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Oceanography > Test 1 > Flashcards

Test 1 Flashcards

0
Q

Arctic ocean…

A

Too small to be considered a real ocean basin, really part of the atlantic

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1
Q

Northern boundary for southern ocean

A

Antarctic convergence at approx 60 degrees s, no geographical boundary but still isolated by physical oceanographic processes

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2
Q

Surface elevations

A

Bimodal because there are two different types of crust

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3
Q

Geoid

A

The shape of the earth as defined by its gravitational field, position of the geoid is sea leaves equilibrium, earths gravitational field is everywhere perpendicular to the geoid

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4
Q

Conduction

A

Movement of thermal energy without movement of material

Occurs in lithosphere

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5
Q

Convection

A

Movement of energy as a result of movement of material
Always faster than conduction
Occurs in asthenosphere and mesosphere

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6
Q

MOHO

A

10-40 km depending on type of crust
Caused by a change in the type of rock
Change between crust and mantle

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7
Q

100 km discontinuity

A

Seismic wave activity decreases (increases at all other discontinuities)
Caused by a decrease in rigidity (partial melting) of mantle material

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8
Q

400 km discontinuity

A

Olivine undergoes polymorphic transition
Atoms rearrange themselves into beta spinel, a more rigid/dense material
Gradually changes to gamma spinel from 400-650 km

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9
Q

650-700 km discontinuity

A

Gamma spinel and pyroxene change to perovskite

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10
Q

Kimberlites

A

“Diamond pipes”

Represent upper mantle material that has moved upwards as the surface of the earth eroded

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11
Q

Hypocenter

A

The exact location of earthquake
Represents the actual place the rock breaks and the potential energy is released; defined by latitude longitude and depth
Usually less than 60 km deep because deeper, rock is too warm to develop strain

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12
Q

Epicenter

A

Defined by latitude and longitude, not depth

Right above the hypocenter

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13
Q

Transverse waves

A

The earth is moving at right angles to the direction of the wave

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14
Q

Longitudinal wave

A

The earth is moving in the same direction as the wave

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15
Q

P waves

A

Longitudinal motion only, first to arrive (greatest speeds)
Velocity increases as rigidity increases
Velocity decreases as compressibility and density increase

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16
Q

S waves

A 
Transverse motion only, arrive second
Velocity increases as rigidity increases
Velocity decreases as density increases 
Does not depend on compressibility
Do not travel through liquids
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17
Q

Seismic discontinuity

A

Represents a surface where there is a significant change in wave velocity

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18
Q

Composition of oceanic and continental crust

A

Oceanic is mafic igneous rock
Continental is felsic igneous rock
(Mantle is ultra mafic)

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19
Q

Geotherm

A

The actual temperature we think exists in the earths core

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20
Q

Anisotropic

A

Different characteristics in different directions

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21
Q

Poles

A

Defined as the points where the magnetic field is perpendicular

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22
Q

Dielectric material

A

Does not conduct electricity
Mantle is made of this
Does not impact the earths magnetic field

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23
Q

Diamagnetic materials

A

Only paired electrons

Can not be magnetized

24
Q

Paramagnetic material

A

Have unpaired electron(s)

Can be magnetized but not permanently

25
Q

Ferromagnetic material

A

Unpaired electrons
Can become permanently magnetized if they cool below the Curie temperature in the presence of an external magnetic field
Most common is magnetite

26
Q

Earths magnetic field is produced by…

A

Convection currents in the liquid outer core

27
Q

Flood basalts

A

Large outpourings of lava

2-12 km thick

28
Q

Adiabatic decompression

A

Solid material moves up until about 100 km below the surface, then melts

29
Q

Layer 1 of crust

A

Sediment layer
Average thickness 1 km in open ocean, can be up to 15 km in continental margin areas
Absent along ridges/rises
Slow accumulation of sediments (about 1 cm per 1000 years)

30
Q

Layer 2 of crust

A

Basement layer
About 2 km thick
Layer 2A- tholeiitic sheet and pillow basalts
Layer 2B- tholeiitic basaltic dikes

31
Q

Intrusive igneous rock

A

Form deep within the earth, cool slowly

Large crystals

32
Q

Extrusive igneous rock

A

Cool rapidly

Small crystals

33
Q

Layer 3 of crust

A

Oceanic layer
Not present under ridge/rise crests
About 6 km thick
Composed of tholeiitic gabbro (intrusive)

34
Q

Homogeneous accretion theory

A

Describes what we think happened with the formation of the earth from the formation of the solar system

35
Q

Planetary differentiation

A

Describes how the earth rearranged itself from a homogeneous mass into a heterogenous structure
Impact with a mars-sized object allowed beginning
About 90% of water in earths surface today was released during planetary differentiation

36
Q

Isostatic equilibrium

A

The vertical balance between gravity and buoyancy in the earths lithosphere

37
Q

Driving force for plate tectonics is…

A

Movement of thermal energy from inside earth to outside

38
Q

Relative plate motion

A

Arrows indicate plate motion relative to ridges/rises, etc. (whatever is at the boundary)

39
Q

Divergent motion

A

Two plates moving apart

Ridges and rises (called spreading centers)

40
Q

Convergent motion

A

Two plates moving together
Trenches (called subduction zones)
Continent-continent collision zones (no trench, ex. Himalayas)

41
Q

Tangential motion

A

Two plates slide past one another

Transform faults

42
Q

Tholeiitic magma

A

Source material for new sea floor

Results from the partial melting of peridotite

43
Q

Mature oceanic lithosphere

A

100 million years old

About 100 km thick

44
Q

Magnetic anomalies

A

Small deviations from the average strength of the earths geomagnetic field

45
Q

Subduction zones

A

Deepest and highest magnitude earthquakes associated with these zones because the subducting lithosphere is cool enough to develop strain-Benioff zone

46
Q

Island arc system

A

Usually produced by cooler, less buoyant subducting lithosphere
Like a mini spreading center
Deep subduction angle

47
Q

Continental arc

A

Usually produced by younger, warmer, more buoyant subducting lithosphere
Shallow subduction angle

48
Q

Soft collisions

A

Occur when lithospheric plates carry geological features into continental subduction zones

49
Q

Hard collisions

A 
Continent-continent collision
Thrust wedges (oceanic crust) caught, squeezed, and uplifted forming suture zone -marked by ophiolites (rock layer that may contain all 4 layers of oceanic lithosphere)
50
Q

Hot spot

A

Anomalous hot areas at the CMB, loses density and slowly rises to the surface, hot spot magma produced at about 100 km from surface

51
Q

Wilson cycle

A

Describe the birth, death and decay of ocean basins
Embryonic, juvenile, mature, declining, terminal, suturing
About 1/2 billion years to complete one cycle

52
Q

Normal faulting indicates…

A

Tensional geological forces

Ridges and rises

53
Q

Exotic terranes

A

Small fragments of unusual crustal material attached to continental edges via soft collision

54
Q

Conrad discontinuity

A

Broad seismic discontinuity in continental crust separating felsic rocks above from mafic rocks below

55
Q

Back arc basin

A

Small ocean basic that separates volcanic arc in an oceanic subduction zone from land basin, grows in width with time

56
Q

Deep sea fans

A

“Delta like” sediment deposits at the foot of submarine canyons, formed by turbidity currents

57
Q

Apparent gravitational acceleration

A

The vector sum of the true gravitational acceleration and centrifugal acceleration caused by the earths rotation

58
Q

Turbidity current

A

High density mixture (slurry) of sediments and water that moves downward through submarine canyons

Oceanography (1 decks)

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