[meteorite-list] Re: Mercury Meteorite Puzzle

From: E.P. Grondine <epgrondine_at_meteoritecentral.com>
Date: Thu Apr 22 10:04:49 2004
Message-ID: <20020518152605.87274.qmail_at_web11606.mail.yahoo.com>

Hi all -

Hmmmm - Oxygen isotopes from a large parent body, but
minerally apparently different than Mercury?

This is returning to that old problem of the size of
the parent(s) of different types of meteorites. My
thinking is that it may also be related to the LPBE.

I any case, the key problem seems to me to be
accretion processes, which are still on-going.

looking forward to what comes next -
ep








--- Robert Verish <bolidechaser_at_yahoo.com> wrote:
> "NWA 011 has an oxygen isotope ratio that indicates
> it
> came from a body larger than a big asteroid."
>
> Okay. This article explains to me why this
> meteorite
> came from a body larger than an asteroid. But it
> doesn't explain how the other "planet-sized bodies"
> in
> our solar system are being ruled-out in favor of
> Mercury.
>
> Is there an upper limit for the suspect
> "planet-sized"
> parent body, that would exclude Mars, Venus, or
> Earth!
> (The 81Kr-Kr age for NWA011 is 39 ± 5 Ma, which can
> be
> interpreted as an upper limit of the cosmic-ray
> exposure age, which would exclude the proto-versions
> of these inner planets)?
>
> Same-sized planetary bodies? We know enough about
> the
> Moon to rule out a Lunar-origin, but do we know
> enough
> about the Galilean moons of Jupiter to rule them
> out?
>
> It would be interesting to see a matrix showing
> suspect parent bodies vs. NWA 011 data, and to see
> which evidence favors which "planet-sized body".
>
> Here's what we already know:
>
> April12th issue of Science, Akira Yamaguchi
> (National
> Institute of Polar Research, Tokyo)
>
<http://www.sciencemag.org/cgi/content/short/296/5566/334>
>
> Meteoritical Bulletin 84, Table 9
>
> ----------------------------------
> [meteorite-list] MAPS and Mercury
>
> Bernd Pauli HD
> bernd.pauli_at_lehrer1.rz.uni-karlsruhe.de
>
> Sun, 14 Apr 2002 15:20:10 +0200
>
> Marco wrote:
>
> > By the way, I remember that some time ago a paper
> on
> the characteritsics and expected numbers of
> meteorites
> from several parent bodies (including Mercury and
> Venus) has been published in Meteoritics & Planetary
> Science.
> > Sorry I do not have an exact reference ready at
> the
> moment: that's because I am packing up to move to
> another house currently. But a search on NASA ADS
> will
> probably reveil it to you.
>
>
> LOVE S.G. et al. (1995) Recognizing mercurian
> meteorites (MAPS 30-3, 1995, 269-278).
>
> ROBINSON M.S. et al. (2001) Ferrous oxide in
> Mercury's
> crust and mantle (MAPS 36-6, 2001, pp. 841-847).
>
> Best regs,
>
> Bernd
> -------------------------------------------
>
> [meteorite-list] Mercury Meteorite Puzzle
>
> Ron Baalke baalke_at_zagami.jpl.nasa.gov
> Thu, 16 May 2002 10:38:56 -0700 (PDT)
>
>
http://news.bbc.co.uk/hi/english/sci/tech/newsid_1991000/1991394.stm
>
> Mercury meteorite puzzle
>
> Is this from Mercury, the planet closest to the Sun?
>
> By Dr David Whitehouse
> BBC News
> May 16, 2002
>
> The first meteorite that may have come from Mercury
> has been identified.
>
> NWA 011 was found in the Moroccan Sahara in December
> 1999 and was immediately regarded as something
> unusual.
>
> It clearly had a molten past and was formed from
> lighter materials than most meteorites. This implied
> it had once been part of a much larger body.
>
> It was originally classified as a eucrite, a group
> of
> meteorites thought to be from the asteroid Vesta.
> But
> a detailed analysis of NWA 011 showed it to be
> different.
>
> Now, researchers speculate that it is the first
> known
> meteorite from our Solar System's innermost planet,
> Mercury.
>
> Rocks blasted off Mercury by a large impactor would
> have a difficult journey to reach the Earth, say the
> researchers - but not impossible. Nevertheless, the
> calculations show such rocks would be an extremely
> rare find on Earth.
>
> NWA 011 has an oxygen isotope ratio that indicates
> it
> came from a body larger than a big asteroid.
> Japanese
> researchers say the basalt in NWA 011 suggests the
> body from which it did originate had a core of
> molten
> iron with an outer covering of silicon and aluminium
> that formed a basaltic crust.
>
> And that means a planet-sized body. Could it really
> be
> Mercury?
> ---------------------------------------------------
>
>
>
>
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Received on Sat 18 May 2002 11:26:05 AM PDT