Deck 4: Up From the Inferno: Magma and Igneous Rocks

Question 1

The composition of magma will ________ when it erupts and turns into lava.

A)remain the same
B)become more felsic
C)become more mafic
D)have more silica

Answer 1

A

Question 2

Given the solidus and liquidus curves below,which location represents material that is partially melted?

A)A
B)B
C)C
D)D

Answer 2

C

Question 3

Important volatiles in magmas include ________.

A)mafic minerals,such as olivine
B)potassium and aluminum
C)water and carbon dioxide
D)silicon and iron

Answer 3

C

Question 4

Volatiles refer to substances that ________.

A)crystallize most rapidly out of a melt
B)remain molten even after lava is erupted at the surface
C)melt immediately upon contact with a hot body of magma
D)are gases at surface temperature and pressure

Question 5

The difference between magma and lava is that ________.

A)magma cools more rapidly than lava
B)magma is found at the surface,whereas lava is found below the surface
C)magma is found beneath the surface,whereas lava is found at the surface
D)There is no difference;the two terms mean the same thing.

Question 6

Despite the fact that the temperatures within Earth are hot enough to melt rock,Earth is mostly solid.Why do the rocks within Earth NOT melt?

A)The pressure is too high.
B)The pressure is too low.
C)There is not enough water.
D)They are not in contact with air.

Question 7

Injecting hot fudge into ice cream and causing the ice cream to melt is an appropriate analogy for which cause of magma melt?

A)melting due to a decrease in pressure
B)melting due to an addition of volatiles
C)melting due to heat transfer from rising magma
D)melting due to an increase in pressure

Question 8

All things equal,a magma will have ________ viscosity than a lava.

A)the same
B)fractional
C)lower
D)higher

Question 9

Which type of magma has the greatest silica content?

A)felsic
B)intermediate
C)mafic
D)ultramafic

Question 10

If a body of magma is subjected to fractional crystallization,the first rock that is expected to crystallize from the magma will be ________.

A)identical in chemical composition to the magma
B)more mafic than the magma
C)more felsic than the magma
D)The composition of the rock is not predictable.

Question 11

Viscosity controls how ________.

A)hot the fluid is
B)fast a rock will melt
C)quickly the fluid cools
D)fast a fluid flows

Question 12

The extremely high ________ within Earth keeps the rocks solid.

A)temperature
B)pressure
C)silica content
D)water content

Question 13

The formation of magma within Earth is NOT caused by which of the following processes?

A)decompression (drop in pressure)
B)addition of volatiles
C)transfer of heat from adjacent magma or very hot rocks
D)loss of volatiles to the atmosphere

Question 14

The interior of Earth consists almost entirely of ________ rock.

A)solid
B)molten
C)sedimentary
D)felsic

Question 15

Decompression melting occurs at both ________ and ________.

A)mid-ocean ridges;hotspots
B)mid-ocean ridges;trenches
C)subduction zones;hotspots
D)subduction zones;mid-ocean ridges

Question 16

Viscosity does NOT depend on ________.

A)temperature
B)volatile content
C)silica content
D)volume of the magma

Question 17

The mantle is composed entirely of ________.

A)solid peridotite
B)solid basalt
C)molten peridotite
D)molten basalt

Question 18

Why is the outer core the only layer in Earth that is molten?

A)The pressure decreases within Earth,thus allowing iron to melt.
B)The pressure increases within Earth,thus allowing iron to melt.
C)The temperature is high enough but pressure low enough to melt iron.
D)The temperature is high enough but pressure low enough to melt olivine.

Question 19

________ melting occurs at subduction zones because the down-going plate ________.

A)Heat transfer;is extremely hot
B)Heat transfer;creates abundant friction
C)Flux;contains abundant water
D)Decompression;rises toward the surface

Question 20

In Bowen's discontinuous reaction series,the first mineral to crystallize from a mafic melt is ________.

A)olivine
B)plagioclase
C)pyroxene
D)quartz

Question 21

An irregular-shaped and blob-like igneous rock body that cooled beneath the surface of Earth is a ________.

A)dike
B)pluton
C)sill
D)laccolith

Question 22

If the volatile content of magma is increased,its viscosity will ________.

A)increase
B)decrease
C)stay the same
D)Volatile content has no effect on viscosity.

Question 23

In general,if a body of igneous (source)rock is subjected to partial melting,the magma that is produced is expected to be ________.

A)identical in chemical composition to the source rock
B)more mafic than the source rock
C)more felsic than the source rock
D)The melt composition is not predictable.

Question 24

The presence of vesicles in an igneous rock is evidence that the source melt ________.

A)had a mafic composition
B)contained dissolved volatiles
C)underwent fractional crystallization
D)was stoping and assimilating wall rock

Question 25

Dikes serve an alternate purpose besides being an area where magma solidifies.For what else are dikes used?

A)pathways for geyser flow
B)linear holes that fill with sand
C)storage space for nuclear materials
D)magma pathways to surface volcanoes

Question 26

Most commonly,felsic igneous rocks ________.

