Deck 7: Metamorphism and Metamorphic Rocks

Question 1

Which series shows the progression of a metamorphic rock from original deposition to the highest grade of metamorphism?

A) Mud shale slate phyllite schist gneiss migmatite.
B) Mud gneiss migmatite schist phyllite slate shale.
C) Mud schist phyllite gneiss slate shale migmatite.
D) Mud slate schist phyllite migmatite shale gneiss.

Answer 1

A

Question 2

Landslides commonly occur in metamorphic terrains if:

A) the metamorphic rocks are exposed at the surface.
B) the planes of foliation (cleavage planes) are parallel to the slopes.
C) the planes of foliation are perpendicular to the slopes.
D) sedimentary rocks overlie the metamorphic rocks.

Answer 2

B

Question 3

In metamorphic rocks, foliation is caused by:

A) heat.
B) circulating fluids.
C) lithostatic pressure.
D) directed pressure.

Answer 3

D

Question 4

The most important factor contributing to metamorphism is:

A) confining pressure.
B) directed pressure.
C) heat.
D) fluids.

Question 5

The term "foliation" in metamorphic rocks refers to:

A) a quantitative measure of the degree of metamorphism.
B) folding of the rock by lateral pressure.
C) the inclusion of fossilized plant remains in the rock.
D) a consistent orientation of the mineral grains perpendicular to the direction of greatest pressure.

Question 6

Metamorphism that results entirely from the heat of magma is:

A) shock metamorphism.
B) dynamothermal metamorphism.
C) regional metamorphism.
D) contact metamorphism.

Question 7

What generally accelerates the pace of chemical reactions?

A) Heat.
B) Circulating fluids.
C) Pressure.
D) Faulting.

Question 8

Metamorphic rocks form through all of the following processes EXCEPT:

A) compacting under tremendous pressure.
B) chemically changing under the influence of ion- containing fluids.
C) chemically changing under the influence of heat.
D) melting and recrystallizing.

Question 9

Metamorphism of quartz sandstone produces:

A) gneiss.
B) hornfels.
C) quartzite.
D) marble.

Question 10

All of the following areas were profoundly altered by regional metamorphism EXCEPT:

A) Alaska.
B) Appalachians of eastern United States.
C) Gulf coast of Louisiana.
D) central Canada.

Question 11

Water facilitates metamorphic reactions by:

A) aiding movement of atoms and ions.
B) expanding fractures in the mineral surface.
C) adding heat to the reaction.
D) removing heat from the reaction.

Question 12

All of the following rock/formation temperature pairs are correct EXCEPT:

Question 13

Continental crust is composed mostly of rocks formed by:

A) Fault- zone metamorphism.
B) Regional metamorphism.
C) Contact metamorphism.
D) Burial metamorphism.

Question 14

The most common source for water in hydrothermal metamorphism is:

A) water derived from magma.
B) seawater penetrating divergent zone fractures.
C) groundwater percolating down from the continental surface.
D) water driven off from rocks undergoing metamorphism.

Question 15

What is the main effect of lithostatic pressure?

A) Change in shape and size.
B) Change in shape.
C) No change in shape just compression.
D) Foliation develops.

Question 16

Pyrometamorphism involves processes of:

A) ultra- high heat and low pressure.
B) heat and directed pressure.
C) heat and circulating fluids.
D) heat and confining pressure.

Question 17

The rock that results from the metamorphism of relatively pure limestone is:

A) marble.
B) hornfels.
C) quartzite.
D) gneiss.

Question 18

The first criterion used to classify metamorphic rocks is:

A) its mineral composition.
B) whether it is foliated or nonfoliated.
C) whether its parent rock was sedimentary, metamorphic, or igneous.
D) the metamorphic environment under which the rock was formed.

Question 19

The technique of thermobarometry is used to determine what?

A) Past temperatures and pressures.
B) The melting point of rocks.
C) The nature of the parent rock.
D) The type of metamorphism.

Question 20

Of the following, which is NOT a basis for classifying metamorphic rocks?

A) Their appearance and the conditions under which they formed.
B) Whether their parent rock was igneous, sedimentary, or metamorphic.
C) Texture and composition.
D) The presence or absence of foliation.

Question 21

All of the following statements concerning contact metamorphism are true EXCEPT:

A) solid rocks are changed by heat.
B) only rocks near the magma are highly metamorphosed.
C) pressure is not a significant factor.
D) it only occurs at great depths.

Question 22

Schist can be distinguished from other metamorphic rocks by:

A) its large flakes of mica.
B) its metallic sheen.
C) its glassy luster.
D) its dark and light mineral bands.

Question 23

Water often facilitates the metamorphism of which kind of rock?

A) Rhyolite.
B) Granite.
C) Basalt.
D) Diorite.

Question 24

The ultimate mineralogy of a metamorphic rock is determined by:

A) composition of the parent rock.
B) fluids.
C) heat.
D) pressure.

