The Building Blocks for Life on Earth:

Discussion in 'Earth Science' started by paddoboy, Mar 12, 2020.

  1. paddoboy Valued Senior Member

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    https://phys.org/news/2020-03-blocks-life-earth-thought-billion-year-old.html

    Building blocks for life on Earth arrived much later than we thought, billion-year-old rocks show:

    Ancient rocks from Greenland have shown that the elements necessary for the evolution of life did not come to Earth until very late in the planet's formation—much later than previously thought.
    extract:
    "If you combine this with the evidence for very ancient life on Earth, it reveals that life got started on our planet surprisingly quickly, within only a few hundred million years. Now this might sound like a lot of time, and it is, but it is far different from what we used to think, that life took half a billion, or even a billion years to get started.

    "And this gives hope for finding life on other planets that had a shorter geological history and period of 'warm and wet' conditions than Earth, because if life could get started quickly here, then perhaps it got started quickly elsewhere."

    Professor Dr. Carsten Münker, also at the University of Cologne, added: "The fact that we are still finding traces of rare platinum metals in the Earth's mantle means that we can assume they were only added after the formation of the core was completed—they were certainly the result of later collisions of the Earth with asteroids or smaller planetesimals."
    more at link.....

    the paper:
    https://www.nature.com/articles/s41586-020-2069-3


    Ruthenium isotope vestige of Earth’s pre-late-veneer mantle preserved in Archaean rocks:

    Abstract:
    The accretion of volatile-rich material from the outer Solar System represents a crucial prerequisite for Earth to develop oceans and become a habitable planet1,2,3,4. However, the timing of this accretion remains controversial5,6,7,8. It has been proposed that volatile elements were added to Earth by the late accretion of a late veneer consisting of carbonaceous-chondrite-like material after core formation had ceased6,9,10. This view could not be reconciled with the ruthenium (Ru) isotope composition of carbonaceous chondrites5,11, which is distinct from that of the modern mantle12, or of any known meteorite group5. As a possible solution, Earth’s pre-late-veneer mantle could already have contained a fraction of Ru that was not fully extracted by core formation13. The presence of such pre-late-veneer Ru can only be established if its isotope composition is distinct from that of the modern mantle. Here we report the first high-precision, mass-independent Ru isotope compositions for Eoarchaean ultramafic rocks from southwest Greenland, which display a relative 100Ru excess of 22 parts per million compared with the modern mantle value. This 100Ru excess indicates that the source of the Eoarchaean rocks already contained a substantial fraction of Ru before the accretion of the late veneer. By 3.7 billion years ago, the mantle beneath southwest Greenland had not yet fully equilibrated with late accreted material. Otherwise, no Ru isotopic difference relative to the modern mantle would be observed. If constraints from other highly siderophile elements besides Ru are also considered14, the composition of the modern mantle can only be reconciled if the late veneer contained substantial amounts of carbonaceous-chondrite-like materials with their characteristic 100Ru deficits. These data therefore relax previous constraints on the late veneer and are consistent with volatile-rich material from the outer Solar System being delivered to Earth during late accretion.

     
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  3. Write4U Valued Senior Member

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    What are his criteria of "life"? Are you sure this guy is not a young earth advocate?
    If we compare this to the mainstream science of earliest life (let alone the building blocks) the difference is much too large to come to a compromise. Somebody is totally wrong or just plain lying.
    What are these volatile rich material from the outer solar system?
    Science has pretty well established this material was accreted from the earth's collision with Theia.
    As Theia was composed mainly of ice, the collision introduced water to earth and allowed for the appearance of the first bio-chemicals, the building blocks of life, probably from deep sea volcanic vents (smokers).

    This chronology fits very neatly with the fossil evidence of bio-chemistry and abiogenesis.
    https://en.wikipedia.org/wiki/Earliest_known_life_forms

    This does not even address the building block but the very appearance of living things.
    But this does.
    https://simple.wikipedia.org/wiki/Earliest_known_life_forms
     
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  5. DaveC426913 Valued Senior Member

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    Uh. No it hasn't.

    But I'm open to reading publishing papers on the theory.

    That's one theory. It is by no means the leading theory.

    The leading theory, unless it's been surpassed recently, is comet bombardment from the outer solar system.
     
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  7. Write4U Valued Senior Member

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    There is strong physical evidence of the giant-impact hypothesis
    https://en.wikipedia.org/wiki/Giant-impact_hypothesis
    Apparently it is.
    Can you explain why that is a better model than the one I just quoted?

    The evidence of the abundance of water on earth, where there was very little in the beginning, suggests a delivery by a large celestial body and not a bunch of small stuff delivering large volumes of water over long periods of time.

    That just doesn't fit the accepted model of emergence of life, which almost certainly did not happen recently, but offers a perfect chronology for the hypothesis of a large delivery of water just before the emergence of life.

