Chondrule-like objects and Ca-Al-rich inclusions in Ryugu may potentially be the oldest Solar System materials.

ABSTRACT: Chondrule-like objects and Ca-Al-rich inclusions (CAIs) are discovered in the retuned samples from asteroid Ryugu. Here we report results of oxygen isotope, mineralogical, and compositional analysis of the chondrule-like objects and CAIs. Three chondrule-like objects dominated by Mg-rich olivine are ¹⁶O-rich and -poor with Δ¹⁷O (=δ¹⁷O - 0.52 × δ¹⁸O) values of ~ -23‰ and ~ -3‰, resembling what has been proposed as early generations of chondrules. The ¹⁶O-rich objects are likely to be melted amoeboid olivine aggregates that escaped from incorporation into ¹⁶O-poor chondrule precursor dust. Two CAIs composed of refractory minerals are ¹⁶O-rich with Δ¹⁷O of ~ -23‰ and possibly as old as the oldest CAIs. The

SUBMITTER: Nakashima D 

PROVIDER: S-EPMC9935534 | biostudies-literature | 2023 Feb

REPOSITORIES: biostudies-literature