Abstract

The results of study of the intrinsic oxygen fugacity (fO₂) of various types of tektites from the European and Australasian scattering fields (moldavites, indochinites, philippinites, and australites) performed by the electrochemical method using an apparatus with two solid electrolytes are reported. The fO₂ values of tektite glasses in the temperature range of 800–1050°C studied are between the fO₂ of the iron–wustite and wustite–magnetite buffer equilibria. They demonstrate a significantly more reduced character of tektites in comparison with magmatic melts (volcanic glasses) of the crustal and mantle origin. Among the Australasian tektites, the widest fO₂ variations are typical of indochinites including more diverse tektite species (Muong-Nong type and splat-forms), which are much closer to the hypothetical parental impact crater than philippinites and australites. At temperatures above that of complete melting (≥1000°C), fO₂ for all tektite glasses is significantly higher than the fO₂ values that correspond to the equilibrium of the metallic phase of iron with the silicate melt. It is assumed that the presence of microinclusions of metallic iron together with wustite, as well as magnetite and hematite in some tektites, is associated with nonequilibrium processes at different stages of tektite formation.

中文翻译：

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不同散射场的陨石的氧化还原状态：基于本征逸度电化学研究的数据

摘要

报道了使用具有两种固体电解质的装置通过电化学方法对欧洲和澳大利亚的散射场（分子筛，印支石，亚辉石和奥氏体）中各种类型的陨石的固有氧逸度（fO ₂）进行研究的结果。在800-1050°C的温度范围内，钛铁矿玻璃的fO ₂值介于铁-钙铁矿和钙铁矿-磁铁矿缓冲平衡的fO ₂之间。与地壳和地幔起源的岩浆熔体（火山玻璃）相比，它们显示出陨石的特性大大降低。在澳大利亚的陨石中，最宽的fO ₂印支矿的典型变化形式包括较多的陨石种类（Muong-Nong型和片状），其比假设的辉石岩和奥氏体更接近假想的父母撞击坑。在温度高于该完全熔融（≥1000℃），FO ₂为所有熔融石眼镜比FO显著更高_2个值对应于铁的金属相的与硅酸盐熔体的平衡。假定在某些陨石中，金属铁与镁铁矿以及磁铁矿和赤铁矿的微夹杂物的存在与陨石形成不同阶段的非平衡过程有关。