Question 1

A ______ is an intrusive structure that formed from magma that solidified within the "throat" of a volcano.

Accepted Answer

A)  volcanic neck
B)  sill
C)  laccolith
D)  batholith
E)  diapirF) B) and D)
G) None of the above A

Question 2

Lava is magma on the Earth's surface.

Accepted Answer

A) True 
 B)False

Question 3

Both andesite and ___ are composed of feldspars and 30% to 50% ferromagnesian minerals.

Accepted Answer

A)  granite
B)  diorite
C)  pegmatite
D)  gabbro
E)  rhyoliteF) All of the above
G) B) and D)

Question 4

Ultramafic igneous rocks are composed almost entirely of __.

Accepted Answer

A)  feldspar
B)  quartz
C)  ferromagnesian minerals
D)  calcite
E)  diamondsF) A) and B)
G) A) and E) C

Question 5

On its slow journey through the crust,mafic magma evolves into intermediate magma by differentiation and assimilation of ______.

Accepted Answer

A)  mantle rocks
B)  basalt
C)  gabbro
D)  silicic rocksE) None of the above
F) A) and B)

Question 6

A dike is a discordant intrusive igneous structure.

Accepted Answer

A) True 
 B)False

Question 7

Imagine two magmas that are identical in all respects (for example,same chemistry,pressure,volume) except that one magma is hotter than the other.Which magma will have the higher viscosity?

Accepted Answer

A)  The hotter magma will be more viscous.
B)  The cooler magma will be more viscous.
C)  The magmas will have the same viscosity.
D)  There is not sufficient information to establish the relative viscosities of these magmas.
E)  Temperature does not affect magma viscosity.F) B) and E)
G) C) and D)

Question 8

What is the sequence of crystallization along the discontinuous branch of Bowen's reaction series?

Accepted Answer

A)  sodium-rich to calcium-rich plagioclase
B)  quartz,potassium feldspar,biotite
C)  silicic,felsic,mafic,intermediate
D)  olivine,pyroxene,amphibole,biotite
E)  framework,double chain,single chain,sheet,isolatedF) B) and E)
G) C) and E)

Question 9

The sequence in which minerals crystallize in a cooling igneous melt is called Bowen's Reaction Series.

Accepted Answer

A) True 
 B)False

Question 10

The huge volume of mafic magma that erupted to form the Columbia plateau basalts of Washington and Oregon are attributed to ___.

Accepted Answer

A)  sea floor spreading
B)  a hot mantle plume
C)  subduction
D)  magma mixing
E)  meteorite impactF) A) and C)
G) B) and E) B

Question 11

The geothermal gradient,on average,is about _____.

Accepted Answer

A)  0.004 ∘\circ∘ C/km
B)  2.5 ∘\circ∘ C/km
C)  25 ∘\circ∘ C/km
D)  30 ∘\circ∘ C/km
E)  2500 ∘\circ∘ C/km F) None of the above
G) A) and B)

Question 12

Mafic magma generated in the _______ rises to the base of the crust.

Accepted Answer

A)  continental crust
B)  outer core
C)  asthenosphere
D)  spreading ridges
E)  mantle plumesF) B) and E)
G) A) and B)

Question 13

The melting point of a rock decreases with increasing pressure.

Accepted Answer

A) True 
 B)False

Question 14

Igneous rocks may be either ____ if they form on or near Earth's surface,or ___ if they solidify under ground.

Accepted Answer

A)  intrusive; volcanic
B)  volcanic; extrusive
C)  extrusive; intrusive
D)  plutonic; intrusive
E)  intrusive; extrusiveF) A) and E)
G) All of the above

Question 15

___ is a coarse-grained igneous rock (grains > 1 mm diameter) with visible grains of quartz.

Accepted Answer

A)  Gabbro
B)  Granite
C)  Basalt
D)  Peridotite
E)  AndesiteF) B) and D)
G) A) and B)

Question 16

Igneous rock names are based on grain shape and chemical composition.

Accepted Answer

A) True 
 B)False

Question 17

Hawaii and __________ eruptions are related to intraplate igneous activity.

Accepted Answer

A)  Japan
B)  Cascade
C)  Yellowstone
D)  Honduras
E)  CaliforniaF) C) and D)
G) A) and C)

Question 18

Although batholiths may contain mafic and intermediate rocks,they almost never composed of granite.

Accepted Answer

A) True 
 B)False

Question 19

What is the process through which magma differentiation takes place?

Accepted Answer

A)  crystal settling
B)  partial melting
C)  viscosity of the magma
D)  heating of the country rock
E)  subductionF) A) and C)
G) All of the above

Question 20

A useful tool illustrating the relationships among igneous,sedimentary,and metamorphic rocks is called the ___.

Accepted Answer

A)  weathering and erosion of surface features
B)  plate tectonic cycle
C)  relationships between preexisting rock
D)  rock cycle
E)  Bowen's reaction seriesF) B) and E)
G) A) and B)

Exam 11: Igneous Rocks, Intrusive Activity, and the Origin of Igneous Rocks

A ______ is an intrusive structure that formed from magma that solidified within the "throat" of a volcano.

Correct AnswerverifiedA

Lava is magma on the Earth's surface.

Correct AnswerverifiedShow Answer

Both andesite and ___ are composed of feldspars and 30% to 50% ferromagnesian minerals.

Correct AnswerverifiedShow Answer

Ultramafic igneous rocks are composed almost entirely of __.

Correct AnswerverifiedC

On its slow journey through the crust,mafic magma evolves into intermediate magma by differentiation and assimilation of ______.

Correct AnswerverifiedShow Answer

A dike is a discordant intrusive igneous structure.

Correct AnswerverifiedShow Answer

Imagine two magmas that are identical in all respects (for example,same chemistry,pressure,volume) except that one magma is hotter than the other.Which magma will have the higher viscosity?

Correct AnswerverifiedShow Answer

What is the sequence of crystallization along the discontinuous branch of Bowen's reaction series?

Correct AnswerverifiedShow Answer

The sequence in which minerals crystallize in a cooling igneous melt is called Bowen's Reaction Series.

Correct AnswerverifiedShow Answer

The huge volume of mafic magma that erupted to form the Columbia plateau basalts of Washington and Oregon are attributed to ___.

Correct AnswerverifiedB

The geothermal gradient,on average,is about _____.

Correct AnswerverifiedShow Answer

Mafic magma generated in the _______ rises to the base of the crust.

Correct AnswerverifiedShow Answer

The melting point of a rock decreases with increasing pressure.

Correct AnswerverifiedShow Answer

Igneous rocks may be either ____ if they form on or near Earth's surface,or ___ if they solidify under ground.

Correct AnswerverifiedShow Answer

___ is a coarse-grained igneous rock (grains > 1 mm diameter) with visible grains of quartz.

Correct AnswerverifiedShow Answer

Igneous rock names are based on grain shape and chemical composition.

Correct AnswerverifiedShow Answer

Hawaii and __________ eruptions are related to intraplate igneous activity.

Correct AnswerverifiedShow Answer

Although batholiths may contain mafic and intermediate rocks,they almost never composed of granite.

Correct AnswerverifiedShow Answer

What is the process through which magma differentiation takes place?

Correct AnswerverifiedShow Answer

A useful tool illustrating the relationships among igneous,sedimentary,and metamorphic rocks is called the ___.

Correct AnswerverifiedShow Answer

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Igneous rocks may be either __ if they form on or near Earth's surface,or _ if they solidify under ground.

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