Complex mixture of organic matter in a xenolithic clast from the Zag meteorite revealed by coordinated analyses using AFM-IR, NanoSIMS and STXM/XANES

Yoko Kebukawa, Jérémie Mathurin, Emmanuel Dartois, Alexandre Dazzi, Ariane Deniset-Besseau, Jean Duprat, Laurent Remusat, Takaaki Noguchi, Akira Miyake, Yohei Igami, Maximilien Verdier Paoletti, Michael E. Zolensky, Cécile Engrand, Christophe Sandt, Ferenc Borondics, Shohei Yamashita, Daisuke Wakabayashi, Yasuo Takeichi, Yoshio Takahashi

In Press, Journal Pre-proof, Available online 18 April 2023


“Primitive carbonaceous xenolithic clasts found in sturdy metamorphosed meteorites often provide opportunities to reach labile volatile-rich materials which are easily destroyed during atmospheric entry and materials which we do not have sampled as individual meteorites. Among them, a xenolithic carbonaceous clast in the Zag H3–6 ordinary chondrite has been providing us with the opportunity to analyze a possible sample from D/P-type asteroids. Here we performed a new suite of coordinated analyses of organic matter in the Zag clast using the atomic force microscope infrared spectroscopy (AFM-IR) combined with nanoscale secondary ion mass spectrometer (NanoSIMS), X-ray absorption near-edge spectroscopy (XANES) coupled with scanning transmission X-ray macroscope (STXM), Raman, and (scanning) transmission electron microscopy [(S)TEM] on adjacent ultramicrotomed thin sections from a single sample grain. We successfully demonstrated the practicality of coordinated analyses using AFM-IR, Raman and NanoSIMS on the same sample area, as well as STXM/XANES on adjacent (and nearly identical) thin sections to those used for AFM-IR. The AFM-IR map and STXM maps provided consistent and complementary results. We found that at least two types of organics were closely mixed in this specimen. One was deuterium-rich, C=O rich organics with likely smaller aromatic domains, possibly originating in relatively oxidized environments from D-rich precursors. The other type was less deuterium-rich, but aromatic-rich organics, possibly produced in relatively reduced and higher temperature environments with less deuterium-rich precursors. These characteristics point to complex mixtures of materials with different origins and sampling a wide heliocentric range of the Solar System before accretion in the parent body of the clast.”