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

Namur, Olivier; Charlier, Bernard; Holtz, François; Cartier, Camille; McCammon, Catherine

doi:10.1016/j.epsl.2016.05.024

Cited by 118 publications

(209 citation statements)

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“…Mercury's oxygen fugacity is expected to range between 2.6 and 7.3 log units below the iron‐wustite (IW) buffer (e.g., McCubbin et al ()). The high sulfur content of Mercury's surface is consistent with the increase of sulfur solubility in silicate melt when the f O 2 decreases below IW‐2 (Beermann et al, ; Berthet et al, ; Malavergne et al, ; McCoy et al, ; Namur et al, ). Over the f O 2 range predicted for Mercury, S solubility in silicate melts at sulfide saturation (SCSS) increases from ∼1% wt to over 10% wt.…”

Section: Introductionmentioning

confidence: 60%

“…The model tracks the evolving sulfur content of the magma ocean relative to the maximum SCSS that has been measured experimentally in previous studies (Beermann et al, ; Berthet et al, ; Malavergne et al, ; McCoy et al, ; Namur, Charlier, et al, ). When the magma ocean reaches sulfide saturation, sulfides precipitate, to keep the residual magma ocean at the saturation condition.…”

Section: Model Descriptionmentioning

confidence: 81%

“…The role of the core on mantle composition is neglected. Studies that address the issue of chemical partitioning between silicate, sulfides, and metal (e.g., Boujibar et al (),Namur, Charlier, et al ()) can be used in the future to relate consistently the mantle bulk sulfur content with oxygen fugacity. The MO oxygen fugacity is assumed to be constant throughout both the MO solidification and the MO depth (but see, Hirschmann ()).…”

Section: Model Descriptionmentioning

confidence: 99%

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Production and Preservation of Sulfide Layering in Mercury's Mantle

et al. 2019

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A striking feature of Mercury's volcanic surface is its high S and low FeO contents, which is thought to be produced by very reducing conditions compared to other terrestrial bodies. Experiments show that S solubility in silicate melts increases to % wt levels for oxygen fugacities lower than three log units below the iron‐wustite (IW) buffer. During magma ocean solidification, large amounts of sulfide could potentially precipitate. This work investigates the effects of primordial sulfide layering on the first 750 Myr of Mercury's mantle dynamics. It is proposed that sulfide layering could have been produced by fractional solidification in the highly reduced Mercury magma ocean (MMO). Such chemical layering implies mantle sources with variable sulfur contents that might have played an important role in early Mercurian magmatism. Our models investigate the production of sulfide‐rich layers and their preservation during post‐MO solid‐state mantle dynamics. An intriguing question is the role of these sulfide‐rich layers on mantle dynamics as they are expected to incorporate a substantial amount of heat‐producing elements (U, Th, and K). We use experimentally determined sulfur solubility in silicate melts to predict the depth at which sulfides precipitate in the MMO. The model produces primordial sulfide layers whose thickness and locations depend upon the oxygen fugacity (fO2) and initial sulfur content (Sinit) of the MMO. Several geodynamic regimes have been identified in the fO2‐Sinit space. This study shows that oxygen fugacity, bulk sulfur content, and sulfide segregation are key for the early thermochemical evolution of Mercury.

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Section: Introductionmentioning

confidence: 60%

Section: Model Descriptionmentioning

confidence: 81%

Section: Model Descriptionmentioning

confidence: 99%

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Production and Preservation of Sulfide Layering in Mercury's Mantle

et al. 2019

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“…At these conditions, it is therefore the dependence of the oxide-forming reaction 271 on pressure that controls the partitioning behavior of M. The location of the inflection point will 272 depend upon the partitioning behavior of sulfur, in concert with the P-T-X dependencies of the 273 individual metal-oxide and metal-sulfide species. It is worth noting that at extremely reducing 274 conditions, the dominant complexing agent for S in the silicate melt may be Ca or Mg, rather than Fe 275 (Namur et al, 2016). The pressure dependence for the metal-silicate partitioning of sulfur determined at 276 more oxidizing conditions may therefore not apply in these instances.…”

Section: Developing a Relationship That Considers Sulfide Species 199mentioning

confidence: 99%

“…Significant increases in S solubility with more reducing conditions, however, do 63 not manifest until below ~IW -2 and are dependent upon temperature (Namur et al, 2016). As 64 conditions become highly reducing, the sulfur content of silicate melt can exceed the iron content and 65 Namur et al (2016) suggest in these instances that reaction with Mg and Ca is a significant solution 66 mechanism for S. This assertion is supported by the Raman spectra of silicate melts in equilibrium with 67 sulfide liquid, that display increasingly intense peaks corresponding to MgS and CaS with decreasing 68 fO 2 (IW -3.6 to -8.4) and increasing S content (Namur et al, 2016). Terrestrial core-formation is 69 associated with relatively reducing conditions (fO 2 < IW) and thus metal-silicate partitioning 70 experiments are typically performed at similarly reducing conditions, where sulfur solubility as sulfide 71 species is favored.…”

