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Carbonates and CI chondrites: Orgueil Age
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
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