Argon behavior in basaltic melts in presence of a mixed H2O-CO2 fluid at upper mantle conditions
Argon behavior in basaltic melts in presence of a mixed H2O-CO2 fluid at upper mantle conditions
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DOI：
10.1016/j.chemgeo.2016.11.014
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发表时间：
2017-01-05
期刊：
影响因子：
3.9
通讯作者：
Laporte, D.
中科院分区：
文献类型：
--
作者：
Fabbrizio, A.;Bouhifd, M. A.;Laporte, D.
在 1-5 GPa 的压力范围和 1350 至 1600 摄氏度之间的温度下，对氩气在含 H2O-CO2 的玄武岩熔体中的行为进行了实验研究。我们的实验数据模拟了在岩浆上升和脱气过程中发生的含 Ar-H2O-CO2 的流体和硅酸盐熔体之间氩气的分配。实验结果显示出几个特征： - 在 1 GPa 压力下，H 2 O 从 035 到约 2 wt.%（CO 2 含量恒定）的变化不会引起溶解在玄武岩熔体中的氩的任何系统变化。对于较高的水含量（>2 wt.%），我们观察到水对氩溶解度的积极影响。 - 在 3-5 GPa 范围内，我们没有观察到水浓度从 0.35 到 5.3 wt.% 时玄武岩熔体中的氩含量有任何系统变化，而在 CO2 含量为 0.5 wt.% 时，当CO2 含量从 0.5 wt.% 增加到 0.8 wt.%。 - 在本研究中研究的所有压力下，观察到浓度 < 5000 ppm 的 CO2 对硅酸盐熔体中氩含量的影响可以忽略不计。 - 更重要的是（尽管存在所有这些变化），1 至 5 GPa 范围内的压力影响似乎是玄武岩熔体中氩溶解度的主要参数。压力对氩气在含 H2O-CO2 的玄武岩熔体中的掺入具有积极影响，在 3 GPa 下达到类似于 038 wt.% 的浓度。该最大值类似于 038 wt.%，相当于标准温度和压力下的 6.8 x 10(-5) cm(3) g(-1) bar(-1)，该值与由氩气平衡的无挥发物玄武岩熔体得出的值处于同一数量级。实验数据可以通过假设挥发性物质和氧在硅酸盐熔体中混合的热力学模型来很好地描述。研究结果可用于更好地理解岩浆上升过程中脱气过程中发生的稀有气体/稀有气体和稀有气体/CO2 分馏。 (C) 2016 年由 Elsevier B.V. 出版
The behavior of argon in H2O-CO2 bearing basaltic melts was experimentally investigated in the pressure range 1-5 GPa and at temperatures between 1350 and 1600 degrees C. Our experimental data simulate the partitioning of argon between an Ar-H2O-CO2 bearing fluid and a silicate melt occurring during magma ascent and degassing. The experimental results show several features:- At a pressure of 1 GPa the variation of H2O from 035 to about 2 wt.% (at constant CO2 content) does not induce any systematic variation of argon dissolved in basaltic melt. For higher water contents (>2 wt.%) we observe a positive effect of water on argon solubility.- In the range of 3-5 GPa, we did not observe any systematic variation of the argon content in the basalt melt for water concentration from 0.35 to 5.3 wt.% and at CO2 content 0.5 wt.%, argon concentration in basalt melt decreases from about 3800 to 2400 ppm when the CO2 content increases from 0.5 to 0.8 wt.%.- At all pressures investigated in the present study, a negligible effect of CO2 for concentration < 5000 ppm on argon content in the silicate melt is observed.- More importantly (despite all these variations) it seems that the effect of pressure in the range of 1 to 5 GPa is the dominant parameter on argon solubility in basaltic melt. Pressure has a positive effect on argon incorporation in the H2O-CO2 bearing basaltic melt reaching at 3 GPa a concentration of similar to 038 wt.%. This maximum of similar to 038 wt.% corresponds to 6.8 x 10(-5) cm(3) g(-1) bar(-1) at standard temperature and pressure, a value of the same order of magnitude as that derived from volatiles free basaltic melts equilibrated with argon. The experimental data can be well described by a thermodynamic model assuming mixing of volatile species and oxygen in the silicate melt. The results can be applied for a better understanding of the fractionation noble gas/noble gas and noble gas/CO2 occurring in degassing processes during magma ascent. (C) 2016 Published by Elsevier B.V.