Deck 6: Sedimentary Rocks

Question 1

How does a sediment become transformed into a sedimentary rock?

A)by compaction and dewatering, followed by cementation
B)by destruction of all bedding and original depositional features
C)by multiple cycles of redeposition
D)by processes of polymorphism

Answer 1

A

Question 2

The type of diagenesis that occurs in the transformation of aragonite to calcite is ________.

A)weathering
B)decarbonation
C)dehydration
D)re-crystallization

Answer 2

D

Question 3

What do dense crystalline rocks and shales have in common?

A)The are both deposited in fresh water rivers and lakes.
B)They are usually made out of sediment sized rock fragments.
C)They both have low porosity and will be impermeable to oil or water.
D)They are both too stupid to pass a geology test!

Answer 3

C

Question 4

How do unconsolidated sediments originate?

A)by spontaneous decomposition in place of underlying rocks
B)by weathering, erosion, transport, and deposition
C)from the rock cycle by interrupted transmission
D)from meteorite showers breaking up rocks

Question 5

________ cement produces dark red and orange colours in some sandstone.

A)Clay
B)Calcite
C)Quartz
D)Iron oxide

Question 6

Which type of sediment undergoes the most compaction as it lithifies to sedimentary rocks?

A)marine mud
B)desert dune sand
C)reef limestone
D)coarse gravel

Question 7

Sedimentary rocks account for about what percentage of the Earth's outermost 10 kilometres of rock (first percentage).Also, what percentage of the Earth's continental area is covered by sedimentary rocks (second percentage)?

A)5%; 75%
B)3)5%; 100%
C)65%; 10%
D)85%; 100%

Question 8

What do orange red or brown colours indicate in sedimentary rocks?

A)original deposition on a beach
B)deposition below water in a swamp or muddy estuary
C)an oxidizing environment to produce iron (ferric)oxides or hydroxides
D)high organic matter contents

Question 9

In what setting would you expect to find massive, poorly sorted deposits ranging in size from boulders to clays?

A)channels deposits from the middle portions of rivers
B)eolian deposits from deserts with large dune fields
C)high latitude or high altitude glacial settings
D)sediments from lagoons and estuaries on a temperate coastline

Question 10

Hot regions having basins with limited input and restricted circulation tend to have ________ deposits.

A)sandy beach
B)glacial dropstone
C)limestone reef and bank
D)evaporite

Question 11

How are cements formed in sedimentary rocks?

A)They are always present in the original sediment, but they take a while to react.
B)They are injected as a slurry as dense fluids are forced through the sediments.
C)Most are introduced as dissolved substances in pore waters.
D)From decomposition of buried organic matter.

Question 12

What percentage of the Earth's crust is composed of sedimentary rocks?

A)5%
B)15%
C)25%
D)75%

Question 13

Which characteristic is absolutely necessary for a sedimentary rock to have potential as a possible reservoir rock for oil or gas?

A)high porosity
B)clastic texture
C)chemical origin
D)good stratification

Question 14

Which statement concerning sedimentary rocks is false?

A)They may contain fossils that provide clues about ancient life forms.
B)They probably show some evidence of stratification.
C)They were originally deposited at depth below the bottom of the sea.
D)They are composed of materials derived from weathering and erosion of other rocks.

Question 15

The process of turning a sediment into a sedimentary rock is called ________.

A)conglomeration
B)crystallization
C)lithification
D)redeposition

Question 16

Which of the following is not a common cementing agent for sandstones?

A)quartz
B)calcite
C)fluorite
D)iron oxides

Question 17

What are the most common cementing agents in sedimentary rocks?

A)CaO
B)Ca(OH)?
C)calcite, silica, and iron oxides
D)clays and bitumen

Question 18

Diagenesis occurs at temperatures below ________ in the outer few kilometres of Earth's crust.

A)10°
B)50°
C)100°
D)200°

Question 19

Compaction is a very important part of the lithification process for which of the following sediments?

A)gravel
B)sand
C)mud
D)cobble

Question 20

What setting is suggested by a circular region about 40 km across with predominant shales, a thick sandy delta sequence at one end, and both of them surrounded by a thin rim of sandy, well sorted beach deposits?

