Coordinated TEM/NanoSIMS microanalysis of structurally or
isotopically rare presolar silicon carbides.
Daulton T. L., Stadermann F. J., Bernatowicz T. J., Amari S.,
and Lewis R. S. (2009)
Meteorit. Planet. Sci. 44 (7, Suppl.), A56.
Submicron- to micron-sized grains of SiC originating from
asymptotic giant branch (AGB) stars and supernovae (SN) can be
ubiquitous in the matrices of primitive chondrites. Previous work
has shown that presolar SiC occurs as three fundamental polytypes or
stacking sequences (cubic 3C, hexagonal 2H, and one-dimensionally
disordered hexagonal structure) along with their intergrowths. It
has also been shown that presolar SiC occurs as several isotopic types
termed mainstream, A+B, X, Y and Z. We are presently performing
coordinated Transmission Electron Microscopy (TEM) and NanoSIMS
measurements of individual presolar SiC grains to more fully understand
their histories. We report our preliminary results on
structurally or isotopically rare SiC grain types.