Intrinsic oxygen fugacity measurements: techniques and results for spinels from upper mantle peridotites and megacryst assemblages
Intrinsic oxygen fugacity measurements: techniques and results for spinels from upper mantle peridotites and megacryst assemblages
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固有氧逸度测量：上地幔橄榄岩和巨型晶体组合尖晶石的技术和结果
DOI：
10.1016/0016-7037(81)90118-6
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
J. Delano
中科院分区：
文献类型：
--
作者：
R. Arculus;J. Delano
本文介绍了一种用固体ZrO 2氧电解质测定单相和多相地质样品的本征氧逸度的新方法。基本上，该过程涉及将来自样品的电动势信号与由样品承载传感器内的残余气氛可避免地施加的电动势信号隔离。通过改变残余大气的CO2，可以确定传感器记录的恒定CO2的“平台”值，该值代表样品单独的反向固有CO2测量值，平台的程度反映了样品的固有缓冲能力。测量所获得数据的精确度和准确度的一个标准是，无论是在样品+相容气氛系统的加热循环还是冷却循环中，都获得了相同的CO2值。这些技术已应用于澳大利亚、西德德国和美国的橄榄岩和巨晶组合中尖晶石的本征氧含量的测量。氧化态范围从比铁-方铁矿（IW）缓冲层氧化的10 - 0.25 log 10单位到比IW缓冲层氧化的1 log 10单位。尖晶石的整体减少的性质和范围内的氧化物2的获得的数据是显着的功能。结果的一个含义是，大多数幔源岩浆最初高度还原，在地表观察到的相对氧化值（氧化程度比IW高10个数量级）反映了后期蚀变，可能是由于H2损失（Sato，1978年）。
A new technique for the determination of intrinsic oxygen fugacities (ƒ O 2's) of single and polyphase geological samples with solid ZrO 2, oxygen-specific electrolytes is described. Essentially the procedure involves isolating the emf signal from the sample from that unavoidably imposed by the residual atmosphere inside the sample-bearing sensor. By varying the ƒ O 2 of the residual atmosphere, it is possible to determine a ‘plateau’value of constant ƒ O 2 recorded from the sensor which represents a reversed intrinsic ƒ O 2 measurement for the sample alone, and where the extent of the plateau reflects the innate buffering capability of the sample. A measure of the precision and accuracy of the data obtained is the fact that identical ƒ O 2 values are obtained whether on a heating or cooling cycle of the sample+ compatible atmosphere system. These techniques have been applied to measurements of the intrinsic ƒ O 2 of spinels from peridotites and megacryst assemblages from Australia, West Germany and the USA Oxidation states range from∼-0.25 log 10 units more oxidized to 1 log 10 unit more reduced than the iron-wüstite (IW) buffer. The overall reduced nature of the spinels and the range of ƒ O 2's obtained are striking features of the data. One implication of the results is that the majority of mantle-derived magmas are initially highly reduced, and the relatively oxidized values observed at surface (∼-4–5 log 10 orders more oxidized than IW) reflect late-stage alteration, perhaps by H 2 loss (Sato, 1978).