Final Report Summary - ISOSYC (Initial Solar System Composition and Early Planetary Differentiation)
During the project, we have measured the Nd isotope systematic of more than forty Antarctic enstatite and ordinary chondrites for high-precision multi-static Nd measurements to further investigate this issue. No systematic variation has been observed between groups or petrological types. As previously observed, ordinary chondrites (OC) are statistically different from Earth in µ145Nd and µ148Nd, while EC are indistinguishable from terrestrial values for those isotopes. Analytical error on µ150Nd precludes firm interpretation. On the other hand, both EC and OC share a similar µ142Nd value of -15 ± 5 and -15 ± 12 respectively. Reconciling a discrepancy in 145Nd and 148Nd between OC and Earth-EC on one side, with a discrepancy in 142Nd between EC-OC and Earth on the other side, cannot solely be related to s-process nucleosynthetic anomaly. This implies that the present-day accessible Earth is not chondritic anymore, hence requiring the presence of a hidden reservoir, either deep in the Earth but never sampled, or lost at some point during the evolution of the Earth.