A)glacial location of a former ice cap
B)lake
C)small marine basin in the middle of the ocean
D)meandering river deposits

Question 21

Beaches, bars, deltas, lagoons, and tidal flats are all ________ environments.

A)continental
B)marine
C)transitional
D)alcoholic

Question 22

What kind of depositional environment (facies)makes linear sand bodies?

A)atolls
B)bars, spits, and barrier islands
C)deltas
D)lagoons

Question 23

Detrital grains of which mineral(s)are extremely rare in detrital sediments? Why?

A)calcite; it is soft and relatively soluble
B)clays; they are rare in soils and regolith
C)quartz; it is very hard and insoluble
D)feldspars; they occur only in granites

Question 24

Which common mineral of igneous rocks is the most abundant mineral in detrital sedimentary rocks?

A)calcite
B)orthoclase
C)quartz
D)biotite

Question 25

Other than detrital, what other origin can sediments have?

A)accumulation from inorganic precipitation or organic deposition
B)erosion and transport
C)They were put there by the Devil to confuse us.
D)accumulation of debris from meteorite showers

Question 26

Where would you expect turbidites to form?

A)on sandy beaches
B)at the base of the continental slope
C)limestone reefs and banks
D)out the rear end of a dinosaur

Question 27

Which sediment gets lithified to become conglomerate?

A)gravel
B)sand
C)clay and fine silt
D)all clay-sized sediment

Question 28

Shales are distinguished from other mudrocks by their ________.

A)colour
B)sand content
C)fissility
D)fossil content

Question 29

What proportion of sedimentary rocks do the mudstones and shales comprise?

A)5%
B)25%
C)50%
D)95%

Question 30

In what environment are deltas typically formed, and why are they formed there?

A)around the middles of large lakes far from shore; there is no farther for the sediments to go
B)in desert environments in the middles of continents far from the mountains; there is no water or wind left to carry sediment any farther
C)in submarine river systems because of the "delta" shape of the seafloor basins
D)transitional; decrease in slope (gradient)and sediment carrying power

Question 31

The aspect, thickness, and appearance of a rock unit, and reflecting its environmental conditions of origin, is collectively referred to as its ________.

A)agglomerate properties
B)stratal index
C)facies
D)lithology

Question 32

Which sediment gets lithified to become shale?

A)all clay sized sediment
B)gravel
C)clay and fine silt
D)sand

Question 33

Shales are usually described as weak because they are ________.

A)so porous and permeable
B)devoid of quartz
C)only compacted but not well cemented
D)too thinly bedded to use for building stone

Question 34

Zircon and tourmaline are dense, highly insoluble, physically tough, chemically stable, minor minerals of igneous and metamorphic rocks.In which sedimentary rock might you expect to find these minerals concentrated?

A)sandstone lithified from quartz-rich beach sand
B)limestone representing lithified coral-reef carbonates
C)a thin, upper, mudstone portion of a thick wacke bed with graded bedding
D)evaporite deposits of gypsum and salt

Question 35

Which sediment gets lithified to become sandstone?

A)sand
B)gravel
C)clay and fine silt
D)all clay sized sediment

Question 36

The dominant sediment of tidal flats would likely be ________.

A)cobbles and other very coarse grained sediments
B)sands and broken shell fragments
C)muds and silts with some organic content
D)turbidites with graded bedding

Question 37

How wide is a typical continental shelf?

A)10 kilometres
B)80 kilometres
C)> 1800 kilometres
D)8000 kilometres

Question 38

Which major component of detrital sedimentary rocks only rarely occurs as a primary mineral in igneous rocks?

A)clays
B)carbonates
C)quartz
D)ferromagnesian minerals

Question 39

Laterally shifting depositional environments with time always produce ________.

A)unloading as more sediments accumulate
B)evaporites
C)major earthquakes
D)vertical facies successions

Question 40

What economic value do shales have, such as the Queenston Formation below the Niagara escarpment?

A)cut dimension stone for buildings
B)fine grained detrital gold
C)high oil contents
D)raw materials for brick making, pottery or tiles

Question 41

What rock type would be made mostly from particles 0.5 to 2.0 millimetres with a few larger rounded grains >4 mm in size?

