Explanations for Pangea

The particles are not in orbit. They are in a gas, colliding exceedingly frequently one with another, though going in straight lines between collisions. Each center of gravitational attraction is simply a region of denser gas compared to 'outlying' areas (made denser by their mutual gravitational attraction), and the two centers, as a whole, are in orbit about each other. Were it not for the loss of energy due to radiation (the clouds are glowing white hot, in a 'fog' of hot gas surrounding it), the clouds would not contract and get denser. However, because they do radiate away their energy, gravitational collapse ensues, causing the gas to become denser and denser (higher internal pressure) until eventually the point is reached at which the gas molecules begin to turn to liquid.

Imagine a gas of two components - say Radon and Nitrogen, one much heavier than another. In a box in deep space, they would be evenly mixed.

Place that box in gravity, say a basement of a house. One would now expect a gradient, with the heavier ones spending more time closer to the earth's center.

Or, take a centrifuge with two different molecules of different weights in the tube, and apply many g's to the molecules. Again, there will be a gradient. Gaseous centrifugal enrichment of U-235 works by a similar principle.

The greater the difference in the masses, the greater the ease of obtaining the gradient.

Any additonal insight by others on how to express this well, would be appreciated.

 

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Why do you need additional insight to express it? Is there something else about it that you don't understand? I don't know what else you're trying to express?

 

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Walter: What I mean to say is that you expressed it very clearly. I don't see why Laika has a problem with iron and other heavier elements sinking down in a gradient. He does have a point though that the particles are all still in orbit around the sun, but it's really a trivial point for the sake of argument about the formation of the earth. The particles are still colliding randomly (Brownian motion) in a condensing gas until the concentration eventually becomes denser and they turn to liquid, as you clearly state.

 

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Valich, the motion of the bodies around the Sun is of no significance here.

Walter, I understand that if the gas cloud is static, and the component particles subject only to thermal motion, then the heavier elements might well accumulate at the centre of mass. But my understanding of your idea is this: The proto-Earth and proto-Moon form from the same (chemically homogeneous) cloud and, therefore, share the same initial composition. The two mass concentrations are in orbit around their common centre of gravity. In order for material to be exchanged between them (so that the Earth can become relatively enriched in iron), that material has to give up some of its orbital momentum, otherwise it cannot leave its orbit and spiral downwards. Inside the respective bodies it's a different matter, of course, and differences in density allow them to stratify. At the risk of labouring my point, here it is again: The fact that the intial cloud 'contains' enough angular momentum to maintain two separate mass concentrations seems to me to render impossible the relative concentration of a particular element at the centre of the system.

 

I'm not certain I follow your query.

It should very well be that the proto-Earth acquires a greater percentage of the original angular momentum, if that is what you are suggesting. Whatever angular momentum is contained in the cloud as a whole is converted into angular momentum in each separate proto-Earth and proto-Moon by their spins, as well as the angular momentum of both combined by their orbit about their common center (centre).

Just because the ions become concentrated in one gravitational center or the other does not mean they give up their angular momentum only to the preservation of the angular momentum of the orbit about their common center. As the gravitational centers become denser and denser (due to gravitational collapse and emission of radiant energy), the rotation of each gravitational center would also slowly increase, preserving the net angular momentum that was inherent in the original gaseous cloud (and obtained from its orbit about the proto-Sun). Eventually, the two rotating clouds separate (no longer exchange ions), with the proto-Earth spinning approximately one revolution per 24 hours (after complete rain-out), and the proto-Moon likely much less.

It's very much like the proverbial ice skater. As the mass of the ice-skater (her/his arms) are brought closer to the center, the spin increases. So too with the proto-Earth. As the ions as a whole are brought closer to the center of the gravitational center, each gravitational center will increase its spin rate, even as they are still a single cloud, not yet separated. In other words, there would be two clouds slowly spinning [swirling] (preserving the angular momentum of the ions being attracted to each), each of which is yet inside of a still larger cloud that is itself even more slowly turning, still free to exchange ions, though in the process of concentrating the iron preferentially over the lighter ions. Those two swirling masses of hot gaseous Hydrogen inside the entire cloud would still be exchanging iron ions between each other, though concentrating the iron ions preferentially in the greater gravitational gradient. The angular momentum of their rotation as a whole would be converted to angular momentum of spin as each cloud separates out into two clouds. The spin would be most pronounced (at its largest) once the gravitational contraction reaches the stage of completed rain-out, and the cloud no longer shrinks much in size, now being a sphere of nearly incompressible liquid Hydrogen, extending nearly 35,000 miles from its center towards the nearby proto-Moon. The tidal bulges of the hot liquid Hydrogen on the proto-Earth and proto-Moon would be tremendous.

