Gee, Doug,
For once, I am not creating a crackers theory of my own.
I am merely explaining how a certain geochemical test procedure
works. Not being a geo- or a cosmo- chemist, I am taking the
word of Matthies, D. and Kroeberl, C., Fluorine and Boron
Geochemistry of Tektites, Impact Glasses, and Target Rocks,
Meteoritics, 26 (1991), 41-45, both of whom AM geochemists.
Also, see K. H. Wedepohl, Handbook of Geochemistry (1978).
Blah, blah.
Think about it. You gotta rock. Mixture of complicated
crystals. Many elements. Huge heating event. Rock melts.
Rock vaporizes. Molecules dissociate. Now it's a plasma,
composed entirely of elements, too hot to form compounds.
The volatile elements in this plasma escape from the plasma
faster than the less volatile, which in turn escape faster
than the "refractory" (who are stubborn and hang around).
The plasma continues to heat. Volatiles go faster and faster.
At a high enough temperature, the mean free path of atoms
and their rate of escape is pretty much totally determined
by the thermal energy of the plasma and the mass of the atom
and the chemical characteristics of the substance matter not
at all. It's physics now, not chemistry. Element 5 (mass 11)
and element 9 (mass 19) are both moving like there was
a 38,000 degree plasma on their tail (and there is). They
now escape at a similar rate. Get the literature. Look at
the pretty graphs that show how it works. There's some
chemical reason why this happens about the time they're
at the same concentration, but I forget it. It's chemistry.
Me, when I look at things like equilibrium condensation
diagrams or the reverse of same, my eyes start to glaze
over... So I just take their word for it. But as a physical
phenomenon, it fits my intuition. Look at the other light
atoms. Not many of them hanging around either.
Makes silly hand gestures, points to self. I no chemist.
Physicist. Like big things (universe, stars, planets, rocks
the size of countries). Like little things (quarks, leptons,
cute little bosons, petite atoms). Don't like things inbetween.
That's why God made chemists and botanists. Let them
sort it out. They like that sort of thing for some reason...
In 1962, when the number of "elementary" particles
officially went over 200, Enrico Fermi, getting old and
cranky, yelled, "Look at this f***g zoo! If I wanted this
mess, I'd have become a botanist!" (He was right; how
can you have more "elementary" particles making up
elements than there are elements? Maybe it means that
making elements is hard.)
Crusty old physicists. Show me String Theory when
you can put the whole thing on ONE PAGE. Otherwise,
go back and work on it some more.
Deep breath. The F/B ratios for ALL terrestrial rocks
comes from Kroeberl and Company (all of this does). That's
for the bulk compositional analyses of crustal rocks everywhere
that geologists have made 100,000's of for the last century
or so. Boring... Boron's just not as common as fluorine. The
ratios run 10:1, 20:1, 30:1. Earth rock just isn't (in bulk)
boronic. That crusty stuff in Death Valley doesn't count...
If boron was common, would they have send Ronald Reagan
and those 20 mules into Death Valley? (Old TV referrence.)
If you think this is all hooey, complain to Kroeberl and Co.
Also Wedepohl, who publishes thick books full of endless
tables of bulk elemental compsitions. Lemme know what
happens.
Seriously, I am miffed. I don't think this stuff is whacky
enough to be one of my whacky notions, and I'm insulted
that anyone should think so... Obviously, I'm not being
whacky enough.
I'm quiting. It's late enough that I could go out
and wave at that comet myself.
Sterling K. Webb
--------------------------------------------------
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>;
<[EMAIL PROTECTED]>; <Meteorite-list@meteoritecentral.com>
Sent: Sunday, March 05, 2006 2:34 AM
Subject: Re: [meteorite-list] Largest Crater in the Sahara Desert and LDG
Sterling W. writes:
<< I don't know the values for the Nubia Sandstone,
but the range of sandstones is fluorine 180 to 450
ppm and boron about 10 to 85 ppm. The figures
for LDG is fluorine 7 ppm and boron 7 ppm, so
you see how the ratios shift as the content drops.
As the temperature rises (microsecond by microsecond),
the fluorine content drops much faster than the boron
content. At some very high temperature (variable
for each source rock), both fluorine and boron
levels become the same, but at a higher level than
in the final product.
After that point, both are driven out of the melt
plasma at the same rate, their petty chemical
differences totally overwhelmed by the energy
available. So, fluorine goes faster until that point
is reached, after then, they drop together. >>
Hola Sterling,
Petty chemical differences....hmmmmm.....overwhelmed at moment x when they
behave identically (this is the cartoon "and then a miracle happens and we
get
the desired solution")...I hope you can do better than this! This last
paragraph has pegged my bogometer and the needle broke as I see physical
laws being
bent to accomodate your interesting and provolking speculations. It's
either
the most unfounded, unscientific argument and counterintuitive I've ever
heard
you seriously make - or - you speak about this thermometer as if you
actually
were there watching the impact and taking notes by the microsecond on how
Boron and Fluorine behave under singular circumstances and states that are
poorly
defined to start with! I didn't dispute the use of [F]:[B] to compare
different forms from the same source rock (a reasonable use of the
"thermometer"),
that is not what you are doing. I hope you can see how you are pulling
numbers
from out of the air which are all over the map and cooking pretty
conclusions
out of them. To answer my question, I'd back up and ask for the following
modest data:
1. reference - Where you got moldavites bottoming out at [B]=30 ppm (for
[F]=30 ppm, at least)?
2. Based on how many samples is your "typical" value [F]:[B] of Ivory
Coast
tektites and what was the low end for the ratio? Was it a lot less than
1?
How would your physics' scheme explain a value below 0.5 for the
ratio....since
you have re-enforced the point I most object to by saying they magically
reach
the same concentration and then decrease equally...
3. Without the respective values of F,B in Nubian sandstone near the
crater,
my question isn't anywhere near answered:( !!
You mentioned:
<<It looks like LDG had a very hot forming event,
so the high water content is a real puzzle.>>
It's only a real problem puzzle in this context because you have read too
much into and extrapolated much too far with the halogen thermometer
concept.
The water, rather than being a problem to explain, might be telling you
that the
F:B interpretation and extrapolations are all wet..., there is also a
failure
to consider different resident times for the measureables in the melt as
yet
another additional consideration. Not to mention of course the
alternative or
coincident possibility that LDG's have that content due to the low or
surface
altitude at which they formed...
And this:
<<ALL terrestrial rocks have a F/B ratio greater
than 5.0 (often 20 or 30). but all impact glasses,
even the weakest dirtiest just barely melted impact
glasses have a F/B ratio less than 5.0 -- the result
of a few thousand degrees of heating.>>
"ALL" is a very encompasing term. Are you sure it wasn't mentioned
principally regarding a total of two dozen tektite samples and three
events for which
the craters are known, weighted grossly in favor of Indochinites - rather
than
the whole wide world? Sure, 5 quite possibly is the minimum in
unimpacted
sediments worldwide but I'd need more than an arbitrary statement to
believe it
after reading the other assertations...are we still refering to Dr.
Koerbel's
work?
Bedtime, I have a date with a comet in a couple of hours:), 'Night,Doug
______________________________________________
Meteorite-list mailing list
Meteorite-list@meteoritecentral.com
http://six.pairlist.net/mailman/listinfo/meteorite-list
