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Thread: Question about some strange tectonic shapes

  1. #1 Question about some strange tectonic shapes 
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    I was looking at this picture the other day of the tectonic plate formations around the ring of fire.



    Looking at the long line in the center of the image, I read that the string of features there was formed by a hotspot underneath the plate causing the formation as the plate moved over the spot. Gradually over time the string of underwater mountains was caused.

    Interestingly, it is obvious that at the line changes direction thereby indicating a change in the motion of the tectonic plate.

    The WHY is what is uncertain.

    This made me look at the other features in this picture and some of the struck me as unusual.

    Note the big semi circular plate boundary in the lower left.

    There are also vast "splash" like markings on the plate to the west of this area, and what appears to be stretched plates to the east.

    I studied a topographical map of the rest of the world, and these "splashlike" formations do not appear anywhere else in the world.

    Anyway, with all this pseudo-evidence, I pondered the idea of this being the location of a supermassive asteroid impact. Being on the boundary of a tectonic plate, and accounting the motion of the pacific plate, the impact crater could have long been swallowed by the ridge, while still permanently effecting its shape along this point.

    It is also interesting to note that this is the location of some of the deepest parts of the earth.

    Is this something that has already been pondered/disproved?

    Surely I am not the first person to think this?

    Is there any evidence that would disprove this occurrence.

    I am interested in everyone's opinions on this.

    Please discuss!


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  3. #2  
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    Could you clarify which features you are describing? How do they suggest an impact? I'm not sure exactly what you mean.


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  4. #3  
    Universal Mind John Galt's Avatar
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    Welcome to the forum. Interesting thought, but I doubt there is anything to it. Oceanic subduction zones are typically curved, because of the intersection of a flat (relatively) plane with the curved surface of the Earth. Moreover we know from seismic and other evidence that there is a descending plate at that location.
    Lke The Matt I am not sure which other features you are talking about.
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  5. #4  
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    This has notes with what I am referring to.

    I'm no scientist, but this glares at me.



    Oceanic subduction zones are typically curved, because of the intersection of a flat (relatively) plane with the curved surface of the Earth. Moreover we know from seismic and other evidence that there is a descending plate at that location.
    This curve is far more anomalous than normal curves along plate boundaries. It is also in a much smaller area than a normal boundary curve as is seen along the north face of this plate.

    A Descending plate only aids my thought. After an impact at a plate boundary, why wouldn't the plate descend? It just got hit by a giant asteroid

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  6. #5  
    Universal Mind John Galt's Avatar
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    Quote Originally Posted by ohmss
    This curve is far more anomalous than normal curves along plate boundaries. It is also in a much smaller area than a normal boundary curve as is seen along the north face of this plate.
    1. The curve is more pronounced because the dip of the plate is steeper.
    2. Plates and their boundaries vary in size. this is natural.
    3. The 'splash zone' you have identified is composed of chains of volcanic islands. There is no doubt as to their origin. In addition meteoric impacts have splash zones that are, on a large scale, evenly distributed.

    I applaud your original thinking, but it does not fit the facts.

    You ask would a large impact not cause a plate to subside? The answer is no.
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    This curve is far more anomalous than normal curves along plate boundaries. It is also in a much smaller area than a normal boundary curve as is seen along the north face of this plate.
    I'd beware of map projection distortions. I don't know what projection that map uses, but all of them distort the size and shape of features to some degree- There's no perfect way to plot a spherical (or thereabouts) shape in 2d.

    Your 'splash marks' seem to be an oceanic plateau composed of basaltic lava:
    http://www.earth.cf.ac.uk/people/summaries/116.LIP.htm

    You might also be interested to learn that the bend in the Emperor-Hawaiian chain has been suggested to be as a result of a moving magma source, rather than a change in plate movements:
    http://www.mala.bc.ca/~earles/hotspot-motion-aug03.htm
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  8. #7  
    Forum Junior Twaaannnggg's Avatar
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    Interstingly enough there's new data suggesting that the hot spot that formed the Hawai-Emperor Seamounts is not fixed in position, thus the bend in the chain of seamounts from Hawai to Kamchatka. Appeared in the last NewScientist I think.
    Build a man a fire and he will be warm for a day, set a man on fire and he will be warm for the rest of his life.
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    Thanks for the interesting and informative answers. And thanks for reigning in my wild imagination.
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