The sulfur solubility minimum and maximum in silicate melt

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1144/jgs2021-125. This is version 2 of this Preprint.

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Authors

Ery Catherine Hughes, Lee Saper, Philippa Liggins, Edward M. Stolper

Abstract

The behaviour of sulfur in magmas is complex because it dissolves as both sulfide (S2-) and sulfate (S6+) in silicate melt. An interesting aspect in the behaviour of sulfur is the solubility minima (SSmin) and maxima (SSmax) with varying oxygen fugacity (fO2). We use a simple ternary model (silicate–S2–O2) to explore the varying fO2 paths where these phenomena occur. Both SSmin and SSmax occur when S2- and S6+ are present in the silicate melt in similar quantities due to the differing solubility mechanism of these species. At constant T, a minimum in dissolved total S content (wmST) in vapour-saturated silicate melt occurs along paths of increasing fO2 and either constant fS2 or P; for paths on which wmST is held constant with increasing fO2, the SSmin is expressed as a maximum in P. However, the SSmin is not encountered during closed-system depressurisation in the simple system we modelled. The SSmax occurs when the silicate melt is multiply-saturated with vapour, sulfide melt, and anhydrite. The SSmin and SSmax influence processes throughout the magmatic system, such as mantle melting, magma mixing and degassing, and SO2 emissions; and calculations of the pressures of vapour-saturation, fO2, and SO2 emissions using melt inclusions.

DOI

https://doi.org/10.31223/X5WG8B

Subjects

Earth Sciences, Physical Sciences and Mathematics

Keywords

sulfur, silicate melt, solubility, vapour, sulfide melt, anhydrite, minimum, maximum

Dates

Published: 2021-10-09 09:05

Last Updated: 2021-10-16 00:49

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License

CC BY Attribution 4.0 International

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Conflict of interest statement:
None.