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Thread: Supercontinent Cycle

  1. #1 Supercontinent Cycle 
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    Why o why do the continents break up and then come back together again?


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    Quote Originally Posted by billiards View Post
    Why o why do the continents break up and then come back together again?
    The conventional view is that heat accumulates under supercontinents, this heat fragilize the lithosphere so that the continents finally break up. Then they come back together by luck as they are dragged by sinking slabs of oceanic lithosphere.

    Interestingly, continental break up is not limited to Earth. Dark and old icy continents of Ganymede do break up as can be seen on this picture:

    Ganymede.jpg


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    Quote Originally Posted by florian View Post

    The conventional view is that heat accumulates under supercontinents, this heat fragilize the lithosphere so that the continents finally break up. Then they come back together by luck as they are dragged by sinking slabs of oceanic lithosphere.

    I don't think it's luck that causes the continents to come back together.

    They come back together by the Wilson cycle. But what causes the Wilson cycle and why do the individual Wilson cycles for each fragment conspire to all get back together again intermittently?
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    Consider two continents, lying on a pair of antipodes. Whatever their relative motion, so long as it is not zero, they will ultimately collide, will they not?
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    Quote Originally Posted by drowsy turtle View Post
    Consider two continents, lying on a pair of antipodes. Whatever their relative motion, so long as it is not zero, they will ultimately collide, will they not?
    From a purely kinematic perspective I'm not sure they will. One can imagine paths where they just miss each other, if the two continents ever end up in exactly the same starting configuration then the motion will be cyclic and they will continue to miss each other forever.

    The real world isn't like that of course!

    In fact continents grow apart and then seem to come together along pretty similar lines by subduction of the ocean that previously separated them.
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    Quote Originally Posted by billiards View Post
    From a purely kinematic perspective I'm not sure they will. One can imagine paths where they just miss each other, if the two continents ever end up in exactly the same starting configuration then the motion will be cyclic and they will continue to miss each other forever.
    Actually, for two moving continents, I think there are more paths that will lead to a miss than a hit. That should be mathematically demonstrable. That would be surprising if noone proved it.
    So you glimpse that the odds that many continents will all meet at the same time is even lower. The odds favour a regular distribution of continents/ocean with time.

    Quote Originally Posted by billiards View Post
    In fact continents grow apart and then seem to come together along pretty similar lines by subduction of the ocean that previously separated them.
    That's the core of Wilson's hypothesis of supercontinent cycles, but you see that your own questions raise serious concern. It finally appears very "ad hoc", isn't it?
    Besides, I already showed the demonstration in this forum that these cycles are not real, and how the data interpreted as multiple supercontinent cycles can be easily explained, see this post: plate tectonics
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    Quote Originally Posted by florian View Post
    Actually, for two moving continents, I think there are more paths that will lead to a miss than a hit. That should be mathematically demonstrable. That would be surprising if noone proved it.
    Obviously it depends on the size of the continents. The larger the continents the fewer the number of missing paths.

    Quote Originally Posted by florian View Post
    So you glimpse that the odds that many continents will all meet at the same time is even lower. The odds favour a regular distribution of continents/ocean with time.
    If the movements were random then the odds that they would regroup would be low -- but it would still happen from time to time -- like some kind of Poincaré recurrence. However, the point is the movements are not random, they are governed by the Wilson cycle.

    Continents certainly do not behave like a perfect gas (which tend to favour a regular distribution).

    Quote Originally Posted by florian View Post
    That's the core of Wilson's hypothesis of supercontinent cycles, but you see that your own questions raise serious concern. It finally appears very "ad hoc", isn't it?
    No. The theory makes sense in light of all the observations we have. Spreading ridges are pretty well symmetric, the ocean gets to about 160 Ma old before it starts to subduct. Subduction zones swallow up oceans, they even swallow up the spreading ridge, e.g. the Juan de Fuca. Mountain ranges then form, and these orogenies leave their imprint on the surface geological record.

    We also see that the geoid has big highs associated with deep mantle structures, these features tie up well with the mantle structures we would expect to see in relation to the surface features. The Atlantic superplume structure is situated at the palaeo-site of Pangaea, suggesting that the superplume may well have formed in response to the presence of Pangaea, probably because the supercontinent acted as a giant insulator which super heated the mantle geotherm top-down. Palaeo subduction zones also leave their pattern on the Geoid. Geoidal features match seismic tomography models very well, giving us greater confidence.

    Quote Originally Posted by florian
    Besides, I already showed the demonstration in this forum that these cycles are not real, and how the data interpreted as multiple supercontinent cycles can be easily explained, see this post: plate tectonics
    You have only shown an alternative theory, which suffers from the fact that it is unphysical (it requires an expanding Earth - which in turn requires violation of thermodynamics (or -- if you prefer -- an unknown source or mass/energy)). You have by no means debunked the Wilson cycle. Remarkably, the subduction of the Iapetus is still seen by the deformation of the Moho beneath Scotland! (Di Leo et al. Nature of the Moho beneath the Scottish Highlands from a receiver function perspective. Tectonophysics (2009) vol. 479 (3-4) pp. 214-222)
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    Quote Originally Posted by florian View Post
    Actually, for two moving continents, I think there are more paths that will lead to a miss than a hit. That should be mathematically demonstrable. That would be surprising if noone proved it.
    It depends on the size of the continents and the timescale in which they must collide.

    Quote Originally Posted by florian View Post
    So you glimpse that the odds that many continents will all meet at the same time is even lower. The odds favour a regular distribution of continents/ocean with time.
    Assuming they all meet at the same time, and do not form supercontinents like Gonwana and Laurentia before ultimately forming Pangea. These supercontinents are so large that I doubt there are many paths they can take that do not lead to their collision. Even an entirely transform motion will result in their collision due to the curvature of the Earth.

