Sulfide resorption during crustal ascent and degassing of oceanic plateau basalts

Reekie, C. D. J.; Jenner, F. E.; Smythe, D. J.; Hauri, E. H.; Bullock, E. S. and Williams, H. M. (2019). Sulfide resorption during crustal ascent and degassing of oceanic plateau basalts. Nature Communications, 10, article no. 82.

DOI: https://doi.org/10.1038/s41467-018-08001-3

Abstract

Mantle plume-related magmas typically have higher chalcophile and siderophile element (CSE) contents than mid-ocean ridge basalts (MORB). These differences are often attributed to sulfide-under-saturation of plume-related melts. However, because of eruption-related degassing of sulfur (S) and the compositional, pressure, temperature and redox effects on S- solubility, understanding the magmatic behavior of S is challenging. Using CSE data for oceanic plateau basalts (OPB), which rarely degas S, we show that many OPB are sulfide- saturated. Differences in the timing of sulfide-saturation between individual OPB suites can be explained by pressure effects on sulfur solubility associated with ascent through over- thickened crust. Importantly, where S-degassing does occur, OPB have higher CSE contents than S-undegassed melts at similar stages of differentiation. This can be explained by resorption of earlier-formed sulfides, which might play an important role in enriching degassed melts in sulfide-compatible CSE and potentially contributes to anomalous enrich- ments of CSE in the crust.

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