[meteorite-list] Asteroid Color Clans

From: John Divelbiss <j.divelbiss_at_meteoritecentral.com>
Date: Thu Apr 22 10:06:13 2004
Message-ID: <000701c284c3$1dd9d720$35015a0c_at_0m824>

Hi Al,

Great stuff Al. As always, thank you for responding to my question and
comments. You guys are going to force me back into the books to see what I
read, but obviously didn't learn.

As I remember it, the evidence with Vesta has to do with the large "gouge"
in it's side that shows different levels of crust (eucrite) and sub crust
(diogenite). This leads to another challenge or question, "if we think all
or most of HED's come from Vesta, then why do they look so different from
each other?". Some eucrites are white or grey, while others are a shade of
light brown/yellow. The differences in diogenites are even greater. Is the
new olivine diogentite thought to be from Vesta also?

My answer would be "they sure could be". My experience in finding plutonic
rocks here on earth is that the same area of exposure searched can have a
wide variety (in appearance) of same type type rock. Some are more rich in
one mineral than another...but for the most part still made up of the same
ingredients. Temperature and pressure of the magma at one location versus
another precipitates out minerals at different rates. Also the makeup of the
magma then changes as it losses more of one element than others, changing
the resulting rock formation mineral ratios. I think I answered my own
question, but I'M WAY OVER MY HEAD HERE!!!

HELP.....John



----- Original Message -----
From: "almitt" <almitt_at_kconline.com>
To: "John Divelbiss" <j.divelbiss_at_worldnet.att.net>
Cc: "Bernd Pauli HD" <bernd.pauli_at_lehrer.uni-karlsruhe.de>; "Meteorite List"
<meteorite-list_at_meteoritecentral.com>
Sent: Tuesday, November 05, 2002 1:23 AM
Subject: Re: [meteorite-list] Asteroid Color Clans


> Hi John,
>
> I'll take a stab at this but Bernd really has great resources for
answering this no
> doubt better than I can. The topic that Bernd had started was on asteroid
color clans
> and that at least 90 percent of asteroids are associated with families
(from
> collisions in the past). No doubt the Vesta HED's are from chunks broken
off from
> Vesta in an impact and that have made their way into an orbit that upon
further impact
> has allowed meteoroids to end up in some of the kirkwood gaps where they
can be
> purbatrated into Earth crossing orbits. Yes they are from other sources
but they
> originated from the same source or asteroid. No doubt this is true for the
other
> related asteroid family groups and again the color clans that they are
beginning to
> piece together with the new research.
>
> I don't know if we can say for sure or not if a certain meteorite is from
a particular
> asteroid chunk or fragment but there is very strong evidence to show the
HED's are
> indeed from Vesta and also a strong link of the H type chondrites to
asteroid Hebe. I
> don't think there is much doubt about the Mars type meteorites (SNC's) are
from Mars
> and the Lunar meteorites are from the moon as we have been there and have
material to
> compare to. With the color clans coming into play we can at least say that
certain
> meteorites are from certain families now.
>
> On a related note Mar's moon Phobos is very similar to the CV3's like
Allende but
> there are also many other asteroids out there with that spectral match
(could it be
> the same clan?) I have always thought with the larger crater I see in the
photos taken
> by NASA that Phobos was a good candidate for that source material.
>
> Another question or comment. Perhaps some of the meteorites of different
classes
> sample the same asteroid (or family, clan). We could have iron meteorites,
pallasites
> and chondrites or achondrites all from the same parent body but we are
looking at
> different depths of material all from the same parent body or asteroid
family clan.
> This is no doubt true of the meteorites we have from Vesta and shows
material from
> different depths. My best!
>
> --AL
>
> John Divelbiss wrote:
>
> > Hi Al, Rob, Bernd and others,
> >
> > I think it is wonderful to think we can match types with asteroids that
are
> > labeled and watched.
> >
> > I have a question. Is it safe to say that what we are doing is matching
> > spectrums of types with those same specturms for a given asteroid, but
not
> > necessarily committing to say that is probably from that asteroid. In
other
> > words, their maybe(must be) several to hundreds of a given type asteroid
out
> > there. And that one LL4 could come from one rock, and another from a
> > different rock with the same spectrum on the opposite side of the belt.
I
> > maybe stating the obvious, but for instance I so often read that an HED
is
> > probably from the asteroid Vesta, when in truth it maybe from another
one.
>
>
Received on Tue 05 Nov 2002 07:01:45 AM PST