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Identification of Presolar Spinel Grains from a Murray Residue by Multi-Detection Raster ImagingGrain size separate CG from the Murray CM2 carbonaceous chondrite contains mostly spinel grains of average diameter 0.5 m. Zinner et al. found that approximately 1% of these spinel grains are of presolar origin as determined by their large O isotopic anomalies. These O isotopic measurements were made with the NanoSIMS on individual grains that were well separated from one another on a gold foil. The grains were selected for analysis from secondary electron and secondary O-16(-) images. The primary beam was then successively deflected onto these single grains for O isotopic analysis. While single grain analysis on dispersed samples is effective for finding relatively abundant anomalous grains, ion imaging in a raster mode on tightly packed grains might be more efficient for locating few anomalous grains among predominantly isotopically normal grains. In fact, this was the analysis mode used by Messenger et al. to discover presolar silicates in interplanetary dust particles. In an exploratory effort that is also geared toward establishing the optimum isotopic imaging technique in the search for presolar silicate grains in primitive meteorites, we measured O isotopic ratios in spinel grains from the Murray CG separate by raster imaging of areas with more or less tightly packed grains.
Document ID
20030111235
Document Type
Conference Paper
Authors
Nguyen, A. (Washington Univ. Saint Louis, MO, United States)
Zinner, E. (Washington Univ. Saint Louis, MO, United States)
Lewis, R. S. (Chicago Univ. Chicago, IL, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Publication Information
Publication: Lunar and Planetary Science XXXIV
Subject Category
Lunar and Planetary Science and Exploration
Funding Number(s)
CONTRACT_GRANT: NAG5-11545
Distribution Limits
Public
Copyright
Public Use Permitted.

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