Zhang Bidong, Chabot Nancy L, Rubin Alan E
Department of Earth, Planetary and Space Sciences, University California, Los Angeles, CA 90095-1567, USA.
Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA.
Sci Adv. 2022 Sep 16;8(37):eabo5781. doi: 10.1126/sciadv.abo5781.
The parent cores of iron meteorites belong to the earliest accreted bodies in the solar system. These cores formed in two isotopically distinct reservoirs: noncarbonaceous (NC) type and carbonaceous (CC) type in the inner and outer solar system, respectively. We measured elemental compositions of CC-iron groups and used fractional crystallization modeling to reconstruct the bulk compositions and crystallization processes of their parent asteroidal cores. We found generally lower S and higher P in CC-iron cores than in NC-iron cores and higher HSE (highly siderophile element) abundances in some CC-iron cores than in NC-iron cores. We suggest that the different HSE abundances among the CC-iron cores are related to the spatial distribution of refractory metal nugget-bearing calcium aluminum-rich inclusions (CAIs) in the protoplanetary disk. CAIs may have been transported to the outer solar system and distributed heterogeneously within the first million years of solar system history.
铁陨石的母体核心属于太阳系中最早形成的天体。这些核心在两个同位素不同的储库中形成：分别在内太阳系和外太阳系的非碳质（NC）型和碳质（CC）型。我们测量了CC铁族的元素组成，并使用分离结晶模型来重建其母体小行星核心的整体组成和结晶过程。我们发现，CC铁核中的S含量普遍低于NC铁核，P含量高于NC铁核，并且一些CC铁核中的高度亲铁元素（HSE）丰度高于NC铁核。我们认为，CC铁核之间不同的HSE丰度与原行星盘中含难熔金属的富钙铝包体（CAIs）的空间分布有关。CAIs可能在太阳系历史的头一百万年被输送到外太阳系并呈非均匀分布。