Question 25

A rock that has partially melted and is thus part igneous and part metamorphic is a:

A) migmatite.
B) phyllite.
C) gneiss.
D) schist.

Question 26

Rocks and minerals are most stable when they:

A) are surrounded by fluids.
B) are at temperatures comparable to those of the Earth's surface.
C) are in the environment in which they formed.
D) are over 1 million years old.

Question 27

The rock that results from the metamorphism of granite is:

A) blueschist.
B) greenschist.
C) greenstone.
D) gneiss.

Question 28

Which metamorphic rock is often used by sculptors?

A) Marble.
B) Schist.
C) Quartzite.
D) Gneiss.

Question 29

A metamorphic index mineral is:

A) a mineral found only in gneiss.
B) a mineral that identifies the parent rock.
C) each new mineral that appears from low to high grade conditions.
D) a mineral formed only during contact metamorphism.

Question 30

Gneiss can be distinguished from other metamorphic rocks by:

A) its dark and light mineral bands.
B) its metallic sheen.
C) its large flakes of mica.
D) its slaty cleavage.

Question 31

Most of the information we have about metamorphic processes is derived from:

A) laboratory studies and theoretical models.
B) information gathered by probes placed deep within the Earth.
C) direct observation of metamorphic processes deep within the Earth.
D) direct observation of volcanic magma acting on surrounding rock.

Question 32

Serpentinite is formed by:

A) burial metamorphism of sandstone.
B) contact metamorphism of granite.
C) regional metamorphism of granite.
D) hydrothermal metamorphism of mantle rock.

Question 33

Burial metamorphism involves processes of:

A) heat and circulating fluids.
B) low heat and very high pressure.
C) heat and confining pressure.
D) heat and directed pressure.

Question 34

The type of metamorphism that occurs when rocks are caught between two converging plates during mountain building is:

A) shock metamorphism.
B) dynamothermal metamorphism.
C) burial metamorphism.
D) contact metamorphism.

Question 35

The foliated rock that results from the metamorphism of basalt is:

A) quartzite.
B) gneiss.
C) greenschist.
D) marble.

Question 36

Metamorphic rocks are often well exposed in:

A) deep sea trenches.
B) the craters of active volcanoes.
C) the ocean basins.
D) mountain belts.

Question 37

The term "metamorphic grade" refers to:

A) the severity of metamorphic conditions on the parent rock.
B) the economic value of the minerals found in a metamorphic rock.
C) the number of distinct mineral zones, or aureoles, found in a body of metamorphic rock.
D) the angle or slope of a body of metamorphic rocks.

Question 38

The average geothermal gradient is approximately:

Question 39

Which of the following types of rocks can become metamorphic rocks?

A) Sedimentary, igneous, or metamorphic rocks.
B) Sedimentary or igneous rocks only.
C) Sedimentary or metamorphic rocks only.
D) Sedimentary rocks only.

Question 40

The presence of the minerals stishovite and coesite indicates:

A) shock metamorphism.
B) burial metamorphism.
C) hydrothermal metamorphism.
D) contact metamorphism.

Question 41

What is the relationship of metamorphic rocks to other rocks in the rock cycle?

Question 42

Discuss the metamorphosis of igneous rocks.

Question 43

What are the functional differences between lithostatic pressure and directed pressure?

Question 44

Why is asbestos so dangerous?

Question 45

By what criteria are metamorphic rocks classified?

Question 46

What are metamorphic index minerals? Describe the drawback that limits the use of index minerals as indicators of metamorphic environments.

Question 47

What is meant by the geothermal gradient? How does it apply to the processes of metamorphism?

Question 48

Discuss the difference between low- grade and high- grade metamorphism.

Question 49

Describe the process of metamorphic differentiation by which gneiss develops its banding.

Question 50

Blueschist rocks are formed:

A) under the deepest parts of subduction zones, well below the roots of mountains.
B) around intruding igneous rocks such as batholiths.
C) within transform faults as a result of heat produced by friction.
D) within shallower parts of subduction zones.

Question 51

The primary difference between lithostatic pressure and directed pressure is:

A) lithostatic pressure breaks many of the bonds in minerals, unlike directed pressure, which merely deforms existing crystals.
B) lithostatic pressure pushes in on rocks equally from all sides, while directed pressure acts in one principal plane.
C) lithostatic pressure, unlike directed pressure, is accompanied by high temperatures and significant amounts of circulating fluids.
D) lithostatic pressure is caused by the movement of rocks, while directed pressure is caused by the weight of rocks.

Question 52

What type of metamorphism is indicated by the presence of serpentinization, or the minerals stishovite and coesite? How are each of these constitutive elements formed?

Question 53

Which type of asbestos mineral is most commonly used for commercial purposes?

A) Serpentine ("white") asbestos.
B) Tremolite asbestos.
C) Chrysotile asbestos.
D) Amphibole asbestos.