Lecture 5: Plate tectonics 2 Flashcards
Describe Divergent plate margins: Use
Seismicity, melting and volcanism
Divergent – plates move apart
Seismicity: shallow earthquakes
Melting: decompression melting
Volcanism: creation of oceanic crust at mid-ocean ridge
Other features: hydrothermal activity
What are the two topography’s created by divergent plate tectonics
- Continental rifts
Plates: Continental lithosphere rifts (splits)
Topography: rift valleys - Mid-ocean ridges
Plates: Oceanic-oceanic lithosphere
Topography: ridge + abyssal plains
How are continental rifts formed?
REVIEW SLIDE 6 need to know the places
How are Mid Ocean ridges formed? What does this process create?
- Plates pull apart
- Asthenosphere wells up to fill gap
- Decompression of asthenosphere
lowers melting point - Partial melting of mantle produces
mafic magma - Magma cools, creating new
oceanic crust (basalt and gabbro)
Describe Convergent plate margins: Use
Seismicity, melting and volcanism
Convergent – plates move together
Seismicity: ranges from shallow to the deepest earthquakes on Earth
Melting: flux melting
Volcanism: creation of continental crust at volcanic arc
Other features: accretionary wedge
What are the two topography’s formed by convergent plate tectonics?
- Subduction zones
Plates: oceanic-oceanic OR continental-oceanic
Topography: trench, volcanic arc
- Continental collision zones
Plates:
continental-continental lithosphere (no subduction)
Topography: mountains, thick crustal root
Describe Transform plate margins: Use
Seismicity, melting and volcanism
Transform – plates slide against each other
Seismicity: shallow earthquakes
Melting: none
Volcanism: none
Other: offset surface features
What are the two topography’s formed by transform plate tectonics?
- Continental
Plates: continental-continental
Link any two types of plate boundaries - Oceanic
Plates: oceanic-oceanic lithosphere
Link divergent segments at mid-ocean ridges
