Abstract
The behavior of argon in H2O-CO2 bearing basaltic melts was experimentally investigated in the pressure range 1–5GPa and at temperatures between 1350 and 1600°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 1GPa the variation of H2O from 0.35 to about 2wt.% (at constant CO2 content) does not induce any systematic variation of argon dissolved in basaltic melt. For higher water contents (>2wt.%) we observe a positive effect of water on argon solubility.-In the range of 3–5GPa, we did not observe any systematic variation of the argon content in the basalt melt for water concentration from 0.35 to 5.3wt.% and at CO2 content <0.5wt.%. For CO2 content >0.5wt.%, argon concentration in basalt melt decreases from about 3800 to 2400ppm when the CO2 content increases from 0.5 to 0.8wt.%.-At all pressures investigated in the present study, a negligible effect of CO2 for concentration<5000ppm 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 5GPa 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 3GPa a concentration of ~0.38wt.%. This maximum of ~0.38wt.% corresponds to 6.8×10−5cm3g−1bar−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.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
