Deck 18: Deserts and Winds

Question 1

Which metamorphic reaction takes up water to make hydrous minerals?

A) high temperature decomposition of muscovite to form K- feldspar and corundum
B) low temperature alteration of olivine in basalt to form serpentine or talc
C) high temperature decomposition of biotite and amphibole to make pyroxene
D) contact metamorphism of clays like kaolinite to form sillimanite and corundum

Answer 1

B

Question 2

Which facies would you expect to find with hydrous low temperature- low pressure burial metamorphism?

A) zeolite
B) amphibolite
C) blueschist
D) granulite

Answer 2

A

Question 3

What major change occurs during metamorphism of limestone to marble?

A) Limestone grains react to form quartz and feldspars.
B) Calcite grains grow larger and increase in size.
C) Calcite grains are dissolved away leaving only marble crystals.
D) Clays crystallize to micas, forming a highly foliated, mica- rich rock.

Answer 3

B

Question 4

Amphibolite is a foliated metamorphic rock composed principally of hornblende and plagioclase. How does it form?

A) by contact metamorphism of quartzose sandstone cut by a granitic batholith
B) by gouging and crushing of limestone along a fault
C) by regional metamorphism of volcanic rocks such as andesite and basalt
D) by the impact of an asteroid on interbedded sandstone and shale

Question 5

In 1915, which geologist proposed a series of metamorphic facies to describe the progressive mineralogic and textural changes in basalt as a function of temperature and pressure?

A) Norman Bowen
B) William Logan
C) Pennti Eskola
D) George Dawson

Question 6

Which facies would you expect to find with high temperature- low pressure contact metamorphism?

A) granulite
B) hornfels
C) amphibolite
D) blueschist

Question 7

Which is a coarse- grained, high- grade, metamorphic rock with alternating bands or stringers of light and dark minerals?

A) marble
B) gneiss
C) hornfels
D) phyllite

Question 8

What texture results from the alignment of abundant, coarse- grained, mica flakes in a medium grade regional metamorphic rock?

A) gneissic banding
B) schistosity
C) slaty cleavage
D) shatter cones

Question 9

A large block of sedimentary rock that has fallen into the top of a magma chamber and become metamorphosed is called .

A) a roof pendant
B) an amphibolite boudin
C) an astrobleme
D) an inverted aureole

Question 10

What are tekites?

A) globular to teardrop- shaped, dark, glassy, silica- rich impact melts
B) hard, foliated, hornfels chips in a shale heated by an intrusive granite
C) unusually coarse- grained migmatites that crystallized in a caldera
D) granular breccias produced by fault zone shattering

Question 11

Where and how does metamorphism occur?

A) mainly at low temperatures in the roots of volcanic mountain belts
B) wherever solid rocks are subjected to new conditions of temperature, pressure, strain, and a change in their constituent fluids
C) in response to sudden catastrophic geologic changes, mostly in the Precambrian.
D) beneath the thick accumulations of in sedimentary basins

Question 12

Which rock forms by contact metamorphism of fine grained mudstones, shales, and volcanics?

A) phyllite
B) gneiss
C) limestone
D) hornfels

Question 13

Which of the following forms at a medium grade of regional metamorphism?

A) hornfels
B) phyllite
C) slate
D) schist

Question 14

Which one of the following is not genetically associated with the terrestrial impact of an asteroid or large meteorite?

A) impact crater
B) blueschists
C) tekites
D) shatter cones

Question 15

Which is a nonfoliated metamorphic rock consisting mostly of calcite?

A) marble
B) hornfels
C) phyllite
D) gneiss

Question 16

What is the end product (highest grade) reached by subduction zone metamorphism of basalt?

A) granulite
B) gneiss
C) eclogite
D) gabbro pegmatite

Question 17

What do you call a coarse grained, foliated metamorphic rock having thick bands of dark ferromagnesian minerals alternating with pink feldspar and quartz layers?

A) phyllite
B) hornfels
C) schist
D) gneiss

Question 18

Under the application of uniform, confining pressure, rocks will generally .

A) shatter and turn into a breccia
B) increase in density but retain primary bedding orientations
C) bend, fold, buckle, and shear to make typical deformed metamorphic textures
D) grow or crystallize a new set of low density hydrous minerals

Question 19

is thought to form by partial melting and in situ crystallization of the melted portion at the highest grade of regional metamorphism of crustal rocks.

A) Meltite
B) Magmatite
C) Migmatite
D) Magnetite

Question 20

is a strong, parallel alignment of coarse mica flakes and/or of different mineral bands in a metamorphic rock.

A) Rock cleavage
B) Foliation
C) Shear stress
D) Brecciation

Question 21

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

A) granulite
B) hornfels
C) blueschist
D) amphibolite

Question 22

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

Question 23

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.

Question 24

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

Question 25

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

Question 26

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

Question 27

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

A) fault breccia
B) quartzite
C) gneiss
D) phyllite

Question 28

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

Question 29

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

Question 30

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

A) phyllite
B) mica schist
C) slate
D) hornfels

Question 31

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

Question 32

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°

A) The Canadian Rockies
B) The Grenville Orogen stretching between Georgian Bay Ontario and Newfoundland
C) The Trans Hudson Orogen of Saskatchewan and Manitoba
C) forming in its roots. Where was this located?
D) The Coast Mountains of B.C.

Question 33

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

A) hornfels
B) gneiss
C) marble
D) phyllite

Question 34

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

A) granulite
B) amphibolite
C) blueshist
D) hornfels

Question 35

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

Question 36

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

Question 37

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

Question 38

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.

Question 39

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

Question 40

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

Question 41

What term describes the zone of contact metamorphism where hornfels forms, surrounding an intrusive magma body?