A)pebbly sandstone
B)conglomeratic mudstone
C)granular shale
D)Fred Flintstone

Question 42

What is the main difference between a conglomerate and a sedimentary breccia?

A)Breccia clasts are angular; conglomerate clasts are rounded.
B)A breccia is well stratified; a conglomerate is poorly stratified.
C)Breccia clasts are the size of baseballs; conglomerate clasts are larger.
D)Breccia has a compacted, clay-rich matrix; conglomerate has no matrix.

Question 43

What rock type would be made mostly from particles 1/256 millimetres and has lots of thin flat laminae and a reddish colour?

A)ferruginous shale
B)carbonaceous mudstone
C)calcareous siltstone
D)Wilma Flintstone

Question 44

What does the degree of rounding indicate in a sediment?

A)the distance travelled or duration of time involved in sediment transport
B)where the minerals originally came from
C)the velocity of transport
D)whether the sediment was deposited in a stream or the ocean

Question 45

What clues about their environments of deposition do all sandstones have?

A)cement types
B)fossils and bedding planes
C)particle composition, shape, and sorting
D)fluid type (oil or water)

Question 46

Which of the following rocks is lithified from sediment that was deposited in deep water and was essentially unmodified by post-depositional current action?

A)cross-bedded dune sandstone
B)wacke with graded bedding
C)well-sorted, quartz sandstone
D)reddish mudstone with mud cracks

Question 47

What is a wacke?

A)a limestone with abundant, sand-sized, quartz grains
B)a sandstone with immature lithic sand grains embedded in a clay-rich matrix
C)a dark-grey, calcite-rich mudstone or shale containing pyrite
D)a dark, organic-rich, chemical sedimentary rock containing small crystals of halite

Question 48

Which type of sandstone contains abundant feldspar, suggesting that the sand was derived by weathering and erosion of granitic bedrock?

A)quartz-rich
B)lignitic
C)arkose
D)oolitic

Question 49

What does a sand that contains significant amounts of sand-sized rock fragments, blocky feldspar, and angular prismatic grains of ferromagnesian minerals suggest?

A)that it has travelled a short distance and was likely deposited very close to the source of the particles
B)that it has travelled a great distance in a uniform flow or has had more than one cycle of weathering, transport, and deposition.
C)that it had a very low velocity of transport and likely a shallow stream gradient
D)that it was derived from uplifted and eroded older sedimentary rocks

Question 50

Black shales contain abundant ________ and were probably deposited in a/an ________ environment.

A)calcium carbonate, tropical marine
B)carbon, anoxic
C)iron oxides, swampy
D)glass fragments, volcanic

Question 51

Which type of sandstone contains abundant, clayey, matrix material?

A)brownstone
B)wacke
C)arkose
D)cherty

Question 52

What sedimentary rock type most commonly contains terrestrial plant fossils?

A)quartzite breccia
B)silty limestone
C)dark organic rich shales
D)massive sandstones

Question 53

Of sedimentary rocks, what proportion are sandstones?

A)2%
B)20%
C)50%
D)75%

Question 54

What does poor sorting indicate in a sediment?

A)a big velocity increase during deposition
B)that the particles are not the same shape but all the same size
C)short transport distance and/or very rapid deposition
D)there was no environment of deposition

Question 55

What does a sand that is: very well rounded, well sorted, and quartz rich suggest?

A)that it has travelled a short distance and hasn't had time to get contaminated
B)that it has travelled a great distance in a uniform flow or has had more than one cycle of weathering, transport, and deposition.
C)that it had a very high velocity of transport
D)that it was derived from a young mountain belt with lots of granite

Question 56

Which type of sandstone contains abundant detrital feldspar grains?

A)pegmatitic
B)arkose
C)wacke
D)orthoquartzite

Question 57

Which sediment gets lithified to become mudstone?

A)clay and fine silt
B)sand
C)gravel
D)all clay-sized sediment

Question 58

What rock type would be made from angular rock fragments >70 millimetres in size?