    Quote Originally Posted by florian View Post
    I already showed the demonstration in this forum that these cycles are not real
    You made an alternative hypothesis, you never supported it. You took the existing data and said "what if?" - there is no data that specifically suggests your position is correct and the conventional plate tectonics paradigm is false.
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    Quote Originally Posted by drowsy turtle View Post
    You made an alternative hypothesis, you never supported it. You took the existing data and said "what if?" - there is no data that specifically suggests your position is correct and the conventional plate tectonics paradigm is false.
    This alternative theory existed before I was born, is very well supported by multiple evidence and goes along with multiple clear refutations of plate tectonics.

    Read Carey for details (I will scan it if you can't access it): S. Warren Carey 1983 "The Necessity for Earth Expansion" pp375-393 in Carey, SW (ed): Expanding Earth Symposium, Sydney, 1981.

    Or this older review:
    "The Expanding Earth - an Essay Review" SW Carey (1975) ESR 11 p 105-143 (pdf: http://tinyurl.com/6yzgaq4)

    Or these different authors:
    "Fossils, frogs, floating islands and expanding Earth in changing-radius cartography – A comment to a discussion on Journal of Biogeography" G Scalera (2007) Ann Geophys 50(6) p789 (pdf: http://tinyurl.com/ycs8en6)


    "Earthquakes, phase changes, fold belts: from Apennines to a global perspective" G Scalera (2010) GeoActa, Special Publication 3, pp. 25-43. (pdf: http://tinyurl.com/3bv2e8c)


    "Mantle plumes and dynamics of the Earth interior — towards a new model" Geol Rev 52, p817 (pdf: http://tinyurl.com/3vpafys)

    Sorry to highjack your discussion, but you must understand that trying to explain the data, that were wrongly interpreted as supporting supercontinent cycles on a fixed earth radius, does not make more sense than interpreting them on a flat-earth model. They can't be interpreted correctly without a growing earth model.
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    Quote Originally Posted by florian View Post
    This alternative theory existed before I was born, is very well supported by multiple evidence
    "Is supported by" and "is not refuted by" are not the same thing.
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    Quote Originally Posted by florian View Post
    Sorry to highjack your discussion, but you must understand that trying to explain the data, that were wrongly interpreted as supporting supercontinent cycles on a fixed earth radius, does not make more sense than interpreting them on a flat-earth model. They can't be interpreted correctly without a growing earth model.
    The expanding Earth theory is flawed. There are problems that weren't even brought up in the plate tectonics thread, such as the fact that the Eastern half of the Pacific has clearly been subducted.

    Plate tectonics is simple, powerful, and beautiful. All those in all the disparate fields of the Earth sciences have seen the beauty of plate tectonics in their subfield alone. It is a marvel and a testament to the accuracy of the theory that palaeontologists and volcanologists alike are singing from the same song sheet, furthermore the theory makes predictions in all of these disciplines!

    You have utterly failed to convince anybody of your own beliefs of an expanding earth in the plate tectonics thread. There are many holes in the expanding earth theory which require some extremely speculative patches to cover up, and the theory needs to be twisted in all its various forms to fit the data. It is the sign of a theory which is quite plainly wrong. However, if you wish to continue in your efforts to convince the world that the Earth is expanding then please do so somewhere else, I ask that this thread be kept "clean".

    Your contributions that stay away from expanding earth are appreciated and I welcome your input if you have something insightful to say. There are many interesting and exciting things that I would like to discuss. For example I would like to discuss the processes which formed the continents.... what were they and are they still active today? What is it that makes a tectonic plate, what is the lithosphere/asthenosphere boundary?

    This thread is built on the premise that supercontinent cycles are real. The only interjection to the contrary that I will acknowledge is one that proves that supercontinent cycles are false.
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    Quote Originally Posted by billiards View Post
    The expanding Earth theory is flawed.
    Hardly. The same is not true for plate tectonics, one of the biggest blunder in the recent history of Science. I scanned Carey's 1983 paper "The Necessity for Earth Expansion" (Link to the pdf ; 12.5 MB). You will learn a lot by reading it. Enjoy!

    Quote Originally Posted by billiards View Post
    There are problems that weren't even brought up in the plate tectonics thread, such as the fact that the Eastern half of the Pacific has clearly been subducted.
    Actually not. The ridge formed and are currently forming along the Americas. For example, in the gulf of california is a nascent ridge that is propagating southward to the EPR and northward toward the San Andreas Fault. The later should soon open as a ridge and complete the connection to the Juan de Fuca ridge.
    The situation is not so much different than with the red sea ridge propagating to the Jordan rift valley that evolves from transform fault to rift then ridge. You can verify it using google earth (see this file)

    The current position of the zodiac fan proves the formation of fresh crust at the periphery of the ocean by progressive mantle exposure following continent retreat related to mantle bulging (see Eduction process by Yu Chudinov): the fan formed in the gulf of alaska and is now found to the south-west of the gulf, see figure. The isochrons on which the fan lies have actually the shape of the former continental margin. This is really specific to the north pacific because it is the sole ocean that originally opened equatorially (See Carey). This also explains the triangular shape of the isochrons with the older crust inside and younger crust outside, like for tree rings. Very very specific growth that is now entirely supplanted by classical ridge spreading.
    Iso5Npacific.jpg



    Quote Originally Posted by billiards View Post
    furthermore the theory makes predictions in all of these disciplines!
    Plate tectonics is a scenario. What predictions does it make? Does it predict the relative position of old cratons 500 Ma ago (I say predict not describe!). No. Does the EE theory predicts the relative positions of old cartons 500 Ma ago? yes. Is this prediction verified? Yes again (See Rodinia's empirical reconstruction and Maxlow's predicted reconstruction).


