Abstract
Precise barium isotopic compositions of chemical separates in tweleve carbonaceous chondrites were determined to discuss about nucleosynthetic affairs in the early solar system. The barium isotopic data in most chemical separates show variable 135Ba excesses correlated with 137Ba excesses, suggesting the presence of nucleosynthetic components for s- and r-processes in the solar system. The samples from Orgueil reveal larger 135Ba excesses than those of other samples, although it is also accompanied by a small 137Ba excess. Judging from the high Cs/Ba elemental ratios in the leachates, the 135Ba excesses of Orgueil may include the contribution of 135Cs decay.
