Deck 2: Minerals: the Building Blocks of Rocks

Question 1

What is the heat source for "black smokers"?

A) biologic heat from thermophyllic bacteria and densely populated vent communities
B) chemical oxidation of sulphide minerals below the seafloor
C) magmatic heat below the seafloor
D) deeply circulating currents of hot, dense ocean brines, deflected to follow the ridge system

Answer 1

C

Question 2

What was the latest technological addition to seafloor mapping, developed in response to mapping the ocean floor for national security, resource development, and directing seabed cable and pipeline crossings?

A) fleets of remotely telemetered, miniature drifter buoys
B) swath echo sounding by mechanical multi- beam sonar
C) walking it off one step at a time by the "Pirates of the Caribbean"
D) airborne sounding methods, by overflying the oceans

Answer 2

B

Question 3

The geologic process responsible for the most rugged relief to be found on a passive margin's

A) turbidity currents
B) glacial erosion and deposition
C) eustatic sea level changes
D) earthquake induced submarine landslides

Answer 3

B

Question 4

Which one of the following would typically have the narrowest continental shelf?

A) an atoll
B) a tectonically passive, mid- ocean ridge and trench system
C) a tectonically passive, trailing continental margin
D) a tectonically active continental margin next to a deep ocean trench

Question 5

The geologic process responsible for the most rugged relief on the seabed of a passive continental margin is .

A) active explosive submarine volcanism
B) glacial erosion and deposition modified by rising sea levels.
C) dredging and bottom dragging in shelf fisheries for scallops and groundfish
D) deposits of major river deltas

Question 6

Geologically, are actually submerged parts of the continents.

A) coastal guyots
B) continental trenches
C) abyssal plains
D) continental shelves

Question 7

How deep is the deepest portion of the ocean floor and what are these regions called?

A) 2000 m, submarine canyons
B) >10,000 m, trenches
C) 2500 m, rift zones
D) 4000 m, abyssal plains

Question 8

The continental rise is located .

A) at the seaward edge of a deep ocean trench
B) at the top of a mid- ocean ridge
C) between an abyssal plain and continental slope
D) at the top of the continental slope

Question 9

An echo sounder operates by measuring the time required for a .

A) light beam to travel from a satellite at a known altitude to the sea bottom and back
B) sound pulse to travel from a ship or survey towfish to the seafloor and back
C) radar beam to travel from a ship to the seafloor and back
D) radar beam to travel from a harbour patrol boat to a fuzz- buster on a speeding yacht

Question 10

A(n) is a low lying, coral reef island perched above a sunken, truncated volcano.

A) guyot
B) atoll
C) seamount
D) re- entry cone

Question 11

What was the original cause of the 1929 turbidity currents that cut submarine cables off of Newfoundland?

A) a tsunami
B) a ML 7.2 earthquake
C) a submarine landslide
D) the grounding of a massive iceberg that caused the seafloor to fail

Question 12

On average, the continental shelf is about kilometres wide and metres deep.

A) 400; 2000
B) 1800; 80
C) 80; 130
D) 20; 50

Question 13

The largest regions underlain by deformed marine sediments occur on .

A) mid- ocean ridges
B) deep ocean basins
C) active continental margins
D) passive continental margins

Question 14

Which one of the following would typically have the widest continental shelf?

A) an atoll
B) a tectonically passive, trailing continental margin
C) a tectonically active continental margin next to a deep ocean trench
D) a tectonically passive, mid- ocean ridge and trench system

Question 15

Which one of the following statements regarding turbidity currents is true?

A) They are shaken loose by earthquakes and move from abyssal plains to the continental shelf.
B) They flow down submarine canyons to estuaries at the edge of the continental shelf.
C) The moving sediment- laden waters are less dense than the surrounding seawater.
D) They form on the continental shelf and flow down submarine canyons to deeper water.

Question 16

How much of the Earth's surface is covered by the deep ocean basins?

A) 15%
B) 65%
C) 30%
D) 50%

Question 17

marks the edge of a continent.

A) The highest part of the continental shelf
B) The lowest part of the continental slope
C) The centre of an abyssal plain
D) An offshore, barrier island system

Question 18

As a result of the 1831 expedition of the H.M.S. Beagle, proposed the correct theory of how atolls formed.

