Fang Linru, Moynier Frederic, Barrat Jean-Alix, Yamaguchi Akira, Paquet Marine, Chaussidon Marc
Université Paris Cité, Institut de Physique du Globe De Paris, CNRS, 1 rue Jussieu, Paris, France.
CNRS, IRD, Institut Français de Recherche pour l'Exploitation de la Mer, LEMAR, Univ Brest, Brest, France.
Sci Adv. 2024 Aug 16;10(33):eadl1007. doi: 10.1126/sciadv.adl1007. Epub 2024 Aug 14.
Volatile element abundances vary substantially among terrestrial planetary bodies like Earth, Mars, Moon, and differentiated asteroids, leading to intense debate about the governing processes. howardites-eucrites-diogenites (HED) meteorites, most likely from asteroid 4-Vesta, represent highly volatile-depleted Solar System samples, offering critical insights into these processes. Zinc is a moderately volatile element and its isotopic composition reveals sources of volatiles in planetary bodies. Our study finds Zn isotopic anomalies in diogenites overlapping with noncarbonaceous reservoirs, indicating negligible contributions of outer solar system materials to 4-Vesta's volatiles. Besides, zinc isotopic composition of 4-Vesta is lighter than that of chondrites, contrary to the expected signature of evaporation-based volatile depletion. This suggests that after 4-Vesta lost all its volatiles through evaporation during the magma ocean stage, partial kinetic recondensation occurred that produced the observed isotopically light composition. These insights, combined with previous data, underscore the process of global evaporation followed by partial condensation as a key factor influencing the final volatile budget of planetary bodies.
诸如地球、火星、月球和分异小行星等类地行星体中的挥发性元素丰度差异很大，这引发了关于控制过程的激烈争论。钙长辉长无球粒陨石（HED）最有可能来自小行星灶神星，代表了高度贫挥发分的太阳系样本，为这些过程提供了关键见解。锌是一种中度挥发性元素，其同位素组成揭示了行星体中挥发分的来源。我们的研究发现，无球粒陨石中的锌同位素异常与非碳质储库重叠，这表明外太阳系物质对灶神星挥发分的贡献可忽略不计。此外，灶神星的锌同位素组成比球粒陨石轻，这与基于蒸发的挥发分亏损的预期特征相反。这表明在灶神星在岩浆海洋阶段通过蒸发失去所有挥发分之后，发生了部分动力学再凝聚，从而产生了观测到的同位素轻组成。这些见解与先前的数据相结合，强调了全球蒸发随后部分凝聚的过程是影响行星体最终挥发分预算的关键因素。
