Study of noble gas carrier "Q" in meteorites

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1. Laboratory experiments of change of Q by aqueous alterationWe put Allende matrix in a pressure vessel, and kept it at 200℃ for 1, 2, 3, and 4 weeks. The concentrations of Q and HL noble gases in both host phases (phase Q and presolar diamonds) decreased with increasing the duration time of the experiment. Furthermore, the phase Q seems to be more easily damaged compared to presolar diamonds. We found that cosmogenic and radiogenic components are also removed by the aqueous treatment.2. An attempt to separate Q and HLThe black floating material obtained by the freeze-thaw decomposition of the Allende meteorite is carbon and is very similar to the typical chemical residue of Allende in noble gas concentrations and isotopic components. We prepared 10 fractions of this material by the density separation. The noble gases are mostly enriched in the fraction with the density of 1.65g/cm3, and decrease in the higher density fractions. However, the isotopic compositions are more or less similar in all fractions, suggesting that the separation of Q and HL was not successful. It is likely that the phase Q is on the surface of presolar diamonds.3. The extraction of Q by organic solventsWe put Allende in toluene and tried to extract Q by organic solvent. We measured noble gas concentrations and isotopes in the extracted material and the residue. The noble gas components have no change by this treatment, indicating that Q is not removed by toluene.