O–Fe–Ti isotopic evidence for classifying Oued Chebeika 002 as a CI chondrite and its genetic affinities with CY chondrites, Ryugu, and Bennu

ABSTRACT This paper reports the chemical and isotopic compositions of Oued Chebeika 002 (OC 002). High-precision, mass-independent O, Fe, and Ti isotope data confirm that it is the first desert-derived CI chondrite. Trace elemental data indicate that the sample experienced minimal terrestrial weathering, making it a significant supplement for the lack of CI samples representing the compositions of Solar system and bulk planets. Notably, we observed 58Fe excess in OC 002, indicating Earth and CI chondrites have different mass-independent Fe isotope compositions. We also present high-precision oxygen isotope data for seven ‘CY’ chondrites. All ‘CY’ chondrites exhibit two distinct groups in their mass-independent oxygen isotope compositions (Δ17O), suggesting they originated from two separate parent bodies. This interpretation is consistent with their differing petrology, as well as variations in metal elemental and isotopic compositions. CI1T chondrites share Δ17O values with CI chondrites, implying a common parent body. In contrast, CY2 chondrites have Δ17O values distinct from those of CM chondrites. Furthermore, CI1T and CI chondrites have Δ17O values similar to those measured in Ryugu samples, suggesting they may have accreted in similar regions of the Solar system. However, any genetic relationship between CI-Ryugu and Bennu remains uncertain and requires further investigation.