A) Charles Lyell
B) Charles Darwin
C) Isaac Newton
D) James Hutton

Question 19

Which one of the following statements concerning submarine canyons is not true?

A) They extend from the continental shelf to the base of the continental slope.
B) They were cut by streams and rivers during the Pleistocene when sea level had dropped to the base of the continental slope.
C) They channel turbidity currents down the continental slope to deeper waters.
D) They generally connect across the continental shelf to specific river valleys on land.

Question 20

Which one of the following would most likely be covered with thick turbidite layers?

A) axial rift zone of an active mid- ocean spreading centre
B) deep- sea fan at the base of a continental slope
C) upper flanks of a steep, narrow, submarine canyon
D) lagoon floor inside an atoll

Question 21

is the oceanward edge of a continental shelf.

A) The top of the abyssal plain
B) The base of the continental rise
C) The deepest portion of a deep- ocean trench
D) The top of the continental slope

Question 22

Which method did not contribute significant geologic knowledge about the rocks, structures, and mineral deposits of the mid- ocean ridges?

A) mapping of slices of ocean crust added to the continents by tectonic activity
B) geophysical surveys and soundings of the ocean floor
C) deep diving submersibles traverses by manned and unmanned subs
D) remote sensing and mapping of mineral deposits by satellites

Question 23

What are the flattest and most level places on Earth?

A) continental shelves
B) oceanic volcanic plateaus
C) mid- ocean ridges
D) abyssal plains

Question 24

Oceanic ridges are elevated compared to the surrounding ocean floor because _.

A) of the shield volcanoes that develop due to seafloor spreading
B) the mantle is pushing up the lithosphere along the ridge
C) newly formed lithosphere is hotter and therefore less dense than the surrounding rocks
D) the older, colder lithosphere is less dense and tends to rise

Question 25

On average, the slope across a continental shelf is about .

A) 0.001°
B) 1°
C) 5°
D) 1.5°

Question 26

How does the continental rise form?

A) tectonic uplift and tilting of the edge of the continental margin
B) deep sea pelagic oozes that drape guyots and seamounts
C) outbuilding of major river deltas
D) coalescing deep- sea fans built from turbidites

Question 27

Which ocean floor sediment type includes manganese nodules?

A) biogenous
B) orogenous
C) terrigenous
D) hydrogenous

Question 28

Which is the deepest ocean trench?

A) Mariana
B) Kurile- Kamchatka
C) Aleutian
D) Peru- Chile

Question 29

What is the magma source for mid- ocean ridge basalt?

A) by spontaneous melting in mafic magma chambers within oceanic crust
B) along block faults by frictional heating deep in the oceanic lithosphere
C) It all comes from Hawaii then flows out laterally along the ridge system.
D) decompression melting in the shallowest part of the asthenosphere beneath the ridge

Question 30

What do the tube worms of the hydrothermal vent communities directly rely on for their survival?

A) pelagic organic debris settling slowly from the sea surface and local decaying organic matter from crabs, clams, fish, and stupid marine biologists
B) photosynthesis from weak sunlight filtering down to the seafloor
C) symbiotic chemosynthetic (sulphur based) bacteria residing in their trophosomes (guts)
D) direct chemical oxidation of sulphide minerals by their root- like, chitinous tube- feet

Question 31

Pieces of the complete cross section of ocean crust that have been added to continents are called

A) gabbro plutons
B) lithosphere
C) ophiolites
D) pillow lavas

Question 32

If your ship is out in the middle of the North Pacific Ocean on the edge of the abyssal plain south of the Aleutian trench, how deep is the seabed if it took 6 seconds to get a bottom return from your 3500 kilohertz echo sounder? Use the equation: depth (m) = 0.5 * (1500 m/s * total 2- way travel time in sec)

A) 1286 m
B) 2625 m
C) 6000 m
D) 4500 m

Question 33

consists of diatom and radiolarian remains.

A) Terrigenous ooze
B) Reddish clay ooze
C) Siliceous ooze
D) Calcareous ooze

Question 34

Which one of the following is not typical of sandy turbidite deposits?

A) Within a depositional layer, they show graded bedding but little stratification.
B) They form very gently sloping deep- sea fans at the mouths of submarine canyons.
C) They occur on the continental shelf in cross- stratified dunes with very low silt and clay contents.
D) They contain land- derived and shallow- water fossil materials, even deposited in deep waters.

