Phase relations in the Fe1bC1bO1bS1bH2O system and its geological application
Phase relations in the Fe1bC1bO1bS1bH2O system and its geological application
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Fe1bC1bO1bS1bH2O体系中的相关系及其地质应用
DOI：
10.1016/0009-2541(71)90027-1
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发表时间：
1971
期刊：
影响因子：
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通讯作者：
M. Seguin
中科院分区：
文献类型：
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作者：
M. Seguin
Fe1bC1bO1bS 系统在 75°–800°C 的温度和大约 1–2,500 atm 的压力下进行了研究。当 H2O 添加到系统中时，通常会降低组合体的稳定性约 15-20°C。本文讨论了在总压2000atm下进行的具有地质意义的实验结果。实验结果的地质应用可分为四个部分。第 1 部分对人工和自然组合的纹理进行了比较（Seguin，1965）。在第二部分中，强调了组合体作为地温计的用途。例如，如果所考虑的组合是磁铁矿-菱铁矿-黄铁矿-赤铁矿，并且假设该组合是在平衡条件下形成的，则形成或变质作用的最高温度为313°C。在第 3 部分中，将组合用作风压计仅限于单变量曲线。单变量组合不适合测量总压力，但确实提供了有关逸度的信息。第 4 部分展示了如何以及在多大程度上可以将这些组合用作铁地层的起源和变质程度的指标。控制铁硫化物、氧化物和碳酸盐形成的起源和变质条件的重要因素是O2、S2、SO2的逸度和温度。有人指出，结果可能并不像人们希望的那样准确，因为天然化合物并不总是像人造化合物一样纯净。例如，并非所有天然菱铁矿都是纯 FeCO3，也并非所有天然磁铁矿都是纯 Fe3O4；铁橄榄石是绿钠铁矿和明尼苏达铁矿等的较差替代品。将实验结果应用于魁北克北部拉布拉多海槽和加拿大纽芬兰的铁矿石，表明在 290°–350°C 范围内发生变质作用。对加拿大安大略省米奇皮科滕地区铁矿石的类似研究表明，变质作用在 290°–410° 范围内。
The Fe1bC1bO1bS system was studied at temperatures of 75°–800°C and at pressures of approximately 1–2,500 atm. When H2O was added to the system, it generally lowered the stability of the assemblages by some 15–20°C. The experimental results of experiments conducted at a total pressure of 2,000 atm and which are of geological significance are discussed in this paper.The geological application of the experimental results may be divided into four parts. In part 1, a comparison is made between the textures of artificial and natural assemblages (Seguin, 1965). In part 2, the uses of the assemblages as geothermometers are stressed. For instance, if the assemblage considered is magnetite-siderite-pyrite-hematite and if it is assumed that the assemblage was formed under equilibrium conditions, then the maximum temperature of formation or of metamorphism is 313°C. In part 3, the uses of assemblages as geomanometers are limited to univariant curves. The univariant assemblages are unsuitable for measurements of total pressure but do give information about fugacities. In part 4, it is shown how and to what extent the assemblages can be used as indicators of the origin and of the degree of metamorphism of the iron formations. The important factors controlling the conditions of origin and metamorphism of iron sulfides, oxides and carbonates formations are the fugacities of O2, S2, SO2and the temperature. The point is made that the results may not be as exact as one would hope, because natural chemical compounds are not always as pure as artificial chemical compounds. For instance, not all the natural siderites are pure FeCO3and not all the natural magnetites are pure Fe3O4; fayalite is a poor substitute for greenalite and minnesotaite etc.Applications of the experimental results to ironstones from the Labrador Trough, northern Quebec and Newfoundland, Canada, indicated metamorphism in the 290°–350°C range. Similar studies of the iron ores in the Michipicoten area, Ontario, Canada, indicated metamorphism in the 290°–410° range.