Implications from the absence of a ⁴¹K anomaly in an Allende inclusion

Abstract

CLAYTON¹ has elaborated on his unorthodox interpretation² of the occurrence in meteorites of the decay products of the extinct radionuclides ¹²⁹I and ²⁴⁴Pu. He has suggested that these radioactive species did not decay in the meteorites but rather in interstellar grains which, on the formation of the meteorites, were incorporated without much alteration. Thus, the concentration in the meteorites of the decay products does not reflect the time of meteorite formation relative to the cessation of nucleosynthesis but is essentially governed by the fraction of interstellar grains mixed with the meteoritic matter proper. If that is true, anomalies will occur in the isotopic composition of numerous elements. The decisive criterion of whether an over-abundance of a given isotope can be expected is the production yield during nucleosynthesis of a radioactive precursor; the half life of that precursor is of only minor importance.