Landforms Associated With Destructive P.b

Question 1

What landforms are associated with destructive Pb?

Answer 1

Young fold mountains
Island
Deep sea trenches

Question 2

How is an ocean trench formed ?

Answer 2

At subduction zones - oceanic / oceanic or continental / ocean.
Denser plate subducts under lighter plate into Benioff zone in mantle.

Ocean trench is created at the point in which the denser plate subducts - creates large depressions

Usually under water

Question 3

Example of ocean trench

Answer 3

Marianas trench 11km

Question 4

What hazards occur at ocean trenches?

Answer 4

Earthquakes
As friction builds up.

Volcanoes as plate heats up and melts and basaltic magma less denser then surrounding mantle so rises

Question 5

How is island arc formed?

Answer 5

Subduction occurs under ocean
2 oceanic plates.
Descending plate encounters very hot surrounding couplets with heat / friction which melts the plate.
Material less dense then surrounding asthenosphere it rises to surface as plutons of magma.
Form complex composite volcanoes.
Occur offshore island arcs

Question 6

What else can form next to island arcs ?

Answer 6

Deep ocean trenches

Question 7

What kind of hazards at island arcs

Answer 7

Volcanoes

Shallow to deep EQs

Question 8

How are Young fold mountains formed?

Answer 8

Destructive Pb
2 continental plates
No subduction as they have similar density/ buoyancy.
Collide.
Geocyncline obtains lots of sediment when plates converge which forces sediment to be folded creating anticlines- unfolds and synclines - downfold

Question 9

Example of young fold mountain

Answer 9

Himilayas