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Re: (meteorobs) Re: Kaigorod and brecciation

>Hi everyone...
>
>I recently obtained a beautiful brecciated sample of Kaigorod from Mike
>Farmer which prompts the following question.   We are assuming that the
>brecciated nature of this and other meteorites is the result of impact at
>some earlier time.  However, the metalflake in this meteorite is relatively
>evenly distributed throughout all portions of the breccia.  Is this even
>distribution the result of heating in the atmosphere or is there some other
>explanation for its presence and even distribution?  Does anyone know the
>current explanation for this phenomenon?
>
>Thanks in advance!
>
>
>
>
>Steve Ervin
>*************************************
>Dr. Stephen Ervin
>Department of Biology
>California State University, Fresno
>Fresno, Ca.  93740-0073
>servin@csufresnodot edu
>*************************************
>

Steve:
        You would have to ask a geologist about the even flake distribution
in your meteorite.  It is definitely not a result of heating during its
flight through the atmosphere.  A meteoroid behond the earths atmosphere is
at outer space temperature, very cold, and the time of flight through the
atmosphere is short.  As it penitrates the earths atmosphere at high
velocity the surface heats up and is ablated off.  Most of the heat has thus
left the meteoroid itself.  At a height of around 5 to 8 miles or so the
meteoroid has lost its hypersonic entry velocity and stops glowing.  As it
falls the rest of the way, the cold temperature of the interior cools the
outer surface.  The meteorite may even have a layer of frost on it upon
landing, not hot as is the popular belief.  This has probably resulted from
the fact that meteorites may be slightly warmer than nearby terestrial
stones.  Most meteorite surfaces are dark, black or chocolate brown shortly
after being found.  Earth rocks are often a light colour and absorb less
solar heat and are thus colder to the touch.  If you get a geological
explination, let me know what it is.  I will check some of the reference
material that I have to see if there is a further explination.

Ed
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Edward Majden                         epmajden@mars.ark.com
1491 Burgess Road                     Meteor Spectroscopy
Courtenay, B.C.                       AMS Affiliate
CANADA  V9N-5R8                       MIAC Associate
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