PNAS: No evidence of nanodiamonds in Younger Dryas sediments to support an impact event

no evidence of nanodiamonds in Younger Dryas sediments to support an impact event

  • Steve Garcia

    This article was posted on another blog I frequent and I have posted there this:

    #

    It seems that an EXTEMELY curious particular in this story is the graphene/graphane itself.
    Lazy guy that I am, for non-AGW stuff I go see what Wikpedia has to say. Let’s start with graphane:

    Graphane is a 2-dimensional polymer of carbon and hydrogen with the formula unit (CH)n where n is large…. Graphane is hydrogenated graphene

    Simple enough. Graphane is 2-D, which means pretty much VERY thin. As in (see below) 1-atom thick apparently

    It is a very short Wiki entry on graphane, but a very long one on graphene.

    And graphene is a VERY interesting – AND essentially NEW – material, having been kind of “rediscovered” in 2004.

    Oddly enough, for a form of carbon, graphene

    The (original source) Science Daily article says this:

    Instead, graphene- and graphene/graphane-oxide aggregates [emphasis added] were found in all the specimens examined (including carbon spherules dated from before the YD to the present). Importantly, the researchers demonstrated that previous YD studies misidentified graphene/graphane-oxides as hexagonal diamond and likely misidentified graphene as cubic diamond.

    Now, after reading about graphene, that word “aggregate” jumped out like a lit arc lamp. You see, graphene basically is a one-atom-thick, 2-dimensional material. So what is this about “aggregates”?

    Because it was found in the “black mat” (which seemingly NEEDS to be in quotes, btw), I went searching for how graphene is formed in nature. Simple enough, yes? Is it common in meteoric material? Is it formed in impacts? Is it common in graphite?

    The article certainly suggests the latter, when it says they

    show that the material reported as diamond is instead forms of carbon related to commonplace graphite, the material used for pencils.

    You see, THAT is supposed to be them laughing down their nosest at the Y-D people – RUBBING their noses in it, even – who evidently can’t even tell nano-diamonds from common everyday graphite.

    The article says

    the presence of hexagonal diamond in YD boundary sediments represented the strongest evidence suggesting shock processing,” Daulton, who is also a member of WUSTL’s Center for Materials Innovation, says.

    Well in a LONG Wiki entry, guess what? They don’t mention graphene being made naturally at ALL. Does that strike any of you as odd?

    (Note: I’d actually not long ago had reason to look up graphene. I can’t recall exactly why, but it MIGHT have been when I was reading Firestone’s popular book. I recognized the name and then recognized the Wiki entry.)

    It seems that graphene is sort of the current Wunderkind of materials science.

    “As of 2009, graphene appears to be one of the strongest materials ever tested. Measurements have shown that graphene has a breaking strength 200 times greater than steel.[89]”

    Since 2004, labs have been working on ways of making graphene, which is NOT easy, yet there have been several developments. One thing they can NOT do is make “large” sheets of it. . .

    Larger graphene molecules or sheets (so that they can be considered as true isolated 2D crystals) cannot be grown even in principle. An article in Physics Today reads:

    “Fundamental forces place seemingly insurmountable barriers in the way of creating [2D crystals] … Nascent 2D crystallites try to minimize their surface energy and inevitably morph into one of the rich variety of stable 3D structures that occur in soot. [emphasis added]But there is a way around the problem. Interactions with 3D structures stabilize 2D crystals during growth. So one can make 2D crystals sandwiched between or placed on top of the atomic planes of a bulk crystal. In that respect, graphene already exists within graphite … One can then hope to fool Nature and extract single-atom-thick crystallites at a low enough temperature that they remain in the quenched state prescribed by the original higher-temperature 3D growth.”[19]

    Wow.

    So we have this REALLY odd material that has only been known really since 2004. Firestone was getting his book published about that time. No wonder if his labs didn’t recognize it. The work was being done in Manchester, England, and not many people in the world really knew about it. One MIGHT forgive them for mistaking some new material – especially one in a form not known even now, if I read Wiki correctly. Nano-diamonds are not 2-D, but the material in the “black mat” is an “aggregate,” whereas graphene is only 1 atom thick 2-D material.

