Silicon isotopes in meteorites and planetary core formation
Silicon isotopes in meteorites and planetary core formation
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DOI：
10.1016/j.gca.2011.03.044
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发表时间：
2011-07-01
影响因子：
5
通讯作者：
Halliday, A. N.
中科院分区：
文献类型：
--
作者：
Armytage, R. M. G.;Georg, R. B.;Halliday, A. N.
利用MC-ICPMS测定了42个陨石和地球样品的硅同位素组成，旨在解决目前关于它们的组成及其对成核的影响的争论。未解决两个样品之间的系统性δ Si-30差异（δ Si-30 = -0.49 +/-0.15 ‰，2 σ（SD））和无球粒陨石（δ Si-30 = -0.47 +/-0.11份/千，2 σ（SD）），尽管顽火辉石陨石与其他陨石群相比始终较轻（δ Si-30 = -0.63 +/-0.07 ‰，2 σ（SD））。这里报告的陨石和陆地样品的数据显示出Delta Si-30（BSE-陨石）* = 0.15 +/- 0.10千分之一的平均差异，这与以前的研究在不确定性范围内是一致的。样本异质性、制备、化学或质谱分析的影响均未被确定为导致当前数据集之间报告差异的原因。散装硅酸盐地球的较重的组合物是一致的，与以前的结论，硅分配到金属相在金属硅酸盐平衡时的核心形成。将地核形成的温度固定在橄榄岩液相线上，并使用适当的金属硅酸盐分馏因子（δ = 0.89），这项研究得出的Delta Si-30（BSE-陨石）* 值表明，地核含有至少2.5重量%，可能高达16.8重量%的Si。(C)2011爱思唯尔有限公司版权所有。
The silicon (Si) isotope compositions of 42 meteorite and terrestrial samples have been determined using MC-ICPMS with the aim of resolving the current debate over their compositions and the implications for core formation. No systematic delta Si-30 differences are resolved between chondrites (delta Si-30 = -0.49 +/- 0.15 parts per thousand, 2 sigma(SD)) and achondrites (delta Si-30 = -0.47 +/- 0.11 parts per thousand, 2 sigma(SD)), although enstatite chondrites are consistently lighter (delta Si-30 = -0.63 +/- 0.07 parts per thousand, 2 sigma(SD)) in comparison to other meteorite groups. The data reported here for meteorites and terrestrial samples display an average difference Delta Si-30(BSE-meteorite) * = 0.15 +/- 0.10 parts per thousand, which is consistent within uncertainty with previous studies. No effect from sample heterogeneity, preparation, chemistry or mass spectrometry can be identified as responsible for the reported differences between current datasets. The heavier composition of the bulk silicate Earth is consistent with previous conclusions that Si partitioned into the metal phase during metal-silicate equilibration at the time of core formation. Fixing the temperature of core formation to the peridotite liquidus and using an appropriate metal silicate fractionation factor (epsilon similar to 0.89), the Delta Si-30(BSE-meteorite) * value from this study indicates that the Earth core contains at least 2.5 and possibly up to 16.8 wt% Si. (C) 2011 Elsevier Ltd. All rights reserved.