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Update on Tectonic Plate Dynamics

  1. Jan 22, 2017 #1

    Astronuc

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    This caught my attention the other day, and I don't yet have time to review/explore the topic.

    A discovery about the movement of tectonic plates will have scientists rewriting (or update?) textbooks
    http://www.businessinsider.com/what-moves-tectonic-plates-2017-1

    20 TW is pretty impressive.

    Kinematics and dynamics of the East Pacific Rise linked to a stable, deep-mantle upwelling
    http://advances.sciencemag.org/content/2/12/e1601107
    I'm starting this thread for discussion on this topic (primarily on tectonic plate dynamics, but also on the EPR) since we apparently don't have a relevant one open.
     
  2. jcsd
  3. Feb 6, 2017 #2

    Astronuc

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    Related to plate tectonics -

    Radioisotope studies show the continental crust formed 3 billion years ago
    Read more at: https://phys.org/news/2015-07-radioisotope-continental-crust-billion-years.html#jCp

    This relates to the use of strontium and rubidium isotopes in determining the age of a rock bearing these isotopes. "Rubidium (87Rb) becomes strontium-87 (87Sr) through radioactive decay. Strontium-87 has a half-life of 48.8 billion years. Strontium-86, the most abundant isotope of Sr, is stable and does not undergo radioactive decay. Therefore, the abundance of 87Sr in the continental crust can be traced to the radioactive decay of 87Rb, and based on its half-life, one can determine the age of a rock sample."

    https://www.physicsforums.com/threads/radioisotopic-dating-with-isotopes-of-different-masses.902975/

    The above Phys.org article leads to another, somewhat more sensationally entitled one - "Earth's crust slowly being destroyed", or it's not growing as fast.

    Read more at: https://phys.org/news/2012-03-earth-crust-slowly.html#jCp
     
  4. Feb 7, 2017 #3

    DrDu

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    Yes, but given that big power plants already reach several GW, and we are talking about the forces moving whole continents, I find this number not surprising.
     
  5. Feb 9, 2017 #4
    Very interesting subject.

    My criticism would be that it seems bit circular. They use their model to show that the Earth is not as expected if the preexisting hypothesis is true. Then they use the same model to support their alternative hypothesis. At least that's my understanding.

    Furthermore, they concede that similar models from other groups give a different picture.

     
  6. Feb 12, 2017 #5
    Actually that's not a completely new thing. The mid-ocean ridges were considered as active participants of the tectonic cycle decades ago, only later it's been shown that most ridges exhibit features indicating extension instead of compression – hence the notion of 'slab pull' as the motor of the plate tectonics. It's nice to know that some people have done the maths to reexamine the old notion of 'ridge push' as well. And 20 terawatts does not look so impressive if you notice that this is a sum over ~153 million square kilometers of the core–mantle boundary. It corresponds to only 0,13 W/m2, just a bit more than the mean heat flux through the oceanic crust (0,10 W/m2).
    Although it is probably not uniform due to inhomogeneities in the lowest mantle.
     
    Last edited: Feb 12, 2017
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