NationStates Jolt Archive

Just a hypothesis:

Plate tectonics requires water to work. Without water, there is no lubricant and the plates get stuck to each other and can't move.
A good example would be the planet venus.

Just a hypothesis:

Plate tectonics requires water to work. Without water, there is no lubricant and the plates get stuck to each other and can't move.
A good example would be the planet venus.
Water actually has nothing to do with it. It's not that good a lubricant, especially at the depths and pressures we are talking about.

The moon, on the other hand, keeps the interior of the Earth in a constant state of agitation, driving palte tectonics. Venus has no moon.

Water has nothing to do with plate tectonics.

Unless by "water" you mean "hot, molten, magma deep, deep within the Earth."

Umm... I was given to understand that water is important for plate tentonics. When you look at the difference between shield volcanos located in the middle of tentonic plates, and andriasitic volcanoes located on at the edges of tentonic plates where water rich seafloor crust plunges beneath continents, you can see that water content has quite an effect. Haiwaii's volcanoes are broad and flat and kind of laid back compared to the steeper and more explosive volcanos such as Mt. Fuji (Formally quite active), Mt. Saint Helens, etc. Water obviously has a big effect.

That's only a local effect in volcano formation. A tectonic plate is much bigger and different to a volcano.

Umm... I was given to understand that water is important for plate tentonics. When you look at the difference between shield volcanos located in the middle of tentonic plates, and andriasitic volcanoes located on at the edges of tentonic plates where water rich seafloor crust plunges beneath continents, you can see that water content has quite an effect. Haiwaii's volcanoes are broad and flat and kind of laid back compared to the steeper and more explosive volcanos such as Mt. Fuji (Formally quite active), Mt. Saint Helens, etc. Water obviously has a big effect.

Plate tectonics is not about the appearance of volcanos, but about the movement of the plates themselves, and for that water is not necessary at all - what controls the movement of tectonic plates are currents in the molten magma underneath them. The "lubricant effect" of water is probably insignificant, if it's even existent.

Umm... I was given to understand that water is important for plate tentonics. When you look at the difference between shield volcanos located in the middle of tentonic plates, and andriasitic volcanoes located on at the edges of tentonic plates where water rich seafloor crust plunges beneath continents, you can see that water content has quite an effect. Haiwaii's volcanoes are broad and flat and kind of laid back compared to the steeper and more explosive volcanos such as Mt. Fuji (Formally quite active), Mt. Saint Helens, etc. Water obviously has a big effect.
I think you might be confusing the thinner oceanic plates with the thicker contental (sp?) plates. Here's a really good overview of the process that talks about why the plates float the way they do: http://pubs.usgs.gov/publications/text/dynamic.html (From the USGS)

From the USGS Another factor is composition, which influences the ability of a body to convect. For example, a liquid interior, such as may exist within Ganymede, is more likely to convect and drive plate tectonics than the "stony" interiors of the Moon, Mercury, Venus, and Mars.

Water saturates the Earth's crust. So would this make plate tentonics easier on Earth than on a world that has lost most of its water (Venus?)

On a human scale it is easy to see the effects water has on regolith. If we removed all the Earth's water, would plate tentonics continue as they do? Wouldn't the lack of water increase the density of the crust making it more similar to the underlying mantle? Would this allow for a greater mixing of crust and mantle material? Could this clog up plate tentonics? I don't know. But I was surprised to see where people had written that it has no effect when the presence of water seems to be an important difference between the crust and the mantle.

Plate tectonics is not about the appearance of volcanos, but about the movement of the plates themselves, and for that water is not necessary at all - what controls the movement of tectonic plates are currents in the molten magma underneath them. The "lubricant effect" of water is probably insignificant, if it's even existent.
I think you are talking about the movement of the plates on top of the mantle. I am talking about the plates sliding past or below each other. The hypothesis was that for the plates to not get stuck together, you need huge volumes of water to keep the ground wet and lubricated. Otherwise they stick together and the pressure (that would normally be removed by their moving around) ends up building up to the point that you would have catastrophic global volcanic eruptions. An end of the world scenario if you would. Also the planet would be much hotter than it is now. And hence, there would be no life as the planet would be quite sterile.

