Mössbauer spectroscopy of the samples from carbonaceous asteroids

Abstract

The iron (Fe) speciation and the valence states of meteorites reflect the redox environment during the formation and evolution of protoplanetary bodies. In this study, we performed X-ray diffraction analysis and synchrotron Mössbauer spectroscopy using carbonaceous chondrites with clay minerals (CM type, CR type, and Tagish Lake meteorites), as well as samples collected from the asteroid Bennu. The results were compared with data from previous studies on samples collected from the asteroid Ryugu and CI-type meteorites. Our results revealed distinct iron redox properties for each meteorite type, with variations observed in the amounts of metallic Fe, Fe sulfides, Fe in carbonates, and the valence states of Fe in hydrated minerals. This suggests that parent bodies of each meteorite type underwent formation and evolution under distinct redox conditions.