Asteroids accretion, differentiation, and break-up in the Vesta source region: Evidence from cosmochemistry of mesosiderites
Asteroids accretion, differentiation, and break-up in the Vesta source region: Evidence from cosmochemistry of mesosiderites
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灶神星源区小行星的吸积、分化和分裂：来自中菱铁矿宇宙化学的证据
DOI：
10.1016/j.gca.2022.05.003
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发表时间：
2022
影响因子：
5
通讯作者：
Iannini Lelarge S
中科院分区：
文献类型：
--
作者：
Iannini Lelarge S
陨石的宇宙化学提供了关于小行星吸积、分化、碰撞分裂和重组的独特线索，这些过程对于了解早期太阳系行星的形成至关重要。中菱陨石是一组复杂的无球粒陨石，其金属-硅酸盐成分接近50：50，在文献中被解释为来自不同小行星的核心和地壳物质混合的结果。由于其复杂的性质和对比鲜明的地球化学，同位素和光谱数据，中菱铁矿的形成机制仍然知之甚少，是开放的各种行星分化方案和碰撞的历史。在这项研究中，新的岩相学和地球化学数据的基础上，16 mesosidites，我们详细调查的建议，mesosidites有关的howardite-eucrite-diogenite（HED）陨石群，其母体被广泛认为是小行星4灶神星（直径约500公里），最近美国宇航局的黎明使命的目标。我们提出了第一个高精度的氧同位素分析的矩阵的一组mesosiderite样品，再加上新的化学和岩相分析的mesosiderites嗯哈迪德，埃斯特维尔，和帕德伯里山。中菱铁矿（-0.241 ± 0.015（2σ））和霍华钠长闪长岩（-0.241 ± 0.017‰（2σ））之间的Δ 17 O值一致，表明它们来自相同的氧同位素储层，但岩石学证据，特别是中菱铁矿中明显较低的Fe/Mn比值和较大的岩性多样性，表明它们形成于不同的母体。这表明，中陨铁岩和霍瓦铁-钙铝榴辉岩-闪长岩起源于不同的母体，它们在4维斯塔源区增生，但经历了不同的地壳分异和碰撞历史，在中陨铁母体中，这些地质演化更为复杂和灾难性。
The cosmochemistry of meteorites provides unique clues on asteroids accretion, differentiation, collisional break-up and reassembly - processes of critical importance for understanding planet formation in the early solar system. Mesosiderites are a complex group of achondrites whose nearly 50:50 metal-silicate composition is interpreted in the literature as resulting from the mixing of core and crustal materials derived from differentiated asteroids. Because of their complex nature and contrasting geochemical, isotopic, and spectroscopic data, the formation mechanism of mesosiderites is still poorly understood and is open to a large variety of planetary differentiation scenarios and collisional histories. In this study, based on new petrographic and geochemical data of 16 mesosiderites, we investigate in detail the proposal that mesosiderites are related to the howardite-eucrite-diogenite (HED) meteorite group, whose parent body is widely considered to be asteroid 4 Vesta (∼500 km diameter), the target of the recent NASA’s Dawn mission. We present the first high precision oxygen isotope analyses on the matrix of a set of mesosiderite samples, coupled with new chemical and petrographic analyses of mesosiderites Um Hadid, Estherville, and Mount Padbury. Concordant Δ17O values between mesosiderites (–0.241 ± 0.015 (2σ)) and howardite-eucrite-diogenites (−0.241 ± 0.017‰ (2σ)) indicate that they derived from the same oxygen isotope reservoir, but petrological evidence, in particular the distinctly lower Fe/Mn ratios and the larger lithological diversity in mesosiderites, indicates that they formed within different parent bodies. This suggests that mesosiderites and howardite-eucrite-diogenites originated in distinct parent bodies that accreted in the 4 Vesta source region but experienced different geologic evolution in terms of crustal differentiation and impact history, which were more complex and catastrophic in the mesosiderite parent body.