Oxygen fugacity from the melt sulfur content
Oxygen fugacity is a key thermodynamic parameter to estimate in magmatic systems because of its effects on the chemical and physical properties of the melt (e.g., Carmichael and Ghiorso, 1990; Hughes et al., 2024; Kolzenburg et al., 2018). In certain circumstances, the sulfur content of the melt can be used to place bounds on the oxygen fugacity based on sulfide and anhydrite saturation (e.g., Beerman et al., 2011; Muth and Wallace, 2022; Hughes et al., 2023).
This calculation was outlined in detail in Section “Using wm ST as an oxybarometer” in Hughes et al. (2023) (schematic of the calculation shown in the figure below; Hughes et al., 2025).
In these examples we will show you how to run this calculation for:
Example 3a: One analysis entered as a DataFrame using default options.
Example 3b: Multiple analyses in a csv file using default options.
Example 3c: Multiple analyses in a csv file using user-specified options.
Example 3d: Including uncertainties on inputs into the calculation outputs.