Presolar Diamonds from Efremovka & Boriskino: C, N and Noble Gas Isotopes in Grain Size Fractions and Implications for the Origin of Diamonds
نویسندگان
چکیده
In addition to the four grain size fractions of diamonds separated from the Efremovka (CV3) meteorite reported earlier [1], six more diamond size-fractions from the same meteorite have been generated with sizes both coarser and finer than the original set. Isotope analyses of C, N and noble gases in the new fractions confirmed most of the trends observed earlier for concentrations and isotopic compositions. In addition, three new size fractions of diamond grains from the Boriskino (CM) meteorite are found to show similar variations in isotopic compositions and elemental concentrations with grain size. This new information helps to refine our hypothesis concerning the origins and histories of the diamond grains.
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