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Ocean environment > midterm part 1 > Flashcards

midterm part 1 Flashcards

1
Q

list the different stages of wilson’s cycle with examples

A

Stage 1: Embryonic - East African Rift Valley
Stage 2: Juvenile - Red Sea
Stage 3: Mature - Atlantic & Arctic Ocean
Stage 4: Declining - Pacific Ocean
Stage 5: Terminal - Mediterranean Sea
Stage 6: Suturing - Himalayas

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2
Q

What is a rift valley?

A

formed by the interaction of earth’s tectonic plates

Magma rises into the crustal fractures forming rift valley

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3
Q

What are the types of convergent boundaries between crusts?

A
  • Ocean / continent convergence: the oceanic plate subducts
  • Ocean / ocean convergence: the older cooler denser plate subducts
  • Continent / continent convergence: Both uplift
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4
Q

What are the differences between continental and oceanic crust?

A
  • The continental crust is made mostly of rocks with a composition similar to granite
  • The oceanic crust is made mostly of rocks with a composition of basalt
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5
Q

What is earth’s chemical layer made up of?

A

crust -> upper mantle -> transition zone -> lower mantle -> outer core -> inner core.

- Oceanic crust: (Basalt: Oxygen, silicon,
magnesium and iron)
- Continental crust: (Granite: Oxygen,
silicon and aluminium)
- Mantle (Oxygen, iron, magnesium and
silicon) 68% Earth´s mass – 83 % Earth´s
volume
- Core (Iron and nickel)
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6
Q

What is earth’s physical layer made up of?

A

Lithosphere -> Asthenosphere -> Mesosphere -> Fluid -> Solid

  • lithosphere (rigid),
  • asthenosphere (melted, flowing),
  • lower mantle (not melted, slow flow),
  • outercore (viscous liquid)
  • inner core (solid).
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7
Q

In which direction does the core of the Earth rotates?

A

inner: eastward
outer: westward

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8
Q

What are mantle plumes?

A

Continent-sized columns of superheated mantle

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9
Q

What is currently lifting all of Africa, fracturing the center of the continent?

A

A superplume

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10
Q

How is a line of islands formed?

A

Hot spots form straight chains of volcanoes and volcanic islands (Hawaii)

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11
Q

Explain the tectonic plates theory

A

suggests that Earth´s
surface is not static.
The theory states that the Earth’s solid outer crust, the lithosphere, is separated into plates that move over the asthenosphere, the molten upper portion of the mantle. Oceanic and continental plates come together, spread apart, and interact at boundaries all over the planet

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12
Q

Explain the seafloor spreading theory

A

a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge

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13
Q

Explain the continental drift theory

A

Was proposed by Alfred Wegener (1912)
• States that originally there was a single
supercontinent: Pangaea, surrounded by an
ocean called Panthalassa
• And that Pangea was broken into pieces 200 million years ago and pieces are still moving

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14
Q

Which one is denser the continental or the oceanic crust?

A

oceanic

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15
Q

What is paleomagnetism?

A

When magma forms oceanic plates, magnetite aligns with Earth´s magnetic
field and “freezes”

when rocks solidify “capturing” the magnetic field orientation of Earth in
that moment

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16
Q

What protects the earth from radiation? and how does the Earth have a magnetic field?

A

Rotation of the metallic core produces a magnetic field.

The magnetic field of the Earth protect us from radiation

caused by the movement of molten
metal in outer core

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17
Q

what are Terranes?

A

buoyant plateaus,

isolated segments of seafloor,

ocean ridges,

ancient island arcs,

and parts of continental crust squeezed into continent face when the plate is subducted

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18
Q

What are the types of plumes?

A

Mantle plumes = Continent-sized columns of superheated mantle
• A Superplume is now lifting all of Africa, fracturing the center of the
continent (i.e. East African Rift)
• Hot spots = Surface expressions of plumes rising from stationary sources of
heat in the mantle

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19
Q

What are the different steps of the scientific method?

A

observation, question, hypothesis, test, analysis, conclusion

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20
Q

What percentage of Earth´s surface water is salty?

A

97.5

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21
Q

How old is the Earth?

A

4.5 billion yrs

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22
Q

What protects the earth from radiation?

A

Rotation of the metallic core produces a magnetic field. The magnetic
field of the Earth protect us from radiation

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23
Q

Why are stars relevant to the formation of the ocean?

A

Most of Earth’s, sea and human beings atoms were formed within stars billions of years
ago

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24
Q

What percent of the earth’s surface is covered by water?

A

71% of Earth’s surface is covered by water

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25
Q

How did the oceans become salty?

A

Water vapor formed clouds and rain dissolved minerals, accumulating salty water

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26
Q

What is the name of the oldest Fossils and where can they be found?

A

Stromatolites, Australia

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27
Q

What is a supernova?

A

A supernova is a powerful and luminous stellar explosion. a dying star.

28
Q

What is the big bang theory? How do we explain the origin of the universe?

