Nickel isotopic evidence for late-stage accretion of Mercury-like differentiated planetary embryos.
Nickel isotopic evidence for late-stage accretion of Mercury-like differentiated planetary embryos.
复制标题
DOI：
10.1038/s41467-020-20525-1
复制
发表时间：
2021-01-12
影响因子：
16.6
通讯作者：
Li W
中科院分区：
文献类型：
--
作者：
Wang SJ;Wang W;Zhu JM;Wu Z;Liu J;Han G;Teng FZ;Huang S;Wu H;Wang Y;Wu G;Li W
地球的可居住性与其后期吸积密切相关，在此期间，撞击物提供了大部分生命必需的挥发物。然而，这些最终构件的性质仍然受到很大的限制。镍（Ni）可以是一个有用的示踪剂，在表征这种吸积的散装硅酸盐地球（BSE）中的大多数镍来自后期的冲击。在这里，我们应用镍稳定同位素分析大量的陨石和陆地岩石，并发现BSE有一个较轻的镍同位素组成相比，陨石。使用基于密度泛函理论的第一性原理计算，我们表明，核幔分异不能产生所观察到的轻镍同位素组成的BSE。相反，亚南极洲的镍同位素特征是在地球的后期吸积过程中建立的，可能是通过形成月球的巨大撞击。我们认为，一个高度还原的硫化物丰富，汞样的身体，其地幔的特点是轻镍同位素组成，碰撞并合并到原地球在月球形成的巨大影响，产生亚南极洲的镍同位素签名的BSE，同时提供硫和其他挥发物到地球。通过对陨石和陆源岩石的镍同位素分析，认为块状硅酸盐地球的镍同位素组成属于亚南极型。这一特征被认为是来自太阳系最内层的一个类水星撞击物的撞击和吸积造成的。
Earth’s habitability is closely tied to its late-stage accretion, during which impactors delivered the majority of life-essential volatiles. However, the nature of these final building blocks remains poorly constrained. Nickel (Ni) can be a useful tracer in characterizing this accretion as most Ni in the bulk silicate Earth (BSE) comes from the late-stage impactors. Here, we apply Ni stable isotope analysis to a large number of meteorites and terrestrial rocks, and find that the BSE has a lighter Ni isotopic composition compared to chondrites. Using first-principles calculations based on density functional theory, we show that core-mantle differentiation cannot produce the observed light Ni isotopic composition of the BSE. Rather, the sub-chondritic Ni isotopic signature was established during Earth’s late-stage accretion, probably through the Moon-forming giant impact. We propose that a highly reduced sulfide-rich, Mercury-like body, whose mantle is characterized by light Ni isotopic composition, collided with and merged into the proto-Earth during the Moon-forming giant impact, producing the sub-chondritic Ni isotopic signature of the BSE, while delivering sulfur and probably other volatiles to the Earth. Based on Nickel isotope analysis of meteorites and terrestrial rocks, the authors suggest that the Bulk Silicate Earth has a sub-chondritic Nickel isotope composition. This signature is thought to result from the impact and accretion of a Mercury-like impactor which originated from the innermost Solar System.
登录
查看更多内容
影响因子：
56.9
作者：
Alexander, C. M. O'D.;Bowden, R.;Nittler, L. R.
通讯作者：
Nittler, L. R.
影响因子：
2.2
作者：
Burkhardt, Christoph;Dauphas, Nicolas;Papanastassiou, Dimitri A.
通讯作者：
Papanastassiou, Dimitri A.
影响因子：
4.5
作者：
Cartier, Camille;Wood, Bernard J.
通讯作者：
Wood, Bernard J.
影响因子：
5
作者：
Chernonozhkin, Stepan M.;Goderis, Steven;Vanhaecke, Frank
通讯作者：
Vanhaecke, Frank
影响因子：
3.8
作者：
Gueguen, Bleuenn;Rouxel, Olivier;Fouquet, Yves
通讯作者：
Fouquet, Yves