Plate Margins And Magma Plumes

Question 1

Within a destructive plate boundary where oceanic plate meets continental plate. What happens when 2 plates converge?

Answer 1

2 plates converge the continental land in uplifted, compressed, buckled and folded. Which forms chains of fold mountains.

Question 2

What happens if compression continues after the two plates have converged in a destructive plate boundary of oceanic and continental?

Answer 2

Simple folding which is asymmetrical and over folded to become a recumbent fold.
This is increases further in middle as it is thin and break - nappe

Question 3

What is a magma plume and how are they formed

Answer 3

Areas of hot unwelling magma

1. Radioactive decay earth core = hot temp
2. Decay is concentrated which causes hot spots to form around core
3. Hot spots heat lower mantle = localised thermal current
   Magma plumes rise vertically

Question 4

What happens if hot spots remain stationary in magma plumes

Answer 4

Movement overlying plate forms chain active and subsequently extinct volcano as plate moves away from hotspot

Eg hawian islands

Question 5

Within mid oceanic ridges what is marked by the middle of ridges and when wouldn’t they occur?

Answer 5

Marked by deep rift valley
Wouldn’t occur in rapidly separating plate margins in east of Pacific

Question 6

How do volcanic islands like Surtsey in mid Atlantic Ocean forms?

Answer 6

Volcanic eruption along ridge can build to create submarine volcanoes

Overtime they grow to rise about sea level
To form volcanic islands

Question 7

How do rift valleys form

Answer 7

Lithosphere stretches causing fracture in sets on parrelel faults

Land between fault collapses into deep wide valley

Separated by horsts ( unright blocks land)

Eg great African rift valley

Forms oceans