The chemistry of volcanic gases: 2. Use of equilibrium calculations in the interpretation of volcanic gas samples
The chemistry of volcanic gases: 2. Use of equilibrium calculations in the interpretation of volcanic gas samples
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火山气体的化学性质：2.平衡计算在火山气体样品解释中的应用
DOI：
10.1029/jz068i002p00545
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发表时间：
1963
影响因子：
--
通讯作者：
I. L. Barnes
中科院分区：
文献类型：
--
作者：
E. F. Heald;J. Naughton;I. L. Barnes
给出了 1959 年至 1960 年夏威夷基拉韦厄火山喷发期间和喷发后收集的火山气体样本的分析结果。这些结果的解释是根据在含有碳、硫、氢和氧元素的多组分气态系统中达到化学平衡来进行的。使用数字计算机计算该系统的平衡组成随温度、压力、氧分压和水分压的变化的变化。实验分析与计算出的样品平衡组成的比较表明，平衡通常在气相中达到，除了在火山气体和非火山气体（例如加热的地表水或有机材料）之间的某些情况下。根据硫磺喷气孔硫库排放的气体成分随时间的变化得出的结论是，气相与周围岩石之间通常不会发生完全的非均质平衡。基拉韦厄一奇火山渣锥排放的气体成分随时间的变化可用于评估在初始排放后改变原始岩浆气体成分的一些因素。结果表明，在某些情况下，火山气体可以被视为封闭系统，至少在第一近似上是这样。这给人们带来了希望，即可以从最有利条件下获得的火山气体样本推断出玄武岩形成条件下的气体成分。
Analytical results are given for volcanic gas samples collected during and after the 1959–1960 eruption of the Hawaiian volcano Kilauea. Interpretation of these results is made in terms of attainment of chemical equilibrium in a multicomponent, gaseous system containing the elements carbon, sulfur, hydrogen, and oxygen. Changes in the equilibrium composition of this system with changes in temperature, pressure, oxygen partial pressure, and water partial pressure are calculated using a digital computer. Comparison of the experimental analyses with the calculated equilibrium compositions of the samples shows that equilibrium is usually attained in the gas phase, except in certain instances between volcanic gases and gases of nonvolcanic origin, such as heated surface water or organic material. On the basis of changes in the composition of gases emitted by the solfataric fumarole Sulphur Bank with time it is concluded that complete heterogeneous equilibrium usually does not take place between the gas phase and the surrounding rocks. Changes in the composition of the gases emitted by the Kilauea Iki cinder cone with time are used to evaluate some of the factors changing the composition of the original magmatic gas after its initial emission. It is shown that in some cases volcanic gas may be regarded as a closed system, at least to a first approximation. This gives hope that extrapolation to the gas composition at the conditions of formation of basaltic rocks may be possible from volcanic gas samples obtained under the most favorable conditions.