Plate tectonics Flashcards

After midterm 1

1
Q

Which is more dense, a continental plate or oceanic plate

A

Oceanic plate is more dense - 3.0g/cm^3
Continental plate is less dense - 2.7g/cm^3

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2
Q

Oceanic plates are composed of what type of rock

A

Basaltic rock

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3
Q

Continental plates are composed of what type of rock

A

silica rich

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4
Q

At what rate do lithospheric plates move

A

cm/year

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5
Q

What are the 3 types of lithospheric plate boundaries

A

Divergent, convergent, transform

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6
Q

Are divergent boundaries tension or compression

A

Tension

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7
Q

Do divergent boundaries create r destroy crust

A

they’re constructive, so they create crust

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8
Q

in divergent boundaries, new lithosphere can be created by what

A

volcanism

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9
Q

What is an example of a divergent plate boundary rift valley

A

east-African rift valley

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10
Q

Divergent plate boundaries typically create continental or oceanic crust

A

oceanic crust

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11
Q

The mid-Atlantic ridge is what type of boundary

A

ocean-ocean divergent

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12
Q

Why is there a lot of volcanic activity in Iceland

A

the mid-Atlantic ridge passes through it

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13
Q

What kind of deposits do we find at divergent plate boundaries

A

metal deposits

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14
Q

Is convergent plate boundaries compression or tension

A

Compressions, they’re in collision

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15
Q

Convergent:
the_______ plate is forced beneath the other and down into
the mantle, this process is known as subduction

A

denser

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16
Q

Do subduction zones have shallow or deep earthquakes

A

Both

17
Q

Is mt Fuji and Mt St Helens on a divergent or convergent boundary

A

convergent, its at a subduction zone

18
Q

Do convergent or divergent have higher heat flow?

A

Divergent has a high heat flow. Convergent has a low heat flow. Relative to the geothermal gradient

19
Q

if we have a oceanic-oceanic boundary, which plate will subduct

A

the cooler and more dense one

20
Q

Oceanic-oceanic can cause: a trench, volcanism, islands arcs

A

All of those

21
Q

Which type of convergent boundaries are most powerful

A

oceanic-continental
continental-continental

22
Q

Which type of convergent boundary does subduction not occur

A

continent-continent
instead mountains are built

23
Q

The Alps and Himalayas are examples of what type of plate boundary

A

Convergent continental-continental

24
Q

Which type of convergent boundary has little to no volcanism

A

continent-continent

25
Q

Which type of boundary does lithospheric material neither be created nor consumed

A

Transform

26
Q

Are the earthquakes from transform boundaries shallow or deep? and what is their intensity

A

Shallow but destructive earthquakes

27
Q

Which of the following occurs at a transform boundary: subduction, volcanism, trench, earthquakes

A

earthquakes

28
Q

transform faults are generally found ____________ to divergent ocean
rift zones such as the Mid-Atlantic ridge

A

perpendicular

29
Q

Are hot spots associated with plate boundaries

A

No

30
Q

Describe how hotspots work

A

Mantle plume: upwelling of hot rocks
in convectional cells in the mantle to
the base of the lithosphere

Heat from the plume melts overlying
rocks and magma seeps up to surface
creating a volcano.

31
Q

Hot spots leave clues and can tell us about the movement of ______

A

plates

32
Q

Can use _______ evidence to work out direction, speed of plate movement over time

A

hotspot