Question 35

Trenches are often parallel to, and genetically related to .

A) volcanic island arcs or continental margin mountain belts with active volcanism
B) hot spot volcanic island chains
C) mid- ocean ridges
D) oceanic transform faults

Question 36

Which is the longest ocean trench?

A) Java
B) Peru- Chile
C) Aleutian
D) Kurile- Kamchatka

Question 37

What is the most readily observable change in the seafloor as it moves away from the position of the mid- ocean ridges?

A) It gets deeper and smoother as it cools off, contracts, and gets buried by sediments.
B) The rugged ridge topography is eroded smooth by strong, deep ocean currents.
C) It gets covered by deep water biologic communities to make seafloor reef systems.
D) Violent large earthquakes cause the ridge system to collapse upon itself generating large tsunamis.

Question 38

are highly detrimental to healthy growth of coral reefs.

A) Warm water temperatures
B) Vigorous wave action and water circulation
C) Clear, sunlit waters
D) Nutrient- rich waters, cloudy with luxuriant plankton growth

Question 39

What is the most active, long term, deep diving, manned submersible used for studying the seafloor and deep ocean depths?

A) Alvin
B) Simon
C) Nautilus
D) Theodore

Question 40

Why are the deep sea clays mostly red or brown?

A) They are mostly volcanic ash particles erupted onto the seafloor; this is their colour.
B) These are the residues of red algae blooms, dispersed by ocean currents to settle out everywhere.
C) Slow settling of fine clay- sized mineral particles allows for complete oxidation of their iron by dissolved oxygen.
D) They are eroded mostly from desert areas and carried to the sea by winds or rainstorms.

Question 41

How were water depths and seafloor bathymetry (submarine topography) determined by the Challenger surveys?

A) by early deep sea divers
B) multi- beam, towed echo sounders
C) timing the descent of heavy bricks with sand glasses and listening for the echoes with early hydrophones
D) hand thrown and retrieved weighted lead- lines

Question 42

What geologic studies finally confirmed Darwin's hypothesis that coral atolls all had a volcanic substrate underneath that formed the original platform for corals to colonize?

A) scientific drilling of Eniwetok and Bikini Atolls by the U.S. government in preparation for nuclear weapons tests
B) submersible traverses down the flanks of North Atlantic atolls by the C.S.S. Hudson
C) exploration drilling of the Great Barrier Reef by Petro Canada for offshore oil production
D) seismic imaging of the West Pembina Pinnacle Reefs in the Alberta Basin by Amoco

Question 43

Seafloor spreading occurs along relatively narrow areas at the crests of oceanic ridges called

A) submarine canyons
B) rift zones
C) seamounts
D) trenches

Question 44

The lies at the base of the continental slope.

A) continental rift
B) continental rise
C) offshore shelf
D) off- slope reef

Question 45

Which one of the following did not accompany the 1929 Newfoundland ML 7.2 earthquake?

A) A tsunami struck the Burin Peninsula of Newfoundland.
B) Turbidity currents moved down the continental rise to the edges of the North Atlantic abyssal plain.
C) Submarine telegraph cables were broken on the floor of the North Atlantic.
D) Explosive volcanic eruption of pillow basalts occurred on the west edge of the Grand Banks.

Question 46

What sedimentary process is mainly responsible for the accumulation of up to 9 kilometres of sediment in deep ocean trenches?

A) pelagic, biogenous ooze slowly settling from the top of the water column
B) sunken or subsided coral reefs
C) offshore dumping of unending bargeloads of garbage from major cities
D) turbidity currents and submarine landslides from the continental slope and trench walls

Question 47

Calcareous ooze is composed of sediment.

A) terrigenous
B) androgynous
C) biogenous
D) hydrogenous

Question 48

Below the coral limestone, surface rocks of an atoll, what would you find?

A) a slab of rifted, continental crust extending down to ocean floor depths
B) a magma chamber of an active shield volcano
C) basaltic volcanic rocks of a truncated seamount
D) an upraised, abyssal plain covered with turbidites

Question 49

develop where oceanic lithosphere bends downward and sinks into the mantle.

