Total Pageviews

Thursday, January 21, 2016

Adamant about Wit, Waters, (R) And Diamonds in Plate Tectonics Timing

      By using an ion probe to analyze the carbon and nitrogen isotope compositions of Witwatersrand, South African diamonds, which have been preserved for more than three billion years, researchers found that plate tectonics was likely in operation on earth as early as 3.5 billion years ago. 



      The location of the Witswatersrand Basin mines in South Africa is shown here: 








     In an article published this week, researchers at the University of Witswatersrand describe the diamonds as being like miniature time capsules recording information about the movement of the earth's tectonic plates on the earth's surface.






     Lead researcher Dr. Katie Smart noted, “The nitrogen isotope composition of the Witwatersrand diamonds indicated a sedimentary source (nitrogen derived from the Earth’s surface) and this tells us that the nitrogen incorporated in the Witwatersrand diamonds did not come from the Earth’s mantle, but that it was rather transported from Earth’s surface into the upper mantle through plate tectonics. This is important because the nitrogen trapped in the Witwatersrand diamonds indicates that plate tectonics, as we recognise it today, was operating on ancient Archaean Earth, and actively transported material at Earth’s surface deep into the mantle.”




     In other words, these carats are able to tell us "What's Up, Doc?" from at least 3.5 billion years ago.




Your thoughts on these carbon gems (or emeralds ;-)) and plate tectonics? 

Steph

P.S. Yes, I am all set with a costume as a tardigrade for Halloween 2016:



36 comments:

  1. So, the presence of any crustal material in the mantle is proof of plate tectonics? Is there no other conceivable mechanism for getting stuff down from the surface of a partially molten planet? I don't know, dragged down my a heavy meteorite, e.g.?

    ReplyDelete
    Replies
    1. That should be "dragged down BY a heavy meteorite", of course.

      Delete
    2. Possible, I suppose, but it's a bit far down there. . .

      Delete
    3. Aren't iron metorites denser than magma?

      Delete
    4. Yes. To Wit: perhaps an alternate hypothesis...

      Delete
    5. On the other hand, is there any reason why crustal subduction wouldn't have been occurring early on?

      Delete
    6. We know a lot about Pangaea and that break up thanks to the fossil record, but not as much about earlier continental movements. Presuming a similar mechanism for that earlier time is a reasonable place to start; now we just need more evidence.

      Delete
  2. BTW, our mascot appeared on Jeopardy! on Monday, in the category "LONG-LIVED CREATURES":

    The microscopic water this -- we nicknamed it "Ursus smallus" -- can slow its metabolism to 0.01% of normal & live up to a century.

    Once could argue with that "microscopic". I've never seen a tardigrade in person, but my senior eyes can resolve the millimeter markings on a ruler just fine.

    ReplyDelete
  3. jan,
    First Will Shortz appears on Jeopardy! Now the beloved tardigrade! You go, Jeopardy!

    Poem for David, skydiveboym et al:

    The Mariners, Seahawks or erstwhile Supersonics?
    Which pro Seattle team knows most about tectonics?
    Earth shifted ‘neath the Sonics, who one day just found themselves
    In Oklahoma! Blame it on the continental shelves?
    The Seahawks play on frozen tundra, fields that glaciate…
    But Mariners? They play on DIAMONDS, hang around home PLATE.

    LegoTechIsTheBestTonic

    ReplyDelete
    Replies
    1. Oh, good, time to post my Halloween costume for 2016 (at the end of this week's post, coming next).

      That type of poetry is HARD to come by, Lego. I really like it; you're a gem!

      And I thought "techtonics" might be what Microsoft coders drink after work. . . (just add gin).

      Delete
    2. Take Maizie trick-or-treating along with one of this week's gems: a diamond 'n' the rrruff.

      Delete
    3. Grrreat idea, jan. Maizie is on board, although she does have many facets to reveal for her 10th birthday in October.

      Delete
    4. Lego, everyone thinks that the cause of the big increase in Oklahoma earthquakes is fracking, but maybe the ex-Sonics brought the earthquakes with them.

      Delete
    5. David,
      Your earthquake comment brought to mind the late great Darryl Dawkins, whose nickname could have well been “The Human Earthquake.” His real nickname, of course, was “Chocolate Thunder,” so he would have been a perfect fit with the “Sonics-Boom-That-Became-The-Okie-City-Thunder.” Wrong place at the wrong time… a shame.

      LegoSuggestsThatPhiladelphia,InDD’sMemory,RenicknameItself”TheCityOfBrotherlyLove…tron”

      Delete
    6. And, SOE (Speaking of Earthquakes) this USGS article is a good, intermediate depth ;-), article on the 7.1 earthquake in Alaska yesterday.

      Delete
  4. Replies
    1. And it's fun to see them come out of their shells. . .

      Delete
  5. Frigging interesting for our Icelandic field trip. . .

    ReplyDelete
    Replies
    1. As Schiller said (and Asimov borrowed), against stupidity the gods themselves contend in vain.

      Delete
  6. Replies
    1. This comment has been removed by the author.

      Delete
    2. Haven't listed to the whole thing yet, but if the Soviets got 12 km down with their Kola borehole, why are we getting excited by a hole just a couple of km deep?

      I do like saying Mohorovičić, and I always thought Project Mohole had a good name, if nothing else.

      Delete
  7. New post on "{Geologic!} Hotspot in Eastern Australia, Bass Strait, and Tasmania" is up!

    ReplyDelete