Empirical equations to predict the sulfur content of mafic magmas at sulfide saturation and applications to magmatic sulfide deposits

Li, Chusi; Ripley, Edward M.

doi:10.1007/s00126-005-0478-8

Cited by 218 publications

(125 citation statements)

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“…Several predictive models of SCSS in silicate melts have been previously published and allow prediction of SCSS in magmas relevant to the Earth or Mars (Holzheid and Grove, 2002;Li and Ripley, 2005;Righter et al, 2009;Ding et al, 2014). These models do not reproduce our experimental results ( Supplementary Fig.…”

Section: Modeling Sulfur Solubility In Silicate Meltscontrasting

confidence: 56%

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Sulfur solubility in reduced mafic silicate melts: Implications for the speciation and distribution of sulfur on Mercury

Namur

Charlier

Holtz

et al. 2016

Earth and Planetary Science Letters

118

160

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Chemical data from the MESSENGER spacecraft revealed that surface rocks on Mercury are unusually enriched in sulfur compared to samples from other terrestrial planets. In order to understand the speciation and distribution of sulfur on Mercury, we performed high temperature (1200-1750 • C), lowto high-pressure (1 bar to 4 GPa) experiments on compositions representative of Mercurian lavas and on the silicate composition of an enstatite chondrite. We equilibrated silicate melts with sulfide and metallic melts under highly reducing conditions (IW-1.5 to IW-9.4; IW = iron-wüstite oxygen fugacity buffer). Under these oxygen fugacity conditions, sulfur dissolves in the silicate melt as S 2− and forms complexes with Fe 2+ , Mg 2+ and Ca 2+ . The sulfur concentration in silicate melts at sulfide saturation (SCSS) increases with increasing reducing conditions (from <1 wt.% S at IW-2 to >10 wt.% S at IW-8) and with increasing temperature. Metallic melts have a low sulfur content which decreases from 3 wt.% at IW-2 to 0 wt.% at IW-9. We developed an empirical parameterization to predict SCSS in Mercurian magmas as a function of oxygen fugacity ( f O 2 ), temperature, pressure and silicate melt composition. SCSS being not strictly a redox reaction, our expression is fully valid for magmatic systems containing a metal phase. Using physical constraints of the Mercurian mantle and magmas as well as our experimental results, we suggest that basalts on Mercury were free of sulfide globules when they erupted. The high sulfur contents revealed by MESSENGER result from the high sulfur solubility in silicate melt at reducing conditions. We make the realistic assumption that the oxygen fugacity of mantle rocks was set during equilibration of the magma ocean with the core and/or that the mantle contains a minor metal phase and combine our parameterization of SCSS with chemical data from MESSENGER to constrain the oxygen fugacity of Mercury's interior to IW-5.4 ± 0.4. We also calculate that the mantle of Mercury contains 7-11 wt.% S and that the metallic core of the planet has little sulfur (<1.5 wt.% S). The external part of the Mercurian core is likely to be made up of a thin (<90 km) FeS layer.

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Section: Modeling Sulfur Solubility In Silicate Meltscontrasting

confidence: 56%

“…5). We used an equation with a form similar to that of recent models of SCSS (Li and Ripley, 2005;Righter et al, 2009;Ding et al, 2015). We replaced the Gibbs free energy term of Eq.…”

Section: Modeling Sulfur Solubility In Silicate Meltsmentioning

confidence: 99%

Sulfur solubility in reduced mafic silicate melts: Implications for the speciation and distribution of sulfur on Mercury

Namur

Charlier

Holtz

et al. 2016

Earth and Planetary Science Letters

118

160

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“…Unlike in the Bushveld Complex where mixing of compositionally distinct magmas is proposed to have caused sulfide melt saturation, formation of both PGE mineralization in the MSZ and the uppermost cyclic unit (Cyclic Unit 1) chromitite layers in the Great Dyke may have been triggered by silicate fractionation and magma mixing between resident magma and unevolved replenishing magma [14,25,43,45,48,49,74,94]. [96] have suggested that sulfide melt saturation in the hybrid magma can be triggered only if both mixing magmas themselves are nearly saturated in sulfide melt, which seems unlikely to be the case in the Great Dyke in relation to the new replenishing magma.…”

