentary

rocks. Name those three rocks.

9) Name three rocks that are produced by contact metamorphism.

8.4 Matching Questions

Match the type of foliation to the metamorphic grade. (Note: Some answers may be used more

than once.)

A) Low Grade Metamorphism

B) Medium Grade Metamorphism

C) High Grade Metamorphism

1) Slaty Cleavage

Diff: 2

Bloom’s Taxonomy: Comprehension

Global Sci Out: 2

Section: 8.3 – Metamorphic Textures

Focus/Concepts: 8.3

Earth Science LO: 4.6 – Earth materials take many different forms as they cycle through the

geosphere.

2) Gneissic Banding

Diff: 2

Bloom’s Taxonomy: Comprehension

Global Sci Out: 2

Section: 8.3 – Metamorphic Textures

Focus/Concepts: 8.3

Earth Science LO: 4.6 – Earth materials take many different forms as they cycle through the

geosphere.

3) Schistosity

Diff: 2

Bloom’s Taxonomy: Comprehension

Global Sci Out: 2

Section: 8.3 – Metamorphic Textures

Focus/Concepts: 8.3

Earth Science LO: 4.6 – Earth materials take many different forms as they cycle through the

geosphere.

4) Phyllitic Texture

Diff: 2

Bloom’s Taxonomy: Comprehension

Global Sci Out: 2

Section: 8.3 – Metamorphic Textures

Focus/Concepts: 8.3

Earth Science LO: 4.6 – Earth materials take many different forms as they cycle through the

geosphere.