Plate Tectonics- Plate Movements 😊 Flashcards
1
Q
Why do plates move? X2
A
- 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.
- 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.
2
Q
What happens at divergent plate boundaries?
A
Plates move apart
3
Q
What happens at constructive boundaries?
A
Plates move together
4
Q
What happens at constructive boundaries?
A
Plates slide past each other either in the same or opposite direction to each other
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
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
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
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
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
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