Constructive Plate Margins Flashcards
1
Q
Constructive plates move _________ due to what?
A
Apart - Convection currents and ridge push (distant slab pull)
2
Q
What kind of melting is at a constructive plate boundary?
A
Decompression as pressure falls
3
Q
As the plate thins, what is formed?
A
Tensional cracks
4
Q
What are the lithospheric blocks that fall called?
A
Grabens
5
Q
What is formed at this stage? Name an example?
A
Rift valley - great African
6
Q
Why does the new rock sit higher than surrounding?
A
Newer so less dense and will sit higher
Rising partial melt will also make it sit higher
7
Q
What is this higher area called? Name an example
A
ocean ridge - mid-Atlantic ridge
