[S-GC33] 固体地球化学・惑星化学

[SGC33-P02] Laser ultrahigh-pressure experiment on Chondrite-Type Allende meteorite

*中西 悠輔¹、尾崎 典雅^1,2、佐野 孝好²、瀬戸 雄介³、富岡 尚敬⁴、兒玉 了祐^1,2 (1.大阪大学大学院工学研究科、2.大阪大学レーザー科学研究所、3.大阪公立大学大学院理学研究科、4.海洋研究開発機構高知コア研究所)

キーワード：レーザー衝撃圧縮、隕石、不均質構造、衝撃波

Celestial body collisions are a necessary process in the formation of planets in the Solar System, and the current terrestrial planets are thought to be the result of the repeated growth of microplanets a few kilometers in diameter through collisions and mergers. During such collisions, astronomical objects sometimes experience extreme pressure exceeding several hundred of gigapascals, making the study of extraterrestrial materials very important for understanding the history of the Solar System. Scientists have used spacecraft to collect samples of extraterrestrial materials for study, but this is expensive and time-consuming, and samples are not readily available. On the other hand, meteorites are easily accessible and provide many mineralogical and petrological specimens for study. Scientists have used scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to study high-pressure minerals in meteorites and to investigate the impact history of these space rocks. In addition, since the 1970s, shock experiments have been conducted to study the impact evolution of small bodies, thus simulating meteorite samples.[1] However, because a gas gun was used as a shock driver, it was only possible to simulate impacts up to several km/s. On the other hand, laser shock ultrahigh-pressure experiments have made it possible to reach giant-impact class impact pressures. In planetary science, impact compression properties of homogeneous single crystals simulating planetary materials such as olivine have been frequently investigated, but few experiments have been conducted on natural meteorites themselves, which have heterogeneous structures [2,3]. In this study, we performed the world's first laser impact compression experiment on a thin Allende meteorite sample. We investigated the shock wavefront shape, temperature distribution, and other properties of the sample due to compositional and structural heterogeneity under conditions equivalent to a meteorite impact of several hundred GPa.

[1] Sugita, S. et al., Science 310, 274 (2005).
[2] T. Okuchi et al.: Nat. Commun., 12, 4305 (2021).
[3] B.A. Chidester et.al., Earth Space Sci., 48, 8 (2021).