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Why Earth's mantle is solid
Every solid save water ice and a few semi-metals is denser than the
liquid of the same composition, and the same temperature and pressure. This means that a liquid other than water will not exist beneath a solid of the same composition in a planet. A magma ocean therefore can only freeze from the bottom up, except for the granitic crust which, owing to its composition, is lighter than the liquid mantle. The amount of granitic crust which could exsolve is pretty high, if the mean composition is that of albite perhaps 20% of the mantle in the extreme - but this would not be reached until far below the solidus. Freezing from the bottom up is a much faster process than freezing from the top down, as the heat flux from below continues to decrease (yes, there is convection, but the effective viscosity is much higher in a solid than a liquid), and therefore should go to completion. Andrew Usher |
#2
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Why Earth's mantle is solid
Andrew Usher wrote:
Every solid save water ice and a few semi-metals is denser than the liquid of the same composition, and the same temperature and pressure. Bull****. Silicon, bismuth, clathrates... have denser liquids than solids. Ditto silicate melts vs. zeolites. Metal-organic frameworks. It's a trivial thing to do given crystal structure. This means that a liquid other than water will not exist beneath a solid of the same composition in a planet. A magma ocean therefore can only freeze from the bottom up, Since it can only cool from the top down you might want to rethink that. Hawaii is frozen at the top and liquid at the base. except for the granitic crust which, owing to its composition, is lighter than the liquid mantle. The amount of granitic crust which could exsolve is pretty high, if the mean composition is that of albite perhaps 20% of the mantle in the extreme - but this would not be reached until far below the solidus. Freezing from the bottom up is a much faster process than freezing from the top down, as the heat flux from below continues to decrease (yes, there is convection, but the effective viscosity is much higher in a solid than a liquid), and therefore should go to completion. So sad. -- Uncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/lajos.htm#a2 |
#3
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Why Earth's mantle is solid
On Sep 4, 4:51 pm, Uncle Al wrote:
Andrew Usher wrote: Every solid save water ice and a few semi-metals is denser than the liquid of the same composition, and the same temperature and pressure. Bull****. Silicon, bismuth, clathrates... have denser liquids than solids. Ditto silicate melts vs. zeolites. Metal-organic frameworks. It's a trivial thing to do given crystal structure. Silicon and bismuth are the semi-metals I was thinking of, along with Ge, Sb, As, graphite. I consider clathrates a type of water ice. Zeolites are not equilibrium phases and can't coexist with a melt. Saying it's 'trivial' is pointless; of course it's a function of crystal structure. This means that a liquid other than water will not exist beneath a solid of the same composition in a planet. A magma ocean therefore can only freeze from the bottom up, Since it can only cool from the top down you might want to rethink that. So? Convection is faster than heat loss in a liquid. Hawaii is frozen at the top and liquid at the base. Hawaii, like all volcanoes, has liquid under it but that's only possible locally as the magma is less dense than the surrounding rock. This is simply hydrostatic equilibrium. except for the granitic crust which, owing to its composition, is lighter than the liquid mantle. The amount of granitic crust which could exsolve is pretty high, if the mean composition is that of albite perhaps 20% of the mantle in the extreme - but this would not be reached until far below the solidus. Freezing from the bottom up is a much faster process than freezing from the top down, as the heat flux from below continues to decrease (yes, there is convection, but the effective viscosity is much higher in a solid than a liquid), and therefore should go to completion. So sad. I don't think you're really this stupid. Andrew Usher |
#4
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Why Earth's mantle is solid
Andrew Usher wrote:
