[meteorite-list] Chondrule formation mechanism (Info Please)

From: E.P. Grondine <epgrondine_at_meteoritecentral.com>
Date: Sun Oct 22 11:24:25 2006
Message-ID: <20061022152415.4368.qmail_at_web36906.mail.mud.yahoo.com>

Hi Rob -

You noticed the contradiction in cooling periods as
well.

What I am thinking is that there was at least one
larger parent body which was "disrupted" about 3.9 Gya
(at time of LPBE). When this larger parent body was
disrupted, then the "effervescent" "foaming" that led
to some chondrules occured - sudden cooling, as
gravitation pressure had been released, and much lower
local gravity. Local processes suddenly take over - a
sharp gravitational and pressure transition, and a
sudden cooling. Gross processes - perhaps sufficiently
gross to overwhelm other small forces.

Through collisions of the resulting fragments, we see
some of the meteorite types we see today.

The problem here is that vibrations and accelerations
from the "disruption" should show up in the
chondrules.

Getting enough cosmic dust particles of exactly the
same type together to be melted together by some
process into a chondrule of exactly the same
composition all the way across does not seem too
likely - but then there may have been some process to
gather together cosmic dust particles of identical
composition. The energy source for the dust melting
should be seen in the chondrules - at least the
melting energies can be calculated.

Perhaps there is some non-euclidian solution for the
composition problem, but id so it is well beyond me
now, as is detailed measuring of chondrule boundaries.

Oh well. Researching Krasnojarsk, I have at least
discovered why some people become meteorite dealers -
they do it so they can afford meteorites.

good hunting,
Ed

--- Rob McCafferty <rob_mccafferty_at_yahoo.com> wrote:

