[meteorite-list] Question about the chemistry of the Martian atmosphere and Martian meteorites

From: Carl Agee <agee_at_meteoritecentral.com>
Date: Sat, 1 Mar 2014 22:03:04 -0700
Message-ID: <CADYrzhpRWOJ-KdR8stg1-2VbutrS+G0jrOdW0b71cMgRe6gV3A_at_mail.gmail.com>

MikeG,

Really good question! When you look at the data there are actually
few, if any, martian meteorites that are a perfect match for noble gas
isotopes of Viking. They tend to be a mixture of Viking and Earth
atmosphere, and there are spallation effects for Ar-isotopes. It has
been proposed that ALH 84001 contains ancient martian atmosphere that
is different from Viking, especially for Xe. However NWA 7034, which
is also ancient (albeit a breccia), has some of the most Viking-like
noble gas values. This is not my field so I am treading on thin ice
perhaps, but I would say that the picture is still not clear and Earth
contamination is always a factor. Also, it is possible that some of
the atmospheric gases were implanted at the time of impact that
launched the material off Mars (i.e. recent).

Carl Agee
*************************************
Carl B. Agee
Director and Curator, Institute of Meteoritics
Professor, Earth and Planetary Sciences
MSC03 2050
University of New Mexico
Albuquerque NM 87131-1126

Tel: (505) 750-7172
Fax: (505) 277-3577
Email: agee at unm.edu
http://meteorite.unm.edu/people/carl_agee/



On Sat, Mar 1, 2014 at 7:05 PM, Galactic Stone & Ironworks
<meteoritemike at gmail.com> wrote:
> Hi List,
>
> The CRE of the various Martian meteorites ranges from just under one
> million years to almost twenty million years. In terms of overall
> geologic history, this is a recent window of impact events that has
> produced the Martian meteorites in our collections.
>
> Scientists have confirmed the Martian origin of these meteorites by
> analyzing trapped atmospheric gases inside the meteorites. However,
> the composition of the trapped gases is being compared against very
> recent data (starting with Viking).
>
> Does this mean that the Martian atmosphere has not changed in millions
> of years? Or, do the analyses take into account observed/theorized
> changes in the atmospheric chemistry?
>
> I am a little unclear on this.
>
> Best regards,
>
> MikeG
> --
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Received on Sun 02 Mar 2014 12:03:04 AM PST