Hope that clarifies, or at least perhaps helps you narrow your question.

Regards,


Walter

P.S. Are you from England (with your spelling of center/centre)? PM me your email, and I'll email you a paper I'm preparing for publication on this.

 

Laika has a good point until he states:

Who is stating that an "exchange" of particles took place? This is an unreasonable assumption, but the last part of Laika's post is very credible.

Walter: You're getting ahead of the game in your post relative to what Laika states.

Further, we can't just pretend that the process of accretion doesn't exist. Mass accumulates via the inward gravitation of the particles, and this occurs in gaseous matter orbiting stars, binary systems, and black holes. Loss in angular momentum is due to the dynamics involved in creating the disk and the downward accretion into the central massive object. In current nebular theory, accretion occurs due to the collision and sticking of cooled microscopic particles electrostatically, and this then leads to planetisimals from the proto-planetary disks. The gaseous and/or small particles must first accrete, then form the disk, and then the planetisimal. It seems to me that the loss in angular momentum occurs due to the transformation from the preliminary round gaseous accumulation (accretion) into a nebular disk?

 

I'm not certain what you mean by "loss of angular momentum". Energy can be 'lost' from the local system due to radiation (glowing white hot, emitting photons to deep space), though there is no net loss, because of conservation of energy. Likewise, there is conservation of angular momentum. Unlike the energy, however, which can be transformed into photons and shed into deep space, the angular momentum has to be conserved, and there are no particles to carry it away. Hence, there is no loss in angular momentum. The original angular momentum of the originally spinning cloud is transferred to the smaller band of gas that then orbits the proto-Sun, which is then transferred to the proto-Earth-Moon cloud slowly spinning as it orbits about the proto-Sun, some of which is then transferred to the yet still smaller rotating clouds which are the proto-Earth and proto-Moon, with the rest of the angular momentum being contained in the two proto-planets orbiting about their common center.

It's actually quite interesting that the conservation of angular momentum of the original spinning gaseous Hydrogen cloud that became our proto-Solar-System is still retained in part, now as the angular momentum of our planet Earth.

Only in the cooler (and more tenuous) regions, far away from the great bulk of the hot gas, would the hot gases precipitate out 'snowflakes', or 'dust' as it is more usually called. These indeed would be 'sticky' at first, and should readily form small pebbles too. However, under the theory posited, the great bulk of the mass remains hot and gaseous, until it forms a liquid rain in the hot dense regions that undergo gravitational collapse.

 

P.S. Don, I posted in the Biology section about the Pseudogenes article. Thought you might wish to read and comment. I find it a fascinating topic. Walter

 

Thanks Walter, I'll try to find it.

The conservation of angular momentum can only exist in a closed system.

 

Valich, the exchange of material between the proto-Earth and proto-Moon is required in order for the two bodies to have the different relative abundances of the elements that they do. That is assuming that they formed from a cloud that was chemically uniform. No exchange would have had to have occurred if the initial cloud had already undergone segregation before the two main mass concentrations formed and started to orbit. For me, this is the paradox that forms the crux of my argument: the segregation can only occur if the cloud is relatively static and the particles subject to pressure and thermal motion. If the proto-Earth and proto-Moon coalesced subsequent to this, what provided sufficient momentum for the Moon to orbit the Earth? - given that the prior state was necessarily static (by my reasoning, anyway), and that the accumulation of matter into the cloud was already more or less complete (because further significant addition would have drowned out the initial compositional imbalance). However, if the proto-Earth and proto-Moon formed before segregation had occurred within the cloud, then I don't see how the iron managed to fall from orbit in order to enrich the Earth.

 

Laika: No, an exchange - or transfer - of material would be required for the two bodies to have similar, not different, relative abundances of the elements that they do have. And this is what we see - the similarilties. Why would you think that an exchange would lead to a relative difference?

Smaller gaseous bodies would have a lower gravitational downward pull to sink heavier elements to the center to form the iron core that earth has. From what I've heard, the moon has no liquid iron core.

 

I see what you're saying. But by exchange, I didn't mean a balanced exchange of material that might blur initial differences. Rather, I meant that matter (specifically, iron) must have been transferred from the region in which the proto-Moon was orbiting to that in which the proto-Earth was located. Assuming the cloud was compositionally uniform from the start, that is (I don't know why it wouldn't have been).

Anyway, Walter has provided me with a copy of his paper, which I haven't read it yet. When I do, perhaps my objections will be be nullified.

 

Assuming they were two gaseous clouds to begin with. But if a meteor impacted the outer Earth when the earth's iron core had already started to form and the iron in the Earth had already sunk down, then wouldn't this solve that problem.

