Chapter 8 Metamorphism and Metamorphic Rocks
Earth: An Introduction to Physical Geology, 9e (Tarbuck/Lutgens)
8.1 Multiple-Choice Questions
1) Which of the following forms at the highest grade of regional metamorphism?
A) hornfels
B) schist
C) slate
D) phyllite
Answer: B
Diff: 1
2) What platy, parallel, mineral grains are the most visual aspect of foliated metamorphic
rocks?
A) micas
B) feldspars
C) carbonates
D) quartz
Answer: A
Diff: 1
3) What major change occurs during metamorphism of limestone to marble?
A) calcite grains grow larger and increase in size
B) clays crystallize to micas, forming a highly foliated, mica-rich rock
C) limestone grains react to form quartz and feldspars
D) calcite grains are dissolved away leaving only marble crystals
Answer: A
Diff: 1
4) Which low-grade metamorphic rock, composed of extremely fine-sized mica and other
mineral grains, typically exhibits well-developed rock cleavage?
A) schist
B) hornfels
C) quartzite
D) slate
Answer: D
Diff: 1
1
Match the rock with the appropriate description.
A. hornfels
B. marble
C. gneiss
D. phyllite
5) ________ forms by contact metamorphism of mudstones and shales
Answer: A
Diff: 1
6) ________ foliated, fine-grained metamorphic rock formed from mudstone and shale
Answer: D
Diff: 1
7) ________ nonfoliated metamorphic rock consisting mostly of calcite
Answer: B
Diff: 1
8) ________ coarse-grained, metamorphic rock with alternating bands or stringers of light and
dark minerals
Answer: C
Diff: 1
9) ________ is thought to form by partial melting and in situ crystallization of the melted
portion.
A) Magmatite
B) Magnetite
C) Migmatite
D) Megatite
Answer: C
Diff: 1
10) Tektites originate in what metamorphic environment?
A) low pressure and high temperature associated with volcanism
B) high temperatures associated with meteorite impacts
C) very high pressures and temperatures associated with deep subduction
D) high temperatures and shearing stresses in an oceanic-crust transform fault
Answer: B
Diff: 1
11) Which one of the following is not likely to be genetically associated with impact of an
asteroid or large meteorite?
A) tektites
B) blueschists
C) coesite
D) impact crater
Answer: B
Diff: 1
2
12) Which of the following statements concerning slate is not true?
A) forms from shales and mudstones
B) has abundant, coarse-grained mica
C) rock cleavage is common
D) sedimentary features may be visible
Answer: B
Diff: 1
13) ________ is a strong, parallel alignment of coarse mica flakes and/or of different mineral
bands in a metamorphic rock.
A) Rock cleavage
B) Foliation
C) Stress streaking
D) Marbleizing
Answer: B
Diff: 1
14) ________ is a nonfoliated rock formed by contact metamorphism of a shale or mudstone.
A) Schist
B) Marble
C) Gneiss
D) Hornfels
Answer: D
Diff: 1
15) Which of the following would exhibit sheared and mechanically fragmented rocks?
A) fault movements at shallow depths
B) intense compression in a deep-seated, regional metamorphic zone
C) heating of shales and mudstones near a pluton
D) regional metamorphism of pyroclastic volcanic rocks
Answer: A
Diff: 1
16) Which of the following best describes the conditions of contact metamorphism?
A) Pressures are very high, the rock is deeply buried, and temperatures are raised by the
Earth's internal heat.
B) Pressures are fairly low, the rock is in the upper part of the crust, and heat is supplied
from a nearby magma body.
C) Heat is generated by shearing and mechanical movements along faults.
D) Depths are fairly shallow, but temperatures and pressures are so high that the rocks
begin to partially melt.
Answer: B
Diff: 1
3
17) ________ forms from the metamorphism of limestone or dolostone.
A) Migmatite
B) Amphibolite
C) Marble
D) Quartzite
Answer: C
Diff: 1
18) What foliated, metamorphic rock is texturally intermediate between slate and schist?
A) fault breccia
B) phyllite
C) quartzite
D) gneiss
Answer: B
Diff: 1
19) ________ is characterized by the segregation of light- and dark-colored minerals into thin
layers or bands.
A) Garnet hornfels
B) Granitic gneiss
C) Slate
D) Quartzite
Answer: B
Diff: 1
20) What type of foliation results from the parallel alignment of abundant, coarse-grained, mica
flakes in a metamorphic rock?
A) schistosity
B) gneissic banding
C) slaty cleavage
D) phyllitic structure
Answer: A
Diff: 1
21) Which of the following metamorphic rocks could be used to neutralize acidic mine waters?