> Ed
>
> Thanks for the reply. I'd really like to take a look
> at any data but to help be more specific on my
> requirements I'll give you an outline on my idea.
>
> The appearance of the unaltered chondrites seems to
> show that the outer rim of the chondrules are of a
> significantly diferent structure to the interior.
> Petrographic slides seem to show this as a dark
> boundary between the matrix and the chondrul and
> generally, the lower the petrographic type, the
> clearer this boundary is. 3.x it is impossible not
> to
> spot it.
> Now my understanding of this is that this is
> evidence
> of a rapid quenching period and the good internal
> structure is due to a much longer cooling period and
> this is where the current literature seems to stop.
>
> I do not believe that it need necessarily be
> evidence
> for rapid quenching and is instead a natural
> phenomena
> which occurs in true microgravity.
>
> A few months ago I was discussing Einstein's
> theories
> on Brownian Motion (as you do) with Canadian
> Astronaut, Bjarni Tryggvasson and he said that a few
> years ago he noticed Einstein missed a term for
> external energy and wanted to know what may happen
> if
> you removed external enegy sources (vibrations).
>
> Even on Mir and The Space Shuttle, the environment
> was
> not true microgravity (it's milligravity) you get
> minor accelerations due to vibrations in the
> spacecraft.
> So he developed a device to remove these vibrations
> and the environment in his equipment is of the order
> of 10^-6 g.
> He found that brownian motion is altered hugely by
> the
> lack of vibrations from an external source. Mixing
> is
> reduced by a factor of 3. A lot of what he was
> talking
> about was too abstract to fully comprehend at the
> time
> but it was fascinating so I read his paper and was
> astounded.
>
> Amazingly the temperature gradient at the surface of
> a
> liquid in microgravity is much steeper than on
> earth.
> Liquids are cooler at the surface because they lose
> heat outwards but by losing most of your brownian
> motion which would otherwise mix the outer and inner
> layers it increases the temp gradiaent massively.
> (convection is eliminated by microgravity and other
> forms of convection due to surface tension are
> removed
> in the experiment. These do not occur in small
> enough
> droplets anyway)
> Then I came accross one of his images of a glass
> bead
> forming in microgravity. It's about 0.5mm across
> (sound familiar?) and in thin section it has this
> beautiful outer rim that I instantly thought "hmm!
> I've seen that before".
> I'm pretty convinced that nobody else has made this
> connection. Meteoritics and brownian motion in
> microgravity are pretty far apart in the library of
> knowledge I'd have thought. I wondered if I could be
> right.
>
> Over the last couple of months I've tried to contact
> this guy again with no sucess to ask for more
> details
> of his experiments.
> This is why I'm asking you lot for help on the
> chondrule issue. I'd like to see some proper
> analysis
> of the structure of the chondrule boundary. It's
> likely that the similarity is coincidental but I'd
> like to check anyway.
> It's why I want to know the theory on the solar
> nebula
> conditions. Too great a density would produce
> vibrations which prevent this happening but I
> suspect
> interplanetary vibrations, even that early on, at
> the
> distances these things formed at from a protostar is
> going to be unlikely to prevent chondritic glasses
> forming the boundary they exhibit.
>
> I personally think this is an elegant idea which
> does
> away with a lot of the messy heating, cooling stuff.
> The outer layer would form a nice insulating layer
> which would then allow the interior of chondrules to
> cool slowly and exhibit the structures we see. It
> neatly requires chondrules to form first. Other
> stuff
> would disrupt the pattern we see. The way I see it
> they needn't take too long to form either.
> But then, I'm probably not seeing it correctly.
> That's
> why I need information.
>
> I don't know enough yet about the birth of solar
> systems to even guess at the implications of my idea
> if it ever proved correct. I'd like to work on it
> and
> prove SOMETHING, anything.
>
> My mum always had aspirations of me becoming a
> doctor...ahem.
>
> Rob McCafferty
>
> --- "E.P. Grondine" <epgrondine_at_yahoo.com> wrote:
>
> > jeez Bob,
> >
> > and all I was trying to do was to come up with a
> > good
> > excuse to personally examine that Krasnojarsk
> RSPOD
> > Oct 15.
> >
> > You're just about ready to handle some of my
> > asteroid
> > and comet impact correspondence.
> >
> > Ed
> >
> > --- Rob McCafferty <rob_mccafferty_at_yahoo.com>
> wrote:
> >
> > > Hi list
> > >
> > > What I have ben able to find personally on
> > chondrule
> > > formation is rather sketchy.
> > >
> > > Even the otherwise comprehensive Encyclopedia of
> > > Meteorites by O. Richard Norton seems to skim
> over
> > > the
> > > mechanism in a paragraph. It's almost as if
> there
> > is
> > > something which defies explanation and
> scientists
> > > abhor that more than nature abhors a vacuum.
> > >
> > > The "slow cooling followed by a rapid quenching"
> > > period is that which interests me most.
> > >
> > > I would dearly like to know where to find the
> most
> > > up-to-date theories on chondrul formation. I
> know
> > > about the R-R Lyrae heating, timescales and
> > > frequecies
> > > for newly forming stars. I need theory of
> > > protostellar
> > > nebula. Maybe Nebula density/stellar distance
> > > formula.
> > > The conditions in which and the timescale in
> which
> > > these 0.1- 3mm chondules formed.
> > >
> > > Contact off list if you wish. I need this
> > > information
> > > to assist me with a theory I have, the
> information
> > > for
> > > which comes from branches of science so diverse,
> > > that
> > > their relevance has not been realised. It is
> only
> > by
> > > serendipity that I make the connection.
> > > My thoughts will appear here first (though I
> will
> > > ruthlessly hunt down and murder anyone who tries
> > to
> > > plagarise my theory, hehe)
> > >
> > > Rob McCafferty
> > >
> > >
> > > --- Darren Garrison <cynapse_at_charter.net> wrote:
> > >
> > > > On Sat, 21 Oct 2006 16:41:48 -0700 (PDT), you
> > > wrote:
> > > >
> > > > >> Chondrule textures depend on the extent of
> > > > melting
> > > > >> of the chondrule precursor- material when
> > > cooling
> > > >
> > > > >> starts.
> > > > >
> > > > >Kind of begs the question - chodrules formed
> by
> > > > >collision, which causes melt - consider if
> one
> > > > started
> > > > >from a steady molten state
> > > > >
> > > > >>If "viable nuclei"
> > > > >
> > > > >I wonder what these "viable nuclei" are?
> viable
> > > > cystal
> > > > >nuclei=Chondrules?
> > > >
> > > > How things appear to be (without trying to
> refer
> > > to
> > > > chemical/minerological
> > > > details that are beyond my level of knowledge)
> > is
> > > > that what became chondrules
> > > > started out as "fluff" that slowly accumulated
> > > from
> > > > the solar nebula, like you
> > > > mentioned earlier. I imagine something like
> > > > snowflakes, or dust-bunnies.
> > > > Something fragile and irregular filled with
> > empty
> > > > spaces. Then, something (and
> > > > there is no consensus on what that "something"
> > > was)
> > > > heated those
> > > > dust-bunnies/snowflakes up to the point where
> > they
> > > > melted-- and in a
> > > > microgravity environment surface tension
> pulled
> > > them
> > > > into little spheres. The
> > > > "viable nuclei" means parts of that original
> > fluff
> > > > that didn't fully melt and
> > > > became seeds for the new minerals to grow on.
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Received on Sun 22 Oct 2006 11:24:15 AM PDT