Nucleosynthetic titanium and chromium isotope anomalies in CAIs

Abstract

Calcium-Aluminum-rich inclusions (CAIs) are the oldest condensates in the solar system. Nucleosynthetic isotope anomalies for heavy elements observed in CAIs provide important information for elucidating the isotopic heterogeneity and the influx, transport, and mixing of materials in the protoplanetary disk. However, data on Cr-Ti isotopic anomalies in CAIs are currently limited. This study obtained the Cr-Ti isotope ratios in coarse-grained (CGs) and fine-grained CAI (FGs) samples from three CV chondrites. The acquired Cr-Ti isotope ratios indicate that some of the FGs have larger isotopic anomalies than CGs. This implies multiple formation reservoirs, at least for the FGs. Given the high abundance of FGs in carbonaceous chondrites, it is necessary to evaluate FGs as an important end member that explains the bulk isotopic composition of carbonaceous chondrites.