Epsc 201 Chapter 7

Front 1

Choose the listing that shows the rocks in increasing degrees of metamorphism (from lower- to higher-grade).

Back 1

Metaconglomerate, gneiss with mica, gneiss without mica, migmatite

(Mica indicates low-grade metamorphism)

Front 2

What is the protolith of marble?

Back 2

Limestone

Front 3

Which of the following locations could not possibly be part of a shield?

Back 3

Hawaii

Front 4

Identify the FALSE statement: A metamorphic rock

- Cannot be formed below 1200°C as all the rock minerals must melt.

- May have preferred mineral orientation caused by differential stress. may be composed of different minerals than its protolith.

- May have developed metamorphic texture of interlocking grains.

- Took thousands to millions of years to develop.

Back 4

Cannot be formed below 1200°C as all the rock minerals must melt.

Front 5

Identify the FALSE statement: Extremely high temperature of metamorphism

Back 5

Is necessary to form chlorite

Front 6

Mylonite:

- Forms due to dynamic metamorphism.

- All the possible answers are correct.

- Is produced by shear stress on softened rock.

- Forms by recrystallization in a fault zone.

- Has pronounced foliation parallel to the direction of faulting.

Back 6

All the possible answers are correct.

Front 7

Pick out the rock that is nonfoliated: hornfels, slate, phyllite, schist, gneiss

Back 7

Hornfels

Front 8

Identify the TRUE statement: Metasomatism

- Does not require heat in order to occur.

- Results in a partially melted rock.

- Requires very high pressure, but needs only low temperatures to occur.

- Cannot occur in cold, dry conditions.

- Requires hot fluids in order to occur.

Back 8

Requires hot fluids in order to occur.

Front 9

Identify the FALSE statement: Metamorphic facies

- Are more reliable indicators of metamorphic conditions than index minerals are.

- Each typically contain several metamorphic rock types with different mineral content.

- Are subdivided into seven major categories.

- Are sets of metamorphic mineral assemblages indicative of specific ranges of pressure and temperature.

- Are identical to metamorphic mineral assemblages.

Back 9

Are identical to metamorphic mineral assemblages.

Front 10

Identify a TRUE statement (there is only one) about metamorphic rocks and their characteristic environments:

- Gneiss is most common in metamorphic aureoles surrounding plutons.

- Mylonites are found along convergent-plate boundaries where magma is rising.

- Slate, phyllite, schist, and gneiss are found in areas of continental collision.

- Blueschists form near mid-ocean ridges.

Back 10

Slate, phyllite, schist, and gneiss are found in areas of continental collision.

Front 11

Which of the following processes results in the exposure of deeply buried rocks at the Earth’s surface?

Back 11

Exhumation

Front 12

Which is NOT a common process by which metamorphic rocks are formed?

Back 12

Schistosity

Front 13

Mountain building due to convergent-margin tectonics and to continental collision

- Can metamorphose former surface rock by differential stress generated by plate interactions.

- Can send surface rock to great depths.

- Can metamorphose former surface rock by proximity to magma.

- Can metamorphose former surface rock by increased pressure.

Back 13

All the possible answers are correct.

Front 14

T/F: Recrystallization occurs because thermal energy causes atoms to vibrate rapidly, break existing chemical bonds, and migrate to new positions on the crystal lattice where they are more stable under the hotter conditions.

Back 14

True

Front 15

T/F: Roofers use the rock schist to shingle roofs because its foliation, called schistosity, causes it to break in convenient size.

Back 15

False, they use slate

Front 16

The mineral sillimanite indicates higher-grade metamorphism than staurolite.

Back 16

True

Front 17

Schist is a medium-grade foliated metamorphic rock that normally contains micas.

Back 17

True

Front 18

Which is NOT a cause of banding in gneiss?

Back 18

Preferential orientation

Front 19

Marble is a favorite material of sculptors because of its relative softness, and uniform texture.

Back 19

True

Front 20

Blueschist is a common metamorphic rock of continental shields.

Back 20

False

Front 21

If the intrusion of magma (a pluton) melts mafic country rock, the resulting metamorphic rock is a schist or gneiss.

Back 21

False

Front 22

Metamorphic aureoles typically contain nonfoliated rock like hornfels, because the pluton intrusion provides heat but not the shearing stress necessary for foliation.

Back 22

True

Front 23

A supercritical fluid permeates rock very thoroughly because it has characteristics of both liquid and gas.

Back 23

True

Front 24

Which of the following is NOT required for pressure solution to occur?

Back 24

Greenschist-facies conditions or higher

Front 25

When geologists say metamorphic grade, they're referring to the general degree of metamorphism of a rock; when they say facies, they mean a subset of the broad temperature and pressure conditions in which metamorphism can occur.

Back 25

True

Front 26

The sequence of increasing metamorphism of the protolith shale (a sedimentary rock) is slate, phyllite, schist, and gneiss.

Back 26

True

Front 27

Dynamothermal metamorphism (regional metamorphism) produces metamorphic rocks in the depths of mountain ranges, which erosion eventually exposes as "mountain roots" hundreds of kilometers wide and thousands of kilometers long.

Back 27

True

Front 28

Dissolved ions freed during the process of metasomatism can precipitate to form mineral-filled cracks called veins.

Back 28

True

Front 29

Contact metamorphism occurs when

Back 29

A mass of rock is affected by the heat of a magma.

Front 30

Which process would you most expect during hydrothermal metamorphism near a mid-ocean ridge?

Back 30

Metasomatism