A)breccia
B)sandstone
C)siltstone
D)shale/mudstone

Question 59

Which type of sand depositional environment would probably have the best degree of sorting?

A)beach face
B)dune
C)river bar
D)delta face

Question 60

What rock type would be made from rounded grains of various rock types ranging from 1 to 250 millimetres?

A)conglomeratic sandstone
B)conglomeratic mudstone
C)lithic sandstone
D)pebbly mudstone

Question 61

Jasper, Flint and Agate are all ________, more commonly called ________.

A)fine-grained detrital silica, quartz
B)microcrystalline calcium carbonate, chalk
C)microcrystalline silica, chert
D)small towns in Alberta, Hicksville

Question 62

Where do most carbonate reefs form?

A)in the arctic
B)from hot springs deposits in the deep sea
C)in the tropics between -30° and +30° Latitude
D)where rivers drain tropical rain forest and bury lots of clastic sediment and biomass

Question 63

Which limestone consists mainly of tiny, marine fossils composed of calcite?

A)dolostone
B)chert
C)coquina
D)chalk

Question 64

Oolitic limestone is most likely to form in what type of depositional environment?

A)quiet, muddy, lagoons and bays
B)shallow, clear, marine waters with vigorous current activity
C)deep, marine waters below most wave action
D)acidic, organic-rich waters in freshwater swamps and bogs

Question 65

Which of the following is the most common type of chemical sedimentary rock?

A)limestone
B)chert
C)phosphate rock
D)quartz sandstone

Question 66

What do most limestones, gypsum, rock salts like halite or potash (sylvite), and chert have in common?

A)They are all directly pertinent to the global carbon cycle.
B)They are all considered chemical or biochemical sediments.
C)They are all organic precipitates.
D)They are all formed by organisms on the ocean floor.

Question 67

Which of the following is not a limestone?

A)arkose
B)coquina
C)chalk
D)travertine

Question 68

How does most calcium-magnesium carbonate rock form?

A)in salt lakes and evaporite basins of continental interiors
B)by diagenetic replacement of Ca by Mg in limestone
C)from volcanic hot springs in the deep sea
D)by direct precipitation from seawater but dolomite selectively dissolves so most carbonate sedimentary rocks are limestone

Question 69

Most chemical sediments derive from ________.

A)industrial waste from multi-national corporations
B)the soluble products of weathering, carried in solution to a warm, evaporating basin
C)detrital minerals that are a single, pure, inorganic compound
D)accumulations of organic matter

Question 70

What is the chemical formula for dolomite, the major mineral in dolostones?

A)NaCl
B)CaSO?? 2H?O
C)SiO?
D)CaMg

Question 71

________ is a form of calcium carbonate.

A)Travertine
B)Chert
C)Lignite
D)Gypsum

Question 72

Which of the following sedimentary rocks would you expect to have originally been deposited by fast-moving streams?

A)mudstone
B)oolitic limestone
C)wacke
D)conglomerate

Question 73

Which of the following sedimentary rocks is usually biochemical in origin?

A)limestone
B)sandstone
C)wacke
D)bedded salt

Question 74

Which one of the following is not a chemical sedimentary rock or evaporite?

A)shale
B)bedded gypsum
C)cherty dolostone
D)oolitic limestone

Question 75

A cherty limestone would contain which major constituents?

A)iron oxide; calcite
B)silica; iron oxide
C)clay minerals
D)silica; calcite

Question 76

Which of the following is a form of calcium carbonate found in cave formations and hot springs deposits?

A)travertine
B)chert
C)lignite
D)gypsum

Question 77

What do you call a porous rock made entirely of coarse shell fragments?

A)coquina
B)chert
C)phosphate rock
D)"ball park breccia"

Question 78

What kind of rock are most dripstones and stalactites in caves?

A)chert
B)gypsum
C)limestone
D)opal

Question 79

Flint, chert, and jasper are microcrystalline forms of which mineral?

A)quartz; SiO?
B)hematite; Fe?O?
C)halite; NaCl
D)calcite; CaCO?

Question 80

What proportion of sedimentary rocks are "limestones"?

A)5%
B)10%
C)20%
D)50%