A

Galaxies and stars formed in nebulae

Sun and planets condensed from dust and gas from supernova

29
Q

What is outgassing?

A

Second atmosphere formed by outgassing: water vapor and other gases from volcanic venting

30
Q

What are guyots?

A

flat-topped seamounts

31
Q

What is the depth of the mariana trench?

A

11 km deep, 70 km wide, 2550 km long

32
Q

What are sea mounts?

A

conical projections higher than 1 km

33
Q

How are oceanic trenches formed?

A

by subduction of lithosphere at converging plate boundaries

34
Q

True or False? the further away you are from the origin center the
colder and denser the crust is

A

true

35
Q

How many people travel to the bottom of the ocean (Mariana´s

Trench)?

A

10

36
Q

what is the ocean basin

A

deep seafloor beyond the continental margin

Ocean basins form at divergent
plate boundaries

37
Q

how is the ocean floor mapped?

A

by bathymetry: weighted line, echo sounder, multibeam echo sounder systems and
satellite altimetry

38
Q

What is a continental margin?

A

submerged outer edge of a continent. 3 main divisions:

  • Continental shelf: nearly flat, close to shore
  • Continental slope: more steeply sloped, seaward
  • Continental rise blends continental margins into deep ocean basin
39
Q

What are passive and active cont. margins?

A
  • Passive continental margins: face the edges of diverging plates, little volcanic or earthquake activity
  • Active continental margins: near the edges of converging plates, ongoing earthquake and volcanic activity
40
Q

What are continental shelves?

A

7.4 % Earth´s ocean area. Part of granitic continental crust.

Influenced by changes in sea level

41
Q

what is the deep ocean floor?

A

oceanic ridges + adjacent sediment plains (50 % Earth´s surface)

42
Q

ocean ridges

A

In average 2 km high.

Projected above: Iceland, Azores or Easter island.
Not straight - transform faults

43
Q

abyssal planes

A

featureless expanses of sediments - hide irregularities in underlying oceanic crust

44
Q

abyssal hills

A

Less than 200 m high, hills bordering oceanic ridges

45
Q

Trench

A

arc-shaped depression in the deep-ocean floor.

46
Q

Island arcs

A

Curving chains of volcanic islands and seamounts, parallel to concave edges of trenches

47
Q

submarine slopes

A

Submarine canyons cut into the Continental shelf and slope
• Sometimes deeper than 3000 m
• Caused by landslides or sediments liquefaction (triggered by earthquakes)

48
Q

Turbidity currents

A

Underwater abrasive “avalanches” of

sediments.

49
Q

hypothermal vents

A

hot springs in oceanic ridges, Water 350 ºC water descends through fissures, superheated water dissolve minerals and gases and escape through the vents

50
Q

How does the process of studying sediment layers work?

A

through the study of the ocean’s past

51
Q

What are neritic sediments?

A

On continental margins. Can form sedimentary rocks by Lithification

52
Q

Examples of Oozes?

A

Ooze is deep ocean sediment with at least 30% biogenous material.

Can be siliceous or
calcareous -

53
Q

What does paleoceanography study?

A

study of the ocean’s past

54
Q

What percent of the seabed is covered by calcareous ooze? What
percent is covered by siliceous ooze?

A

cal 48

sil 14

55
Q

Define pelagic sediments

A

Slope, rise, and deep-ocean floors

56
Q

What is the process of lithification?

A

It refers to the process that loose and underconsolidated Sediment particles transform into hard and solid rocks.

57
Q

Define marine sediments

A

usually combinations of terrigenous

and biogenous deposits

58
Q

How are sediments usually classified?

A

sediments are classified by source, they are Particles of organic or inorganic matter that accumulate in a loose, unconsolidated form

Originate from the weathering and erosion of rocks, living organisms,
volcanos, water chemical precipitation or from space

59
Q

types of sediments

A

Terrigenous sediments
• Biogenous sediments
• Hydrogenous sediments
• Cosmogenous sediments come from space

60
Q

what is a subduction zone?

A

(Earth is not growing up)

• Creation of new crust balanced by destruction of crust

61
Q

types of plate boundaries?

A

-Divergent boundary: two plates move apart from each other
• Convergent boundary: two plates move toward each other and interact
• Transform or transverse boundary: two plates slide laterally past each other

62
Q

what is the main heat source inside earth?

A

Radioactive decay

63
Q

How does heat move towards surface

A

conduction and convection

64
Q

what is buoyancy

A

Ability of an object to float in a fluid by displacing a fluid volume equal in weight to the floating object’s weight

65
Q

what is isostatic equilibrium?

A

the state of gravitational equilibrium between the earth’s lithosphere and asthenosphere

such that tectonic plates float at an elevation which depends on their thickness and density

66
Q

conduction

A

the process by which heat is transferred through objects by contact, heat energy passes from warmer to cooler object.

67
Q

convection

A

heat moves within fluid - heat transferred from warmer to cooler areas through fluid

Ocean environment (8 decks)

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