    From yourdictionary.com:

    aggregate Geol. made up of a mixture of mineral fragments, crystals, or similar materials

    That is pretty much how I understand the term “aggregate”

    Now I am getting a disconnect here. The article is scathing in its laughter at the “Y-D team” for having mistaken graphene/graphane for nano-diamonds – EVEN THOUGH GRAPHENE WAS A NEW MATERIAL, GRAPHENE IS 2-D, AND THE MATERIAL IN THE “BLACK MAT” WAS AN AGGREGATE. GRAPHENE DOES NOT COME AS AN AGGREGATE.

    On the surface, it seems the researchers are not anymore correct than the Y-D impact scientists. If it is an aggregate, it cannot be graphene. If it is graphene OR graphane it cannot be an aggregate.

    So, is it hexagonal diamond? Or is it graphene/graphane? Or is it some OTHER form of carbon, in an aggregate structure? Or is it graphene/graphane or hexagonal diamond attached to the carbon spherules which they mistakenly call “aggregates”?

    In the very long article Wiki does not ever say how graphene is made in nature. Which I find most interesting.

    I am still looking elsewhere. . .

  • Steve Garcia

    Regarding graphene, here is a really good article.

    http://onnes.ph.man.ac.uk/nano/Publications/Naturemat_2007Review.pdf

    These people claim to have found graphene in the wild? This does NOT make sense. Trust me. Read about graphene and make up your own mind.

    They say they found it in “aggregates”. I’d like to see that, since graphene thicker than 10 atoms thick is considered graphite – plus it is always in VERY small wafers (<< 10 micrometers wide/long). Ever seen 10 atoms thick? See the article…

  • Steve you don’t understand what graphene is and you are hung up on the word aggregate.

    Graphene is a sheet structure. To understand it better, consider a deck of cards. You can think of a sheet of graphene as one card from a deck of cards. If the graphene is stacked one on top another, as cards are stacked in a deck of cards, then the deck of cards is called graphite. If the graphene sheets are randomly distributed in three dimensions, for instance in the case where many decks of cards are poured into a box, then the contents of the box can be called an aggregate of graphene.

    There is nothing special about the term aggregate, the words cluster, agglomeration. or pile for that matter could have been used in its place.

  • I read over the Daulton paper again and it states,

    “In the form of a polycrystalline aggregate, as first observed in the cores of many circumstellar graphite spherules isolated from chondritic meteorites (30), graphene sheets are randomly oriented and lack any correlation. When periodically stacked normal to their plane (e.g., AB, AA, or ABC stacking), graphene sheets form various graphite polytype structures or turbostratic graphite if the stacking is disordered.”

    It is quite clear what they mean by graphene aggregate.

    Despite what you wrote Steve, graphene has been observed in nature “in the wild” in meteorites as stated in the paper. So if graphene aggregates are found in meteorites, it is quite possible that they could also form on the earth just as the case for graphite, amorphous carbon, fullerenes, and the host of other minerals which form both in meteorites and on the earth. Just because no one has looked for them before, doesn’t mean they were not there all along.

  • Since many of the scientists who’ve reported NDs in the YDB have now reported NDs in a layer of the Greenland Ice Sheet. I wonder….

    Same scientists…. Same mistaken identity? Are Pinter & Scott going to claim that stuff is “graphene aggregates” too?

    NDs, or nano-scale Graphene Aggregates, take your pick. Either way, I wonder if anyone can ‘splain for me a plusible terrestrial process to get a discrete layer of the stuff in an ice sheet that doesn’t involve an impact event.

  • Blah-De-Blah

    The point is that the Graphene is found above, around, and below the YD boundary. Not isolated at the YD boundary. Second, it is NOT nano-diamonds, something that would come from impact shock pressures. Third, the error bars are huge on the proponents paper for the impact. Could very easily miss read the data. Fourth, the Daulton is commenting on the 2009 Kennett article, not the 2004.

    There is cosmic dust that rains on the planet everyday, and it does reach the surface. If you head down to antarctica, you’ll find ‘tons’ of the stuff on the ice sheets.