A) Abyssal seamounts
B) Rift valleys on mid- ocean ridges
C) Submarine canyons
D) Deep ocean trenches

Question 50

What thicknesses of unconsolidated sediment typically covers the deep abyssal plains?

A) about 1500 to 4500 metres
B) <100 metres
C) about 5000 to 9000 metres
D) about 500 to 1000 metres

Question 51

is/are not part of an ophiolite complex.

A) Intrusive, coarse- grained gabbro
B) Basaltic lavas and pillow lavas
C) Enriched, unmelted, unstrained mantle lithosphere
D) Steeply- inclined, basaltic dykes

Question 52

Which ocean floor sediment type includes quartz sand?

A) terrigenous
B) orogenous
C) biogenous
D) hydrogenous

Question 53

If you are sailing across the continental shelf in Queen Charlotte Sound and your echo sounder reported the bottom at 200 milliseconds (0.200 sec) at the maximum depth crossing the axis of Mitchell Trough, how deep is the seabed in the middle of this drowned submarine valley? Use the equation: depth (m) = 0.5 * (1500 m/s * total 2- way travel time in sec)

A) 1500 m
B) 50 0 m
C) 15 m
D) 150 m

Question 54

How broad an area of seafloor was covered by the 1929 Grand Banks turbidite deposit?

A) 250,000 km3
B) 2,500 km3
C) 25,000 km3
D) 2,500,000 km3

Question 55

Satellites like SEASAT can observe the ocean using to measure sealevel to +/- 2 cm and infer the seabed bathymetry from the exerted by the variable elevation and mass of seabed features.

A) microwave beams, gravitational pull
B) infrared radiation, temperature and heat effects
C) surveying telescopes, tidal pull
D) accelerometers, magnetism

Question 56

How do calcareous oozes form?

A) The particles settle out from calcite- rich turbidity currents at depths greater than 4,500 metres.
B) The particles are precipitated in the water column below the depth of sunlight penetration and then sink to the bottom.
C) The particles are precipitated by deep- ocean, bottom- dwelling, carbon- fixing bacteria.
D) The particles are biogenically or chemically precipitated in warm, surface waters and sink to the bottom.

Question 57

Which is the best description of a mid- ocean ridge?

A) 50- 200 metre- wide rough mounds of metal sulphides that encircle the globe continuously for more than 70,000 kilometres
B) narrow ridges 5- 10 km wide, 3- 4 kilometres high, and 10- 50 km long with active erupting volcanoes every 1- 2 kilometres of ridge length
C) 1000 to 4000 kilometre wide, block faulted regions of sparsely sedimented, basaltic seafloor raised 2- 3 kilometres above the regional abyssal plains
D) thick sequences of folded and faulted sedimentary rocks pushed up 500- 1000 metres above the regional seafloor

Question 58

Which ocean floor sediment type includes diatom ooze?

A) biogenous
B) orogenous
C) terrigenous
D) hydrogenous

Question 59

What sedimentation rates typify the red or brown clays of the abyssal plains?

A) 1- 5 centimetres per year
B) 1 centimetre per 500 years
C) 1 centimetre per 5,000 to 50,000 years
D) > 5 metres per year

Question 60

What is meant by graded bedding?

A) Thin, laminated, storm- beds slope gently back towards the land.
B) Strata have the same thicknesses and bedding contacts are smooth and flat.
C) Particle sizes in a single, sedimentary bed change from pebbles and coarse sands at the base to silt and mud at the top.
D) Muddy and silty strata grade upward into sandy and pebbly strata.

Question 61

are not associated with a mid- ocean ridges.

A) Shallower depths than abyssal plains
B) Submarine basaltic lava eruptions
C) Very thin, ocean floor sediment layer
D) Deep ocean trenches

Question 62

You are doing a hydrographic survey by the Sand Heads Light, off the mouth of the Fraser River in very silty green water. You lower a bar to check its reflection and calibrate your sounder. You find that the fresh river water has dropped the speed of sound to 1483 m/sec. If the bottom registers at 15 milliseconds (0.015 sec), how deep is the top of the Fraser delta? Use the equation: depth (m) =

A) 2250 m
B) 11.12 m
C) 22.25 m
D) 11.25 m

Question 63

Which one of the following is not connected in any way with submarine, hot spring vents?

