The sulfide capacity and the sulfur content at sulfide saturation of silicate melts at 1400°C and 1 bar

Hugh St C. O'Neill; John A. Mavrogenes

The sulfide capacity and the sulfur content at sulfide saturation of silicate melts at 1400°C and 1 bar

Research output: Contribution to journal › Article › Research › peer-review

Abstract

The solubility of sulfur as S² has been experimentally determined for 19 silicate melt compositions in the system CaOMgO-Al₂O₃-SiO₂ (CMAS) ± TiO₂ ± FeO, at 1400°C and 1 bar, using CO-CO₂-SO₂ gas mixtures to vary oxygen fugacity (fO₂) and sulfur fugacity (fS₂). For all compositions, the solubility is confirmed to be proportional to (fS₂/fO₂)^1/2, allowing the definition of the sulfide capacity (C_s) of a silicate melt as C_s = [S](fO₂/fS₂)^1/2. Additional experiments covering over 150 melt compositions, including some with Na and K, were then used to determine C_s as a function of melt composition at 1400°C. The results were fitted to the equation C_S = A_O + ∑_MA_MX_M + B_Fe-_TiX_FeX_Ti, where A_Fe ≫ A_Ca > A_Mg,A_Na/K,A_Ti. The FeO content of natural basalts is the dominant control on C_S. The equation for C_S was then combined with the equation for the thermodynamic equilibrium between silicate melt and immiscible FeS-rich sulfide melt, to develop an expression for the sulfur content at sulfide saturation (SCSS) of the silicate melt. The value of SCSS is independent of fO₂ and fS₂, but shows an asymmetric U-shaped dependence on the FeO content of the silicate melt. Many of the experiments on Fe-containing melt compositions were saturated with immiscible FeS melt, and these experiments were used to calibrate quantitatively SCSS at 1400°C as a function of melt composition.

Original language	English
Pages (from-to)	1049-1087
Number of pages	39
Journal	Journal of Petrology
Volume	43
Issue number	6
Publication status	Published - 2002
Externally published	Yes

Keywords

Silicate melts
Sulfide capacity
Sulfur
Thermodynamics

Cite this

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title = "The sulfide capacity and the sulfur content at sulfide saturation of silicate melts at 1400°C and 1 bar",

abstract = "The solubility of sulfur as S2 has been experimentally determined for 19 silicate melt compositions in the system CaOMgO-Al2O3-SiO2 (CMAS) ± TiO2 ± FeO, at 1400°C and 1 bar, using CO-CO2-SO2 gas mixtures to vary oxygen fugacity (fO2) and sulfur fugacity (fS2). For all compositions, the solubility is confirmed to be proportional to (fS2/fO2)1/2, allowing the definition of the sulfide capacity (Cs) of a silicate melt as Cs = [S](fO2/fS2)1/2. Additional experiments covering over 150 melt compositions, including some with Na and K, were then used to determine Cs as a function of melt composition at 1400°C. The results were fitted to the equation CS = AO + ∑MAMXM + BFe-TiXFeXTi, where AFe ≫ ACa > AMg,ANa/K,ATi. The FeO content of natural basalts is the dominant control on CS. The equation for CS was then combined with the equation for the thermodynamic equilibrium between silicate melt and immiscible FeS-rich sulfide melt, to develop an expression for the sulfur content at sulfide saturation (SCSS) of the silicate melt. The value of SCSS is independent of fO2 and fS2, but shows an asymmetric U-shaped dependence on the FeO content of the silicate melt. Many of the experiments on Fe-containing melt compositions were saturated with immiscible FeS melt, and these experiments were used to calibrate quantitatively SCSS at 1400°C as a function of melt composition.",

keywords = "Silicate melts, Sulfide capacity, Sulfur, Thermodynamics",

author = "O'Neill, {Hugh St C.} and Mavrogenes, {John A.}",

note = "Funding Information: We thank Nick Ware for the EMP routine for analysing S by WDS, and many helpers for carrying out the analyses, both EDS and WDS, on our EMP, which dates from the pre-automatic era. Prominent among these helpers was Dean Scott, who also assisted by making many of the starting compositions and loading these onto wire loops. Mike Shelley kept the gas plumbing and the mass flow controllers in good shape, and also undertook the checking of the flow-rate calibrations as required. J.A.M. acknowledges support from Western Mining Corporation during the early stages of this work. Ed Mathez and Roger Powell are thanked for helpful reviews, and Richard Arculus for editorial handling. Copyright: Copyright 2008 Elsevier B.V., All rights reserved.",

year = "2002",

language = "English",

volume = "43",

pages = "1049--1087",

journal = "Journal of Petrology",

issn = "0022-3530",

publisher = "Oxford University Press",

number = "6",

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TY - JOUR

T1 - The sulfide capacity and the sulfur content at sulfide saturation of silicate melts at 1400°C and 1 bar

AU - O'Neill, Hugh St C.

