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The stardust inventories of CR chondrites QUE
99177 and MET 00426, and the distribution of presolar
silicate and oxide grains in the early solar
system.
Floss C. and Stadermann F. J. (2008)
Lunar & Planet. Sci. 39, Abstract #1280.
ABSTRACT
The CR chondrites are among the most primitive meteorites
and have been compared with IDPs because both types of
materials contain abundant H and N isotopic anomalies
thought to be of interstellar origin. Circumstellar grains
are also abundant in IDPs, but have only rarely been found
in CR chondrites due to the extensive aqueous alteration
they have experienced. However, QUE 99177 and MET 00426
appear to be significantly less altered than most members of
this group and, thus, are good candidates in which to search
for presolar grains. Indeed, we recently showed that QUE
99177 has very high concentrations of presolar grains, with
O-anomalous grain abundances that exceed those of the
primitive chondrites Acfer 094 and ALHA77307. Our continued
investigation of these two CR chondrites shows that MET
00426 also contains high concentrations of both O-anomalous
and C-anomalous presolar grains. Here we report results for
the O-bearing presolar grains in these two meteorites and
discuss implications for the distribution of presolar
materials in the early solar system.
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