    Again I refer to Robert Hazen, who has studied mineral evolution and the origins of abiogenesis in depth and knows about this stuff.
     
    Last edited: Mar 14, 2020
  8. paddoboy Valued Senior Member

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    That's actually silly and stretching the friendship. All that is being suggested is perhaps life started quicker then once thought, with the stuff necessary apparently arriving later..
    The original accretion disk was the one from whence the Sun and planets formed from. That was filled with the volatile rich material you mentioned, with the heavier stuff falling towards the center [where the terrestrial planets are] and the lighter stuff near the rim where the gas and ice giants orbit.
    The Sun is a Pop1 and Gen2 star, so the original accretion disk would have been metal rich.
     
    Last edited: Mar 14, 2020
  9. Write4U Valued Senior Member

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    I'll let you straighten this out all by yourself.....

    Please Register or Log in to view the hidden image!

     
  10. paddoboy Valued Senior Member

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    stuff up
     
  11. paddoboy Valued Senior Member

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    OK thanks, too much haste and not enough time...answer now modified.
     
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  12. paddoboy Valued Senior Member

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    In effect the bodies, Earth and Theia would have both already been metal rich from that original accretion disk.
     
  13. DaveC426913 Valued Senior Member

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    I didn't say Theia wasn't a strong hypothesis; I said it doesn't follow that that's where Earth got its volatiles primarily from Theia.

    See above.

    Is this your contention? Or is there an accepted theory that suggests volatiles and water came primarily from Theia?
     
  14. Write4U Valued Senior Member

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    The Collision that Created the Moon Might Have Also Brought Water to the Early Earth
    https://www.universetoday.com/14229...t-have-also-brought-water-to-the-early-earth/

    And that fits perfectly with the appearance of life which requires water. Occam.
     
  15. DaveC426913 Valued Senior Member

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    Yeah. So it's a competing theory. Not "established" as you asserted.
     
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  16. Write4U Valued Senior Member

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    No Theia did not come from our solar system, it came from further out. And that would account for a lot of extra-solar chemicals and minerals and most of all water.
    https://www.universetoday.com/14229...t-have-also-brought-water-to-the-early-earth/
     
  17. Write4U Valued Senior Member

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    I did not assert that. The quoted passages from reliable sources do.
    https://www.universetoday.com/14229...t-have-also-brought-water-to-the-early-earth/
     
  18. Write4U Valued Senior Member

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    I never claimed that Theia delivered "volatiles " to earth. Those may have well been delivered by many other celestial bodies impacting the earth. But life does not require many volatiles. Life only requires some 10% of the 5000 known minerals . But life does require water and Theia is a perfect "wet carbonaceous" candidate for delivering a single large quantity of water on earth, which may even have facilitated the abiogenetic process.

    https://www.universetoday.com/14229...t-have-also-brought-water-to-the-early-earth/
     
  19. Write4U Valued Senior Member

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    I believe here is where you may be misinformed. Theia was never a part of the accredtion disk before it impacted wih earth and created the moon from the resulting accretion disk. Theia ceased to exist during the impact.

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    1. An artist's depiction of the hypothetical impact of a planet like Theia and the Earth
    2. Animation of collision event between Earth (blue) and Theia (black), forming the Moon (red->grey). Celestial bodies are not to scale.

    https://en.wikipedia.org/wiki/Theia_(planet)

    The earth has a big chunk of Theia in its belly and a lot of its water and minerals as well.
     
  20. paddoboy Valued Senior Member

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    The thing is, if the hypothesis is accurate and correct, Theia was still formed fom the accretion disk that formed all the planets, Asteroids, comets and Sun anyway. Unless you are saying it was formed in another system? To which I would need to ask what evidence is there of that?
    Perhaps from the Oort cloud surrounding solar system out to about 2 or 2.5 L/years? Although strictly speaking, that is also still hypothetical.
    Or perhaps our Sun was just one of other stellar objects that formed in the same accretion disk system.
     
  21. DaveC426913 Valued Senior Member

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    That is literally what you claimed:
     
  22. Write4U Valued Senior Member

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    No, I didn't.
    Based on paddo's quoted claim by his source, I first posed a question what that volatile-rich material from the outer Solar System was (questioning if it was causal to the formation of life), and offered a solution that Theia might contain such volatile rich matrial, being that it came from the very outer Solar System.
    Remember, we were discussing if the necessary materials for life were deposited by Theia or by a constant bombardment of smaller asteroids which is what you claimed.

    p.s. Apparently Theia added considerable mass to the earths core, which is bigger than it is supposed to be. Theia is the prefect candidate because of its size and relatively slow speed which allowed it to penetrate the earths mantle without acting like a giant bomb. That's why large chunks of both Theia and the Earth broke lose when they merged, to form the basis for the moon?
     
    Last edited: Mar 14, 2020
  23. DaveC426913 Valued Senior Member

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    I think you're confused.
     

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