Question 1

Which facies would you expect to find with the development of glaucophane at high pressure?
A) granulite
B) hornfels
C) blueschist
D) amphibolite

Accepted Answer

Glaucophane is a characteristic mineral of the blueschist facies, which forms under high-pressure, low-temperature conditions typically associated with subduction zones.

Question 2

How would you correctly refer to the metamorphic grade of a rock that contains bundles of fibrous sillimanite along with pyroxene and sanidine as its highest temperature minerals such as a coarse grained granulite facies gneiss?
A) high grade > 600° C
B) intermediate grade
C) "S grade"
D) low grade < 200° C

Accepted Answer

The presence of fibrous sillimanite along with pyroxene and sanidine in a coarse-grained granulite facies gneiss indicates a high-grade metamorphic rock, which typically forms at temperatures greater than 600° C.

Question 3

Which one of the following statements is false?
A) In slate, rock cleavage is common.
B) In slate, sedimentary features may be visible.
C) Slate has abundant, coarse- grained mica.
D) Slate forms from shale and mudstones.

Accepted Answer

Slate is characterized by fine-grained texture, not coarse-grained mica. It is a metamorphic rock that forms through the low-grade metamorphism of shale or mudstone, which aligns its constituent minerals, such as fine-grained mica, into parallel layers, giving it a foliated structure. This is in contrast to rocks with coarse-grained minerals, which are typically found in rocks that have undergone higher grades of metamorphism.

Question 4

A________ forms at very high pressures but relatively low temperatures associated with subduction of oceanic crust and sediments.
A) blueschist
B) sillimanite bearing marble
C) migmatite
D) mylonite

Accepted Answer

Blueschist forms under high-pressure, low-temperature conditions typically found in subduction zones, where oceanic crust is forced down into the mantle. This unique environment leads to the formation of the characteristic blue-colored minerals that give blueschist its name.

Question 5

A __________ forms at very high pressures but moderately low temperatures associated with subduction of oceanic crust and sediments.
A) blueschist
B) biotite marble
C) migmatite
D) mylonite

Accepted Answer

Blueschist forms under high-pressure and low-temperature conditions, typically associated with the subduction zones where oceanic crust is forced down into the mantle. These specific conditions lead to the formation of glaucophane, a blue amphibole, which gives the rock its characteristic blue color and name.

Question 6

Metamorphic grade refers to ________.
A) how much we'll have to curve your test mark if you are guessing!
B) recrystallization versus amount of primary mineral grains
C) metamorphic intensity as recorded by particular minerals which are sensitive to T, P
D) economic value of metamorphic rocks

Accepted Answer

Metamorphic grade is an indication of the intensity of metamorphism, meaning the degree to which the parent rock has undergone changes in temperature, pressure, and chemical processes. This is often recorded by the presence of specific minerals, known as index minerals, which form under certain conditions of temperature and pressure.

Question 7

What foliated, regional metamorphic rock is texturally intermediate between slate and schist?
A) fault breccia
B) quartzite
C) gneiss
D) phyllite

Accepted Answer

Phyllite is a foliated, regional metamorphic rock that is texturally intermediate between slate and schist, characterized by its fine-grained, lustrous sheen and more pronounced foliation compared to slate, but less coarse than schist.

Question 8

Which of the following rocks would exhibit visible, textural evidence of having undergone significant partial melting?
A) coarse grained angular fault breccias
B) migmatites
C) porphyroblastic hornfels
D) marbles

Accepted Answer

Migmatites are rocks that have undergone partial melting, often showing a mixture of igneous and metamorphic features, which is a visible, textural evidence of their history of significant partial melting.

Question 9

______is a nonfoliated rock formed by the contact metamorphism of fine grained rocks like shales, mudstones, or volcanics.
A) Schist
B) Hornfels
C) Marble
D) Gneiss

Accepted Answer

Hornfels is the correct answer because it is a nonfoliated metamorphic rock that forms through the contact metamorphism of fine-grained rocks like shales, mudstones, or volcanic rocks. This process occurs when these rocks are subjected to high temperatures and pressures from nearby magma bodies, but without significant deformation or compression, leading to the formation of a dense, hard rock without a layered or banded appearance.

Question 10

Which regional metamorphic rock type listed below represents the highest grade?
A) phyllite
B) mica schist
C) slate
D) hornfels

Accepted Answer

Mica schist represents the highest grade of regional metamorphism among the options given. It forms under higher temperatures and pressures compared to phyllite and slate, indicating a more intense metamorphic process. Hornfels is typically associated with contact metamorphism rather than regional metamorphism.

Question 11

Increasing regional metamorphic grade of a shale or mudstone would produce the sequence
A) hornfels, amphibolite, migmatite
B) breccia, gouge, mylonite, ultramylonite
C) greenschist, amphibolite, granulite
D) slate, phyllite, schist, gneiss

Accepted Answer

The sequence of increasing regional metamorphic grade for shale or mudstone typically progresses from slate, to phyllite, to schist, and finally to gneiss, reflecting increasing temperature and pressure conditions.

Question 12

About 1.2 to 1.0 billion years ago, Canada had a mountain range the size of the modern Himalayas, with high grade metamorphic rocks (>800°C) forming in its roots. Where was this located?
A) The Canadian Rockies
B) The Grenville Orogen stretching between Georgian Bay Ontario and Newfoundland
C) The Trans Hudson Orogen of Saskatchewan and Manitoba
D) The Coast Mountains of B.C.

Accepted Answer

The Grenville Orogeny occurred about 1.0 to 1.2 billion years ago and is known for its high-grade metamorphic rocks, indicating the presence of a significant mountain range, similar in scale to the modern Himalayas, during that period. This orogenic belt stretches from the Georgian Bay area in Ontario through to Newfoundland.

