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I Why is there no "mid-Atlantic ridge" on other planets?

  1. Feb 5, 2017 #1
    Our planet has scars going all the way around it. The most famous of these is the mid-atlantic ridge.


    How come Earth is unique in this respect? There are none on Mars for example:


    How come we don't see any such feature on Mercury, Venus or Mars?
    Last edited by a moderator: Apr 28, 2017
  2. jcsd
  3. Feb 5, 2017 #2
  4. Feb 5, 2017 #3
    Interesting. According to that article:

    "Indeed, the pattern of faults on Venus suggests that plate-tectonics-like movement struggled to begin but never quite succeeded."

    So it looks like Venus failed to do what Earth did do. I wonder could the fact Earth has an atmosphere while the other planets don't help explain why Earth got its tectonic plates going while the other planets didn't.
  5. Feb 5, 2017 #4
  6. Feb 5, 2017 #5
    That would be a tough correlation to make. How would you attempt to explain it?
    Also, the article states,
    "Because Earth's interior has remained warm enough for flow to take place in its mantle."
    I'm guessing this is a big factor.
  7. Feb 5, 2017 #6
    The second article talks about how Mars is in a primitive stage of plate tectonics. Could it possibly be a later stage considering the large, dormant volcanoes such as Olympus Mons that could have formed a long time ago due to the plate tectonics?
  8. Feb 5, 2017 #7
    Recent research has shown there are large oceans of water underneath the surface of the Earth. If these were on Mars, and Mars' atmosphere was stripped away, thus reducing atmospheric pressure and thus reducing the boiling point of water to 10c (which is what it is on Mars), the water underneath the surface of the earth on Mars would boil into gas, expand and burst out in those volcanoes you see on Mars' surface?
  9. Feb 5, 2017 #8
    These volcanoes are dormant, though. Unless you have a source to prove otherwise?
  10. Feb 5, 2017 #9
    I do believe I have read that one of the reasons Mars lacks a significant magnetic field is the core has cooled, (I'll see what I can find to cite that) at any rate this would definitely have an effect on plate tectonics, not so much primitive as extinct or severely reduced. It seems Yin from the UCLA site would be a good person to check with concerning the Martian Geology, I'll see what I can find there also.
  11. Feb 5, 2017 #10
    I'm theorizing that the gas has been ejected at this stage.

    Those volcanoes look like zits on a persons face. Almost like they were formed quickly. They look unusually tall.
  12. Feb 5, 2017 #11
    This article implies that Volcanic activity is very likely not dead on Mars.
    Also the opinion seems to be that plate tectonics is no longer active although the core is believed to be liquid
    From, https://science.nasa.gov/science-news/science-at-nasa/1999/ast29apr99_1/
    "The discovery of this pattern on Mars could revolutionize current thinking of the red planet's evolution," said Dr. Jack Connerney of NASA's Goddard Space Flight Center, Greenbelt, MD, an investigator on the Global Surveyor's magnetometer team. "If the bands on Mars are an imprint of crustal spreading, they are a relic of an early era of plate tectonics on Mars. However, unlike on Earth, the implied plate tectonic activity on Mars is most likely extinct."
  13. Feb 5, 2017 #12
    Dormant, not dead. It might take a while to prove it is active though.

    Also, do we know how old these meteorites are? If not, they could've been there with the penguins for hundreds of millions of years, and we wouldn't have known. It certainly does prove, though, that there was once volcanic activity on Mars.
  14. Feb 5, 2017 #13
    I guess plate tectonics of Earth exist because the interior of Earth is still to some extent fluid not so far under the surface.
    Why that seems not to be so for Venus is an interesting question.
  15. Feb 10, 2017 #14


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    Our Moon has noticeable tidal effects on the oceans and I wonder whether PT could have been enabled by the presence of such a large Moon disturbing theEarth's surface. Venus has nothing significant and the two martian moons are pretty small. As with most planetary features, you need a particular set of circumstances for them to occur. Mass, constituents, age and temperature probably need to be 'just right' to get PT.
    We cannot tell what's happening at the internal solid cores of the Gas Giants.
    Last edited: Feb 10, 2017
  16. Feb 10, 2017 #15

    Stephen Tashi

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    In a lecture on the DVDs of the series "The Great Courses: Oceanography" , the presenter said that oceans are necessary for plate tectonics to work. (As to why they are necessarily, there might be several reasons. I'd have to re-watch the DVD to recount them.)
  17. Feb 10, 2017 #16


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    Its my understanding that rocks exposed to water (oceans?) change chemically (weathering?) and which alters their density (lighter I think).
    This could accentuate density differences between the crust and mantle. Which is probably close to a tectonic driving mechanism.

    This chemically altered material eventually subsides into the mantle. Altered material may come up more frequently than unaltered material. Some will instead mix with the body of mantle, changing it to some degree chemically. This might also affect things.

    This of course could happen along with everything else discussed.
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