[meteorite-list] Dino Killer size

From: mexicodoug at aim.com <mexicodoug_at_meteoritecentral.com>
Date: Sun, 13 Apr 2008 15:30:20 -0400
Message-ID: <8CA6BB3F204AFB8-238-781_at_FWM-D38.sysops.aol.com>

Hi Ted, Darren, Listees,

Thanks to Ted for the link of the first paper (should scientists now
mind their pdf's or perish rather than call them "papers") to use
isotope (vs. elemental, i.e. Iridium) presence/ratios to show the
proposed K/T impactor was a carbonaceous chondrite. As the authors
show, it was done by confirming especially high chromium 54-Cr as well
as a 53-Cr proportion compared with the terrestrial 52-Cr baseline,
according to the pdf.

Darren, I believe Ed asked if it was a carbonaceous chondrite and that
is what Ted responded to, not whether it was "wet" or "dry" with water
and other volatiles, which is another topic entirely.

As to the comment that a dry carbonaceous chondrite is called an
"asteroid" and a wet one, a "comet", while that sounds nice and
logical, I think it is a little misleading in common speech (just like
his comment on dihydrogen monoxide which we all better know as water,
so perhaps Darren is joking around). As we know best, the fate of many
comets is fragmentation (and we've even seen impact), and this is
nearly complete into little grains as far as we can tell in meteoroid
streams. Rubble-Pile is a possibility after "drying" - but has this
been proven? Other asteroids are called "dormant comets" under the
impression that they are mostly inactive at their perihelia, though a
change could "revive" them.

I am not sure we ought to call something a comet that is half baked and
has never errupted. For this reason neither Pluto nor Ceres are
normally called comets. Hidalgo, I couldn't begin to guess... But he
was a great man and also fine Mustang...

Best wishes and Great Health,
Doug


On Sun, 13 Apr 2008 09:32:33 -0700, you wrote:

>According to Cr and Mn isotopic analyses of KTB samples, the impactor
was a
>carbonaceous chondrite - see report at:
>
>http://www.lpi.usra.edu/meetings/impact2000/pdf/3041.pdf
>

Yes, but it appears that comets are essentially carbonaceous chondrites
that
formed far enough from the sun to not lose their volitile mineral
ddihydrogen
monoxide. So saying that it is a carbonaceous chondrite doesn't
conclude if it
iwas a wet one (called a "comet") or a dry one (called an "asteroid




-----Original Message-----
From: Darren Garrison <cynapse at charter.net>
To: meteorite-list at meteoritecentral.com
Sent: Sun, 13 Apr 2008 12:51 pm
Subject: Re: [meteorite-list] Dino Killer size



On Sun, 13 Apr 2008 09:32:33 -0700, you wrote:

>According to Cr and Mn isotopic analyses of KTB samples, the impactor
was a
>carbonaceous chondrite - see report at:
>
>http://www.lpi.usra.edu/meetings/impact2000/pdf/3041.pdf
>

Yes, but it appears that comets are essentially carbonaceous chondrites
that
formed far enough from the sun to not lose their volitile mineral
ddihydrogen
monoxide. So saying that it is a carbonaceous chondrite doesn't
conclude if it
iwas a wet one (called a "comet") or a dry one (called an "asteroid").
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Received on Sun 13 Apr 2008 03:30:20 PM PDT