Question 13

Which is a foliated, fine- grained regional metamorphic rock formed from mudstone and shale?
A) hornfels
B) gneiss
C) marble
D) phyllite

Accepted Answer

Phyllite is a foliated, fine-grained regional metamorphic rock that evolves from mudstone or shale. Its foliation results from the reorientation of minerals in response to high pressure and temperature conditions, distinguishing it from its parent rock.

Question 14

Which facies would you expect to find with intermediate temperature- pressure regional metamorphism?
A) granulite
B) amphibolite
C) blueshist
D) hornfels

Accepted Answer

Amphibolite facies is characteristic of intermediate temperature-pressure conditions in regional metamorphism, typically forming from the metamorphism of mafic rocks and is associated with orogenic events.

Question 15

Long linear metamorphic fold belts mark_______ .
A) zones with the lowest geothermal gradients
B) the youngest mountains with the slowest rates of uplift
C) divergent plate settings (rifts)
D) modern or former convergent continental margins

Accepted Answer

Long linear metamorphic fold belts are typically found at modern or former convergent continental margins, where the intense pressure and heat associated with the collision of continental plates lead to metamorphism and the formation of folded mountain ranges.

Question 16

Which of the following lists the rocks in the order of increasing grain size and increasing grade for regionally metamorphosed mud rocks?
A) slate, schist, phyllite
B) schist, slate, phyllite
C) phyllite, slate, schist
D) slate, phyllite, schist

Accepted Answer

The correct order for increasing grain size and metamorphic grade for mud rocks is slate, phyllite, schist. Slate forms under the lowest grade of metamorphism, followed by phyllite with a slightly higher grade and larger grain size, and schist forms under even higher grade conditions with larger grains.

Question 17

The intensity and grade of________ metamorphism is most intense where_________ .
A) cataclastic (dynamic), muds are shattered by raindrop impacts
B) contact, clays are recrystallized and reacted entirely to chlorite
C) regional, continents collide forming a mountain belt
D) burial (zeolite facies), the soil horizon gives way to unaltered bedrock

Accepted Answer

Regional metamorphism is most intense in areas where continents collide, leading to the formation of mountain belts. This process subjects rocks to high pressures and temperatures, causing significant metamorphic changes.

Question 18

Why is the regional metamorphism of ocean crust in a subduction zone considered separately from regular regional metamorphism?
A) Because this setting does not involve any strain deformation.
B) The ocean crust has no hydrous minerals to destroy or recrystallize.
C) Unlike regular regional metamorphism, this does not occur on plate margins.
D) Both the basaltic composition and very low geothermal gradient (Low T, Hi P) are unique and lead to different facies than seen in continental rocks.

Accepted Answer

The ocean crust undergoing subduction experiences unique conditions due to its basaltic composition and the very low geothermal gradient (Low Temperature, High Pressure) it encounters. This combination leads to the formation of metamorphic facies that are distinct from those found in continental settings, thus necessitating a separate consideration from regular regional metamorphism.

Question 19

Which two, metamorphic rocks are each composed predominantly of a single mineral?
A) mica schist and granitic gneiss
B) fault breccia and graphitic schist
C) marble and quartzite
D) garnet schist and andalusite hornfels

Accepted Answer

Marble is predominantly composed of calcite or dolomite, and quartzite is almost entirely composed of quartz. These rocks are each made up of a single mineral, fitting the criteria.

Question 20

Where would you expect to find chlorite and zeolites filling up voids and fractures in relatively undeformed rocks?
A) high grade metamorphism of layered sandstones and shales
B) high temperature hornfels contact metamorphism of salts and rock gypsum
C) intermediate grade metamorphism of limestones
D) burial metamorphism of sedimentary or volcanic rocks

Accepted Answer

Chlorite and zeolites are typically formed under low-grade metamorphic conditions, such as those found in burial metamorphism of sedimentary or volcanic rocks. These minerals fill up voids and fractures without significantly deforming the rock structure.

Quiz 18: Deserts and Winds

Which facies would you expect to find with the development of glaucophane at high pressure?

How would you correctly refer to the metamorphic grade of a rock that contains bundles of fibrous sillimanite along with pyroxene and sanidine as its highest temperature minerals such as a coarse grained granulite facies gneiss?

Which one of the following statements is false?

A________ forms at very high pressures but relatively low temperatures associated with subduction of oceanic crust and sediments.

A __________ forms at very high pressures but moderately low temperatures associated with subduction of oceanic crust and sediments.

Metamorphic grade refers to ________.

What foliated, regional metamorphic rock is texturally intermediate between slate and schist?

Which of the following rocks would exhibit visible, textural evidence of having undergone significant partial melting?

______is a nonfoliated rock formed by the contact metamorphism of fine grained rocks like shales, mudstones, or volcanics.

Which regional metamorphic rock type listed below represents the highest grade?

Increasing regional metamorphic grade of a shale or mudstone would produce the sequence

About 1.2 to 1.0 billion years ago, Canada had a mountain range the size of the modern Himalayas, with high grade metamorphic rocks (>800°C) forming in its roots. Where was this located?

Which is a foliated, fine- grained regional metamorphic rock formed from mudstone and shale?

Which facies would you expect to find with intermediate temperature- pressure regional metamorphism?

Long linear metamorphic fold belts mark_______ .

Which of the following lists the rocks in the order of increasing grain size and increasing grade for regionally metamorphosed mud rocks?

The intensity and grade of metamorphism is most intense where_ .

Why is the regional metamorphism of ocean crust in a subduction zone considered separately from regular regional metamorphism?

Which two, metamorphic rocks are each composed predominantly of a single mineral?

Where would you expect to find chlorite and zeolites filling up voids and fractures in relatively undeformed rocks?