Characterization of carbon phases in Yamato 74123 ureilite to constrain the meteorite shock history

Abstract

The formation and shock history of ureilite meteorites, a relatively abundant type of primitive achondrites, has been debated since decades. For this purpose, the characterization of carbon phases can provide further information on diamond and graphite formation in ureilites, shedding light on the origin and history of this meteorite group. In this work, we present X-ray diffraction and micro-Raman spectroscopy analyses performed on diamond and graphite occurring in the ureilite Yamato 74123 (Y-74123). The results show that nano-and micro-diamonds coexist with nano-graphite aggregates. This, together with the shockdeformation features observed in olivine, such as mosaicism and planar fractures, suggest that diamond grains formed by a shock event (≥ 15 GPa) on the Ureilitic Parent Body (UPB). Our results on Y-74123 are consistent with those obtained on the NWA 7983 ureilite and further support the hypothesis that the simultaneous formation of nano-and micro-diamonds with the assistance of a Fe-Ni melt catalysis may be related to the heterogeneous propagation and local scattering of the shock wave. Graphite geothermometry revealed an average recorded This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America. The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

Shock degree and graphite geothermometry in ureilites NWA 6871 and NWA 3140

“…Further proof for this kind of carbon associations and the formation of micro‐sized diamonds during a shock event was given by Barbaro et al. (2021, 2022) for the Kenna and Yamato 74123 ureilites.…”

“…(2011) and Barbaro et al. (2020, 2021, 2022), the G‐band Γ G values were corrected for the instrumental peak broadening using the same approach as Barbaro et al. (2020), where a lithospheric diamond of high gem quality was used.…”

“…Ross et al. (2011) reported an FWHM of 3 cm −1 for a kimberlitic diamond, while Barbaro and coauthors reported an FWHM of 6 cm −1 (Barbaro et al., 2020) and 5 cm −1 (Barbaro et al., 2021, 2022) for lithospheric diamonds. In this work, we used a set of six different lithospheric diamonds from Canada to obtain the correction factor for our instrument.…”

“…(2011) and Barbaro et al. (2020, 2021, 2022) which yielded temperatures of 990 ± 120 °C and 1242 ± 120 to 1314 ± 120 °C, respectively.…”

Shock-formed carbon materials with intergrown sp 3 - and sp 2 -bonded nanostructured units

“…5A), indicating that these had achieved sufficiently high temperature during the shock event to complete the thermodynamic transformation. Barbaro et al (50)(51)(52) found nano-and microdiamonds coexisting with nanographite aggregates in ureilite meteorites and estimated 1,200 to 1,300 °C for this phase assemblage. In accordance with these reports, we hypothesize analogous shock T for the Canyon Diablo sample.…”