Section: Sulfur In Silicate Melts and The Existence Of Metal-sulfur Cmentioning

confidence: 99%

Pressure, sulfur, and metal-silicate partitioning: The effect of sulfur species on the parameterization of experimental results

Bennett

Fei

2018

American Mineralogist

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11Performing well-controlled metal-silicate partitioning experiments at conditions directly simulating 12 those of a deep magma ocean is difficult. It is therefore common to perform experiments at lower 13 pressures and temperatures, which are used to determine the effects of salient variables. Often, these 14 effects are determined by multiple linear regression of a dataset covering a large range of P-T-15 composition space. In particular, these datasets often contain the results of experiments performed both 16 with and without sulfur in the system. Data are often regressed, however, using a relationship based 17 only upon the formation of oxide species in the silicate melt. Several studies have suggested that, when 18 sulfur is present in the system, siderophile trace metals may also dissolve into silicate melt as S-bearing 19 species. We have derived a relationship for regressing experimental metal-silicate partitioning data that 20 considers the formation of both oxide and sulfide species in the silicate melt. Using model datasets, we 21have assessed the ability of this relationship, and the more typical single-species relationship, to 22 accurately parameterize data in which the formation of S-bearing species is important. We have also 23 applied this new relationship to experimental results on the metal-silicate partitioning of gold and find 24 This is a preprint, the final version is subject to change, of the American Mineralogist (MSA) from the resulting solubility data. Most metal-silicate partitioning data have been produced at pressures 36 below ~27 GPa due to the difficulty of achieving higher pressures using large-volume press techniques. 37Although these conditions overlap with lower estimates for the maximum depth of core-segregation 38 from a magma ocean (e.g., Li & Agee, 1996;, it is significantly below the 39 maximum pressures invoked in some studies (e.g., 40-80 GPa;Corgne et al., 2009; Rubie et al., 2011; 40 Siebert et al., 2013). Considerable extrapolation of the experimentally determined metal-silicate 41 partition coefficients to relevant conditions is therefore required. This is typically achieved by 42 parameterizing the available data using multiple linear regression, as a function of pressure (P), 43 temperature (T), composition and in some cases oxygen fugacity (fO 2 ). These parameterizations are 44 based on reactions where the element of interest dissolves in silicate melt as an oxide species. For 45 systems containing sulfur, however, it has been suggested for several elements that the formation of 46 sulfur-bearing complexes is important (e.g. Botcharnikov et al. 2010;Laurenz et al. 2013; Mungall & 47 Brenan, 2014;). Here, we consider whether these elements require a different 48 This is a preprint, the final version is subject to change, of the American Mineralogist (MSA) Cite as Authors (Year) Title. American Mineralogist, in press. DOI: https://doi.org/10.2138/am-2018-6282Always consult and cite the final, published document. See http:/www.minsocam.org or Geosci...

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Experimental constraints on the rheology, eruption, and emplacement dynamics of analog lavas comparable to Mercury's northern volcanic plains

et al. 2017

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We present new viscosity measurements of a synthetic silicate system considered an analogue for the lava erupted on the surface of Mercury. In particular, we focus on the northern volcanic plains (NVP), which correspond to the largest lava flows on Mercury and possibly in the Solar System. High‐temperature viscosity measurements were performed at both superliquidus (up to 1736 K) and subliquidus conditions (1569–1502 K) to constrain the viscosity variations as a function of crystallinity (from 0 to 28%) and shear rate (from 0.1 to 5 s−1). Melt viscosity shows moderate variations (4–16 Pa s) in the temperature range of 1736–1600 K. Experiments performed below the liquidus temperature show an increase in viscosity as shear rate decreases from 5 to 0.1 s−1, resulting in a shear thinning behavior, with a decrease in viscosity of ~1 log unit. The low viscosity of the studied composition may explain the ability of NVP lavas to cover long distances, on the order of hundreds of kilometers in a turbulent flow regime. Using our experimental data we estimate that lava flows with thickness of 1, 5, and 10 m are likely to have velocities of 4.8, 6.5, and 7.2 m/s, respectively, on a 5° ground slope. Numerical modeling incorporating both the heat loss of the lavas and its possible crystallization during emplacement allows us to infer that high effusion rates (>10,000 m3/s) are necessary to cover the large distances indicated by satellite data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft.

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

Cited by 118 publications

References 73 publications

Production and Preservation of Sulfide Layering in Mercury's Mantle

Production and Preservation of Sulfide Layering in Mercury's Mantle

Pressure, sulfur, and metal-silicate partitioning: The effect of sulfur species on the parameterization of experimental results

Experimental constraints on the rheology, eruption, and emplacement dynamics of analog lavas comparable to Mercury's northern volcanic plains

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