A)contain more iron and magnesium than intermediate rocks
B)are lighter in color than mafic rocks
C)are darker in color than mafic rocks
D)are found in oceanic crust

Question 27

Ash,and larger fragments of pumice are all examples of ________.

A)intrusive igneous rocks
B)hot spots
C)volatiles
D)pyroclastic debris

Question 28

As compared to coarse-grained igneous rocks,fine-grained igneous rocks ________.

A)cool and solidify more quickly
B)cool and solidify more slowly
C)solidify at higher temperatures
D)solidify at lower temperatures

Question 29

A sill is a(n)________.

A)tabular intrusion that lies parallel to surrounding layers of sedimentary rock
B)cooled layer of an ancient lava flow
C)intrusion formed within the magma chamber of a volcano
D)tabular intrusion that cuts across preexisting layers

Question 30

All other factors being equal (i.e. ,depth,volume,temperature,etc. ),which type of igneous intrusion would cool fastest?

A)pluton
B)dike
C)batholith
D)All intrusions cool at the same rate.

Question 31

Which of the following is NOT a characteristic of the extrusive igneous rock obsidian?

A)It is composed of volcanic glass.
B)It possesses conchoidal fracture.
C)It is typically felsic in composition.
D)It likely cooled very slowly.

Question 32

An igneous rock with a mixed texture of coarse crystals (phenocrysts)surrounded by fine crystals (groundmass)is termed ________.

A)porphyritic
B)phaneritic
C)aphanitic
D)necrotic

Question 33

As compared to mafic igneous rocks,all felsic igneous rocks ________.

A)cool and solidify more quickly
B)cool and solidify more slowly
C)solidify at higher temperatures
D)solidify at lower temperatures

Question 34

Magma tends to ________.

A)move upward,away from where it formed
B)move downward,away from where it formed
C)move laterally
D)stay in one place

Question 35

In the figure provided below,what type of igneous intrusion is the horizontal rock unit shown by letter A?

A)dike
B)sill
C)pluton
D)laccolith

Question 36

Stoping by magmas occurs when ________.

A)pieces of surrounding country rock are broken off and assimilated
B)the magma stops flowing and starts to solidify
C)the magma becomes fully solidified to form intrusive rock
D)the magma alters a thin rind of surrounding country rock

Question 37

Coarse-grained granite is most similar in mineral composition to fine-grained ________.

A)andesite
B)basalt
C)gabbro
D)rhyolite

Question 38

A batholith is a(n)________.

A)large body of sedimentary rock
B)large body of metamorphic rock
C)amalgamation of plutons
D)amalgamation of aureoles

Question 39

The image below is of a ________.

A)sill
B)pluton
C)dike
D)batholith

Question 40

All other factors being equal,if a body of magma becomes more felsic,its viscosity will ________.

A)increase
B)decrease
C)stay the same
D)Chemical composition has no effect on viscosity.

Question 41

Which type of plate boundary hosts the most explosive volcanoes?

A)convergent only
B)divergent only
C)transform and convergent
D)convergent and divergent

Question 42

Which of the places listed below was formed by a hotspot?

A)Mount St.Helens,Washington
B)Mount Fuji,Japan
C)Kilauea,Hawaii
D)Mount Pinatubo,Philippines

Question 43

Volcanic arcs form along ________ boundaries.

A)transform
B)transvergent
C)convergent
D)divergent

Question 44

Volcanoes whose magma source is NOT linked to a plate boundary are associated with ________.

A)continental rifts
B)hot spots
C)mid-ocean ridges
D)subduction zones

Question 45

Describe the process of decompression melting;be sure to include an example of where this type of melting occurs within Earth.

Question 46

Volcanic eruptions at divergent boundaries generally take the form of ________.

A)pillow basalts
B)pyroclastic flows
C)lava domes
D)pyroclastic falls

Question 47

Describe the difference between the relative viscosity of felsic versus mafic magma and how this affects the rate of flow of each type.

Question 48

Label the cross-section of the convergent boundary shown below.Be sure to use all of the following words/phrases: down-going plate,overriding plate,trench,volcanic arc,volatiles being released,magma forming,Moho,magma rising.

Question 49

Which of the following silicate minerals is often found in granite?

A)olivine
B)calcite
C)pyroxene
D)quartz

Question 50

An oceanic plate subducting under another oceanic plate will create a(n)________.

A)island arc
B)continental arc
C)continental rift
D)transform fault

Question 51

The two images below are of a rhyolite and a granite.First,label each rock with its proper rock name.Second,describe the difference in cooling history of the two rocks.

Question 52

The formation of a hotspot is thought to be associated with ________.

A)convergent boundaries
B)divergent boundaries
C)mantle plumes
D)mid-ocean ridges

Question 53

List the four major magma compositions in order of silica content.

Question 54

Which of the following pictures of volcanoes is the result of a convergent boundary?

A)A
B)B
C)C
D)D

Question 55

Large igneous provinces involve more than just the formation of large volumes of igneous rock.Which of the following global events has NOT been attributed to large igneous provinces?

A)sea-level rise
B)climate change
C)extinction
D)large outcrops of granite