ABSTRACT

An enrichment of oxygen-16 of about 8% relative to the Earth has been found in a chondrule from the Acfer 214 carbonaceous chondrite. In contrast, isotopic abundances of major cations, Mg and Si, are similar to those of the Earth. These suggest that oxygen isotopic heterogeneity in the early solar system was much larger ever thought and assist mass-independent-isotopic fractionation for the origin. Because the chondrule has solar abundance for refractory and normal lithophile elements, we propose that silicate dusts in the early solar system were initially enriched in ¹⁶O corresponding to the ¹⁶O-rich reservoir.