Chapter 2-Plate tectonics Flashcards

1
Q

When did the theory of plate tectonics start and when did it become accepted?

A

Started in the 1960’s and was accepted my most all geologists by 1968

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2
Q

How many tectonic plates are there?

A

20

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3
Q

Where do earthquakes occur in relation to tectonic plates?

A

On the boundaries of the plates

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4
Q

How do divergent plate boundaries interact?

A

They go away from each other. E.g. a mid ocean ridge

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5
Q

What is the difference between active and passive continental margins?

A

Passive are far from plate boundaries, active are beat plate boundaries

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6
Q

How do convergent boundaries interact?

A

Come together e.g. continental shelf or subduction zone.

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7
Q

How do transform boundaries interact?

A

Slide side by side e.g. a fault

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8
Q

What is a pillow basalt?

A

Magma that cools under water commonly on the ocean floor

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9
Q

What are dikes?

A

Preserved magma conduits

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10
Q

What is gabbro?

A

Below dikes made from magma

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11
Q

What angle does a subducting plate usually dive into the mantle?

A

45 degrees

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12
Q

What kind of earthquakes occur at subduction zones?

A

Wadati-Benioff earthquakes

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13
Q

What unique features are associated with subduction zones?

A

Acretionary prisms
Volcanic arcs
Back arc basins

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14
Q

What is a back arc basin?

A

A marginal sea behind a volcanic arc

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15
Q

What are 2 indicators of a transform boundary?

A

Earthquakes and an absence of volcanism

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16
Q

What is a triple junction?

A

Where three plate boundaries coincide. Eventually they migrate

17
Q

What is a “hot spot”?

A

A volcanic plume independent of tectonic plates made of magic magma from the lower mantle

18
Q

What is continental rifting?

A

Where the continental lithosphere stretches and thins

19
Q

Where are some examples of rifting?

A

East Africa Arabian peninsula is pulling away from Africa

20
Q

What happens when two continental plates collide?

A

Oceanic plate subducts and plates collide to form mountains.

21
Q

What are the driving mechanisms of plate motion?

A

Elevated mid ocean ridges push lithosphere away, gravity pulls a subducting plate downward, and the convection in the aesthenosphere adds or subtracts