Magnesium isotope evidence that accretional vapour loss shapes planetary compositions.
Magnesium isotope evidence that accretional vapour loss shapes planetary compositions.
复制标题
DOI：
10.1038/nature23899
复制
发表时间：
2017-09-27
期刊：
影响因子：
64.8
通讯作者：
Elliott T
中科院分区：
文献类型：
--
作者：
Hin RC;Coath CD;Carter PJ;Nimmo F;Lai YJ;Pogge von Strandmann PAE;Willbold M;Leinhardt ZM;Walter MJ;Elliott T
长期以来，人们已经认识到，地球和其他分化的行星体与原始的南极陨石相比，化学上是分离的，并推断出它们形成的原始圆盘。一个重要的问题是，行星体显著的挥发性消耗是吸积的结果，还是继承自先前的星云分离。行星体的主要成分的同位素组成可能有助于这一辩论。使用一种新的分析方法来解决传统方法中固有的准确性的关键问题，我们表明，所有分化的机构有同位素重镁组成比陨石。我们认为，太阳星云凝结、核心形成和硅酸盐分化过程中可能的镁同位素分馏无法解释这些观察结果。然而，同位素分馏的液体和蒸汽之间的吸积生长过程中的星子产生适当的残留成分，然后蒸汽逃逸。我们的模型表明，Mg，Si和Fe的同位素组成以及地球和其他行星体的主要元素的相对丰度，是通过这种机制从生长的微行星中大量（约40%质量）蒸汽损失的自然结果。
It has long been recognised that Earth and other differentiated planetary bodies are chemically fractionated compared to primitive, chondritic meteorites and by inference the primordial disk from which they formed. An important question has been whether the notable volatile depletions of planetary bodies are a consequence of accretion, or inherited from prior nebular fractionation. The isotopic compositions of the main constituents of planetary bodies can contribute to this debate. Using a new analytical approach to address key issues of accuracy inherent in conventional methods, we show that all differentiated bodies have isotopically heavier magnesium compositions than chondritic meteorites. We argue that possible magnesium isotope fractionation during condensation of the solar nebula, core formation and silicate differentiation cannot explain these observations. However, isotopic fractionation between liquid and vapour followed by vapour escape during accretionary growth of planetesimals generates appropriate residual compositions. Our modelling implies that the isotopic compositions of Mg, Si and Fe and the relative abundances of the major elements of Earth, and other planetary bodies, are a natural consequence of substantial (~40% by mass) vapour loss from growing planetesimals by this mechanism.
登录
查看更多内容
影响因子：
5.3
作者：
Badro, James;Fiquet, Guillaume;d'Astuto, Matteo
通讯作者：
d'Astuto, Matteo
影响因子：
3.4
作者：
Bizzarro, Martin;Paton, Chad;Ulfbeck, David
通讯作者：
Ulfbeck, David
影响因子：
5.3
作者：
Chakrabarti, Ramananda;Jacobsen, Stein B.
通讯作者：
Jacobsen, Stein B.
影响因子：
64.8
作者：
Georg, R. Bastian;Halliday, Alex N.;Reynolds, Ben C.
通讯作者：
Reynolds, Ben C.
影响因子：
5.3
作者：
Javoy, Marc;Balan, Etienne;Lazzeri, Michele
通讯作者：
Lazzeri, Michele