TY - JOUR
T1 - The relative effects of pressure, temperature and oxygen fugacity on the solubility of sulfide in mafic magmas
AU - Mavrogenes, John A.
AU - O'Neill, Hugh St C.
N1 - Funding Information:
We would like to thank WMC for financial support, Dave Green, John Simmonds and Jon Hronsky for the initial conception of, and continued support of this work, Bill Hibberson and Paul Willis for their experimental assistance, and Bob Waterford and Valter Baek Hansen for assistance in developing the Fe-Ir alloy capsules. Discussions with Bob Loucks, and suggestions made by two anonymous reviewers and Tony Naldrett greatly improved the manuscript.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 1999/4
Y1 - 1999/4
N2 - The sulfur contents at sulfide saturation (SCSS) of a basaltic and a picritic melt have been measured experimentally as a function of pressure and temperature from 5 to 90 kb and 1400-1800°C, using piston-cylinder and multi-anvil solid media pressure devices. Three distinct regimes of oxygen fugacity were investigated, imposed by the use of Fe100, Fe40Ir60, and Fe20Ir80 capsules. The compositions of quenched run products, including the S contents of the silicate glasses, were determined by electron microprobe analysis. Theoretical considerations suggest that SCSS values (in ppm) can be described by an equation of the form: ln[S/ppm](SCSS) = A/T + B + CP/T + ln a(FeS)(sulfide) where A and B are functions of the composition of the silicate melt. This equation implies that SCSS is independent of fO2 and fS2, except insofar as these factors influence the nature of the sulfide liquid (hence a(FeS)(sulfide)). The experiments reported here confirm this. The SCSS of both the basaltic and picritic compositions are rather insensitive to temperature, but show a strong exponential decrease with increasing pressure. Consequently, a magma generated in equilibrium with residual sulfide in the mantle becomes under saturated in sulfide during adiabatic ascent. At low pressure, sulfide saturation should occur only after substantial crystallization, under closed-system conditions, or after significant modification via assimilation (e.g., of S-rich sediments).
AB - The sulfur contents at sulfide saturation (SCSS) of a basaltic and a picritic melt have been measured experimentally as a function of pressure and temperature from 5 to 90 kb and 1400-1800°C, using piston-cylinder and multi-anvil solid media pressure devices. Three distinct regimes of oxygen fugacity were investigated, imposed by the use of Fe100, Fe40Ir60, and Fe20Ir80 capsules. The compositions of quenched run products, including the S contents of the silicate glasses, were determined by electron microprobe analysis. Theoretical considerations suggest that SCSS values (in ppm) can be described by an equation of the form: ln[S/ppm](SCSS) = A/T + B + CP/T + ln a(FeS)(sulfide) where A and B are functions of the composition of the silicate melt. This equation implies that SCSS is independent of fO2 and fS2, except insofar as these factors influence the nature of the sulfide liquid (hence a(FeS)(sulfide)). The experiments reported here confirm this. The SCSS of both the basaltic and picritic compositions are rather insensitive to temperature, but show a strong exponential decrease with increasing pressure. Consequently, a magma generated in equilibrium with residual sulfide in the mantle becomes under saturated in sulfide during adiabatic ascent. At low pressure, sulfide saturation should occur only after substantial crystallization, under closed-system conditions, or after significant modification via assimilation (e.g., of S-rich sediments).
UR - http://www.scopus.com/inward/record.url?scp=0032844184&partnerID=8YFLogxK
U2 - 10.1016/S0016-7037(98)00289-0
DO - 10.1016/S0016-7037(98)00289-0
M3 - Article
AN - SCOPUS:0032844184
SN - 0016-7037
VL - 63
SP - 1173
EP - 1180
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
IS - 7-8
ER -