A) granite gneiss
B) quartzite
C) slate
D) marble
Answer: D
Diff: 1
4
22) Which of the following lists the rocks in the order of increasing grain size and increasing
grade of metamorphism?
A) phyllite, slate, schist
B) schist, slate, phyllite
C) slate, phyllite, schist
D) slate, schist, phyllite
Answer: C
Diff: 1
23) ________ is typically formed by metamorphism of a sandstone.
A) Marble
B) Slate
C) Amphibolite
D) Quartzite
Answer: D
Diff: 1
24) Which of the following rocks would exhibit visible, textural evidence of having undergone
some partial melting?
A) fault breccia
B) migmatite
C) slate
D) foliated hornfels
Answer: B
Diff: 1
25) What is the major source of heat for contact metamorphism?
A) deep burial and heat from the Earth's interior
B) heat from grinding and shearing on faults
C) heat from the spontaneous decomposition of micas and feldspars
D) heat from a nearby magma body
Answer: D
Diff: 1
26) In which setting would regional metamorphism be most likely?
A) at shallow depths below an oceanic ridge or rift zone
B) at shallow depths along major transform faults in the continental crust
C) at great depths in the crust where two continents are colliding
D) at shallow depths beneath the seafloor where water pressures are immense
Answer: C
Diff: 2
5
27) Graphite is identified in a particular schist. Which one of the following conclusions is
justified?
A) The rock also contains diamonds; both are crystalline forms of the element carbon.
B) The schist formed from a quartz-rich, sedimentary limestone.
C) The graphite lubricated shearing movements along a fault, causing a schist to form.
D) The pre-metamorphic rock was a shale or mudstone containing organic matter.
Answer: D
Diff: 2
28) Amphibolite is a foliated metamorphic rock composed principally of hornblende and
plagioclase. How does it form?
A) by contact metamorphism of sandstone along the contact with a granitic batholith
B) by regional metamorphism of volcanic rocks such as andesite and basalt
C) by gouging and crushing of limestone along a fault
D) by the impact of an asteroid on interbedded sandstone and shale
Answer: B
Diff: 1
29) What term describes the zone of contact metamorphism surrounding an intrusive magma
body?
A) aura
B) auricle
C) oracle
D) aureole
Answer: D
Diff: 1
30) During metamorphism, what is the major effect of chemically active fluids?
A) increase the pressures in deeply buried, regional-metamorphic zones
B) aid in the movement of dissolved silicate constituents and facilitate growth of the
mineral grains
C) prevent partial melting so solid rocks can undergo very high temperature regional
metamorphism
D) facilitate the formation of schistosity and gneissic banding in hornfels and slates
Answer: B
Diff: 1
31) What two, metamorphic rocks are composed predominantly of single minerals?
A) mica schist and granitic gneiss
B) fault breccia and graphitic schist
C) garnet schist and hornfels
D) marble and quartzite
Answer: D
Diff: 1
6
32) A ________ forms at very high pressures but moderately low temperatures associated with
subduction of oceanic crust and sediments.
A) mylonite
B) migmatite
C) biotite marble
D) blueschist
Answer: D
Diff: 1
8.2 Word Analysis Questions
Examine the words and/or phrases for each question below and determine the relationship among the
majority of words/phrases. Choose the option which does not fit the pattern.
1) A) pressure
B) recrystallization
C) melting
D) chemical fluids
Answer: melting
Diff: 1
2) A) porphyroblastic
B) slaty cleavage
Answer: porphyroblastic
C) schistosity
D) gneissic texture
B) hornfels
C) skarn
D) schist
B) quartzite
C) slate
D) schist
Diff: 1
3) A) aureole
Answer: schist
Diff: 2
4) A) phyllite
Answer: quartzite
Diff: 1
8.3 True/False Questions
1) Partial melting is an important process in the formation of migmatites.
Answer: TRUE
Diff: 1
2) Slate and schist are both derived by metamorphism of shales and mudstones.
Answer: TRUE
Diff: 1
3) Hornfels are metamorphic rocks produced at great depths and high temperatures associated
with regional metamorphism.
Answer: FALSE
Diff: 1
4) Calcite is the main mineral constituent of the sedimentary rock limestone and of the
metamorphic rock marble.
Answer: TRUE
Diff: 1
7
5) Metamorphic rocks formed during episodes of mountain building typically show textural
characteristics indicative of shearing stress and deformation.
Answer: TRUE
Diff: 1
6) Amphibolites have gneissic textures and form by regional metamorphism of granites and
rhyolites.
