Real Science Radio: Earth & Mercury's Decaying Magnetic Fields

gcthomas

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It's all rock. If you have got some reason why heated rock at greater depth becomes less dense than magma does below the crossover depth, we'd sure be glad to hear it. :up:

Irrelevent. What is important is whether heated mantle rock is less dense than the unheated mantle rock. Magma is not a part of the mantle convection.
 

Stripe

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Irrelevent.

Nope, but it's nice to see you've accepted the fact that rock becomes denser upon melting under great pressure. :thumb:

It is all rock. If magma deeper than about 400km becomes more dense than its parent rock because of great pressure, it is certain that deeper material will compact even more upon heating.

Unless you have an explanation to save mantle convection as the driving force for plate tectonics.

Or you could switch to slab pull and stay on the same page as DavisBJ. :chuckle:

What would be better, though, is if you could consider how the depth to compressibility factor nicely explains all the geomorphology we see on the Earth's rock surface, as well as accounting for numerous internal conditions that plate tectonics has no use for, but are critical and fundamental conditions of the Earth.
 

gcthomas

New member
I said

So your "rock becomes denser upon melting" should be "rocks melt by becoming less dense".

And you respond with
Nope, but it's nice to see you've accepted the fact that rock becomes denser upon melting under great pressure. :thumb:

Don't you read posts before responding to what you though I might have written? Silly Stripe. :jump:

It is all rock. If magma deeper than about 400km becomes more dense than its parent rock because of great pressure, it is certain that deeper material will compact even more upon heating.

So because pressure makes stuff denser, then heat must too? What a silly argument. Read it back to yourself and you'll see.

Unless you have an explanation to save mantle convection as the driving force for plate tectonics.

Take mantle rock and heat it it will become less dense. Simple, and none of your magma references deals with that at all, while my reference did.

Or you could switch to slab pull and stay on the same page as DavisBJ. :chuckle:

Slab pull is important, but so is mantle convection. And it is mantle convection that you are systematically misunderstanding due to your inability to separate the words mantle and magma, and the difficulties you are having with heat making stuff expand when there is a constant pressure. Additionally the melting you talk about is due to expansion, not due to heating.
 

Stripe

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I said And you respond with Don't you read posts before responding to what you though I might have written? Silly Stripe. :jump:
Nope.

You said: "Irrelevant."

That is what I responded to.

So because pressure makes stuff denser, then heat must too?
Straw men arguments are not to be part of a rational discussion.

Take mantle rock and heat it it will become less dense.

The evidence says otherwise.

Slab pull is important, but so is mantle convection.
Whack-a-mole.

A maximum of one of these can be called the driving force of plate tectonics. Which is it?
 

gcthomas

New member
The evidence says otherwise.

Where is this evidence that mantle rock gets denser when you heat it?

All your reference mentioned was magma convection and its density variation due to pressure - nothing about mantle rock at all.

Where is this evidence?

:idunno:
 

Stripe

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Mantle rock is hard and magma is runny, so identical. :dizzy:You'd have crashed the Titanic into the iceberg shouting "NO, don't worry! It is just water!"< sound of wind while tumble weed blows across the scene >
:yawn: Wake us up when you're prepared to be sensible.
 

gcthomas

New member
:yawn: Wake us up when you're prepared to be sensible.

Stripe Diversion #37: Ignore the question and pretend it is the asker that is being stupid.

(I didn't expect you to be able to give a reason for your conception that solid rock contracts on heating, it being false, so don't feel bad!)
 

Lighthouse

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man·tle [man-tl] noun

1. a loose, sleeveless cloak or cape.
2. something that covers, envelops, or conceals: the mantle of darkness.
3. Geology . the portion of the earth, about 1800 miles (2900 km) thick, between the crust and the core.
4. Zoology . a single or paired outgrowth of the body wall that lines the inner surface of the valves of the shell in mollusks and brachiopods.
5. a chemically prepared, incombustible network hood for a gas jet, kerosene wick, etc., that, when the jet or wick is lighted, becomes incandescent and gives off a brilliant light.