Section: Discussionmentioning

confidence: 99%

Hydrothermal Alteration in the Main Sulfide Zone at Unki Mine, Shurugwi Subchamber of the Great Dyke, Zimbabwe: Evidence from Petrography and Silicates Mineral Chemistry

Chaumba

2017

Minerals

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Abstract:The main platinum-group element (PGE) occurrence in the Great Dyke of Zimbabwe, the Main Sulfide Zone (MSZ), is a tabular stratabound layer hosted in pyroxenites. A petrographic and silicate composition study across the MSZ at Unki Mine in the Shurugwi Subchamber was conducted to help place some constrains on the origin of the mineralization. The PGE-enriched zone at Unki Mine is a~10 m thick package of rocks ranging from gabbronorites, a chromitite stringer, plagioclase websterite, plagioclase pyroxenite (pegmatitic in one narrow zone), a base metal sulfide zone and it is largely located below the contact of the Mafic and Ultramafic Sequences. Pyroxenes have been partially hydrothermally altered to amphibole and chlorite in most lithologies. In addition, sulfides tend to occur as cumulus phases or as inclusions in all the silicate phases. Two generations of sulfide mineralization likely occurred at Unki Mine with primary sulfides occurring in association with cumulus phases, and the relatively finer-grained, often lath-like, sulfides that occur in association with alteration phases of chlorite and amphibole that were likely formed later during hydrothermal alteration. Chlorite thermometry yields temperatures ranging from 241 to 390 • C, and from 491 to 640 • C, and they are interpreted to be temperatures recording the hydrothermal event(s) of magmatic origin which affected the mineralization at Unki Mine. Two-pyroxene thermometry yields temperatures that range from 850 to 981 • C, and these temperatures are interpreted to indicate a hydrothermal imprint on the minerals that constitute the MSZ.

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“…• La cristallisation fractionnée de minéraux riches en Fe (olivine, pyroxene, magnetite, chromite) qui réduit la solubilité de S (Haughton et al, 1974 ;Li et al, 2001a) • Le mélange de magmas de compositions différentes (Naldrett and VonGruenewaldt, 1989 ;Li et al, 2001a ;Li et Ripley, 2005). …”

Section: >* Processus Pouvant Provoquer La Saturation En Sunclassified

“…The model is based on the suggestion that when a new magma enters the chamber, it mixes with the resident magma to form a mixed magma which becomes saturated in an immiscible sulphide liquid (Campbell and Naldrett, 1979;Li and Ripley, 2005). As PGE have a large partition coefficient into sulphide liquid, the immiscible sulphide liquid collects the PGE then settles onto the cumulate pile (Campbell et al, 1993;.…”

Section: -Collection Of the Pge By An Immiscible Sulphide Liquidmentioning

confidence: 99%

Rôle des liquides sulfurés dans la formation des minéralisations riches en éléments du groupe du platine :

Godel¹

2007

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Empirical equations to predict the sulfur content of mafic magmas at sulfide saturation and applications to magmatic sulfide deposits

Cited by 218 publications

References 50 publications

Sulfur solubility in reduced mafic silicate melts: Implications for the speciation and distribution of sulfur on Mercury

Sulfur solubility in reduced mafic silicate melts: Implications for the speciation and distribution of sulfur on Mercury

Hydrothermal Alteration in the Main Sulfide Zone at Unki Mine, Shurugwi Subchamber of the Great Dyke, Zimbabwe: Evidence from Petrography and Silicates Mineral Chemistry

Rôle des liquides sulfurés dans la formation des minéralisations riches en éléments du groupe du platine :

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