    Quote Originally Posted by billiards View Post
    For example I would like to discuss the processes which formed the continents.... what were they and are they still active today?
    Of course they are. Continents form progressively by episodic emplacements of new crust in between patches of older crust. Its evident from continental crust age and maps.

    Quote Originally Posted by billiards View Post
    What is it that makes a tectonic plate
    A cheated mind


    Quote Originally Posted by billiards View Post
    This thread is built on the premise that supercontinent cycles are real. The only interjection to the contrary that I will acknowledge is one that proves that supercontinent cycles are false.
    But I already posted the refutation made by Carey in this post here: plate tectonics
    Why don't you comment it?
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    Quote Originally Posted by billiards View Post
    There are many interesting and exciting things that I would like to discuss. For example I would like to discuss the processes which formed the continents.... what were they and are they still active today? What is it that makes a tectonic plate, what is the lithosphere/asthenosphere boundary?
    My Bold

    I assume you have already seen this, but because of it's signifigance I will post it.

    The big picture: A lithospheric cross section of the North American continent
    June 2011 issue of GSA Today

    The link is to the archive page to facilitate access to the article and the most excellent cross section.
    I'm sorry, my responses are limited. You must ask the right question.

    "The track of a glacier is as unmistakable as that of a man or a bear, and is as significant and trustworthy as any other legible inscription"
    John Strong Newberry; 1873

    "From observations upon living glaciers, and from the known nature of ice, we may learn to recognize the track of a glacier as readily and unmistakably as we would the familiar foot-prints of an animal." G. F. Wright 1891 (108-109)

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    Quote Originally Posted by jlhredshift View Post

    I assume you have already seen this, but because of it's signifigance I will post it.

    The big picture: A lithospheric cross section of the North American continent
    June 2011 issue of GSA Today

    The link is to the archive page to facilitate access to the article and the most excellent cross section.
    Thank you for sharing this. I had not seen it. A fascinating view of the whole plate and the complexity contained within it. As observed by the authors and the reference therein, the plethora of structures inferred from multiple independent lines of evidence, were clearly created by horizontal forces, which is firm evidence for active plate tectonics (just in case anyone ever really doubted it).
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    Quote Originally Posted by billiards View Post
    Quote Originally Posted by jlhredshift View Post

    I assume you have already seen this, but because of it's signifigance I will post it.

    The big picture: A lithospheric cross section of the North American continent
    June 2011 issue of GSA Today

    The link is to the archive page to facilitate access to the article and the most excellent cross section.
    Thank you for sharing this. I had not seen it. A fascinating view of the whole plate and the complexity contained within it. As observed by the authors and the reference therein, the plethora of structures inferred from multiple independent lines of evidence, were clearly created by horizontal forces, which is firm evidence for active plate tectonics (just in case anyone ever really doubted it).
    Your welcome.

    Searching the extant literature and finding support for an idea that is not accepted, and without doing any of ones own research in the field or lab, is not likely to convince the world that the idea is valid. Plate tectonics it is. Spontaneous matter creation is not something that in any way shape or form has any validity. Carey's theory is dead. But, he joins Dana and Suess in failed theories of the Earth. Lofty company if you ask me.
    I'm sorry, my responses are limited. You must ask the right question.

    "The track of a glacier is as unmistakable as that of a man or a bear, and is as significant and trustworthy as any other legible inscription"
    John Strong Newberry; 1873

    "From observations upon living glaciers, and from the known nature of ice, we may learn to recognize the track of a glacier as readily and unmistakably as we would the familiar foot-prints of an animal." G. F. Wright 1891 (108-109)

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    Quote Originally Posted by billiards View Post
    Thank you for sharing this. I had not seen it. A fascinating view of the whole plate and the complexity contained within it.
    Agree, this is a nice piece of work. I dream for a similar work covering the whole planet (global cross section, yummy!).

    Quote Originally Posted by billiards View Post
    As observed by the authors and the reference therein, the plethora of structures inferred from multiple independent lines of evidence, were clearly created by horizontal forces...
    Not necessarily horizontal. Gravity is a vertical force and is at the heart of nappes gliding. So a vertical force+slope will work.
    Actually, the huge advantage of gravity, is that it is applied to every atoms of the moving strata. So there are no issues with tensile or compressive strength of material.
    By contrast, if one applies a large pushing force at the extremity of a strata, will it move, or will the extremity crumble?
    Similarly, if one applies a pulling force at the extremity of a strata, will it move, or will the extremity break off?
    Think about it
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    Now you are just babbling.
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    Quote Originally Posted by florian View Post
    By contrast, if one applies a large pushing force at the extremity of a strata, will it move, or will the extremity crumble?
    Similarly, if one applies a pulling force at the extremity of a strata, will it move, or will the extremity break off?
    Think about it
    Billiards, To help you, here is a paper about the tensile strength and uniaxial compressive strength of basaltic rock mass: "Strength and deformation properties of basaltic lava flows on Planetary surfaces"
    Note that the tensile strength for the rock mass is -0.1 MPa (see table 1).
    Now, I remind you that the orthodox view of plate tectonics is that "slab pull" is the main driving force, and for example, the 1000s-km wide pacific plate (I let you calculate its mass) is supposed to be dragged into the mantle by slabs along Asia.
    Honestly, if you think about it, does is look possible?
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    Quote Originally Posted by florian View Post
    Now, I remind you that the orthodox view of plate tectonics is that "slab pull" is the main driving force, and for example, the 1000s-km wide pacific plate (I let you calculate its mass) is supposed to be dragged into the mantle by slabs along Asia.
    Honestly, if you think about it, does is look possible?
    Yes, it has been measured quantitatively. [see reports on Haiti and Japan.]