I think you are talking about the movement of the plates on top of the mantle. I am talking about the plates sliding past or below each other. The hypothesis was that for the plates to not get stuck together, you need huge volumes of water to keep the ground wet and lubricated. Otherwise they stick together and the pressure (that would normally be removed by their moving around) ends up building up to the point that you would have catastrophic global volcanic eruptions. An end of the world scenario if you would. Also the planet would be much hotter than it is now. And hence, there would be no life as the planet would be quite sterile.

And I still hold that such a "lubricant" effect is probably insignificant, especially as water is a terribly poor lubricant.

Also, Venus lacking water has nothing to do with its seismic activity or lack thereof. The link posted further up the thread speaks of Venus.

I think you are talking about the movement of the plates on top of the mantle. I am talking about the plates sliding past or below each other. The hypothesis was that for the plates to not get stuck together, you need huge volumes of water to keep the ground wet and lubricated. Otherwise they stick together and the pressure (that would normally be removed by their moving around) ends up building up to the point that you would have catastrophic global volcanic eruptions. An end of the world scenario if you would. Also the planet would be much hotter than it is now. And hence, there would be no life as the planet would be quite sterile.Volcanic eruption are cause by cracks in the crust allowing the magma to burst forth. I think you mean Earthquakes. which are caused when the plates stick then release.

If that were the case, then epicenters for earthquakes would not be in the oceans... however, since they do ocurre in the waters (the earthquake that spawned the Indian ocean tsunami occured in the ocean floor) I don't think water plays that much of a factor.

There is no plate tectonics whatever on Venus despite the fact that Venus also has a very hot molten mantle.

http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1996JGR...101.4765T&db_key=AST

such that it is what the water does to the composition of the land masses that allows tectonics to work.

http://www.asi.org/adb/06/09/03/02/036/hydro-tectonic.html

Interesting articles... however, could it be because water is a cooling factor for the mantle that the plates form. after all, you got rock being constantly heated and cooled by both the core/magma below and the water/air above. the constant temperature fluxes could be what keeps the plates seperate and not "Fused" together like Venus and the Moon.

of course that is just my Hypothesis.

Interesting articles... however, could it be because water is a cooling factor for the mantle that the plates form. after all, you got rock being constantly heated and cooled by both the core/magma below and the water/air above. the constant temperature fluxes could be what keeps the plates seperate and not "Fused" together like Venus and the Moon.

of course that is just my Hypothesis.
that sounds possible.
I was just noticing how all the mantle that comes up continually between plates, does so under the oceans and not on the continents. It only comes up on the continents during sporadic an un uniform volcanic explosions. Below the oceans it is continuous and smooth. Also, I notice that crust formation only occurs in the ocean and not on the continent.

that sounds possible.
I was just noticing how all the mantle that comes up continually between plates, does so under the oceans and not on the continents. It only comes up on the continents during sporadic an un uniform volcanic explosions. Below the oceans it is continuous and smooth. Also, I notice that crust formation only occurs in the ocean and not on the continent.because most (and I mean Most) of the plate lines lie in the water (easliy done since Earth's surface is mostly water.)

where it does meet on land is usually marked by Faultlines and most moutain ranges. (going by memory here so forgive if wrong. :D ) the rocky mountains and several Large mountain ranges I believe were created by Plate Tectonics.

The theory of the "super continent" breaking up would be along those plate lines as well.

However, the articles you provide makes the presence of water less a lubericant and more of a Cooling device...

OMG... the Earth is a Super computer... it's water cooled! :D

I think you are talking about the movement of the plates on top of the mantle. I am talking about the plates sliding past or below each other. The hypothesis was that for the plates to not get stuck together, you need huge volumes of water to keep the ground wet and lubricated. Otherwise they stick together and the pressure (that would normally be removed by their moving around) ends up building up to the point that you would have catastrophic global volcanic eruptions. An end of the world scenario if you would. Also the planet would be much hotter than it is now. And hence, there would be no life as the planet would be quite sterile.

Or they could form mountains.