Every solid save water ice and a few semi-metals is denser than the liquid of the same composition, and the same temperature and pressure. This means that a liquid other than water will not exist beneath a solid of the same composition in a planet. A magma ocean therefore can only freeze from the bottom up, except for the granitic crust which, owing to its composition, is lighter than the liquid mantle. The amount of granitic crust which could exsolve is pretty high, if the mean composition is that of albite perhaps 20% of the mantle in the extreme - but this would not be reached until far below the solidus. Is the crust really all that different material from the mantle? In the early days, I just thought the crust was just cooled mantle material. How do they really know what the mantle is made of? Anyways, what's the liquid (i.e. magma) that exists below the crust made of? Is it liquefied crust, or liquefied mantle? If it's liquefied crust, then isn't that another example of a liquid existing below its solid phase? Yousuf Khan |
#5
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Why Earth's mantle is solid
On Sep 5, 12:08 am, Yousuf Khan wrote:
Andrew Usher wrote: Every solid save water ice and a few semi-metals is denser than the liquid of the same composition, and the same temperature and pressure. This means that a liquid other than water will not exist beneath a solid of the same composition in a planet. A magma ocean therefore can only freeze from the bottom up, except for the granitic crust which, owing to its composition, is lighter than the liquid mantle. The amount of granitic crust which could exsolve is pretty high, if the mean composition is that of albite perhaps 20% of the mantle in the extreme - but this would not be reached until far below the solidus. Is the crust really all that different material from the mantle? In the early days, I just thought the crust was just cooled mantle material. How do they really know what the mantle is made of? The crust is differentiated from the mantle, oceanic crust less so than continental. We know the composition of the mantle, I think, largely from astronomical abundances. Anyways, what's the liquid (i.e. magma) that exists below the crust made of? Is it liquefied crust, or liquefied mantle? If it's liquefied crust, then isn't that another example of a liquid existing below its solid phase? Magma is formed by partial melting of either mantle or crust. Yes, it is less dense than surrounding rock, which is why it moves upward. Andrew Usher |
#6
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Why Earth's mantle is solid
On Sep 5, 6:13*pm, Andrew Usher wrote:
On Sep 5, 12:08 am, Yousuf Khan wrote: Andrew Usher wrote: Every solid save water ice and a few semi-metals is denser than the liquid of the same composition, and the same temperature and pressure.. This means that a liquid other than water will not exist beneath a solid of the same composition in a planet. A magma ocean therefore can only freeze from the bottom up, except for the granitic crust which, owing to its composition, is lighter than the liquid mantle. The amount of granitic crust which could exsolve is pretty high, if the mean composition is that of albite perhaps 20% of the mantle in the extreme - but this would not be reached until far below the solidus. Is the crust really all that different material from the mantle? In the early days, I just thought the crust was just cooled mantle material. How do they really know what the mantle is made of? The crust is differentiated from the mantle, oceanic crust less so than continental. We know the composition of the mantle, I think, largely from astronomical abundances. Anyways, what's the liquid (i.e. magma) that exists below the crust made of? Is it liquefied crust, or liquefied mantle? If it's liquefied crust, then isn't that another example of a liquid existing below its solid phase? Magma is formed by partial melting of either mantle or crust. Yes, it is less dense than surrounding rock, which is why it moves upward. Andrew Usher My guess is that you have no idea of what the mantle is. Am I close to being correct? My second guess is that you've never completed a college course in geology, or even own a textbook on the subject. Am I close again? Seriously, the dyanics of the earth's interior are likely much more complex than a layman might assume. Just for the record, the mantle is an interface point upon which the less denser continental masses float. The interior of the earth is generally considered to be a totally molten mass of mixed heavy metals, starting with iron and going through uranium and possibly even heavier elements. Physicist and geologist tend to disagree on the reason why the core of the earth remains liquid, or ever if it is liquid. Actually, finding out exatly what is going on in the earth's interior remain today unknown. Harry C, |
#7
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Why Earth's mantle is solid
"Andrew Usher" wrote in message