    It might be instructive for you to read, or maybe re-read, T. C. Chamberlin's The Method of Multiple Working Hypotheses.
    I'm sorry, my responses are limited. You must ask the right question.

    "The track of a glacier is as unmistakable as that of a man or a bear, and is as significant and trustworthy as any other legible inscription"
    John Strong Newberry; 1873

    "From observations upon living glaciers, and from the known nature of ice, we may learn to recognize the track of a glacier as readily and unmistakably as we would the familiar foot-prints of an animal." G. F. Wright 1891 (108-109)

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    Quote Originally Posted by jlhredshift View Post
    Yes, it has been measured quantitatively. [see reports on Haiti and Japan.]
    The coseismic displacement resulting from the Japan quake (see figure from USGS) proves that the absolute displacement is not that of the pacific lithosphere toward Japan, but that of the japanese arc toward the pacific. The arc is literally spreading over the passive pacific lithosphere. Not that the arc is convex toward the pacific. This is another indication that the arc is spreading outward and toward the Pacific.

    invertCO.jpg

    Quote Originally Posted by jlhredshift View Post
    It might be instructive for you to read, or maybe re-read, T. C. Chamberlin's The Method of Multiple Working Hypotheses.
    I return you the advice. Plate tectonics is a "ruling theory".
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    Quote Originally Posted by florian View Post
    Quote Originally Posted by jlhredshift View Post
    Yes, it has been measured quantitatively. [see reports on Haiti and Japan.]
    The coseismic displacement resulting from the Japan quake (see figure from USGS) proves that the absolute displacement is not that of the pacific lithosphere toward Japan, but that of the japanese arc toward the pacific. The arc is literally spreading over the passive pacific lithosphere. Not that the arc is convex toward the pacific. This is another indication that the arc is spreading outward and toward the Pacific.

    invertCO.jpg

    Quote Originally Posted by jlhredshift View Post
    It might be instructive for you to read, or maybe re-read, T. C. Chamberlin's The Method of Multiple Working Hypotheses.
    I return you the advice. Plate tectonics is a "ruling theory".
    Not that I expected you to give up your "pet" theory.

    Let me ask you this then, was there any verticle displacement of Japan, and in what direction?
    I'm sorry, my responses are limited. You must ask the right question.

    "The track of a glacier is as unmistakable as that of a man or a bear, and is as significant and trustworthy as any other legible inscription"
    John Strong Newberry; 1873

    "From observations upon living glaciers, and from the known nature of ice, we may learn to recognize the track of a glacier as readily and unmistakably as we would the familiar foot-prints of an animal." G. F. Wright 1891 (108-109)

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    Florian I do not wish to reinvigorate the debate that was dragged out so painfully in the thread entitled plate tectonics.

    You have previously stated in that thread that you believe that some subduction does occur. I am not entirely sure what the intentions of this post are. Perhaps it would help if you could elaborate, first as to exactly what point it is you are trying to make, and then to actually make the point.

    To be clear. The intention of this post seems to be that subduction is not possible because basalt does not have the tensile strength to support slab pull. However, you have previously stated (in the other thread) that you believe some subduction does occur, and so at this point I am confused. So, is it your intention to demonstrate that subduction is not possible? If so then perhaps it would be clearer to us all if you could elaborate on your reasoning -- do the hard work and show us why! I for one would appreciate a well formatted mathematical argument which makes its physical assumptions very clear -- and then I would happily respond with my best attempt at a serious reply. As it stands I cannot reply to this post. As we have seen in the previous thread it is one (very easy) thing to flick up a reference, and quite another (much more difficult) thing to actually pick out the salient point from a reference to add scientific weight to your own argument. Do not rely too heavily on your reference, put in the work, develop your own argument, I for one do not have the time to get bogged down in references trying to work out what on earth you mean.
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    Quote Originally Posted by jlhredshift View Post
    Not that I expected you to give up your "pet" theory.
    What pet theory? If you were referring to the expanding Earth theory, it belongs to Mantovani, Hilgenberg, Carey, Egyed, Owen...

    Quote Originally Posted by jlhredshift View Post
    Let me ask you this then, was there any verticle displacement of Japan, and in what direction?
    Of course there was vertical displacement, massively upward, as expected for a block extrusion.
    VertCoseimsDispl.jpg
    There was both eastward and upward displacement of a block of the front arc.
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    And your/their theory explains the subsidence how?
    I'm sorry, my responses are limited. You must ask the right question.

    "The track of a glacier is as unmistakable as that of a man or a bear, and is as significant and trustworthy as any other legible inscription"
    John Strong Newberry; 1873

    "From observations upon living glaciers, and from the known nature of ice, we may learn to recognize the track of a glacier as readily and unmistakably as we would the familiar foot-prints of an animal." G. F. Wright 1891 (108-109)

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    Quote Originally Posted by billiards View Post
    Florian I do not wish to reinvigorate the debate that was dragged out so painfully in the thread entitled plate tectonics.

    You have previously stated in that thread that you believe that some subduction does occur. I am not entirely sure what the intentions of this post are. Perhaps it would help if you could elaborate, first as to exactly what point it is you are trying to make, and then to actually make the point.

