Geology - Tectonic Theory Flashcards

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1
Q

Evidence of continental drift…

A

Fossils, geological morphology and how continents fit together.

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2
Q

Example of a fossil…

A

Mesosaurus fossils 300MYA in Africa and South America.

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3
Q

Seafloor Spreading

A

A geologic process where tectonic plates split from each other.

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4
Q

Plate Tectonic

A

Units of lithosphere atop the asthenosphere moving with convection

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5
Q

How many tectonic plates?

A

15-20 tectonic plates that being 7-8 major ones.

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6
Q

Types of Plate Boundary

A

Divergent Boundaries
Convergent Boundaries
Transform Faults

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7
Q

Divergent Boundaries

A

This is movement apart of plates with creation of lithosphere

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8
Q

What is a marking feature of divergent boundaries?

A

Mid-ocean ridges

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9
Q

Mid-ocean ridges

A

Sites of divergence by convection exhibiting volcanism, earthquakes and rifting by tensional forces.

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10
Q

What are spreading centres?

A

Sites of upwelling of magma, creating new oceanic crust.

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11
Q

Example of mid-ocean ridge…

A

The mid-atlantic ridge for example, connects south to other such ridges.

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12
Q

Continental rifting

A

A thinning process of the lithosphere leading to rupture of continents are mid-oceanic ridge formation.

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13
Q

Convergent Boundaries

A

Boundaries where one plate subducts beneath the other due to plate movement.

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14
Q

Convergent boundaries in tectonic subduction…

A

Lithosphere sinking into asthenosphere where mantle convection recycles the material.

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15
Q

How do island arcs form?

A

Lithosphere descends with increasing pressure with depth where water squeezes INTO the asthenosphere, causing mantle above to melt

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16
Q

Example of an island arc…

A

Aleutian Islands

17
Q

Island Arc

A

A curving chain of volcanic islands occuring around the margin of ocean basins.

18
Q

Interaction of ocean and continental plates…

A

Continents are less dense so overide oceanic lithosphere, convergence crumpling the subsiding plate, forming mountain belts.

19
Q

How do land-ocean convergence form volcanoes?

A

Subducting oceanic water melts material with magma rise.

20
Q

Example of a continent-continent convergence zone…

A

The Himalayas.

21
Q

Transform Faults

A

A plate boundary along which plate motion is parallel with the strike of the boundary.

22
Q

What forms transform fault?

A

Sliding of tectonic plates slipping horizontally past one another

23
Q

How does mantle convection result in tectonic movement?

A

Cold, dense lithospheric plates fall back on their own weight due to gravity.

24
Q

How did pangea split?

A

Formation acted as an insulation unit, as seafloor spreading was present, where heat was not escaping from the mantle, heat build up occuring forming a mantle plume which bulgus

25
Q

What does lower boundary marks?

A

Depth of which the plates subduct recycling of the material, about 2,890 km deep.

26
Q

Wilson Cycle

A

Describes opening and closing of ocean basins and subduction and divergence of tectonic plates during assembly and dissasembly of supercontinents