Edit: Let me elaborate a bit on one type of movement you mentioned. Remember that plates have two distinct parts: the upper half (roughly), which is solid, and the lower half that is semi-molten. When one plate is moving under another, the plate that is on the bottom is sliding on a viscous liquid, that is, the semi-molten bottom of the upper plate. At the same time the upper solid part of the plate that is moving under the other is melting when it comes in contact with the molten half of the upper plate. A liquid is going to have fairly low friction whether it's liquid rock or liquid water. I can't see how it would make a difference what substance is being used as a lubricant as long as it's liquid.

because most (and I mean Most) of the plate lines lie in the water (easliy done since Earth's surface is mostly water.)

where it does meet on land is usually marked by Faultlines and most moutain ranges. (going by memory here so forgive if wrong. :D ) the rocky mountains and several Large mountain ranges I believe were created by Plate Tectonics.

The theory of the "super continent" breaking up would be along those plate lines as well.

However, the articles you provide makes the presence of water less a lubericant and more of a Cooling device...

OMG... the Earth is a Super computer... it's water cooled! :Dthat's all true but I was saying that new crust can only form where there is water.
The faultlines like the San Andreas for example are only sliding past each, there isn't any new crust being created there. The same with mountains. Mountains are just old crust being mashed together and pushed up.
Again no new crust being created except in the oceans.

that's all true but I was saying that new crust can only form where there is water.
The faultlines like the San Andreas for example are only sliding past each, there isn't any new crust being created there. The same with mountains. Mountains are just old crust being mashed together and pushed up.
Again no new crust being created except in the oceans.and volcanoes... remember... invest in land in Hawaii... it's still being made fresh daily. :D

again, most of the rebuliding of the crust happens underwater because that has the most (and lowest) landmass. What is creating the crust? I would wager its the Smokers on the ocean floor... above water, they would be Volcanoes.

you also have the Ocean eroding the land and transporting the silt to the deep water floor.

Not discounting the theories... but just wondering if there is more to it than just "water creates Tectonic plates"

that's all true but I was saying that new crust can only form where there is water.
The faultlines like the San Andreas for example are only sliding past each, there isn't any new crust being created there. The same with mountains. Mountains are just old crust being mashed together and pushed up.
Again no new crust being created except in the oceans.

Could this senario possibly be the case? If a mountain is being created, there would be an upward movement of crust. That would mean that the space that was once occupied by that crust that is now a mountain would be filled in by the crust below it, and the space that crust filled would then be filled by semi-molten rock that would cool and become solid crust. The space once occupied by the semi-molten rock would then be filled by molten rock below it. The molten rock, having moved up, might cool to a semi-molten state.

I don't know about that. The main cause of plate movement is said to be tensional force on a plate when a particularly hot portion of magma presses against the bottom of it. That would depend on the temperate of magma not being dependent just on it's depth relative to sea level or something. That would bring my senario into question. The molten rock that moves up might stay molten and would therefore never become crust.

and volcanoes... remember... invest in land in Hawaii... it's still being made fresh daily. :D

again, most of the rebuliding of the crust happens underwater because that has the most (and lowest) landmass. What is creating the crust? I would wager its the Smokers on the ocean floor... above water, they would be Volcanoes.

you also have the Ocean eroding the land and transporting the silt to the deep water floor.

Not discounting the theories... but just wondering if there is more to it than just "water creates Tectonic plates"
you mean crust. landmasses are continents (that is dry land).
The movement of silt, does not create new crust.
As for Hawaii, it could be argued that crust is being created there. But hawaii is the only dry place on earth where that is happening.
They're still called volcanoes even under water.

mountains are created when the plates pile into each other head on instead of one sliding beneath the other.
http://gpc.edu/~pgore/geology/geo101/mountain.htm

mountains are created when the plates pile into each other head on instead of one sliding beneath the other.
http://gpc.edu/~pgore/geology/geo101/mountain.htm
They can also be formed by the subduction of one plate beneath the other. clicky (http://home.freeuk.com/gtlloyd/tam/formtn.htm)

We need to have better classes in geology...