Apparently magma is mantle.
 

DavisBJ

New member
I accept facts based on evidence. :thumb:
Let’s see if you really do, or if this is just hot air.

Fact 1 – Stripe shows his abject disregard for scientific accuracy when he extracts passages from a study investigating the properties of a type of magma, and then blithely says the results of that study apply to “all rock”:
It is all rock. If magma deeper than about 400km becomes more dense than its parent rock because of great pressure, it is certain that deeper material will compact even more upon heating.
The authors of the study were meticulous in specifying that their study was focused on komatiite, a very specific type of magma. The very title of the study was:

The Equation of State of a Molten Komatiite

Fact 2: In their introduction the study authors specify why the rocks they are interested in studying are ones containing silicates:

In extreme cases, silicate melts could be denser than surrounding mantle rocks, resulting in a downward segregation of melts,…

Notice they took care to specify “silicate melts”. (Does Stripe know that not all rock have silicates in them? A glance under “non-silicate minerals” in Wiki lists far more than a thousand minerals that have no silicate in them.)

Fact 3: The authors of the study even gave the precise chemical breakdown of the komatiite samples they were using (Table 1 in the article). Reinforcing Fact 1 – notice 45% of the mineral content of the komatiite was silicate.

Fact 4: In the study they take care to specify the known physical properties of the minerals in the samples they are using (Table 2). They do that because several of those physical properties are used in the equations they rely on. For example – density, thermal expansivity, bulk modulus, and heat capacity. (Does Stripe think that all “rocks” have these same values for their physical properties?)

Fact 5: When GCT asked Stripe for a source to back his claim that “Rock under sufficient pressure becomes more dense upon being melted.”, Stripe quoted this from the study:
At low pressure, olivine fractionation lowers the density of basic magmas, but above 13-14 GPa this trend is reversed. All of these basic to ultrabasic liquids are predicted to have similar densities at 13-14 GPa, and this density is approximately equal to the density of the bulk mantle in this pressure range. This suggests that melts derived from a peridotitic mantle may be inhibited from ascending from depths greater than 400 km.
“Perioditic” specifically means the rock being described is ultramafic – low in silica content. For comparison, common granite is at the other extreme – a “felsic” magma high in silica content (and most definitely not a rock type this study applies to).

Fact 6: To support the idea that mantle convection may not exist, Stripe quoted this from the study:
An interesting possibility arises in considering how to use q. Porous shock wave data suggests the form of (19). This form may be overly restrictive, however, particularly for liquids. Note that (19) prohibits y from changing sign. If q were indeed large and if iJytiJV were constant rather than iJlny/iJlnV, then y could become negative at high pressure. Some liquids, most notably water, have negative y in some PT interval. This could be very important for large magma bodies because a negative y implies a negative a., which in turn means that a barrier to convection could exist.
Clarification – the use of Greek symbols in mathematical equations causes parts of the quote to appear incorrectly, or as nonsense. Spelling out the Greek symbols and some math gives:

An interesting possibility arises in considering how to use q. Porous shock wave data suggests the form of (19). This form may be overly restrictive, however, particularly for liquids. Note that (19) prohibits gamma from changing sign. If q were indeed large and if the partial derivative of gamma with respect to the velocity were constant rather than the partial derivative of the natural logarithm of gamma with respect to the natural logarithm of the velocity, then gamma could become negative at high pressure. Some liquids, most notably water, have negative gamma in some PT interval. This could be very important for large magma bodies because a negative gamma implies a negative alpha, which in turn means that a barrier to convection could exist.

Stripe chose to highlight the “barrier to convection could exist” part, but does he have any understanding of the equations or what the qualifiers the authors included mean? Or did he just see some words that sounded like what he wanted to hear? Is the mantle under discussion a liquid (keep in mind what seismic S-waves do in a liquid)?

