Plate Tectonics- Plate Movements 😊 Flashcards

1
Q

Why do plates move? X2

A
  1. Convection currents- heat is emitted from radioactive decay in the core that causes convection currents in the mantle. The sinking and rising of heat pulls the plates down.
  2. Slab pull- movement of a plate downwards due to gravity and convection currents. Some plates move at a faster rate than others as they have different densities.
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2
Q

What happens at divergent plate boundaries?

A

Plates move apart

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3
Q

What happens at constructive boundaries?

A

Plates move together

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4
Q

What happens at constructive boundaries?

A

Plates slide past each other either in the same or opposite direction to each other

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5
Q

How are ocean ridges formed? Divergent X4 steps

A
  • plates move apart
  • magma rises up to fill in the space between the plates
  • a central rift is formed
  • transform faults are also formed which are parallel to one another and move at different speeds
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6
Q

How was rift valleys formed?

Divergent X4 steps

A
  • plates move apart
  • heat causes the land to dome
  • this then causes the land to sink in the middle due to pressure forming a Rift Valley
  • faults run parallel and the land may eventually be covered by the ocean
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7
Q

Oceanic- continental plates

Convergent X5 steps

A
  • plates move together (convection currents and slab pull)
  • denser oceanic subducts under continental
  • an accretionary wedge is formed which water may enter
  • by the Wadati-Benioff zone the plate melts forming basaltic lava that turns andesitic
  • locked faults occur and this can result in megathrust earthquakes
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8
Q

Oceanic- oceanic plates

Convergent X5 steps

A
  • plates move together (convection currents and slab pull)
  • denser of the two plates subducts so a Wadati-Benioff zone is formed
  • may get locked faults which result in megathrust earthquakes
  • magma from the melting of the plate rises to the zone to form an arc of submarine volcanoes
  • these may build up above sea level to eventually form curved island arcs
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9
Q

Continental- continental

Convergent X5 steps

A
  • plates move together to form a collision boundary
  • some subduction may occur
  • rock is forced and folded upwards to create fold mountains
  • some of the continental lithosphere is forced into the asthenosphere
  • mountain roots are created
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10
Q

What happens at a conservative boundary?

A
  • no plate is created or destroyed
  • no volcanic activity or formation of new lithosphere
  • locked faults may occur which may result in seismic activity
  • perpendicular transform faults are formed
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