    To be clear. The intention of this post seems to be that subduction is not possible because basalt does not have the tensile strength to support slab pull. However, you have previously stated (in the other thread) that you believe some subduction does occur, and so at this point I am confused. So, is it your intention to demonstrate that subduction is not possible?
    My point is that of Carey, and the same point I tried to develop in the other thread (see this post): It is believed that the slab of lithosphere in the mantle does provide the driving force for subduction and plate displacement. But the lithosphere cannot afford to drag a whole plate because it has a very low tensile strength.
    The sole valid alternative is that the mantle, not the slab, does provide the driving force for subduction: the mantle extrudes and outpours on the oceanic lithosphere, which in turn, get buried under the mantle weight, in other words, get subducted.
    Every observations we have about subduction zone support this interpretation. For example, the oceanic lithosphere has a flexure fracture zone ahead of the mantle edge illustrating the overburden effect of the mantle. The fact that the outpouring mantle often carries continental lithosphere on its back is rather secondary.
    Hope I was clear enough.

    Now, if you prefer to stick to the subject of this thread, we could discuss the controversies and incompatibilities about reconstructions of Rodinia (SWEAT model for example), and see how these incompatibilities are elegantly solved using an alternative model. It's up to you.
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    You know, I agree with billiards. The area of subsidence was anticlinal prior to the strain being released, you know, the earthquake, when the plate arc boundary equalized. A lot of farmland has now been lost.

    I am going to recommend a reading list and when you can demonstrate that that is done, we can talk further.

    Two books by Naomi Oreskes:

    Plate Tectonics
    The Rejection of Continental Drift

    By Allan Cox:

    Plate Tectonics: How it Works

    By H. W. Menard:

    Oceans of Truth

    And the most difficult of the set by Xavier Pinchon, et. al.:

    Plate Tectonics

    I'm done.
    I'm sorry, my responses are limited. You must ask the right question.

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    Quote Originally Posted by jlhredshift View Post
    And your/their theory explains the subsidence how?
    It is not specific to a theory. It is basic seismology. During a fault rupture, there is always opposite displacement along the fault due to the elasticity of the rock. See this figure:

    firstmotion.jpg
    So if one side of the fault is moving up, the other side moves a bit down.
    In the case of the Japan earthquake you can see from the coseismic displacement model that the western side subside a bit whereas the easter side moved upward. The upward displacement largely dominates the subsidence. It was the case for the Sumatra earthquake, for the 1964 Alaska earthquakes and it is generally the case for every major earthquakes along megathrusts.
    Last edited by florian; August 20th, 2011 at 04:09 PM.
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    Quote Originally Posted by jlhredshift View Post
    I am going to recommend a reading list and when you can demonstrate that that is done, we can talk further.
    Then let me recommend you a reading list as well, if you really want to talk further:

    A. Hallam: Great Geological Controversies
    Shawna Vogel: Naked Earth
    Don Anderson: Theory of the Earth
    Kearey, Klepeis & Vine: Global Tectonics
    Turcotte & Schubert: Geodynamics
    Mercier & Vergely: Tectonique
    Gillian Foulder: Plates vs Plumes, a geological controversy
    Sam W Carey: Earth Universe cosmos and Theories of the Earth and the Universe
    Andrew Kugler: Subduction and Overthrusting
    Yu Chudinov: Global eduction tectonics of the expanding earth and Eduction concept of the earth's expansion theory
    James Maxlow: Terra non Firma Earth
    Last edited by florian; August 20th, 2011 at 04:10 PM.
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    Quote Originally Posted by florian View Post
    It is believed that the slab of lithosphere in the mantle does provide the driving force for subduction and plate displacement. But the lithosphere cannot afford to drag a whole plate because it has a very low tensile strength.
    You have failed to make this point. Throwing an indirect reference out there is not helpful.

    Why not simply write out the equations?

    Quote Originally Posted by florian
    The sole valid alternative is that the mantle, not the slab, does provide the driving force for subduction: the mantle extrudes and outpours on the oceanic lithosphere, which in turn, get buried under the mantle weight, in other words, get subducted.
    So according to this explanation it sounds as though you think subduction occurs at the mid ocean ridge??

    Every observations we have about subduction zone support this interpretation. For example, the oceanic lithosphere has a flexure fracture zone ahead of the mantle edge illustrating the overburden effect of the mantle. The fact that the outpouring mantle often carries continental lithosphere on its back is rather secondary.
    What's the "mantle edge"??

    Hope I was clear enough.
    About as clear as mud.
    You have a LONG way to go.
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    Quote Originally Posted by florian View Post
    Quote Originally Posted by jlhredshift View Post
    And your/their theory explains the subsidence how?
    It is not specific to a theory. It is basic seismology. During a fault rupture, there is always opposite displacement along the fault due to the elasticity of the rock. See this figure:

    firstmotion.jpg
    So if one side of the fault is moving up, the other side moves a bit down.
    There is always relative displacement. Why does one side have to go down? Wouldn't you expect one side to sit still, while the other side moves up?
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    Quote Originally Posted by florian View Post
    Quote Originally Posted by billiards View Post
    The expanding Earth theory is flawed.
    Hardly. The same is not true for plate tectonics, one of the biggest blunder in the recent history of Science. I scanned Carey's 1983 paper "The Necessity for Earth Expansion" (Link to the pdf ; 12.5 MB). You will learn a lot by reading it. Enjoy!
    Thanks for the link. Will read for the lulz.
    (Actually in all seriousness from what I've heard Carey deserves some respect, however, his ideas of an expanding earth are wrong. He was a decent scientist, no contradiction there: it is possible to be a good scientist who happens to believe something which turns out to be wrong. 1983 was before I was even born -- the science has grown up more than I have since then -- expanding earth theory was aborted for being a runt in the womb.)