One of the reasons that "new" crust is beging formed in th oceans is that oceanic crust is a lot thinner than the contenental crust, which is why when an ocean plate meets a contenental plate, the ocean plate subducts (is pushed under) the contenental and a region of volcanos are formed (The west coast of North America is a prime example of this), however crust is formed on the contenents all the time, we just don't have a dry land version of the Mid-Atlantic ridge going on (and thank God for THAT!).

We need to have better classes in geology...

One of the reasons that "new" crust is beging formed in th oceans is that oceanic crust is a lot thinner than the contenental crust, which is why when an ocean plate meets a contenental plate, the ocean plate subducts (is pushed under) the contenental and a region of volcanos are formed (The west coast of North America is a prime example of this), however crust is formed on the contenents all the time, we just don't have a dry land version of the Mid-Atlantic ridge going on (and thank God for THAT!).
the reason that oceanic crust is subducted below continental crust is that oceanic crust is the heavier and denser of the two. the thickness has nothing to do with it. Crust is not being formed on the continents. If it was, we would not be here discussing this.

I think you are talking about the movement of the plates on top of the mantle. I am talking about the plates sliding past or below each other. The hypothesis was that for the plates to not get stuck together, you need huge volumes of water to keep the ground wet and lubricated. Otherwise they stick together and the pressure (that would normally be removed by their moving around) ends up building up to the point that you would have catastrophic global volcanic eruptions. An end of the world scenario if you would. Also the planet would be much hotter than it is now. And hence, there would be no life as the planet would be quite sterile.

Ok - then how do you explain the Subduction Zones on destructive plate margins? These occur when a denser oceanic crust is forced to sink below a less dense continental crust. Every so often, the two crusts 'stick' (regardless of the water present) due to friction. Of course, the friction builds up and the plates jolt, causing earthquakes and volcanic eruptions along the plate boundary.

And what about Conservative plate boundaries, where you get two Continental plates moving past each other? Granted, this is hardly a smooth process but is more often than not generated by the fact that the two plates are moving past each other in the same direction, but at different speeds. We get a buildup of friction, and the energy is released as an earthquake.

I think, perhaps, you are overstating the role of water here. As an A-level Geography student, I can assure you that water has no effect whatsoever on plate tectonics.

Hot spots around the core of the Earth generate thermal convection currents within the semi-molten asthenosphere, which cause magma to rise towards the crust and then spread before cooling and sinking. This circulation of magma is the vehicle upon which the crustal plates move. The crust should be thought of as 'floating' on the more dense material of the asthenosphere. This is a continuous process, with new crust being formed along the line of constructive boundaries between plates (where plates move away from each othere) and older crust being destroyed at destructive plate boundaries (where plates are moving towards each other).

I have an exam on this in two days, I've been doing plate tectonics for 3-4 years now ;) Trust me - water doesn't play a role in this.

used to be a geology student, a long time ago, but i still remember a few of the things.

as far as i can remember, and as stated above, water has little bearing on plate tectonics. I do believe its presence in rocks affect the melting temps, which i believe is one of the reasons you have volcanic regions (like the andes) landwards a bit of an ocean/continental subduction zone.

also, one of the reasons we dont see spreading centers/crust generation on dry land is because it soon turns into ocean:)
i realize that sounds kinda smart-ass, but basically, the continent starts to split apart, you have localized volcanism, 'sagging' of the crust as it is stretched thing, and end up with something akin to death valley-a really really low spot in the continent that collects all the water in the area.
eventually, the continent continues to split, and the body of water in the valley connects with the ocean, and then the spreading center, which used to be on dry land, is now ocean. If im not mistaken, i believe that the rift-lakes in africa are a current example of this. (but they arent connected with the ocean yet, i believe)

cant say much about venus, i dont really know much about the other planets, but im pretty sure plate tectonics(or evidence thereof) was observed on one or two of them(or maybe they were moons...)

used to be a geology student, a long time ago, but i still remember a few of the things.

as far as i can remember, and as stated above, water has little bearing on plate tectonics. I do believe its presence in rocks affect the melting temps, which i believe is one of the reasons you have volcanic regions (like the andes) landwards a bit of an ocean/continental subduction zone.

