Question 1

______ 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) B) and E)
G) A) and E)

Question 2

Mineralogically and chemically equivalent rocks are ___ and __.

Accepted Answer

A)  granite; rhyolite
B)  gabbro; basalt
C)  diorite; andesite
D)  mafic; ultramafic
E)  intermediate; felsicF) A) and D)
G) None of the above

Question 3

Geologists regard basaltic magma (Hawaiian lava,for example) as the result of the partial melting of ultramafic rock in the ____.

Accepted Answer

A)  oceanic crust
B)  continental crust
C)  mantle
D)  outer core
E)  inner coreF) C) and E)
G) A) and E)

Question 4

______ igneous rocks,like gabbro and basalt,are silica-deficient with high magnesium and iron.

Accepted Answer

A)  Felsic/silicic
B)  Intermediate
C)  Mafic
D)  Intrusive
E)  ExtrusiveF) A) and B)
G) B) and E)

Question 5

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 6

Under ideal conditions rock can melt and yield a granite composition at temperatures as low as ___.

Accepted Answer

A)  100 ∘\circ∘  Celsius
B)  225 ∘\circ∘  Celsius
C)  333 ∘\circ∘  Celsius
D)  450 ∘\circ∘  Celsius
E)  650 ∘\circ∘ Celsius F) B) and E)
G) B) and D)

Question 7

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) B) and E)
G) A) and E)

Question 8

A _______ is a tabular (thin but large area) intrusive body that is concordant (parallel to the host rock structure) .

Accepted Answer

A)  dike
B)  mantle
C)  threshold
D)  sill
E)  neckF) D) and E)
G) B) and C)

Question 9

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

Accepted Answer

A) True 
 B)False

Question 10

Viscosity is a property of a fluid that relates to how easily the fluid flows.A material that is viscous __.

Accepted Answer

A)  flows easily
B)  flows less easily
C)  is always hot
D)  is always a solid
E)  is always coldF) A) and D)
G) A) and E)

Question 11

An ultramafic rock is composed almost entirely of quartz.

Accepted Answer

A) True 
 B)False

Question 12

The term mafic comes from the terms magnesium and ferric.

Accepted Answer

A) True 
 B)False

Question 13

Pegmatites are extremely coarse-grained igneous rocks.

Accepted Answer

A) True 
 B)False

Question 14

The geothermal gradient is the rate at which pressure increases with increasing depth beneath the surface.

Accepted Answer

A) True 
 B)False

Question 15

The most common minerals in a granite are the ______.

Accepted Answer

A)  oxides
B)  carbonates
C)  feldspars
D)  ferromagnesians
E)  micasF) A) and C)
G) None of the above

Question 16

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) None of the above
G) A) and C)

Question 17

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 D)
G) A) and C)

Question 18

Fine-grained igneous rocks (grains < 1.0 mm) that have small grains cooled rapidly and are likely to be _______.

Accepted Answer

A)  extrusive
B)  reclusive
C)  intrusive
D)  obtrusive
E)  preclusiveF) C) and D)
G) A) and C)

Question 19

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) A) and D)
G) A) and C)

Question 20

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

Accepted Answer

A) True 
 B)False

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

The most common minerals in a granite are the ______.

Correct AnswerverifiedShow Answer

The geothermal gradient is the rate at which pressure increases with increasing depth beneath the surface.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Crystal settling accounts for important deposits of ______.

Correct AnswerverifiedShow Answer

An ultramafic rock is composed almost entirely of quartz.

Correct AnswerverifiedShow Answer

Mineralogically and chemically equivalent rocks are ___ and __.

Correct AnswerverifiedShow Answer

Pegmatites are extremely coarse-grained igneous rocks.

Correct AnswerverifiedShow Answer

Fine-grained igneous rocks (grains < 1.0 mm) that have small grains cooled rapidly and are likely to be _______.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Geologists regard basaltic magma (Hawaiian lava,for example) as the result of the partial melting of ultramafic rock in the ____.

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

Viscosity is a property of a fluid that relates to how easily the fluid flows.A material that is viscous __.

Correct AnswerverifiedShow Answer

Under ideal conditions rock can melt and yield a granite composition at temperatures as low as ___.

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 rocks,like gabbro and basalt,are silica-deficient with high magnesium and iron.

Correct AnswerverifiedShow Answer

The term mafic comes from the terms magnesium and ferric.

Correct AnswerverifiedShow Answer

A _______ is a tabular (thin but large area) intrusive body that is concordant (parallel to the host rock structure) .

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

Correct AnswerverifiedShow Answer

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Mineralogically and chemically equivalent rocks are _ and .

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