 

I read this abstract some time ago but didn't bookmark it, then I came across it again. It adds depth to our discussion:

"Chronological Correlation of the Oldest Magmatic Events on the Earth and the Moon:

Detailed chronological scales (4.4-3.4 Ga) of the Earth and Moon mantle and crustal events were constructed. There is a distinct correlation between the duration (~100 Ma) and the starting time of some cycles on the Earth and the Moon: 4.5, 4.39 and 4.42, 4.30 and 4.32, 4.20 and 4.21, 4.10 and 4.11, 4.01, 3.9, 3.8, 3.7, 3.6, 3.5, and 3.4. This coherence of dynamics of the crust growth suggests an influence of an external "outer-space" factor common to both bodies. That factor was a "trigger" mechanism that initiated the mantle mafic-ultramafic and crustal acid magmatism and tectonic activity. The origin of periodicity is likely to result from the change of gravity pull from the Galaxy Centre affecting the Solar System, as it follows its elliptical orbit, because the current half-duration (106-135 Ma) of the rotation period ("Galactic Year"- GY) is close to the identified periodicity of processes in the Early Archean and the accretion epoch. With the use of data on the length of separate cycles of the Moon and Earth, it is possible to calculate more precisely the length of the GY for the oldest history of Solar System (~197.8).
http://www.the-conference.com/JConfAbs/4/140.html

Read articles underneath related to iron-core forming process.

There were magma plumes on the moon around 3.9 Ga that filled in some of the crator depressions. What is significant is the origin of this type of tectonic mantle activity. If there were uprising mantle plumes than this indicates that the moon had a liquid core. At this period of time, there was then a sharp change in development of the lunar surface that probably coincided with a similar phase change in development of Earth, Mars, and Venus. On Earth we know that this phase change coincides with the formation of the core. On the moon, there probably wasn't enough iron, or the spherical size was too small? (gravitational pull), to permanently create the same type of liquid iron-nickel core we have on Earth.

 

Yes it would. That's my point - the system needs to have been differentiated before the Moon formed, because otherwise the iron would have been stuck in Earth orbit. I guess that's a reason why the impact hypothesis currently prevails.

 

Laika: I don't see how anyone can dispute that statement.

 

It is a tad shortsighted to imagine that when you have a supercontinent, there are not other landmasses elsewhere on the planet. Some plates push up on top of other plates, while other plates dive down below a plate that it is meeting. This means that while Pangea was dividing, it is very likely that other landmasses were being subsumed on the other side of the moving plates. But since they were pressed back down into magma, all evidence is lost of them. We have to remain open to the overwhelming likelyhood that they existed, and not be blinded by the fact that no evidence for them remains. When California drops off with the shearing of the San Andreas faultline, you will have a glimpse of the other side of continental drift that is going ignored here.

This gaping hole in the logic of geologists reminds me of the same sort of mistakes that archaeologists make when they get too absorbed with stone tools (like the Clovis Tradition freaks). They ignore the fact that the overwhelming material of choice was wood, and wooden tools. Archaeology is more a study of ancient things which refuse to rot than it is a true study of biological history. Glaring bias like this really shocks me when I run across it.

So again, when Pangea existed, there were probably a dozen other landmasses on the Earth at the same time. They just don't draw them in the pretty pictures because they left no trace, and there is no point in conjecture regarding their specifics. But to deny their existence is an exercise in statistical and geological lunacy.

 

Pangea is ancient history so to speek - tongue in cheek. Vaalbara ca. 3.1 was the world's first known supercontinent. We have zircon datings back to 4.2 Ga and evidence of intact rock from early continental crust from the Slave craton (Acasta gneiss) in the Northwest Territories of Canada dating back to over 4.0 Ga.

At ca. 4.5 Ga the earth was still being bombarded by extraterrestrial intergalactic objects (metoerites, asteroids, planetisemals, and particles) before it could solidify. Then, soon after the Earth did undergo accretion, the heavier metals sank to the bottom and radioactive decay produced enough heat to melt the outer layer that had relatively just then solidified, or frozen over. At first there were most likely a hundred or so crustal fragments circulating and being subducted back into the mantle. But as the Earth's core finalized into its current form, the double convection circulating mantle-lithosphere cycle of plate tectonics, as we know it today, began to take shape. Today there are fifteen major plates anchored to the lithosphere while subducting sections curculate back into the mantle along the margins. The oceanic areas consist of early basaltic material that are denser and enable it to be continuously sunk down comparitive to continental crust.

 

Swivel, continental crust tends to escape subduction because it is less dense than oceanic crust. That's why the oldest oceanic crust is about 200 million years old, while the oldest continental crust is more than 3 billion years old.

 

Continental cratons are also much more firmly rooted with "keels" that extend 100's of kilometers down.