- #1
FunkyDwarf
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Hey guys
Im doing research for an assignment on plate tectonics and life. The question is basically how it works and also how it helps maintain Earth as a habitable enviroment. Now i am in no way looking just for answers, more an understanding so i can sound more intelligent in my project and also understand it better just for myself because i do find certain parts interesting (im not doing a geology course, its just an assignment for a unit I am doing, long story :P)
ok, so here's what i know (or think i know anyway :P)
You have the mantle and the crust. The upper part of the mantle is the asthenosphere with a bit of the lithosphere. The upper part of the lithosphere is the crust. Now this lithosphere moves around on the mechanically weaker and softer asthenosphere for a number of reasons.
a.) Convection currents in the mantle driven by the core
b.) Subduction pulling
c.) mid ocean ridge 'pushing'
There are two kinds of crust, continental and oceanic. Oceanic is denser and so sinks and is made of basalt. The continental crust is however made of andesite and granite igneous rocks and their metamorphic and sedimentary companions.
As plumes of hot magma rise in certain parts they partially melt the lithosphere and spew more material up, either through a volcano or mid ocean ridge (undersea volcano). If the oceanic version of this occurs you get seafloor spreading where new oceanic crust is created as the lava (magma underground) flows and cools to form new rock.
Continental crust is on the other hand formed by subduction. If an oceanic plate subducts under an existing continental plate or other oceaninc plate (that can happen right?) the plate undergoing subduction dehydrates. This water then rises up and loweres the melting point of the above plate, causing it to melt and mix with surrounding materials to form the andesite and granite materials that make up the continental crust. Thus without water, you can't have continental crust. And so the crust slowly grows along this zone.
I also understand the whole supercontinent and contiental drift thing, and that supercontinents spell their own doom because they don't allow the Earth to lose heat
Now in terms of making Earth habitable (im sure I've missed heaps in the above section, i didnt go through my notes with a fine toothcomb but the basics are there i think). For this i just had a few general sections
1.) Errosion vs mountain building
If there was no plate tectonics, and thus no mountain building, errosion would eventually weather away everything and remove all sediment, effectively covering the world in water.
2.) The carbon cycle
Volcanoes and the rock cycle play an important role in the carbon cycle and thus the regulation of the Earth's temperature. plate tectonics affect both these cycles
3.) Life was thought to first originate near oceanic fissures where magma was superheating the water. You also find that the water at mid ocean ridges circulates through the material and brings back up with it carbonacous material and metals that are essential for life
Am i on the right track?
Keep in mind this is only a first year assignment for a non-geology unit (its called our solar system so it includes some geology but its not a indepth thing)
Cheers
-G
Im doing research for an assignment on plate tectonics and life. The question is basically how it works and also how it helps maintain Earth as a habitable enviroment. Now i am in no way looking just for answers, more an understanding so i can sound more intelligent in my project and also understand it better just for myself because i do find certain parts interesting (im not doing a geology course, its just an assignment for a unit I am doing, long story :P)
ok, so here's what i know (or think i know anyway :P)
You have the mantle and the crust. The upper part of the mantle is the asthenosphere with a bit of the lithosphere. The upper part of the lithosphere is the crust. Now this lithosphere moves around on the mechanically weaker and softer asthenosphere for a number of reasons.
a.) Convection currents in the mantle driven by the core
b.) Subduction pulling
c.) mid ocean ridge 'pushing'
There are two kinds of crust, continental and oceanic. Oceanic is denser and so sinks and is made of basalt. The continental crust is however made of andesite and granite igneous rocks and their metamorphic and sedimentary companions.
As plumes of hot magma rise in certain parts they partially melt the lithosphere and spew more material up, either through a volcano or mid ocean ridge (undersea volcano). If the oceanic version of this occurs you get seafloor spreading where new oceanic crust is created as the lava (magma underground) flows and cools to form new rock.
Continental crust is on the other hand formed by subduction. If an oceanic plate subducts under an existing continental plate or other oceaninc plate (that can happen right?) the plate undergoing subduction dehydrates. This water then rises up and loweres the melting point of the above plate, causing it to melt and mix with surrounding materials to form the andesite and granite materials that make up the continental crust. Thus without water, you can't have continental crust. And so the crust slowly grows along this zone.
I also understand the whole supercontinent and contiental drift thing, and that supercontinents spell their own doom because they don't allow the Earth to lose heat
Now in terms of making Earth habitable (im sure I've missed heaps in the above section, i didnt go through my notes with a fine toothcomb but the basics are there i think). For this i just had a few general sections
1.) Errosion vs mountain building
If there was no plate tectonics, and thus no mountain building, errosion would eventually weather away everything and remove all sediment, effectively covering the world in water.
2.) The carbon cycle
Volcanoes and the rock cycle play an important role in the carbon cycle and thus the regulation of the Earth's temperature. plate tectonics affect both these cycles
3.) Life was thought to first originate near oceanic fissures where magma was superheating the water. You also find that the water at mid ocean ridges circulates through the material and brings back up with it carbonacous material and metals that are essential for life
Am i on the right track?
Keep in mind this is only a first year assignment for a non-geology unit (its called our solar system so it includes some geology but its not a indepth thing)
Cheers
-G