ABSTRACT

Anomalies observed by Nagao et al. (1984) in the xenon fractions released from the carbonaceous chondrite Belgica can be explained as due to the alterations of the isotopic composition caused by a combined effect of (a) mass-fractionation, (b) high-energy proton spallation and (c) secondary neutron-capture processes, which occurred within the solar system when the Sun was in its T-Tauri phase. The isotopic composition of the xenon fraction released from this meteorite at 1, 800°C seems to represent that of the xenon which is more primordial than the atmospheric xenon.