CORRELATION OF ⁴⁸Ca, ⁵⁰Ti, AND ¹³⁸La HETEROGENEITY IN THE ALLENDE REFRACTORY INCLUSIONS

Precise determinations of ⁴⁸Ca anomalies in Allende calcium–aluminum-rich inclusions (CAIs) are reported in this work. There are endemic positive ⁴⁸Ca/⁴⁴Ca anomalies in all analyzed CAIs after normalization to ⁴²Ca/⁴⁴Ca, and it is clearly shown that there is no simple correlation between ⁴⁸Ca/⁴⁴Ca and ⁵⁰Ti/⁴⁸Ti anomalies, in agreement with Jungck et al. Compared to the ⁴⁸Ca/⁴⁴Ca versus ⁵⁰Ti/⁴⁸Ti correlation line defined by differentiated meteorites, reported by Chen et al., the CAIs plot to elevated ⁵⁰Ti/⁴⁸Ti. Assuming the ⁴⁸Ca/⁴⁴Ca anomalies of both CAIs and differentiated meteorites came from the same source, excess ⁵⁰Ti anomalies in CAIs can be calculated by subtracting the part associated with ⁴⁸Ca/⁴⁴Ca. These excesses show a linear correlation with ¹³⁸La anomalies, a neutrino-process nuclide. According to current stellar nucleosynthetic models, we therefore suggest that the solar system ⁴⁸Ca, ⁵⁰Ti, and ¹³⁸La isotopic variations are made of mixtures between grains condensed from ejecta of neutron-rich accretion-induced SNe Ia and the O/Ne–O/C zone of core-collapse SNe II