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Tectonics pt1 (basics of tectonics) - Coggle Diagram
Tectonics pt1 (basics of tectonics)
Structure of the Earth
Crust
0-100km deep
Split into two types of crust, oceanic and continental.
Solid
Mantle
Semi liquid
2900km thick
Area where convection currents move the plates above.
Outer coure
2200km thick
Made of iron and nickel which is uper heated to over 300oc
Liquid
Inner core
1230km thick
Mainly made of iron that is super heated to above 500oc
Solid, but this is only due to the pressure pushing down on it.
Key words
Lithosphere
-- The rigid layer that is made up of the crust and upper mantle.
Mohorovicic (Moho) discontinuity
-- This is the boundary where the solid crust becomes the mantle.
Asthenosphere
-- This is the area below the lithosphere with high tempretures and rock deformation.
Contiental drift
Continental drift
-- This is the idea that the continents have moved and do still move, the theory was invented by Alfred Wegner in 1912, but was only proved and accepted after his death when new evidence came to light.
Evidence for continental drift
Geology
Jigsaw fit -- the contients look like they fit together like a jigsaw.
Glacial deposits in areas such as Southern Africa and Austialia despite these climates being to warm for the formation of glaciers.
Mountian chains and rock sequences such as the Mountians in Northern Scotland and North East Canada where there are similar rock and mountian types.
Biological
There are similar marine fossils in India and Austrialia.
There are similar similar repetile fossils in South America and Southern Africa.
Paleomagentism
The sea floor is made of iron rich igneous rock that comes from the mantle as the rocks cool they settle into position facing the polarity. The polarity changes every 400,000 to 500,000 years and so we can see when rocks cooled by which way they are facing, we can also see that these form rows of years either side of mid-oceinic ridge.
Sea floor spreading
Sea floor spreading
-- This is the movement of new ocainic crust away from the mid ocainic ridge.
Convection currents
Convection currents
-- this is the movement of warm magma rising from closer to the core, up to the crust and moving horizontally as it cools and then finally dropping back down to the core. This acts as a convoyor belt for the tectonoic plates.
Plate boundaries
Divergent plate boundaries
This is causes when plates move apart and magma rising from the mantle.
Under water
Create mounds of pillow lava when magma erupts from the mantle and then cools sundenly.
Water can seep into the rift valleys and become supper heated, this then sends jets of water from from the sea floor which contain metal sulfides. These jets of water are called Black Smokers.
On land
As plates move apart the land becomes weakened and this creates faults and grabens (suken vallies), if this contuines then mamgma can rise up from the surface.
These create both mid-oceanic rift valleys and rift valleys such as on earth.
Convergent plate boundaries (destructive)
Oceanic-Contiental
The denser oceanic plate subducts under the contiental plate this creates an ocean trench where the subduction takes place.
Sedimentary rock builds up on the oceanic plate and when the plate sunducts the rocks crumple together to form fold mountians (such as the Andeas).
Oceanic-oceanic
The denser of the two oceanic plates subducts and as this heppens this creates an ocean trench.
As the decending plate melts in the Beinoff zone magma rises to the surface and creates volcanic island chains.
Convergent plate boundaries (collision)
Continetal-continetal
These plates are the same density and this means that one plate wont subduct under the other plate Instead they will move upwards and form mountians.
Conservative plate boundaries
This is where plates slide past each other instead of converging or diveringing.
There are no volceanos here, but there are very strong earthquakes.
No landofrms are created on these faults, but the faults themselves can be seen sometimes.