Molybdenum evidence for inherited planetary scale isotope heterogeneity of the protosolar nebula

Abstract

Isotope anomalies provide important information about early solar system evolution. Here we report molybdenum isotope abundances determined in samples of various meteorite classes. There is no fractionation of molybdenum isotopes in our sample set within 0.1‰ and no contribution from the extinct radionuclide ⁹⁷Tc at mass 97 (⁹⁷Tc/⁹²Mo < 3 × 10^-6). Instead, we observe clear anomalies in bulk iron meteorites, mesosiderites, pallasites, and chondrites characterized by a coupled excess in p- and r-process or a mirror deficit in s-process nuclides (Mo-w). This large-scale isotope heterogeneity of the solar system observed for molybdenum must have been inherited from the interstellar environment where the Sun was born, illustrating the concept of "cosmic chemical memory." The presence of molybdenum anomalies is used to discuss the filiation between planetesimals.