Thermodynamics of multicomponent olivines and the solution properties of (Ni,Mg,Fe)2SiO4 and (Ca,Mg,Fe)2SiO4 olivine—Reply
Thermodynamics of multicomponent olivines and the solution properties of (Ni,Mg,Fe)2SiO4 and (Ca,Mg,Fe)2SiO4 olivine—Reply
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DOI：
10.2138/am-2000-1030
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发表时间：
2000-10
影响因子：
3.1
通讯作者：
M. Hirschmann
中科院分区：
文献类型：
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作者：
M. Hirschmann
Fleet（2000）批评了Hirschmann（1991）的含（Ni，Mg，Fe）2SiO 4橄榄石热力学模型的几个方面，并在我的博士论文中对其进行了重新校准。论文（Hirschmann 1992）。他还证明了Fleet（1989）用于提取橄榄石中NiSi0.5O2活度系数的热力学方法是正确的。我很高兴有人花时间读了我的博士论文。我将借此机会回答弗利特对我早期工作的评论，并详细阐述弗利特（1989）的问题。Fleet（2000）发现Hirschmann（1991）的（Ni，Mg，Fe）2SiO 4橄榄石热力学模型的三个方面存在缺陷。他批评了模型的表述，但他的论点反映了对解释长程有序的热力学模型的误解。他质疑用于校准模型的排序数据的质量，但不承认证实场地占用测量的可用数据。他还强调了预测的活性-组成关系的准确性，但未能考虑到实验的不确定性，并对NiSi0.5O2橄榄石活性的模型和实验约束之间的一致性提供了大量证据。Fleet（2000）还为Fleet（1989）的热力学分析中提取的NiSi0.5O2的活度系数进行了辩护。他提出，有后验证据表明，在一系列并非旨在缓冲二氧化硅的实验中，二氧化硅活性几乎恒定，但如下所述，有充分的理由怀疑这些实验中二氧化硅活性存在显著变化。他重申了Fleet（1989）中提出的证据，即实验中的氧硫化物液体是FeS-NiS二元溶液的合理近似物。然而，这些液体不太可能接近单硫化物组成，因为它们的报告组成是关键的。
Fleet (2000) criticizes several aspects of the thermodynamic model for (Ni,Mg,Fe)2SiO4-bearing olivine from Hirschmann (1991) and its subsequent recalibration in my Ph.D. thesis (Hirschmann 1992). He also justifies the thermodynamic methods used by Fleet (1989) to extract activity coefficients of NiSi0.5O2 in olivine. I am pleased that somebody has taken the time to read parts of my Ph.D. thesis and will take this opportunity to reply to Fleet’s comments on some of my early work and elaborate on the problems with Fleet (1989). Fleet (2000) finds fault with three aspects of the thermodynamic model for (Ni,Mg,Fe)2SiO4 olivine from Hirschmann (1991 Hirschmann (1992). He criticizes the formulation of the model, but his contentions reflect misapprehensions regarding thermodynamic models that account for long-range ordering. He questions the quality of the ordering data used to calibrate the model, but does not acknowledge available data that corroborate the site occupancy measurements. He also disparages the accuracy of the predicted activity-composition relations, but fails to account for experimental uncertainties and discounts considerable evidence for agreement between the model and experimental constraints on NiSi0.5O2 olivine activities. Fleet (2000) also defends the activity coefficients for NiSi0.5O2 extracted in the thermodynamic analysis of Fleet (1989). He suggests that there is a posteriori evidence that silica activity was nearly constant in a suite of experiments that were not designed to buffer silica but, as detailed below, there is good reason to suspect significant silica activity variation in these experiments. He reiterates evidence presented in Fleet (1989) suggesting that the oxysulfide liquids in the experiments of interest are reasonable approximations of FeS-NiS binary solutions. However, these liquids are unlikely to be close to monosulfide composition because their reported compositions are critically …