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Re: Carbonates and CI chondrites: Orgueil Age
On Mon, 9 Feb 1998, Bernd Pauli wrote:
> Martin wrote: What is the relationship between primitiveness and age.
> According to Dodd , Orgueil's age is not particularly old, nor is it
> uncommon among meteorites.
>
> I thought this might be of interest:
>
> BRANDENBURG J.E. (1996) Mars as the parent body of the CI carbonaceous
> chondrites: A further examination (Meteoritics 31, 1996, A019): ‘... In
> addition, aqueous-formed minerals such as ferrous magnesite were found
> in quantity only within CIs (Orgueil age 4.5 G.y.) and ALH 84001, which
> are their approximate contemporary at 4.0-4.5 G.y....'
>
> ‘... and indicate that the martian dichotomy in surface ages is now
> fully reproduced in meteorite crystallization ages (Brandenburg (1995)
> Earth, Moon and Planets 67, 35-45). This would allow direct estimation
> of the mean surface ages of the northern (young) and southern (old)
> hemispheres as approximately 0.5 G.y. for the north and approximately
> 4.5 G.y for the south, with ages based upon known martian meteorites
> (Mc.Sween H. (1994) Meteoritics 29, 757-779) and CI ages and the
> assumption of their origin from multiple random impacts.’
>
> Regards, Bernd Pauli
>
To All
CI chondrites do not have a Martian origin. I did write something
a long time ago on this subject, and perhaps somebody has it and can
repost it. This idea has a serious flaw.
CI chondrites SHOW NO EVIDENCE OF BEING LAID DOWN IN A WATER
ENVIROMENT. There is no layering in the matrix. By the fact that they have
been altered by water, does not in any way indicate a sedimentary origin.
It is this fact that inhibits, I beleieve, the whole hypothesis.
Do not take my word for it, as there is a formal argument opposing
the view point of CI chondrites as having a martian origin. I encourage
all who can, to look at Treiman(1996)Geophysical Research Letters V. 23
NO.22, P3275-3276.
Frank Stroik
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