A) thick turbidites on the continental rise
B) black smokers on a mid- ocean ridge
C) ecological communities living without photosynthesis
D) sediment rich in metallic sulphides

Question 64

is/are most soluble in cold seawater at ocean depths in excess of 4500 metres.

A) Clay minerals
B) Calcite
C) Manganese oxides
D) Quartz

Question 65

Graded bedding is .

A) an upwards decrease in clastic particle size within a single sediment layer
B) a Canadian quality- rating scale for different brands of mattresses
C) an accumulation of sedimentary beds beginning with sandy beds at the bottom and ending with clayey beds at the top
D) the layering in coral limestone produced by the combined chemical action of living coral animals and submarine, hot spring emissions

Question 66

What kinds of materials account for the phosphate rich sediments?

A) calcareous ooze
B) mineral rich turbidites
C) hard residues of teeth, scales, bones, and fecal pellets of fish and other marine animals
D) diatoms and radiolarians

Question 67

Which ocean floor sediment type includes turbidity currents?

A) hydrogenous
B) terrigenous
C) orogenous
D) biogenous

Question 68

sediments represent weathered rock and mineral particles eroded mainly from land areas.

A) Biogenous
B) Terrigenous
C) Hydrogenous
D) Exogenous

Question 69

Active continental margins are found .

A) underneath passive continental margins
B) surrounding Africa
C) around the Arctic Ocean
D) mainly around the Pacific Ocean

Question 70

Which ocean floor sediment type includes abyssal plain clay?

A) orogenous
B) biogenous
C) terrigenous
D) hydrogenous

Question 71

Seamounts _ _.

A) are submarine canyons found near Australia
B) form only in the Pacific Ocean basin
C) are a special type of oceanic trench
D) are volcanoes that form on the ocean floor

Question 72

What is the most abundant sediment type on the deep ocean floor for most locations in the world?

A) carbonate ooze
B) sand
C) mud
D) diatom and radiolarian ooze

Question 73

Where in the oceans are biologic communities thriving without sunlight?

A) in shallow water, coral reefs
B) in muds of deep- ocean trenches
C) around fissure vents for flood basalts
D) around seafloor, hot spring vents in areas of active volcanism

Question 74

Where are the greatest number of deep ocean trenches found?

A) around the rim of the Arctic
B) along the western edge of the Pacific
C) along the eastern margins of the Atlantic
D) along the western edge of North America

Question 75

Geologically, what is the best way to explain the thousands of metres of coral limestone beneath most atolls?

A) Sea level has fallen thousands of metres since the reef began to grow.
B) The volcano never reached the surface, but built a very thick cap of coral limestones from its deep submarine hot springs emissions.
C) The eroded volcano slowly sank as sea level remained steady or rose gradually.
D) An eroded volcanic seamount rose thousands of metres after the limestone formed.

Question 76

How long does it take for the ocean crust to cool off and become as dense as it can by compaction and mineral infilling of porosity?

A) 500,000 years to 1.0 Ma
B) 5 to 10 Ma
C) >100 Ma
D) 50- 100 years after the cessation of volcanism

Question 77

Which ocean floor sediment type includes calcareous ooze?

A) hydrogenous
B) biogenous
C) terrigenous
D) orogenous

Question 78

Why are the East Pacific Rise, the Gorda and Juan de Fuca Ridges all the way at the eastern side of the Pacific Ocean?

A) The geophysicists and oceanographers haven't got a clue and mapped them in the wrong location.
B) They are a really young tectonic features and have just jumped to start rifting on this side of the Pacific Ocean, which used to rift down it's middle near Hawaii.
C) The spreading in the Pacific is asymmetric and new ocean crust is mainly made on the western side of the ridge system.
D) Half of the Pacific ocean basin has been overridden by or subducted beneath the plates of the Americas, and the Pacific plate is getting smaller.

Question 79

The chaotic accumulation of deformed sediments and tectonic slices of oceanic crust plastered onto the edge of a continent is called .

A) an agglutinated foram
B) an accretionary wedge
C) a guyot
D) a deep sea fan

Question 80

Which of the following about deep ocean trenches is false?

A) They are sites where plates plunge back into the mantle.
B) They are geologically very stable.
C) They are long and narrow depressions.
D) They may act as sediment traps.