also, one of the reasons we dont see spreading centers/crust generation on dry land is because it soon turns into ocean:)
i realize that sounds kinda smart-ass, but basically, the continent starts to split apart, you have localized volcanism, 'sagging' of the crust as it is stretched thing, and end up with something akin to death valley-a really really low spot in the continent that collects all the water in the area.
eventually, the continent continues to split, and the body of water in the valley connects with the ocean, and then the spreading center, which used to be on dry land, is now ocean. If im not mistaken, i believe that the rift-lakes in africa are a current example of this. (but they arent connected with the ocean yet, i believe)

cant say much about venus, i dont really know much about the other planets, but im pretty sure plate tectonics(or evidence thereof) was observed on one or two of them(or maybe they were moons...)
they used to think there was plate tectonics on Venus but the results of the Magellan mission have proven there is no tectonics taking place on Venus.The reason they gave was that venus had no water whereas earth does.

they used to think there was plate tectonics on Venus but the results of the Magellan mission have proven there is no tectonics taking place on Venus.The reason they gave was that venus had no water whereas earth does.

That's really a moot point in this discussion, no? You were talking about the bearing of water on plate tectonics...

There is none, at least - not directly on the cause of plate tectonics.

That's really a moot point in this discussion, no? You were talking about the bearing of water on plate tectonics...

There is none, at least - not directly on the cause of plate tectonics.
actually its not a moot point. Its the whole point of the discussion. Cause according to some planetary geologists, Venus doesn't have tectonics because Venus has no water.
I just hypothesizing that would be true to earth without water too.

Hmmm - nice hypothesis, I guess...but the crux of the matter is that water - here on Earth - is not related to plate tectonics. Water does not cause plate tectonics to happen.

See my longer post above.

http://newton.ex.ac.uk/aip/physnews.87.html

http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1989JGR....94.2779T&db_key=AST

http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.earth.26.1.23?journalCode=earth

http://astronomy.nju.edu.cn/astron/at3/AT30904.HTM

http://users.zoominternet.net/~matto/M.C.A.S/notes_venus.htm

http://www.xs4all.nl/~carlkop/venus.html

Hmmm - nice hypothesis, I guess...but the crux of the matter is that water - here on Earth - is not related to plate tectonics. Water does not cause plate tectonics to happen.

See my longer post above.
but would it not, as shown in the last link above in the previous post, weaken the lithosphere enough for the mantle to break it into plates?

Earth and Venus being the same size.

But that last article also states that [Venus is] the planet that suffers from the runaway greenhouse effect to give a present-day surface temperature of nearly 900 degrees Fahrenheit

No - Venus is 25,724,740 miles closer to the Sun and has no ability to deflect heat like the Earth - that is why it is hotter.

I can pull up internet articles that irrefutably state that the Earth is flat and that the Four Horsemen of the Apocalypse are nigh...but it doesn't mean that the information in those articles is factually correct.

In all the years I've been doing Geography I have never read anything that claims that water on Earth is the engine by which plate tectonics occurs.

But that last article also states that [Venus is] the planet that suffers from the runaway greenhouse effect to give a present-day surface temperature of nearly 900 degrees Fahrenheit

No - Venus is 25,724,740 miles closer to the Sun and has no ability to deflect heat like the Earth - that is why it is hotter.

I can pull up internet articles that irrefutably state that the Earth is flat and that the Four Horsemen of the Apocalypse are nigh...but it doesn't mean that the information in those articles is factually correct.

In all the years I've been doing Geography I have never read anything that claims that water on Earth is the engine by which plate tectonics occurs.
who said anything bout water being the engine?
I was just surmising that water had a role, not that it was the main ingredient. You were saying that water had no role whatever. Is that not correct?


btw, actually it is the greenhouse effect that makes venus hotter

But that last article also states that [Venus is] the planet that suffers from the runaway greenhouse effect to give a present-day surface temperature of nearly 900 degrees Fahrenheit

No - Venus is 25,724,740 miles closer to the Sun and has no ability to deflect heat like the Earth - that is why it is hotter.
Of coure the distance to the sun matters, but over 90% of the atmosphere on venus is carbon dioxide. I don't think it would be as hot if it had an atmsphere like earth.

Water actually has nothing to do with it. It's not that good a lubricant
What about mud?