Genetic links between IIIE iron meteorites and the core of the HED parent asteroid

Abstract

Rocky planets formed through the differentiation of planetesimals into metal‑rich cores and silicate mantles, yet direct evidence linking these complementary reservoirs remains scarce. Here we show that IIIE irons and howardite-eucrite-diogenite (HED) meteorites are genetically linked, by integrating mineralogical, isotopic, and rare earth element (REE) analyses of the silicate-bearing Aletai IIIE meteorite. The silicates display Fe/Mn-Fe/Mg correlations, concordant oxygen isotope compositions, and strongly fractionated REE patterns consistent with those of HED meteorites. A pronounced negative Eu anomaly in orthopyroxene marks the onset of plagioclase saturation and buoyant segregation during early magma ocean crystallization, supported by thermodynamic modelling. These findings establish a genetic link between magmatic irons and differentiated achondrites, suggesting that IIIE irons and HEDs share a common genetic heritage, and providing direct physical evidence for core-mantle reservoir connections in the early Solar System. IIIE irons share geochemical characteristics with howardite-eucrite-diogenite meteorites suggesting both may have formed from differentiated planetesimal parent bodies, according to analyses on a silicate-bearing inclusion in the Aletai IIIE iron meteorite.