Fact 7: Stripe conveniently failed to give this quote from the conclusion of the study:

While neutral or negative buoyancy would preclude the upward segregation of a liquid from a static matrix, it might be possible to extract the liquid if the matrix were transported upward in part of a large-scale convection system. In this case, both liquid and solid would rise together until the density contrast becomes sufficient for separation to occur. Thus when partial melting is initiated by the adiabatic decompression of upwelling mantle plumes, continued upward transport of the plume may permit escape of the liquid even if it were initially too dense to do so.

Clearly the study authors don’t share Stripe’s claim that mantle convection must be a fiction.

Fact 8: This has been one of the most blatant demonstrations of scientific ignorance that Stripe has ever engaged in. He is way over his head in this one, and so he blithely ignores the clearly stated intent and conditions the study authors were careful to detail.

As Stripe has asserted numerous times now:
It's all rock. If you have got some reason why heated rock at greater depth becomes less dense than magma does below the crossover depth, we'd sure be glad to hear it. :up:
Stripe, if you have got some reason why all rock at greater depth becomes less dense than magma does below the crossover depth, we'd sure be glad to hear it.
 

Stripe

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Stripe, if you have got some reason why all rock at greater depth becomes less dense than magma does below the crossover depth, we'd sure be glad to hear it.

You're so worked up you can't parse properly. :chuckle:
 

DavisBJ

New member
You're so worked up you can't parse properly. :chuckle:
If you actually come up with something technical that supports your nonsense, let me know. But I really don’t expect anything more substantive from you than a comment about parsing.
 

Stripe

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If you actually come up with something technical that supports your nonsense, let me know.
Poisoning the well is a logical fallacy.

You need to let go of your anger and try to engage rationally. :thumb:

But I really don’t expect anything more substantive from you than a comment about parsing.

If you cannot even repeat what I have clearly stated accurately, what hope is there of coming to any substantial agreement? :idunno:

What you need to do is calm down and have a little think through -- rationally -- of what I have said.

It is pretty simple, and I believe relevant and reasonable.
 

DavisBJ

New member
Poisoning the well is a logical fallacy.

You need to let go of your anger and try to engage rationally. :thumb:



If you cannot even repeat what I have clearly stated accurately, what hope is there of coming to any substantial agreement? :idunno:

What you need to do is calm down and have a little think through -- rationally -- of what I have said.

It is pretty simple, and I believe relevant and reasonable.
Listening to you expound on science matters that you know almost nothing about is like listening to someone tell a litany of vulgar jokes. You may be impressed, but you are disgusting to those around you.

I itemized in detail why you are completely wrong about the idiotic “all rocks” nonsense. And in the two replies since you haven’t had one word about the science.

I could care less about how many logical fallacies you try to hide behind. Your science stinks, just like your diaper.
 

Stripe

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You mean like the time you asked me about the imbalanced moon and played your "let's give the creationist a pop quiz" game? Remember that time?

I pass you puerile games with flying colors and I am consistently accurate and reasonable, as I have been in this thread.

You might have some minor points that need addressing in your call-out post, but when you cannot even accurately characterize my position, there seems no point discussing them. Doubly so when you refuse to correct your mistake.

Calm down and have a rational conversation. :thumb:
 
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DavisBJ

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You mean like the time you asked me about the imbalanced moon and played your "let's give the creationist a pop quiz" game? Remember that time?

I pass you puerile games with flying colors and I am consistently accurate and reasonable, as I have been in this thread.

You might have some minor points that need addressing in your call-out post, but when you cannot even accurately characterize my position, there seems no point discussing them. Doubly so when you refuse to correct your mistake.

Calm down and have a rational conversation. :thumb:
Stripe’s efforts now are focused on anything but responding to his errors in understanding the science article he was relying on. A while back I told him that I welcomed his participation in this discussion, but only on condition that he address the science. He has abandoned that, and so I give him free reign to pretend his arguments are anything but grotesque parodies of science. I don’t argue with smelly babies.
 
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