The effect of carbon concentration on its core-mantle partitioning behavior in inner Solar System rocky bodies
The effect of carbon concentration on its core-mantle partitioning behavior in inner Solar System rocky bodies
复制标题
太阳系内岩体碳浓度对其核幔分配行为的影响
DOI：
10.1016/j.epsl.2021.117090
复制
发表时间：
2021
影响因子：
5.3
通讯作者：
Aithala, Sanath
中科院分区：
文献类型：
--
作者：
Grewal, Damanveer S.;Dasgupta, Rajdeep;Aithala, Sanath
碳（C）分配到岩石原行星和行星的核心是其在其块状硅酸盐储层中耗尽的主要原因之一。大多数测定合金/硅酸盐熔体碳分配系数（DC合金/硅酸盐）的实验研究是在石墨饱和条件下进行的。由于碳是一种微量元素，在所有已知的原行星和行星的核心，它是不知道是否石墨饱和的DC合金/硅酸盐值适用于核幔分化的岩石体可能发生在C-贫条件。在这项研究中，我们实验测定了在MgO胶囊中的DC合金/硅酸盐，在固定的P（3GPa）-T（1700° C）下，在IW-6.35和IW-2.59的氧逸度（fO 2）之间变化的体相C含量。硅酸盐熔体的镁铁质-超镁铁质（NBO/T= 1.23-1.72）和轻度含水（本体H= 44-161 ppm）性质导致无水C物质（CO 3 2−+ CO）在较宽的fO 2范围（> IW-4.2）内占主导地位。随着fO 2从IW-2.6降低到IW-4.2，DC合金/硅酸盐的含量增加，在还原条件下由于CH物种的形成而降低。重要的是，DC合金/硅酸盐增加，在给定的fO 2的系统中增加体C含量。C在合金和硅酸盐熔体之间的分配遵循非Henrian行为（即，它取决于体相C含量），因为合金熔体（γ C合金熔体）中C的活度系数随合金中C含量而变化。因此，除了其他强度（P，T，fO 2）和广泛的变量（合金和硅酸盐熔体成分），DC合金/硅酸盐还取决于在核幔分异过程中可用的体C含量。因此，以前确定的DC合金/硅酸盐的富C合金是不直接适用于核幔分异相对贫C岩浆海洋（MO）。由于本研究的实验更真实地模拟了贫碳核和轻度含水的镁铁质-超镁铁质硅酸盐MOs，因此我们的数据可以用于更准确地预测太阳系内岩石体中MOs和核之间的C分馏。我们的研究表明，封闭系统MO核心平衡应该导致不太严重的消耗C的硅酸盐水库内太阳系岩石体比以前预测的。
Partitioning of carbon (C) into the cores of rocky protoplanets and planets is one of the primary causes of its depletion in their bulk silicate reservoirs. Most of the experimental studies that determined the alloy to silicate melt partition coefficient of carbon (D C alloy/silicate) have been conducted in graphite-saturated conditions. Because carbon is a minor element in all known protoplanetary and planetary cores, it is not known whether graphite-saturated D C alloy/silicate values are applicable to core-mantle differentiation in rocky bodies which likely occurred in C-poor conditions. In this study we experimentally determined D C alloy/silicate in MgO capsules with variable bulk C contents between oxygen fugacity (fO 2) of IW–6.35 and IW–2.59 at a fixed P (3 GPa)-T (1700° C). A mafic-ultramafic (NBO/T= 1.23-1.72) and mildly hydrous (bulk H= 44-161 ppm) nature of the silicate melts caused anhydrous C species (CO 3 2−+ CO) to dominate over a wider fO 2 range (> IW–4.2) in comparison to previous studies. This resulted in an increase in D C alloy/silicate with decreasing fO 2 from IW–2.6 to IW–4.2 followed by a drop at more reduced conditions due to the formation of CH species. Importantly, D C alloy/silicate increases with increasing bulk C content of the system at a given fO 2. Partitioning of C between alloy and silicate melts follows non-Henrian behavior (ie, it depends on bulk C content) because the activity coefficient of C in the alloy melt (γ C alloy melt) varies with C content in the alloy. Therefore, in addition to other intensive (P, T, fO 2) and extensive variables (alloy and silicate melt compositions), D C alloy/silicate also depends on the bulk C content available during core-mantle differentiation. Consequently, previously determined D C alloy/silicate for C-rich alloys are not directly applicable for core-mantle differentiation in relatively C-poor magma oceans (MOs). Because the experiments from the present study more realistically simulate C-poor cores and mildly hydrous, mafic-ultramafic silicate MOs, our data can be used to more accurately predict C fractionation between MOs and cores in inner Solar System rocky bodies. Our study suggests that closed system MO-core equilibration should have led to less severe depletion of C in the silicate reservoirs of inner Solar System rocky bodies than previously predicted.
登录
查看更多内容
影响因子：
13.6
作者：
Grewal, Damanveer S.;Dasgupta, Rajdeep;Costin, Gelu
通讯作者：
Costin, Gelu
影响因子：
4.5
作者：
Cartier, Camille;Wood, Bernard J.
通讯作者：
Wood, Bernard J.
亲铁元素的金属-硅酸盐分配对灶神星核心形成的限制
DOI：
--
发表时间：
2016
期刊：
影响因子：
--
作者：
E. Steenstra;J. Knibbe;N. Rai;W. Westrenen
通讯作者：
W. Westrenen
通过天然富含 CO2 的气体分析评估地幔的 C/N 比：地球化学和宇宙化学意义
影响因子：
5.3
作者：
B. Marty;M. Almayrac;P. Barry;D. Bekaert;M. Broadley;D. Byrne;C. Ballentine;A. Caracausi
通讯作者：
A. Caracausi
影响因子：
3.9
作者：
G. Helffrich;R. Brasser;A. Shahar
通讯作者：
A. Shahar