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Thread: Plate tectonics runs out of fuel

  1. #1
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    Plate tectonics runs out of fuel

    I don't believe in perpetual motion, something is powering plate tectonics. Eventually the needle will reach E.
    How long will this take?

  2. #2
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    The Earth may be destroyed by the sun before then. Before being swallowed, the oceans will evaporate and that might seize up whatever's still going on with the plates.
    Et tu BAUT? Quantum mutatus ab illo.

  3. #3
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    Good point.
    But just for curiosity's sake, assume the Earth is eternal and the "machine" will eventually stop.

  4. #4
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    Radioactive decay in the interior of Earth powers plate tectonics. How long will it last is an open question.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright
    "It is the duty of the writers to seduce me into suspending my disbelief!" Paul Beardsley

  5. #5
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    Quote Originally Posted by Noclevername View Post
    Radioactive decay in the interior of Earth powers plate tectonics. How long will it last is an open question.
    Plus residual heat from formation.

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    Quote Originally Posted by geonuc View Post
    Plus residual heat from formation.
    IIRC that had already run out.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright
    "It is the duty of the writers to seduce me into suspending my disbelief!" Paul Beardsley

  7. #7
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    Decay of uranium-238 and thorium-232 will continue to provide enough heat for plate tectonics for at least the next few billion years. Their half-lives are 4.5 and 14.05 billion years. But how much is too little heat to power plate tectonics is difficult to say. Also happening before much of the remaining U-238 and Th-232 decays is loss of water by evaporation into space. Lack of water for lowering the melting point of rock will make subduction more difficult, and may stop the plates.

  8. #8
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    Quote Originally Posted by Noclevername View Post
    IIRC that had already run out.
    I thought estimates put it at 40% to 60% of the total. Guess I gotta look into that.

    ETA:
    The Naked Scientists seem to say both radioactivity and primordial heat are important, but don't give specifics.
    https://www.thenakedscientists.com/a...ic-plates-move

  9. #9
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    Quote Originally Posted by grapes View Post
    I thought estimates put it at 40% to 60% of the total.
    That's about it from what I know and from online sources.

    ETA: Such as this one from the American Geophysical Union:

    http://blogs.agu.org/martianchronicl...-get-its-heat/

    ... simple decay of radioactive isotopes provides about half of the Earthís heat, and will continue to provide heat for billions of years. The rest of the heat is left over from the planetís formation.
    Last edited by geonuc; 2017-Mar-14 at 09:43 AM.

  10. #10
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    How much heating is caused by tidal flexing from the Moon?

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