    Quote Originally Posted by florian View Post
    Quote Originally Posted by billiards View Post
    There are problems that weren't even brought up in the plate tectonics thread, such as the fact that the Eastern half of the Pacific has clearly been subducted.
    Actually not. The ridge formed and are currently forming along the Americas. For example, in the gulf of california is a nascent ridge that is propagating southward to the EPR and northward toward the San Andreas Fault. The later should soon open as a ridge and complete the connection to the Juan de Fuca ridge.
    Hmmm, so much crap to cut through. Where to begin?

    Clearly the EPR is a spreading ridge. Clearly the ocean is asymmetric about this ridge. Clearly the spreading rate is equal either side of the ridge (as evidenced by the age of the ocean floor). So why the asymmetry?

    Could it be that one side of the Pacific is being subducted? The great big ocean trench, the Aleutian arc, the Cascades volcanism (e.g. Mt St Helens), the seismicity -- all are consistent with the scientifically established FACT that half the Pacific has and still is being subducted.

    This nascent ridge you speak of? what of it? What is the evidence for it? Who cares? Does it change the FACTS? Could this be a red herring?

    Quote Originally Posted by florian View Post
    The situation is not so much different than with the red sea ridge propagating to the Jordan rift valley that evolves from transform fault to rift then ridge. You can verify it using google earth (see this file)

    The current position of the zodiac fan proves the formation of fresh crust at the periphery of the ocean by progressive mantle exposure following continent retreat related to mantle bulging (see Eduction process by Yu Chudinov): the fan formed in the gulf of alaska and is now found to the south-west of the gulf, see figure. The isochrons on which the fan lies have actually the shape of the former continental margin. This is really specific to the north pacific because it is the sole ocean that originally opened equatorially (See Carey). This also explains the triangular shape of the isochrons with the older crust inside and younger crust outside, like for tree rings. Very very specific growth that is now entirely supplanted by classical ridge spreading.
    Iso5Npacific.jpg
    Huh? Not following anything at all. The zodiac fan is fresh mantle exposure?? Strange it's sediments then. But let's not get lost chasing another red herring.

    Quote Originally Posted by florian View Post
    Quote Originally Posted by billiards View Post
    furthermore the theory makes predictions in all of these disciplines!
    Plate tectonics is a scenario. What predictions does it make? Does it predict the relative position of old cratons 500 Ma ago (I say predict not describe!). No. Does the EE theory predicts the relative positions of old cartons 500 Ma ago? yes. Is this prediction verified? Yes again (See Rodinia's empirical reconstruction and Maxlow's predicted reconstruction).
    Plate tectonics predicts the distribution of volcanoes, and seismicity. It predicts the presence of mountain belts and sedimentary basin. It predicts the distributions of fossils. It predicts the present and past stress patterns in the earth. It predicts some features of mantle heterogeneity. There is even the "subduction signature" in geochemistry. The evolution of magmas. Topography, the geoid, the shapes of the continents. All fit neatly into the paradigm.

    Quote Originally Posted by florian View Post
    Quote Originally Posted by billiards View Post
    For example I would like to discuss the processes which formed the continents.... what were they and are they still active today?
    Of course they are. Continents form progressively by episodic emplacements of new crust in between patches of older crust. Its evident from continental crust age and maps.
    The answer is not as sign sealed and delivered as you make out. Clearly the Earth is not the same today as it was 4 billion years ago. The rate of mantle convection has slowed dramatically. I would not be surprised if there were volcanic processes acting then that have no modern analogue. Furthermore the initial phase of continent formation would have brewed from a far more primitive "soup" than is available today.

    Quote Originally Posted by florian View Post
    Quote Originally Posted by billiards View Post
    What is it that makes a tectonic plate
    A cheated mind
    With respect, this is probably too sophisticated topic for you. I was getting more at the nature of the lithosphere asthenosphere boundary. Even you must acknowledge such a boundary, so to say a "cheated mind" is unhelpful even for your own cause. It is a subject at the frontier of present day research and there are quite a few relevant papers published by various groups -- with contending viewpoints -- that we could potentially discuss.
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    Quote Originally Posted by billiards View Post
    Quote Originally Posted by florian View Post
    It is believed that the slab of lithosphere in the mantle does provide the driving force for subduction and plate displacement. But the lithosphere cannot afford to drag a whole plate because it has a very low tensile strength.
    You have failed to make this point. Throwing an indirect reference out there is not helpful.<br>

    Why not simply write out the equations?
    Equations are here to get numbers, and we already have the numbers.

    Let's quote Doglioni in ESR 2007

    "At the Earth's surface, oceanic lithosphere has lowstrength under extension (e.g., 8 × 1012 N m− 1, Liuet al., 2004) and is able to resist a force smaller thanthat requested by slab pull (3.3×1013 N m−1,Turcotte and Schubert, 2002). If the slab pull is thecause for the motion of the Pacific plate, this observation argues for a stretching of the Pacificlithosphere before slab pull being able to movethe plate. In other words, the plate cannot sustainthe tensional stresses eventually due to slab pull. "

    The faults at the flexure zone and those visible in seismic profiles illustrate very well the low tensile strength of the oceanic lithosphere.

    Quote Originally Posted by billiards View Post
    Quote Originally Posted by florian
    The sole valid alternative is that the mantle, not the slab, does provide the driving force for subduction: the mantle extrudes and outpours on the oceanic lithosphere, which in turn, get buried under the mantle weight, in other words, get subducted.
    So according to this explanation it sounds as though you think subduction occurs at the mid ocean ridge??
    Not at all, the ridge is above the upwelling, not on the side => the ridge is in the back arc
    Mid ocean ridge are either atop large upwelling (EPR) or are passive extensional features (MAR) with upwelling being the consequence of the extension, not the cause.

