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Oceanography > Test 1 > Flashcards

Test 1 Flashcards

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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

Study These Flashcards
A

Only paired electrons

Can not be magnetized

24
Paramagnetic material
Have unpaired electron(s) | Can be magnetized but not permanently
25
Ferromagnetic material
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
Earths magnetic field is produced by...
Convection currents in the liquid outer core
27
Flood basalts
Large outpourings of lava | 2-12 km thick
28
Adiabatic decompression
Solid material moves up until about 100 km below the surface, then melts
29
Layer 1 of crust
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
Layer 2 of crust
Basement layer About 2 km thick Layer 2A- tholeiitic sheet and pillow basalts Layer 2B- tholeiitic basaltic dikes
31
Intrusive igneous rock
Form deep within the earth, cool slowly | Large crystals
32
Extrusive igneous rock
Cool rapidly | Small crystals
33
Layer 3 of crust
Oceanic layer Not present under ridge/rise crests About 6 km thick Composed of tholeiitic gabbro (intrusive)
34
Homogeneous accretion theory
Describes what we think happened with the formation of the earth from the formation of the solar system
35
Planetary differentiation
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
Isostatic equilibrium
The vertical balance between gravity and buoyancy in the earths lithosphere
37
Driving force for plate tectonics is...
Movement of thermal energy from inside earth to outside
38
Relative plate motion
Arrows indicate plate motion relative to ridges/rises, etc. (whatever is at the boundary)
39
Divergent motion
Two plates moving apart | Ridges and rises (called spreading centers)
40
Convergent motion
Two plates moving together Trenches (called subduction zones) Continent-continent collision zones (no trench, ex. Himalayas)
41
Tangential motion
Two plates slide past one another | Transform faults
42
Tholeiitic magma
Source material for new sea floor | Results from the partial melting of peridotite
43
Mature oceanic lithosphere
100 million years old | About 100 km thick
44
Magnetic anomalies
Small deviations from the average strength of the earths geomagnetic field
45
Subduction zones
Deepest and highest magnitude earthquakes associated with these zones because the subducting lithosphere is cool enough to develop strain-Benioff zone
46
Island arc system
Usually produced by cooler, less buoyant subducting lithosphere Like a mini spreading center Deep subduction angle
47
Continental arc
Usually produced by younger, warmer, more buoyant subducting lithosphere Shallow subduction angle
48
Soft collisions
Occur when lithospheric plates carry geological features into continental subduction zones
49
Hard collisions
``` 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
Hot spot
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
Wilson cycle
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
Normal faulting indicates...
Tensional geological forces | Ridges and rises
53
Exotic terranes
Small fragments of unusual crustal material attached to continental edges via soft collision
54
Conrad discontinuity
Broad seismic discontinuity in continental crust separating felsic rocks above from mafic rocks below
55
Back arc basin
Small ocean basic that separates volcanic arc in an oceanic subduction zone from land basin, grows in width with time
56
Deep sea fans
"Delta like" sediment deposits at the foot of submarine canyons, formed by turbidity currents
57
Apparent gravitational acceleration
The vector sum of the true gravitational acceleration and centrifugal acceleration caused by the earths rotation
58
Turbidity current
High density mixture (slurry) of sediments and water that moves downward through submarine canyons

Oceanography (1 decks)

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