Answer: FALSE
Diff: 1
7) At high pressures and elevated temperatures of regional metamorphism, silicate rocks are
more resistant to flowage and deformation than at low temperatures and pressures.
Answer: FALSE
Diff: 1
8) Foliated metamorphic rocks are composed largely of equidimensional grains of minerals
such as quartz and calcite.
Answer: FALSE
Diff: 1
9) Rock cleavage or slaty cleavage in slates is largely a consequence of abundant, parallelaligned, very fine-grained mica flakes in the rock.
Answer: TRUE
Diff: 1
10) Muscovite, biotite, and chlorite are common minerals found in phyllites and schists.
Answer: TRUE
Diff: 1
11) The distinctive layers or bands of different minerals in gneisses may be complexly folded.
Answer: TRUE
Diff: 1
12) Quartzites and metaconglomerates are formed along faults by intensive fracturing and
fragmentation of conglomerate beds and quartz veins.
Answer: FALSE
Diff: 1
13) High-grade, regional metamorphism produces significant and recognizable changes in the
textures and mineral compositions of rocks.
Answer: TRUE
Diff: 1
14) Talc and graphite are very soft minerals found in some schists.
Answer: TRUE
Diff: 1
8
15) Three major factors involved in metamorphism are elevated temperature, elevated pressure,
and the chemical action of hot fluids.
Answer: TRUE
Diff: 1
16) During metamorphism, most rock is composed of solid mineral grains, but small amounts of
hot fluids or partial melting may facilitate the metamorphic process.
Answer: TRUE
Diff: 1
8.4 Short Answer Questions
1) Give the name of a rock formed by regional metamorphism of a conglomerate.
Answer: metaconglomerate
Diff: 1
2) Which type of metamorphism occurs specifically in the heated zone around a pluton or
other body of magma?
Answer: contact
Diff: 1
3) List the three most important agents of metamorphism.
Answer: heat, pressure, chemically active fluids
Diff: 1
4) What type of sedimentary rock is typically metamorphosed to form slates or phyllites?
Answer: shale or mudstone
Diff: 1
5) Foliation in metamorphic rocks is mainly evident in the parallel alignment of certain mineral
grains. What are they?
Answer: micas
Diff: 1
6) Which metamorphic rock or rocks exhibit alternating layers or bands of different light- and
dark-colored minerals?
Answer: gneiss
Diff: 1
7) Which metamorphic rock, widely used for monuments and buildings, would deteriorate
significantly in contact with acid rain?
Answer: marble
Diff: 1
8) What strongly banded, metamorphic rocks show good evidence for having formed by
partial melting?
Answer: migmatite
Diff: 1
9
9) What metamorphic rock forms by intense ductile deformation along fault zones at depth in
the Earth?
Answer: mylonite
Diff: 1
8.5 Critical Thinking Questions
Use complete sentences, correct spelling, and the information presented in Chapter 8 to answer the
questions below
1) Is it always possible to determine the original parent rock (called a protolith) prior to
metamorphism? Why or why not? List three protoliths and give a possible metamorphic
equivalent for each one.
Diff: 3
2) Briefly outline how regional metamorphism is related to plate boundaries. Are certain types
of metamorphic rocks indicative of particular plate boundaries or tectonic settings? Give two
or three examples of such rocks and indicate the tectonic environment they represent.
Diff: 3
3) Is the texture of a metamorphic rock always indicative of the conditions (degree of
metamorphism) under which it formed? (Hint: Think about the protolith and how it may
influence the resulting metamorphic rock.)
Diff: 2
8.6 Visualization Questions
1) What type of stress (pressure) is illustrated in the diagram below?
Answer: confining pressure
Diff: 1
2) What type of stress (pressure) is illustrated in the diagram below?
10
Answer: differential stress
Diff: 1
3) Carefully examine the photograph below of a metamorphic rock sample. The sample is
shown as its actual size.
Is this rock foliated or nonfoliated? a) ________
What is the name of this metamorphic rock? b) ________
Consider how this rock got its texture. Was is compressed from top to bottom or from side to
side? c) ________
Answer: a) foliated b) gneiss c) side to side
Diff: 1
11
4) Carefully examine the cross section below of a subduction zone, and note the areas labeled
A, B, or C.
At which location (A, B, or C) would a metamorphic regime occur that is characterized by
high temperature and high pressure? a) ________
At which location (A, B, or C) would a metamorphic regime occur that is characterized by
high temperature and low pressure? b) ________
At which location (A, B, or C) would a metamorphic regime occur that is characterized by
low temperature and high pressure? c) ________
At which location (A, B, and C) would blueschist form? d) ________
Answer: a) Box B b) Box C c) Box A d) Box A
Diff: 2
12
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