AU - Mavrogenes, John A.

N1 - Funding Information: We thank Nick Ware for the EMP routine for analysing S by WDS, and many helpers for carrying out the analyses, both EDS and WDS, on our EMP, which dates from the pre-automatic era. Prominent among these helpers was Dean Scott, who also assisted by making many of the starting compositions and loading these onto wire loops. Mike Shelley kept the gas plumbing and the mass flow controllers in good shape, and also undertook the checking of the flow-rate calibrations as required. J.A.M. acknowledges support from Western Mining Corporation during the early stages of this work. Ed Mathez and Roger Powell are thanked for helpful reviews, and Richard Arculus for editorial handling. Copyright: Copyright 2008 Elsevier B.V., All rights reserved.

PY - 2002

Y1 - 2002

N2 - The solubility of sulfur as S2 has been experimentally determined for 19 silicate melt compositions in the system CaOMgO-Al2O3-SiO2 (CMAS) ± TiO2 ± FeO, at 1400°C and 1 bar, using CO-CO2-SO2 gas mixtures to vary oxygen fugacity (fO2) and sulfur fugacity (fS2). For all compositions, the solubility is confirmed to be proportional to (fS2/fO2)1/2, allowing the definition of the sulfide capacity (Cs) of a silicate melt as Cs = [S](fO2/fS2)1/2. Additional experiments covering over 150 melt compositions, including some with Na and K, were then used to determine Cs as a function of melt composition at 1400°C. The results were fitted to the equation CS = AO + ∑MAMXM + BFe-TiXFeXTi, where AFe ≫ ACa > AMg,ANa/K,ATi. The FeO content of natural basalts is the dominant control on CS. The equation for CS was then combined with the equation for the thermodynamic equilibrium between silicate melt and immiscible FeS-rich sulfide melt, to develop an expression for the sulfur content at sulfide saturation (SCSS) of the silicate melt. The value of SCSS is independent of fO2 and fS2, but shows an asymmetric U-shaped dependence on the FeO content of the silicate melt. Many of the experiments on Fe-containing melt compositions were saturated with immiscible FeS melt, and these experiments were used to calibrate quantitatively SCSS at 1400°C as a function of melt composition.

AB - The solubility of sulfur as S2 has been experimentally determined for 19 silicate melt compositions in the system CaOMgO-Al2O3-SiO2 (CMAS) ± TiO2 ± FeO, at 1400°C and 1 bar, using CO-CO2-SO2 gas mixtures to vary oxygen fugacity (fO2) and sulfur fugacity (fS2). For all compositions, the solubility is confirmed to be proportional to (fS2/fO2)1/2, allowing the definition of the sulfide capacity (Cs) of a silicate melt as Cs = [S](fO2/fS2)1/2. Additional experiments covering over 150 melt compositions, including some with Na and K, were then used to determine Cs as a function of melt composition at 1400°C. The results were fitted to the equation CS = AO + ∑MAMXM + BFe-TiXFeXTi, where AFe ≫ ACa > AMg,ANa/K,ATi. The FeO content of natural basalts is the dominant control on CS. The equation for CS was then combined with the equation for the thermodynamic equilibrium between silicate melt and immiscible FeS-rich sulfide melt, to develop an expression for the sulfur content at sulfide saturation (SCSS) of the silicate melt. The value of SCSS is independent of fO2 and fS2, but shows an asymmetric U-shaped dependence on the FeO content of the silicate melt. Many of the experiments on Fe-containing melt compositions were saturated with immiscible FeS melt, and these experiments were used to calibrate quantitatively SCSS at 1400°C as a function of melt composition.

KW - Silicate melts

KW - Sulfide capacity

KW - Sulfur

KW - Thermodynamics

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M3 - Article

AN - SCOPUS:0036081862

SN - 0022-3530

VL - 43

SP - 1049

EP - 1087

JO - Journal of Petrology

JF - Journal of Petrology

IS - 6

ER -

The sulfide capacity and the sulfur content at sulfide saturation of silicate melts at 1400°C and 1 bar

Abstract

Keywords

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