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Re: Bernd: Meteor May Not Have Destroyed Dinosaurs Afterall?

Hello Bernd and all - 

    Let me join others who many times before have
expressed their thanks to Bernd for data from his
amazing database! (If he ever manages to get
publication clearances, it is surely going to make one
stunning DVD or CD set.)

    We now have estimates as to the nickel content of
the impactor.  From the crater size and depth, it may
be possible to arrive at some broad range of estimates
for the total mass and velocity of the impactor. 
Multiply impactor mass times nickel content, then
derive  some estimates of total nickel load, tons
deposited locally, and tons vaporized.
    Then make some estimate of the neutralization
rate:
how much time passed before the nickel combined with
other chemicals to form organically inert or
inacessable compounds?  
     Then work through the toxicity rates.  The
toxicity reports published here indicated that most of
the effects at lower levels seemed to be on higher
centers of brain function, which would not have
affected primitive creatures with primitive brains, in
other words our burrowing creatures would not have
been much affected simply because they lack higher
centers of brain function.  Additionally, the burrows
would have protected the burrowers from initial nickel
exposure.
    Birds would probably have been affected,
especially neural functions. (By the way, Elton, is
there any data on birds riding the blast waves from
the nuclear tests or the Japanese bomb drops?)
    Information on nickel toxicity to plants and
simple organisms is probably also out there somewhere.
    The surface of the Earth was pretty well 
completely burned to ash, so there were plenty of
chemicals for the nickel to react with.  (Maybe the
nickel stopped the acid rain by combining with the
sulfur. :o))
    In any case, it's likely to be many years before a
precise modeling of the K-T blast is arrived at. In
the meantime you can simply state that the blast
killed everything except for burrowing animals and
birds, and that it set the entire surface of the Earth
on fire.

EP



    

  






--- Bernd Pauli HD
<bernd.pauli@lehrer1.rz.uni-karlsruhe.de> wrote:
> "E.P. Grondine" schrieb:
> 
> > I seem to remember a post last year about the
> composition
> > of the K-T impactor, but don't remember the nickle
> content.
> 
> Sky & Telescope, March 1999, p. 22: Piece of a
> Killer Asteroid ?
> 
> "While the mineralogy of the fossil meteorite has
> undoubtedly changed
> over time, K y t e   reports that the amounts of
> iron, chromium, and
> iridium are nevertheless close to the ranges seen in
> carbonaceous
> chondrites, ..."
> 
> BOND P. (1999) Fossilized remnant of dinosaur killer
> found (Astronomy
> Now, 1999, Jan, p. 9):
> 
> "His [= Kyte] findings suggest that the meteorite’s
> composition
> resembles a metal- and sulphide-rich carbonaceous
> chondrite asteroid,
> ..."
> 
> SHUKOLYUKOV A. et al. (1998) Chromium in the K-T
> boundary layer: First
> isotopic evidence for an impactor and its type  -
> carbonaceous material
> (Meteoritics 33-4, 1998, A144):
> 
> "... we have measured the isotopic composition of Cr
> in bulk samples
> of Allende and Orgueil. Treated in the same way as
> the K/T samples,
> preliminary data for Allende and Orgueil show that
> their Cr-isotopic
> signature is very similar to that of the K/T
> samples. Thus, regardless
> of what the "negative" 53Cr/52Cr ratio actually will
> translate into...,
> the obtained results strongly suggest that the K/T
> boundary impactor
> was comprised of carbonaceous-chondrite-type
> material."
> 
> As for nickel content, I found in the bulk analysis
> data:
> 
> 0.29% Ni for Camel Donga 003, a CK3 carbonaceous
> chondrite.
> 0,30% Ni for Watson 002, another CK3 carbonaceous
> chondrite.
> 
> On Mon, 19 Apr 1999, Jeff wrote to the Meteorite
> Central "gang":
> 
> "In fact, Allende has almost no metal, if what you
> mean is metallic
> Fe-Ni. Jarosewich (1990) measured ~0.5 wt% metallic
> iron plus nickel in
> Allende. Most of the metal in these oxidized CV3
> chondrites is the high-Ni alloy awaruite. There was
> once low-Ni metal
> (kamacite), but late stage oxidation has destroyed
> it all. There is a
> big debate going on as to whether this sort of
> process happened during
> parent body aqueous alteration or earlier, in the
> solar nebula."
> 
> Best regards,
> 
> Bernd
> 
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=====

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