AuPdFe ternary solution model and applications to understanding the fO(2) of hydrous, high-pressure experiments

作者：Barr Jay A^*; Grove Timothy L

来源：Contributions to Mineralogy and Petrology, 2010, 160(5): 631-643.

DOI：10.1007/s00410-010-0497-z

• AuPdFe alloy
• Ternary solution model
• Piston cylinder
• Oxygen fugacity
• Fe loss
• Hydrous experiments
• Experimental petrology

This study provides an experimental calibration of the equilibrium constant for AuPdFe alloys with Fe-bearing silicate melts. The ideal metal capsules for H2O-bearing experiments are pure Au, because of its slow hydrogen diffusivity. However, above the melting point of Au, other materials must be used. The solution to this problem is to use AuPd alloy capsules. However, under most relevant fO(2) conditions, this alloy absorbs Fe from the coexisting silicate melt, thus changing the bulk composition of the experimental charge. This study combines previous work on the Au-Pd, Pd-Fe, and Au-Fe binary systems to develop a ternary thermodynamic solution model for AuPdFe. This solution model is used with experiments to calculate an equilibrium reaction coefficient for the FeOmelt -> Fe-alloy + 1/2O(2) exchange reaction. Using a non-ideal ternary solution model, the fO(2) conditions of hydrous, piston cylinder experiments can be estimated by analyzing the sample capsule alloy and the coexisting liquid composition.

• 出版日期2010-11