Deck 7: Deformation and Metamorphism

Question 1

How many measurements does it take to describe the orientation of a rock layer exposed at a given location?

A) one
B) two
C) three

Answer 1

B

Question 2

The angle at which a sedimentary bed is inclined from horizontal is called the

A) dip
B) plunge
C) strike

Answer 2

A

Question 3

Which of the following statements best describes the behavior of rocks during deformation?

A) Brittle materials deform by faulting, whereas ductile materials deform by folding.
B) Brittle materials deform by folding, whereas ductile materials deform by faulting.
C) Both brittle and ductile materials deform by faulting.
D) Both brittle and ductile materials deform by folding.

Answer 3

A

Question 4

The style of deformation that occurs at deep levels in the Earth's crust is referred to as

A) brittle
B) tensile
C) ductile

Question 5

-What type of fault is depicted in the cross section above?

A) left-lateral strike-slip fault
B) reverse fault
C) normal fault
D) right-lateral strike-slip fault

Question 6

Units A, B, and C are sedimentary rocks; unit A is the oldest and unit C is the youngest. The sedimentary rocks are cut by a fault, indicated by the bold line. The fault dips 60° to the northwest as shown by the strike and dip symbol.

-What type of structure is shown in the geologic map?

A) a faulted anticline
B) a faulted syncline
C) a folded strike-slip fault
D) The structure cannot be determined from the information given.

Question 7

Units A, B, and C are sedimentary rocks; unit A is the oldest and unit C is the youngest. The sedimentary rocks are cut by a fault, indicated by the bold line. The fault dips 60° to the northwest as shown by the strike and dip symbol.

-Which way do the sedimentary layers dip?

A) toward the east
B) toward the center
C) toward the west
D) toward the east and west

Question 8

Units A, B, and C are sedimentary rocks; unit A is the oldest and unit C is the youngest. The sedimentary rocks are cut by a fault, indicated by the bold line. The fault dips 60° to the northwest as shown by the strike and dip symbol.

-Why is unit A wider north of the fault than it is south of the fault?

A) Deeper levels of the structure are exposed on the north side of the fault.
B) Erosion has removed most of unit A south of the fault.
C) Faulting has thinned unit A south of the fault.
D) Unit A had a variable thickness prior to faulting.

Question 9

Units A, B, and C are sedimentary rocks; unit A is the oldest and unit C is the youngest. The sedimentary rocks are cut by a fault, indicated by the bold line. The fault dips 60° to the northwest as shown by the strike and dip symbol.

-What type of fault is depicted on the geologic map?

A) a normal fault
B) a reverse fault
C) a right-lateral fault
D) a left-lateral fault

Question 10

-The structure shown in the diagram above is a(n) ___________.

A) anticline
B) basin
C) dome
D) syncline

Question 11

-The structure shown in the diagram above is a ___________.

A) horizontal, symmetric fold
B) plunging, symmetric fold
C) horizontal, asymmetric fold
D) plunging, asymmetric fold

Question 12

What type of forces dominate at transform plate margins?

A) tensional
B) shearing
C) compressive

Question 13

Downfolds, or troughs, of layered rock are called

A) anticlines.
B) faults.
C) synclines.

Question 14

Strike-slip faults have ___ displacement.

A) primarily horizontal
B) primarily vertical
C) no appreciable

Question 15

A fault where the rocks above the fault plane move upward relative to the rocks below the fault plane is called a ___ fault.

A) normal
B) reverse
C) strike-slip

Question 16

A low-angle reverse fault is called a ___ fault.

A) normal
B) thrust
C) strike-slip

Question 17

What type of fold forms in an area of intense deformation where one limb of the fold has been tilted beyond vertical?

A) asymmetric fold
B) overturned fold
C) plunging fold

Question 18

The ___ is an imaginary surface that divides a fold as symmetrically as possible.

A) fold axis
B) fold limb
C) axial plane

Question 19

A plunging fold is one in which the

A) fold axis is at an angle to the horizontal.
B) fold axis is horizontal.
C) axial plane is dipping at an angle from the horizontal.

Question 20

In a symmetrical syncline fold structure, the limbs of the fold dip

A) away from each other.
B) toward each other.
C) in the same direction.

Question 21

Which of the following forces is the most important in a rift valley?

A) compressive
B) shearing
C) tensional

Question 22

What is the pressure on a rock at 15-km depth in the Earth's crust?

A) approximately 4 times atmospheric pressure
B) approximately 40 times atmospheric pressure
C) approximately 400 times atmospheric pressure
D) approximately 4000 times atmospheric pressure

Question 23

Which of the following types of pressure results in the alignment of metamorphic minerals?

