[meteorite-list] Serious question?

From: j.divelbiss_at_att.net <j.divelbiss_at_meteoritecentral.com>
Date: Thu Apr 22 10:29:56 2004
Message-ID: <20030917013247.5045E53586_at_pairlist.net>

Hello all,

Here is my simple, romantic notion of Mars and its red-orange/yellow-brown
rocks.

Living here in Pennsylvania and being close to some very nice Pre-Cambrian
bedrock(mafic and ultamafic) that includes metadiabase gabbro, olivine-rich
gabbro, dunite-like olivine veins, and mica-rich gabbro/peridotite...I've
always had the idea that the weathered yellow-brown to orangish brown outer
skins I've seen on these iron-rich rocks has the same look we've seen from
the pictures taken by the rovers on Mars. Most of the rocks we see in those
pictures on Mars are possibly weathered exteriors of basalts, dunites and
gabbros/peridotites. However those same pictures do have a "dusty" look to
them.

I'm sure it is not that simple, but from an appearance standpoint we have
rocks that develop that same look here on earth...as in colors.

John
> At 11:00 PM 9/16/2003 +0000, you wrote:
>
> >The concept of a red planet as the result of meteorite bombardment is absurd.
>
> Maybe not, if you have the right kind of planet, namely one with an
> atmosphere and appropriate oxidizing compounds. Albert Yen and colleagues
> wrote a paper about this a bit in _Science_ a few years back. I don't
> have the paper at hand, but I think it was sometime around September
> 2000. Yen suggested a "super-oxide" process to explain present day soil
> rusting on Mars with ultraviolet light the catalyst. Since this process is
> very slow, even by geological time scales, many planetologists still
> believe most of the red color probably dates back to a time when Mars was
> wetter.
>
> More recently (see http://www.newscientist.com/news/news.jsp?id=ns99994120)
> Yen has proposed that meteorites form the main source for the red soil. He
> exposed metallic iron in a specially created environment matching the
> atmospheric composition and temperature of Mars. Yen found that red oxides
> began to form within a week -- in other words, orders of magnitude more
> quickly than previously assumed. So there may be something to this idea
> after all.
>
> Properly equipped Martian landers will probably be able to shed more light
> on this subject. If Yen is right, the Martian soil should show an
> overabundance of nickel, indicating a probable meteoric origin. The Mars
> Pathfinder mission has already suggested that the soil contains more
> magnesium and iron than rocks on the surface.
>
> >As you and others have pointed out, water and oxygen are not necessary for
> >oxidization. We have plenty of areas on earth that are pretty bleak but we
> >all know about geological time as opposed to our own inabilaty to comprehend
> >it in a real sense and the amazing affects of weather and all the rest. My
> >only point was that given the fact that iron can turn into red stuff as the
> >result of a variety of reactions, why isn't the earth's moon very very red?
>
> The type of vapor deposition process which weathers the lunar surface may
> initially lead to reddening, but later leads to darkening. See the article
> by Bruce Hapke in the Journal of Geophysical Research, vol. 106, pp.
> 10039-10073.
>
> There is also evidence of reddening on some smaller airless bodies as a
> result of space weathering. This has important consequences for
> determining the parent bodies of meteorites.
>
> >Mars has a violent atmosphere that should mix all that "meteoric" debris up?
> >This is only a question as a student might ask. I'm not trying to engage in a
> >debate.
>
> Actually such atmospheric activity supports Yen's idea. The soil on Mars
> is constantly being mixed up, and so the darkening characteristic of space
> weathering on airless bodies doesn't take place.
>
>
> -- Philip R. "Pib" Burns
> pib_at_pibburns.com
> http://www.pibburns.com/
>
>
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Received on Tue 16 Sep 2003 09:32:40 PM PDT