plate margins (destructive, constructive, conservative)

Question 1

what happens at a destructive plate margin (oceanic:continental)?

Answer 1

oceanic lithosphere is denser than continental so gets subducted beneath the continental lithosphere
the oceanic lithosphere begins to melt due to heat from asthenosphere and friction (also generates earthquakes in Benioff zone)

Question 2

where is a located example of destructive plate margin (oceanic:continental)?

Answer 2

Andes - Nazca (oceanic) and South American (continental)

Question 3

what happens at destructive (oceanic:oceanic)?

Answer 3

older, therefore denser, oceanic crust subducted

- chain of islands (island arc) is created by volcanic activity - layers of lava

Question 4

what happens at destructive (continental:continental)?

Answer 4

young fold mountains formed due to collision/subduction (Himalayas)

Question 5

where is a located example of a destructive plate margin (continental:continental)?

Answer 5

Himalayas - Indo Australian and Eurasian

Question 6

what happens at constructive plate boundaries (oceanic:oceanic)?

Answer 6

convection currents pull oceanic crust apart
volcanoes + earthquakes
-lava is basaltic and eruptions are gentle and effusive
-earthquakes form because crust does not break in a single line, transform fault develop - act as mini conservative plate margins and friction between them causes earthquakes

Question 7

what happens at conservative plate margins?

Answer 7

• two plates are parallel or nearly parallel
• movement sporadic and jerky, frictional forces lock plates together but when frictional forces are overcome they slip suddenly and shallow focus earthquakes are generated
• no crust destroyed or created

Question 8

where is a located example of conservative plate margins?

Answer 8

san andreas fault - N. American and pacific plates