    What's the "mantle edge"??
    I misspelled "mantle wedge".
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    Quote Originally Posted by billiards View Post
    Quote Originally Posted by florian View Post
    Quote Originally Posted by jlhredshift View Post
    And your/their theory explains the subsidence how?
    It is not specific to a theory. It is basic seismology. During a fault rupture, there is always opposite displacement along the fault due to the elasticity of the rock. See this figure:

    firstmotion.jpg
    So if one side of the fault is moving up, the other side moves a bit down.
    There is always relative displacement. Why does one side have to go down? Wouldn't you expect one side to sit still, while the other side moves up?
    Because Rocks are elastic.
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    Quote Originally Posted by billiards View Post
    (Actually in all seriousness from what I've heard Carey deserves some respect, however, his ideas of an expanding earth are wrong. He was a decent scientist, no contradiction there: it is possible to be a good scientist who happens to believe something which turns out to be wrong. 1983 was before I was even born -- the science has grown up more than I have since then -- expanding earth theory was aborted for being a runt in the womb.)
    It is not just ideas, hypotheses, it is a validated theory. It was sided in the 70s-80s based on flawed refutations arguments. Carey is the most brilliant geologist of all times. He was more than 50 years ahead, and counting...

    Quote Originally Posted by billiards View Post
    Quote Originally Posted by florian View Post
    Quote Originally Posted by billiards View Post
    There are problems that weren't even brought up in the plate tectonics thread, such as the fact that the Eastern half of the Pacific has clearly been subducted.
    Actually not. The ridge formed and are currently forming along the Americas. For example, in the gulf of california is a nascent ridge that is propagating southward to the EPR and northward toward the San Andreas Fault. The later should soon open as a ridge and complete the connection to the Juan de Fuca ridge.
    Hmmm, so much crap to cut through. Where to begin?.
    It seems that in your personal language "crap"= "I' don't understand."


    Quote Originally Posted by billiards View Post
    Clearly the EPR is a spreading ridge. Clearly the ocean is asymmetric about this ridge. Clearly the spreading rate is equal either side of the ridge (as evidenced by the age of the ocean floor). So why the asymmetry?
    Yes, the EPR is a spreading ridge, and again, it is propagating north making a connection with the nascent ridge in the gulf of california, the late propagating north toward the juan de fuca ridge, through the San andreas fault system.
    Spreading rates are always equal because there accretion is a symmetrical process, whatever the kinematic scheme.
    There is an asymmetry because the pacific changed of growing regime from peripheral expansion by a continental retreat mechanism to a spreading ridge mechanism. In short the Pacific grew like a bubble pushing away its envelope (the continental lithosphere) then the surface of the bubble failed along the periphery (ridge formation). This process is almost finished, the last stage being the opening of the california ridge which will make the connection with the Juan de Fuca ridge.


    Quote Originally Posted by billiards View Post
    Could it be that one side of the Pacific is being subducted? The great big ocean trench, the Aleutian arc, the Cascades volcanism (e.g. Mt St Helens), the seismicity -- all are consistent with the scientifically established FACT that half the Pacific has and still is being subducted.
    Almost all of the margins of the pacific are marginally subducted. But this subduction is limited to a few hundreds km. The hypothesis (not a fact at all) that half of the pacific got subducted relies on zero evidence. It is just a beliefs resulting from plate tectonics concepts, much like the India/Asia collision.

    Quote Originally Posted by billiards View Post
    This nascent ridge you speak of? what of it? What is the evidence for it? Who cares? Does it change the FACTS? Could this be a red herring?
    Do you deny the existence of a new ridge in the gulf of california?

    Quote Originally Posted by billiards View Post
    Quote Originally Posted by florian View Post
    The situation is not so much different than with the red sea ridge propagating to the Jordan rift valley that evolves from transform fault to rift then ridge. You can verify it using google earth (see this file)

    The current position of the zodiac fan proves the formation of fresh crust at the periphery of the ocean by progressive mantle exposure following continent retreat related to mantle bulging (see Eduction process by Yu Chudinov): the fan formed in the gulf of alaska and is now found to the south-west of the gulf, see figure. The isochrons on which the fan lies have actually the shape of the former continental margin. This is really specific to the north pacific because it is the sole ocean that originally opened equatorially (See Carey). This also explains the triangular shape of the isochrons with the older crust inside and younger crust outside, like for tree rings. Very very specific growth that is now entirely supplanted by classical ridge spreading.
    Iso5Npacific.jpg
    Huh? Not following anything at all. The zodiac fan is fresh mantle exposure?? Strange it's sediments then. But let's not get lost chasing another red herring.
    ??The zodiac fan is formed by sediments coming from alaska. The fan formed in the gulf of alaska. Its present position relative to the gulf of alaska shows that it migrated mostly westward relatively to the gulf of alaska (which refutes plate tectonics predictions). This indicates that oceanic lithosphere formed between the fan and the gulf of alaska, thus along the coast. The age and shape of the isochron completely support this interpretation as well.

    Quote Originally Posted by billiards View Post
    Quote Originally Posted by florian View Post
    Quote Originally Posted by billiards View Post
    furthermore the theory makes predictions in all of these disciplines!
    Plate tectonics is a scenario. What predictions does it make? Does it predict the relative position of old cratons 500 Ma ago (I say predict not describe!). No. Does the EE theory predicts the relative positions of old cartons 500 Ma ago? yes. Is this prediction verified? Yes again (See Rodinia's empirical reconstruction and Maxlow's predicted reconstruction).
    Plate tectonics predicts the distribution of volcanoes, and seismicity.
    It is not a prediction. It is a description using a global framework. Plate tectonics describes the distribution of volcanoes, and seismicity.
    A prediction is ideally something that was not part of the premises used to build the theory.

