Time Interval between Nucleogenesis and the Formation of Meteorites

Abstract

WHILE determining the radiogenic argon-40 content of the Beardsley chondritic meteorite¹, a mass spectrometric search for xenon-129 produced by decay of iodine-129 was made. The total amount of xenon which was observed was 5 × 10⁻⁹ c.c. (s.t.p.) from a 29.86-gm. meteorite sample. Within the limits of experimental error, this xenon had a normal isotopic composition². The ratio of xenon to argon-36 was in essential agreement with that found in air, indicating that this xenon was due to atmospheric contamination. Since a 30 per cent increase in the abundance of xenon-129 over that observed in normal xenon would have been observable, this indicates that radiogenic xenon-129 was present in this meteorite to less than 1.3 × 10⁻¹¹ c.c. (s.t.p.)/gm. H. E. Suess and M. G. Inghram (personal communication) have suggested that if the meteorites had been formed soon after the formation of the elements, they would contain an excess of xenon-129 due to decay of iodine-129.