Sulfur and chlorine solubility in Mt. Unzen rhyodacitic melt at 850°C and 200 MPa
Sulfur and chlorine solubility in Mt. Unzen rhyodacitic melt at 850°C and 200 MPa
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DOI：
10.1016/j.chemgeo.2004.08.044
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发表时间：
2004-12-15
期刊：
影响因子：
3.9
通讯作者：
Sato, H
中科院分区：
文献类型：
--
作者：
Botcharnikov, RE;Behrens, H;Sato, H
在850 ℃、200 MPa、fO（2）与NNO相似的条件下，测定了云仙火山流纹质熔体中S和Cl在混合组分（H-O-Cl-S）流体相平衡下的溶解度。Cl在硅酸盐熔体和流体之间的分配显示出与理想行为的强烈偏离。与含有高达50摩尔% Cl的流体共存的熔体的Cl含量约为0.85重量%。随着硫的加入，Cl浓度降低0.2wt.% Cl（2重量% S;类似于流体中50 mol% Cl）。这种效应最有可能解释为剪切液中含Cl物质的更理想混合。然而，熔体组成的变化与添加的S（铁的贫化）也可以影响Cl的溶解度。硫在熔体中的溶解度是流体组分的活性、熔体的FeOtot含量和S的形态的复杂函数。随着系统中S含量从0增加到2 wt.%，S，磁黄铁矿（Pyr）的量增加（高达2.2体积%），熔体的FeOtot含量降低（从2.8至0.9重量% FeOtot），并且S溶解度略微增加（高达lOOppm）。在所研究的条件下，在含Cl体系中，S的溶解度高达200 ppm，表明Cl的加入增加了S的溶解度，Cl对S溶解度的影响可能与流体中的非理想混合有关，特别是，含S流体物种的活性增加和流体中H2S/SO2比的降低。第一种效应导致硫化物在熔体中的溶解度更高，第二种效应有利于在所研究的条件下在硅酸盐熔体中溶解额外的硫酸盐。(C)2004 Elsevier B. V.保留所有权利。
The solubilities of S and Cl have been determined at 850 degreesC, 200 MPa, andfO(2) similar toNNO in a rhyodacitic melt of the Unzen volcano in equilibrium with a fluid phase of mixed composition (H-O-Cl-S). The partitioning of Cl between silicate melt and fluid shows a strong deviation from ideal behavior. The Cl content of melts coexisting with fluids containing up to 50 mol% Cl is approximately 0.85 wt.%. With the addition of sulfur, the Cl concentration decreases by 0.2 wt.% Cl (2 wt.% S added in the system; similar to50 mol% Cl in fluid). This effect is most probably explained by a more ideal mixing of the Cl-bearing species in Shearing fluids. However, changes of melt composition with the addition of S (depletion of iron) can also influence Cl solubility. The solubility of sulfur in the melt is a complex function of the activity of fluid components, the FeOtot content of the melt, and the speciation of S. With increasing S content in the system from 0 to 2 wt.% S, the amount of pyrrhotite (Pyr) increases (up to 2.2 vol.%), the FeOtot content of the melt decreases (from 2.8 to 0.9 wt.% FeOtot), and S solubility increases slightly (up to 100 ppm). At the investigated conditions in the Cl-bearing systems, S solubilities up to 200 ppm have been determined, indicating that the addition of Cl to the system enhances S solubility.The influence of Cl on the solubility of S can be related to nonideal mixing in the fluid, in particular, the increase in activity of S-bearing fluid species and a decrease of H2S/SO2 ratios in the fluid. The first effect leads to higher solubility of sulfide in the melt and the second one favors the dissolution of additional sulfate in the silicate melt at studied conditions. (C) 2004 Elsevier B.V. All rights reserved.