A) pore pressure
B) directed pressure
C) confining pressure

Question 24

The change in a rock's chemical composition as a result of fluid transport during metamorphism is referred to as

A) metasomatism.
B) prograde metamorphism.
C) exhumation.

Question 25

Which of the following statements about eclogites is not true?

A) Eclogites form at high pressures.
B) Eclogites form in subduction zones.
C) Eclogites form next to granitic intrusions.

Question 26

What geologic conditions are necessary to produce shock metamorphism?

A) high-pressure subduction zone conditions
B) high-temperature conditions at a volcanic arc
C) extremely high pressure metamorphism caused by a meteorite impact

Question 27

Which statement below regarding the metamorphism of rocks is false?

A) During metamorphism the texture of a rock changes.
B) During metamorphism minerals crystallize from magma.
C) During metamorphism hydrothermal fluids can change rock chemistry.
D) During metamorphism the mineral composition of a rock can change.

Question 28

Which is an appropriate approximate value for the rate of pressure increase with increasing depth in Earth?

A) 0.3 kilobars per kilometer (kbar/km)
B) 1.6 kilobars per kilometer (kbar/km)
C) 0.001 kilobars per kilometer (kbar/km)
D) 5.7 kilobars per kilometer (kbar/km)

Question 29

Metamorphism happens only at depths greater than 5 km in Earth.

Question 30

Which of the following rocks represents the lowest metamorphic grade?

A) slate
B) schist
C) phyllite

Question 31

Metamorphosed limestones and dolostones are called

A) quartzites.
B) marbles.
C) schists.

Question 32

Granulite facies rocks commonly have a ___ texture.

A) phyllitic
B) granoblastic
C) schistose

Question 33

-In the metamorphic map above, what is zone A?

A) biotite zone
B) kyanite zone
C) muscovite zone
D) quartz zone

Question 34

-In the metamorphic map above, isograd B is the __________ isograd.

A) garnet
B) mica
C) sillimanite
D) staurolite

Question 35

-Based on the metamorphic map above, what mineral would not be present in the garnet zone?

A) biotite
B) chlorite
C) garnet
D) staurolite

Question 36

-In the metamorphic map above, in which direction is the metamorphic grade increasing?

A) east
B) north
C) south
D) west

Question 37

-Which pressure-temperature regime represents the eclogite facies?

A) area A
B) area C
C) area E
D) area G

Question 38

-Which pressure-temperature regime represents the greenschist facies?

A) area C
B) area D
C) area E
D) area F

Question 39

What is the name for a line on a geologic map that delineates where one metamorphic grade changes to another?

A) contact
B) isotherm
C) isograd

Question 40

Which metamorphic facies represents the lowest metamorphic pressures and temperatures in mafic rocks?

A) hornfels
B) greenschist
C) zeolite

Question 41

Plagioclase feldspar is found in metamorphosed

A) shales.
B) basalts.
C) shales and basalts.

Question 42

What type of pressure-temperature pathway represents subduction zone metamorphism?

A) high pressure and low temperature
B) high pressure and high temperature
C) low pressure and low temperature

Question 43

Which of the following rocks do not have shale as the parent rock?

A) marble
B) phyllite
C) slate

Question 44

The mineral assemblage albite-chlorite-epidote is formed from a parent rock of ___ that was metamorphosed under ___ facies conditions.

A) shale, amphibolite
B) basalt, greenschist
C) limestone, eclogite

Question 45

Which of the index minerals listed is indicative of the highest metamorphic grade?

A) chlorite
B) muscovite
C) sillimanite
D) kyanite

Question 46

Which list places the metamorphic facies in order of increasing metamorphic grade?

A) eclogite, greenschist, amphibolite
B) eclogite, amphibolite, greenschist
C) greenschist, eclogite, amphibolite
D) greenschist, amphibolite, eclogite

Question 47

Which of the metamorphic conditions listed result in blueschist facies metamorphism?

A) moderate pressure and high temperature
B) low pressure and moderate temperature
C) high pressure and moderate temperature
D) low pressure and high temperature

Question 48

Metamorphic facies are identifiable because under any given temperature and pressure conditions all kinds of rocks metamorphose to the same set of minerals.

Question 49

Which of the following characteristics of metamorphic terrains inform geologists about the plate tectonic environment that led to that metamorphism?

A) metamorphic facies
B) rock textures
C) pressure-temperature pathways
D) all of these

Question 50

Which of the following is thought to be an important control on the rate at which metamorphic rocks return to the surface?

A) climate
B) thermal subsidence
C) convective flow in the crust
D) mantle upwelling

Question 51

Metamorphism at continent-continent collision zones reflects a greater geothermal gradient compared to subduction zone metamorphism.

Question 52

Granulite facies metamorphism most commonly occurs in subducted oceanic crust.