Sulfur isotopic signature of Earth established by planetesimal volatile evaporation
Sulfur isotopic signature of Earth established by planetesimal volatile evaporation
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通过星子挥发性蒸发建立的地球硫同位素特征
DOI：
10.1038/s41561-021-00838-6
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发表时间：
2021
影响因子：
18.3
通讯作者：
Wang, Shui-Jiong
中科院分区：
文献类型：
--
作者：
Wang, Wenzhong;Li, Chun-Hui;Brodholt, John P.;Huang, Shichun;Walter, Michael J.;Li, Min;Wu, Zhongqing;Huang, Fang;Wang, Shui-Jiong
地球挥发物含量的形成方式和时间存在争议，存在多种假设机制，包括星子蒸发、核心形成和未分化的球粒陨石类材料的后期输送。硫等挥发性元素的同位素可以在行星吸积和分化过程中被分馏，因此是这些过程的潜在示踪剂。使用第一原理计算，我们研究了核心形成和星子蒸发过程中的硫同位素分馏。我们发现在成核条件下硅酸盐和金属熔体之间没有可测量的硫同位素分馏，这表明观察到的块状硅酸盐地球相对于球粒陨石的轻硫同位素组成不能用金属-硅酸盐分馏来解释。我们的热力学计算表明，当存在星云 H2 时，硫在星子蒸发过程中主要以 H2S 的形式蒸发。观测到的大量地球硫同位素特征和丰度可以通过在星云 H2 消散之前蒸发损失约 90% 的硫（主要以 H2S 的形式从熔融星子中蒸发）来重现。月球相对于地球的重硫同位素组成与月球形成巨撞击期间94%~98%饱和度条件下的蒸发硫损失一致。总之，地球形成之前熔融星子的挥发性蒸发可能在确定地球挥发性元素含量方面发挥了关键作用。
How and when Earth’s volatile content was established is controversial with several mechanisms postulated, including planetesimal evaporation, core formation and the late delivery of undifferentiated chondrite-like materials. The isotopes of volatile elements such as sulfur can be fractionated during planetary accretion and differentiation and thus are potential tracers of these processes. Using first-principles calculations, we examine sulfur isotope fractionation during core formation and planetesimal evaporation. We find no measurable sulfur isotope fractionation between silicate and metallic melts at core-forming conditions, indicating that the observed light sulfur isotope composition of the bulk silicate Earth relative to chondrites cannot be explained by metal–silicate fractionation. Our thermodynamic calculations show that sulfur evaporates mostly as H2S during planetesimal evaporation when nebular H2is present. The observed bulk Earth sulfur isotope signature and abundance can be reproduced by evaporative loss of about 90% sulfur mainly as H2S from molten planetesimals before nebular H2is dissipated. The heavy sulfur isotope composition of the Moon relative to the Earth is consistent with evaporative sulfur loss under 94–98% saturation condition during the Moon-forming giant impact. In summary, volatile evaporation from molten planetesimals before Earth’s formation probably played a key role in establishing Earth’s volatile element content.
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影响因子：
16.6
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
通讯作者：
Li W
影响因子：
5
作者：
Labidi, J.;Farquhar, J.;Oduro, H.
通讯作者：
Oduro, H.
硫同位素对硫陨石解离和蒸发的影响：月壤中 34S 富集的可能机制☆
影响因子：
5
作者：
C. E. McEwinct;H. Thode;C. Rees
通讯作者：
C. Rees
影响因子：
5.3
作者：
William M. Nash;D. Smythe;B. Wood
通讯作者：
William M. Nash;D. Smythe;B. Wood
影响因子：
13.6
作者：
Grewal, Damanveer S.;Dasgupta, Rajdeep;Costin, Gelu
通讯作者：
Costin, Gelu