Effect of oxygen fugacity on the glass transition, viscosity and structure of silica- and iron-rich magmatic melts
Effect of oxygen fugacity on the glass transition, viscosity and structure of silica- and iron-rich magmatic melts
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DOI：
10.1016/j.jnoncrysol.2017.05.013
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发表时间：
2017-08-15
影响因子：
3.5
通讯作者：
Dingwell, Donald B.
中科院分区：
文献类型：
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作者：
Di Genova, Danilo;Vasseur, Jeremie;Dingwell, Donald B.
铁的氧化态影响自然熔体的物理性质和结构，并最终影响岩浆和火山过程，如岩浆输送和喷发方式。在这里，我们研究了富铁过碱性流纹岩的玻璃化转变温度和熔体粘度作为铁氧化态的函数。使用差示扫描量热法测定玻璃化转变温度，最高可达680 ℃。使用同心圆筒技术在1385摄氏度下测量高温粘度。玻璃化转变温度和粘度都随氧逸度条件的增加而增加。虽然预期结构随温度的显著变化，但我们观察到氧逸度对高低温下的本体性质的影响与通过拉曼光谱推断的玻璃结构的聚合之间的直接关系。结果表明，粘度模型应考虑氧逸度对爆发温度下熔体粘度的影响，同时考虑水和晶体含量的影响。
Iron oxidation state affects the physical properties and structure of natural melts and, ultimately, magmatic and volcanic processes such as magma transport and eruptive style. Here, we study the glass transition temperature and melt viscosity of an iron-rich peralkaline rhyolite as a function of the iron oxidation state. Glass transition temperature is determined using a differential scanning calorimetry up to 680 degrees C. High-temperature viscosity is measured at 1385 degrees C using the concentric cylinder technique. Both the glass transition temperature and viscosity increase with oxygen fugacity conditions. Although significant changes in structure with temperature are expected, we observe a direct relationship between the effect of oxygen fugacity on bulk properties at high and low temperature and polymerization of glass structure as inferred by Raman spectroscopy. Our results show that viscosity models should consider the effect of oxygen fugacity on the melt viscosity at eruptive temperature together with the effect of water and crystal content.