... On Sep 4, 4:51 pm, Uncle Al wrote: Andrew Usher wrote: Every solid save water ice and a few semi-metals is denser than the liquid of the same composition, and the same temperature and pressure. Bull****. Silicon, bismuth, clathrates... have denser liquids than solids. Ditto silicate melts vs. zeolites. Metal-organic frameworks. It's a trivial thing to do given crystal structure. Silicon and bismuth are the semi-metals I was thinking of, along with Ge, Sb, As, graphite. I consider clathrates a type of water ice. Zeolites are not equilibrium phases and can't coexist with a melt. Saying it's 'trivial' is pointless; of course it's a function of crystal structure. This means that a liquid other than water will not exist beneath a solid of the same composition in a planet. A magma ocean therefore can only freeze from the bottom up, Since it can only cool from the top down you might want to rethink that. So? Convection is faster than heat loss in a liquid. Hawaii is frozen at the top and liquid at the base. Hawaii, like all volcanoes, has liquid under it but that's only possible locally as the magma is less dense than the surrounding rock. This is simply hydrostatic equilibrium. except for the granitic crust which, owing to its composition, is lighter than the liquid mantle. The amount of granitic crust which could exsolve is pretty high, if the mean composition is that of albite perhaps 20% of the mantle in the extreme - but this would not be reached until far below the solidus. Freezing from the bottom up is a much faster process than freezing from the top down, as the heat flux from below continues to decrease (yes, there is convection, but the effective viscosity is much higher in a solid than a liquid), and therefore should go to completion. So sad. I don't think you're really this stupid. Andrew Usher The "I don't think you're really this stupid" statement is an example of a conditional variation on argumentum ad homenim. Statistically, I don't need to see the rest of the thesis to be fairly certain that the author of that statement has insufficient supporting facts - so if I'm pressed for time and I catch you making a false argument, I'll just assume you're in error and move on. Here's why: The verity of a conclusion may well be independent of the supporting argument's fallaciousness, but nearly all of the times when people resort to fallacy, they generally only do so when there is a glaring lack of supporting evidence. Do a bit of reading (actually, quite a bit of reading!) and you too will discover that the fallacy is only very rarely used in association with an otherwise genuinely valid thesis. Try again... -- Timothy Casey GPEMC! Conditions apply. See www.fieldcraft.biz/GPEMC Essays: http://timothycasey.info; http://speed-reading-comprehension.com Softwa http://fieldcraft.biz; Scientific IQ Test, Web Menus, Security. Science & Technical: http://geologist-1011.com; http://web-design-1011.com |
#8
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Why Earth's mantle is solid
On Sep 5, 9:45 pm, "Number Eleven - GPEMC!"
wrote: Freezing from the bottom up is a much faster process than freezing from the top down, as the heat flux from below continues to decrease (yes, there is convection, but the effective viscosity is much higher in a solid than a liquid), and therefore should go to completion. So sad. I don't think you're really this stupid. Andrew Usher The "I don't think you're really this stupid" statement is an example of a conditional variation on argumentum ad homenim. What do you think his 'So sad' was? Andrew Usher |
#9
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Why Earth's mantle is solid
On Sep 5, 5:37 pm, " wrote:
Physicist and geologist tend to disagree on the reason why the core of the earth remains liquid, or ever if it is liquid. Actually, finding out exatly what is going on in the earth's interior remain today unknown. The Earth's interior is far from unknown. Learn something before posting. Andrew Usher |
#10
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Why Earth's mantle is solid
On Sep 6, 12:02 am, Sam Wormley wrote:
How about that liquid outer core of iron and sulfur that can not support shear waves. I was obviously referring to the mantle only. And that "plastic" Asthenosphere http://en.wikipedia.org/wiki/Asthenosphere "The upper part of the asthenosphere is believed to be the zone upon which the great rigid and brittle lithospheric plates of the Earth's crust move about. Due to the temperature and pressure conditions in the asthenosphere, rock becomes ductile, moving at rates of deformation measured in cm/yr over lineal distances eventually measuring thousands of kilometers. In this way, it flows like a convection current, radiating heat outward from the Earth's interior. Above the asthenosphere, at the same rate of deformation, rock behaves elastically and, being brittle, can break, causing faults. The rigid lithosphere is thought to "float" or move about on the slowly flowing asthenosphere, creating the movement of crustal plates described by Plate tectonics theory". This doesn't contradict anything I said. The asthenosphere is still essentially solid. Andrew Usher |
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