    Similarly, it does not predict the distribution of fossils or geological features. It provides an explanation regarding their location.

    For example, if we find matching 1 billions years geological sequence across oceans, plate tectonics can explain why. But the existence of these matching sequences at these locations could not be predicted from the theory alone. On the contrary, the expanding earth theory predicts where we should find matching sequences, whatever their age, because the expanding earth model is much more constraint by basic geometry. It is a very powerful model that can make predictions.


    Quote Originally Posted by billiards View Post
    Quote Originally Posted by florian View Post
    Quote Originally Posted by billiards View Post
    For example I would like to discuss the processes which formed the continents.... what were they and are they still active today?
    Of course they are. Continents form progressively by episodic emplacements of new crust in between patches of older crust. Its evident from continental crust age and maps.
    The answer is not as sign sealed and delivered as you make out. Clearly the Earth is not the same today as it was 4 billion years ago.
    Clearly not the same as today

    Quote Originally Posted by billiards View Post
    The rate of mantle convection has slowed dramatically.
    Actually, that is one of the rare prediction of plate tectonics and it is refuted. Evidence show that the heat flow was equivalent or even slightly lower than today, more than 4 billions years ago. See Hopkins et al (2008) Nature 456, p 493
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    Quote Originally Posted by florian View Post
    Quote Originally Posted by billiards View Post
    Quote Originally Posted by florian View Post
    Quote Originally Posted by jlhredshift View Post
    And your/their theory explains the subsidence how?
    It is not specific to a theory. It is basic seismology. During a fault rupture, there is always opposite displacement along the fault due to the elasticity of the rock. See this figure:

    firstmotion.jpg
    So if one side of the fault is moving up, the other side moves a bit down.
    There is always relative displacement. Why does one side have to go down? Wouldn't you expect one side to sit still, while the other side moves up?
    Because Rocks are elastic.
    There's no logic in that. Perfectly elastic things don't fault at all.
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    Quote Originally Posted by florian View Post
    Quote Originally Posted by billiards View Post
    Quote Originally Posted by florian View Post
    It is believed that the slab of lithosphere in the mantle does provide the driving force for subduction and plate displacement. But the lithosphere cannot afford to drag a whole plate because it has a very low tensile strength.
    Why not simply write out the equations?
    Equations are here to get numbers, and we already have the numbers.
    Equations give us a a model which let us see what parameters are important and give us a feel for the sensitivity of those parameters. The reality is obvious: you don't have the knowhow to dig into the equations.

    Let's quote Doglioni in ESR 2007

    "At the Earth's surface, oceanic lithosphere has lowstrength under extension (e.g., 8 × 1012 N m− 1, Liuet al., 2004) and is able to resist a force smaller thanthat requested by slab pull (3.3×1013 N m−1,Turcotte and Schubert, 2002). If the slab pull is thecause for the motion of the Pacific plate, this observation argues for a stretching of the Pacificlithosphere before slab pull being able to movethe plate. In other words, the plate cannot sustainthe tensional stresses eventually due to slab pull. "
    All of which tells us that the dynamics of subduction are more complicated than just "slab pull". Who didn't already know this?

    Subduction happens, it is in active process. It is not a passive process as you seem to believe.


    Quote Originally Posted by billiards View Post
    Quote Originally Posted by florian
    The sole valid alternative is that the mantle, not the slab, does provide the driving force for subduction: the mantle extrudes and outpours on the oceanic lithosphere, which in turn, get buried under the mantle weight, in other words, get subducted.
    So according to this explanation it sounds as though you think subduction occurs at the mid ocean ridge??
    Not at all, the ridge is above the upwelling, not on the side => the ridge is in the back arc
    Mid ocean ridge are either atop large upwelling (EPR) or are passive extensional features (MAR) with upwelling being the consequence of the extension, not the cause.[/quote]

    It's not an either/or situation -- the dynamics are complex and slab pull exists. Furthermore what you are saying does not fit with what you said in the "mantle convection -- top down or bottom up?" thread, here you seem to be saying it is bottom up, in the other thread you were saying it's bottom down.
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    I read through this, because this topic is somewhat obsessive with me at the moment. I read a 1988 article in Scientific American I found online about the Super Continent cycle. I think I mostly followed it.

    Where I get hung up, is the origin. How did the original continental crust form and end up in the same place to start the cycle?
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    Quote Originally Posted by MichaelJHuman View Post
    I read through this, because this topic is somewhat obsessive with me at the moment. I read a 1988 article in Scientific American I found online about the Super Continent cycle. I think I mostly followed it.

    Where I get hung up, is the origin. How did the original continental crust form and end up in the same place to start the cycle?
    Well, it does not mean "exactly the same place". It means collison, breakup, collision, breakup, and so on. As to the origin, as soon as the crust cooled after bombardment had slacked off some.
    I'm sorry, my responses are limited. You must ask the right question.

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    Quote Originally Posted by MichaelJHuman View Post
    How did the original continental crust form and end up in the same place to start the cycle?
    this may go some way towards answering your question :

    Early Continents and Oceans
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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    Quote Originally Posted by MichaelJHuman View Post
    I read through this, because this topic is somewhat obsessive with me at the moment. I read a 1988 article in Scientific American I found online about the Super Continent cycle. I think I mostly followed it.

    Where I get hung up, is the origin. How did the original continental crust form and end up in the same place to start the cycle?
    You should read this post that explains why supercontinent cycles are artifactual: plate tectonics
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