Question 1

___ are igneous rocks that are silica-deficient but high in iron and magnesium.

Accepted Answer

A)   Felsic
B)   Intermediate
C)   Oxide
D)   Mafic
E)   SulfateF) None of the above
G) B) and E)

Question 2

A pluton is an igneous structure that crystallized at very shallow depths.

Accepted Answer

A) True 
 B)False  False

Question 3

Crystal settling accounts for important deposits of ______.

Accepted Answer

A)   chromium and platinum
B)   gold
C)   lead and zinc
D)   iron
E)   aluminum and siliconF) B) and C)
G) D) and E)

Question 4

Mafic igneous rocks are silica-poor.

Accepted Answer

A) True 
 B)False

Question 5

______ are fragments of country rock that are distinct from the body of igneous rocks in which they are enclosed.

Accepted Answer

A)   Clasts
B)   Chill zones
C)   Phenocrysts
D)   Xenoliths
E)   NecksF) None of the above
G) C) and D)

Question 6

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

Accepted Answer

A) True 
 B)False  True

Question 7

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 C)
G) A) and E) D

Question 8

___ 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) C) and D)
G) D) and E)

Question 9

Partial melting of the lower continental crust produces a silicic magma that eventually solidifies into granite or rhyolite.

Accepted Answer

A) True 
 B)False

Question 10

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

Accepted Answer

A) True 
 B)False

Question 11

The crust beneath the world's oceans is mafic ________.

Accepted Answer

A)   iron
B)   asthenosphere
C)   granite and rhyolite
D)   basalt and gabbro
E)   Answers iron, asthenosphere, and granite and rhyolite are all correct.F) B) and C)
G) A) and B)

Question 12

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) A) and E)
G) All of the above

Question 13

What type of melting takes place when a body of hot mantle rock moves upward and the pressure is reducted to the extent that the melting point drops to the temperature of the body?

Accepted Answer

A)   decompression melting
B)   subduction melting
C)   depressurized melting
D)   exfoliational melting
E)   mantle plume meltingF) A) and B)
G) B) and D)

Question 14

The first plagioclase crystals to form as a hot melt cools are high in ______.

Accepted Answer

A)   iron
B)   calcium
C)   manganese
D)   carbonate
E)   leadF) C) and E)
G) B) and E)

Question 15

Igneous rocks that are silica-rich with high aluminum, sodium, and potassium are _____ rocks.

Accepted Answer

A)   silicic
B)   ultramafic
C)   mafic
D)   extraterrestrial
E)   intermediateF) All of the above
G) C) and E)

Question 16

Lava is magma on the Earth's surface.

Accepted Answer

A) True 
 B)False

Question 17

Most of the basalt and gabbro on the ocean floor is created at mid oceanic ridges, which are also ____.

Accepted Answer

A)   divergent plate boundaries
B)   ocean-ocean convergent plate boundaries
C)   transform plate boundaries
D)   ocean-continent plate boundaries
E)   intraplate igneous areasF) C) and D)
G) A) and E)

Question 18

The geothermal gradient for a volcanic region is greater than that for the continental interior.

Accepted Answer

A) True 
 B)False

Question 19

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) B) and C)
F) None of the above

Question 20

Mineralogically and chemically equivalent rocks are ___ and __.

Accepted Answer

A)   granite; rhyolite
B)   gabbro; basalt
C)   diorite; andesite
D)   mafic; ultramafic
E)   intermediate; felsicF) B) and E)
G) A) and B)

Exam 3: Igneous Rocks, Intrusive Activity, and the Origin of Igneous Rocks

___ are igneous rocks that are silica-deficient but high in iron and magnesium.

Correct AnswerverifiedShow Answer

A pluton is an igneous structure that crystallized at very shallow depths.

Correct AnswerverifiedFalse

Crystal settling accounts for important deposits of ______.

Correct AnswerverifiedShow Answer

Mafic igneous rocks are silica-poor.

Correct AnswerverifiedShow Answer

______ are fragments of country rock that are distinct from the body of igneous rocks in which they are enclosed.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedTrue

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

Correct AnswerverifiedD

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

Correct AnswerverifiedShow Answer

Partial melting of the lower continental crust produces a silicic magma that eventually solidifies into granite or rhyolite.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

The crust beneath the world's oceans is mafic ________.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

What type of melting takes place when a body of hot mantle rock moves upward and the pressure is reducted to the extent that the melting point drops to the temperature of the body?

Correct AnswerverifiedShow Answer

The first plagioclase crystals to form as a hot melt cools are high in ______.

Correct AnswerverifiedShow Answer

Igneous rocks that are silica-rich with high aluminum, sodium, and potassium are _____ rocks.

Correct AnswerverifiedShow Answer

Lava is magma on the Earth's surface.

Correct AnswerverifiedShow Answer

Most of the basalt and gabbro on the ocean floor is created at mid oceanic ridges, which are also ____.

Correct AnswerverifiedShow Answer

The geothermal gradient for a volcanic region is greater than that for the continental interior.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Mineralogically and chemically equivalent rocks are ___ and __.

Correct AnswerverifiedShow Answer

Correct Answer
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False

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True

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D

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Mineralogically and chemically equivalent rocks are _ and .

Correct Answer
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