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Plate Tectonics-- Geological features of Convergent Plate Boundaries : Geological features of Convergent Plate Boundaries
相關課程
- We've already talked a lot about plate boundaries
- Where essentially new crust material has been created and the plates are actually moving apart
- we call these divergent boundaries, and the example we showed of this was the mid-atlantic ridge
- Where essentially new crustal material is being created
- the other side of the equation you have areas where plates are ramming into each other
- we see that over here where the nazca plate is running into the south american plate
- we see it over here where the pacific plate is running into the phillipino plate- they're running into each other
- so what happens over there? so what we're gonna do is just go through the different scenarios.
- the general idea is that one plate is going to get subducted under another
- they're ramming into each other one is going to get essentially pushed under the other one
- this diagram shows some subduction over here
- this is essentially an oceanic plate being subducted under another oceanic plate
- so not too different than what might happen when the pacific plate runs into the filipino plate
- right over here, then on this side of the diagram
- we see an oceanic plate and the oceanic plate getting subducted under a continental plate, right over here
- and this is what's happening when the nazca plate is getting subducted under the south american plate
- and when that happens you have a couple of things
- so you have the oceanic plate being pushed under
- and what happens at the same time the continental plate gets pushed upwards causing mountain ranges like the andes
- and that's exactly what causes- what has created the andes
- it's the upward force from the nazca plate being pushed under the south american plate at that coast line
- and what you're also going to see is, and if you can imagine you have these huge plates grinding past each other
- it's not a very smooth process, every now and then you reach a breaking point where hug amount of energy
- get released so you're also going to see a lot of earthquakes in those areas
- and we know that chile has a lot of earthquakes
- and then on top of that, this is going to result in a lot of heat
- and a lot of friction of the plates grinding past each other
- essentially allowing magma to form at that part of the rock
- and it's getting so heated that you'll also have volcanoes in these areas
- where essentially something is being subducted underneath a continental plate
- now we also talked about what's happening in the pacific
- where we have the pacific plate being subducted under the filipino plate
- that's what we keep referring to over here
- and that's doing a couple of interesting things
- so whenever so have subduction you have trenches
- but it's most interesting - or at least in my mind
- the deepest trenches have been created where you have an oceanic plate being subducted under another oceanic plate
- so a couple of things are going to happen
- you're going to have deep trenches form
- you're going to have a trench form
- over here you see in this diagram we also have a trench
- and the first example
- but you have trenches form where one oceanic plate is being subducted under another
- and then you have that same type of friction that you saw over here create volcanoes
- and those volcanoes will initially be under water volcanoes
- so if these are both oceanic plates, or we're dealing with oceanic crusts
- at that point of the plate it doesn't have to be entirely and oceanic plate
- and there'll first be underwater volcanoes
- but as the lave piles up and hardens
- it'll eventually turn into a group of islands
- and we've had that happening where the pacific plate runs into the filipino plate
- and first we have the trench
- let me just draw everything right here
- so, this is the boundary, roughly, roughly speaking
- this is the boundary between the two plates
- the pacific plate and the filipino plate right over here
- and where it's being subducted you have the mariana trench
- which is the deepest trench in the world!
- it goes down eleven kilometres- eleven thousand metres!
- that's deeper than mount everest is high
- mt everest is about nine thousand metres high
- and we'll see that's also due to another convergent plate boundary
- another plate boundary where plates are running into each other
- so not only do you see the mariana trench here
- because one plate is being subducted under the other
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