近日，中国地质大学（武汉）朱柯团队报道了镍同位素揭示安格利特母体的高能撞击和蒸汽再凝结历史。该项研究成果发表在2025年11月10日出版的《美国科学院院刊》杂志上。

安格里岩母体（APB）是太阳系中已知分异天体中最富集难挥发元素的，但其形成机制仍不明确。

研究组通过高精度镍（Ni）同位素数据重建了APB的挥发性元素亏损历史。深成安格里岩含有异常高比例的金属铁，其δ^60/58Ni值接近球粒陨石（0.202 ± 0.028‰；以美国国家标准与技术研究院（NIST）标准参考物质（SRM）986为基准的千分偏差）。这表明APB核心形成后具有均一的Ni同位素组成，随后深成安格里岩中混入了内生核心物质。相反，火山安格里岩中的辉石岩和巨晶橄榄石（来源于地幔）显示超球粒陨石型δ^60/58Ni值（0.4至0.7‰）。

研究组认为这符合以下过程：在初始的²⁶Al加热引发熔岩海洋形成并导致挥发性元素损失后，一次高能撞击事件进一步导致Ni蒸发损失。热力学模型证实，在硅酸盐液体蒸发过程中Ni的挥发性高于Mn、Fe、Si和Mg，与观测到的同位素分馏相对大小一致。火山安格里岩基质显示变化的且常低于球粒陨石的δ^60/58Ni值（低至-0.5‰），反映了与富集同位素的巨晶橄榄石混合以及轻Ni蒸气向地壳的再凝结。这些发现表明APB中挥发性元素呈分层分布（核心-地幔-地壳），并为分异天体上撞击驱动的气相损失和再凝结提供了直接的同位素证据。

附：英文原文

Title: High-energy impact and vapor recondensation history of the angrite parent body revealed by nickel isotopes

Author: Zhu, Ke, Yamaguchi, Akira, Sossi, Paolo A., Bouvier, Audrey, Chen, Lu, Ni, Peng

Issue&Volume: 2025-11-10

Abstract: The angrite parent body (APB) is the most volatile-depleted among known differentiated bodies in the Solar System, yet the mechanisms responsible remain poorly constrained. Here, we present high-precision nickel (Ni) isotope data from a suite of angrite samples to reconstruct the APB’s volatile depletion history. Plutonic angrites contain unusually high proportions of metallic iron and exhibit chondritic δ60/58Ni values (0.202 ± 0.028‰; per mille mass-dependent 60Ni/58Ni deviation relative to National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 986). These observations are consistent with a homogeneous Ni isotope composition of the APB after core formation and the subsequent incorporation of endogenous core material in plutonic angrites. In contrast, a dunite and megacrystic olivines from volcanic angrites, derived from the mantle, display suprachondritic δ60/58Ni values (0.4 to 0.7‰). We argue that these values are consistent with Ni loss via evaporation during a high-energy impact that follows an initial stage of volatile loss from a magma ocean generated by 26Al heating. Thermodynamic modeling confirms Ni to be more volatile than Mn, Fe, Si, and Mg during evaporation from silicate liquids, in agreement with the observed relative magnitude of isotopic fractionation. Volcanic angrite matrices show variable and often subchondritic δ60/58Ni values (down to 0.5‰), reflecting mixing with isotopically heavy megacrystic olivines and recondensation of light Ni vapor onto the crust. These findings imply that volatile elements are stratified (core–mantle–crust) in the APB and provide direct isotopic evidence for impact-driven vapor loss and recondensation on a differentiated planetary body.

DOI: 10.1073/pnas.2519759122

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2519759122