A) aureole
B) astrobleme
C) hydrothermal vein
D) oracle

Question 42

Increasing regional metamorphism of a basalt or gabbro would produce the sequence .

A) slate, phyllite, schist, gneiss
B) greenschist, amphibolite, granulite
C) breccia, gouge, mylonite, ultramylonite
D) hornfels, amphibolite, migmatite

Question 43

A massive mudstone metamorphosed to biotite hornfels facies would have .

A) irregular spots of randomly oriented biotite platelets called porphyroblasts
B) biotite defining wavy parallel foliations throughout the rock
C) remnants of biotite, now mostly recrystallized to garnet in discreet layers
D) breccia of angular biotite clasts crushed and sheared out of shape

Question 44

Tektites originate in what metamorphic environment?

A) high temperature melting associated with meteorite impacts
B) low pressure and high temperature associated with volcanism
C) very high pressures and temperatures associated with deep subduction
D) high temperatures and shearing stresses in an oceanic transform fault

Question 45

What is the major source of heat for contact metamorphism?

A) heat from a nearby magma body
B) heat from grinding and shearing on faults
C) deep burial and heat from Earth's interior
D) heat from the spontaneous decomposition of micas and feldspars

Question 46

A sillimanite hornfels would .

A) usually form from the complete subduction of ocean crust deep into the mantle
B) lie on the outermost edge of a contact aureole where hornfels are preserved
C) lie entirely within the core of the contact aureole occupied by the high grade
D) be formed at the highest grade of regional metamorphism

Question 47

What type of environment is typified by brittle deformation?

A) shallow very high temperature settings as in contact metamorphism
B) intermediate depths with long slow heating and gradual strain rates
C) deep burial with great confining pressure
D) shallow, low temperature settings with high strain rates

Question 48

How would you correctly refer to the metamorphic grade of a rock that contains abundant chlorite as its highest temperature mineral such as a greenschist or phyllite?

A) intermediate grade
B) low grade < 200° C
C) high grade > 600° C
D) "C grade"

Question 49

Which of the following best describes the conditions of contact metamorphism?

A) Depths are so deep and temperatures are so high that the rocks begin to partially melt.
B) Pressures are fairly low, the rock is in the upper part of the crust, the heat for baking the neighbouring rocks is supplied quickly from the intrusion of a nearby magma body.
C) Pressures are very high, the rock is deeply buried, and temperatures are raised gradually by Earth's internally generated heat.
D) Heat is generated very quickly by shearing and mechanical movements along faults.

Question 50

In the formation of migmatites, which minerals start to melt first?

A) zircon and magnetite
B) amphibole, biotite, and garnet
C) quartz and feldspar
D) chlorite and calcite

Question 51

Graphite is identified in a particular schist. Which one of the following conclusions is justified?

A) The graphite lubricated shearing movements along a fault, causing a schist to form.
B) The rock also contains diamonds; both are crystalline forms of the element carbon.
C) The pre-metamorphic rock was a shale or mudstone containing organic matter.
D) The schist formed from a quartz-rich, sedimentary limestone.

Question 52

What platy, parallel, mineral grains are the most visual aspect of foliated metamorphic rocks?

A) carbonates
B) quartz
C) feldspars
D) micas

Question 53

In which setting would regional metamorphism most likely occur?

A) on the rims of large meteorite impact craters
B) at shallow depths below an oceanic ridge or rift zone
C) at shallow depths along major transform faults on the continental crust
D) at great depths in the crust where two continents are colliding

Question 54

is characterized by the segregation of light- and dark- coloured minerals into thin layers or bands.

A) Quartzite
B) Slate
C) Granite gneiss
D) Garnet hornfels

Question 55

Chemically active fluids like tend to transport ions and mineral components and their activity with increasing temperature.

A) HCl and hydrogen sulphide, ceases
B) water and carbon dioxide, increases
C) petroleum hydrocarbons, increases
D) water and carbon dioxide, decreases

Question 56

forms from the metamorphism of limestone or dolostone.

A) Quartzite
B) Migmatite
C) Marble
D) Amphibolite

Question 57

contain the oldest dated metamorphic rocks in Canada.

A) The Acasta Gneiss, NWT
B) The Ungava Orogen
C) The Nuwuagittuq Greenstone, Quebec
D) The Grenville Province

Question 58

is typically formed by metamorphism of a mature sandstone.

A) Marble
B) Amphibolite
C) Slate
D) Quartzite

Question 59

During metamorphism, what is the major effect of chemically active fluids like water and carbon dioxide?

A) aid in the movement of dissolved ions and silicate constituents from parent minerals and facilitate growth of new metamorphic mineral grains
B) facilitate the formation of schistosity and gneissic banding in hornfels and skarns
C) increase the pressures in deeply buried, regional- metamorphic zones
D) prevent partial melting so solid rocks can undergo very high temperature regional metamorphism

Question 60

Which low- grade metamorphic rock, composed of extremely fine mica and other mineral grains, typically exhibits well- developed rock cleavage?

A) quartzite
B) schist
C) slate
D) hornfels

Question 61

are formed from the impact of an asteroid or meteorite.

A) Subduction zones
B) Batholiths
C) Volcanoes
D) Astroblemes

Question 62

What effect does the application of directed pressure have on the texture of rocks.

Question 63

Where does burial metamorphism occur, how is it recognized and what conditions does it represent?

Question 64

Which type of metamorphism occurs specifically in the heated zone around a pluton or other body of magma?

Question 65

What is the facies name for the unique high pressure- low temperature hydrous metamorphism seen on top of subducting oceanic crust?