Compositional and temperature effects on sulfur speciation and solubility in silicate melts

Nash, William; Smythe, Duane J.; Wood, Bernard J.

doi:10.1016/j.epsl.2018.12.006

Cited by 109 publications

(148 citation statements)

References 38 publications

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“…Clinopyroxene is in equilibrium with garnet such that (Fe 3+ /∑Fe) clinopyroxene = 2* (Fe 3+ /∑Fe) garnet ( 36 ). Sulfur oxidation state (S 6+ /∑S) can be calculated via S 6+ /S 2− −Fe 3+ /Fe 2+ equilibrium ( 37 ) and electron conservation in the melt. Residual garnet leads to high S 6+ /∑S and high Dy/Yb in the melt.…”

Section: Resultsmentioning

confidence: 99%

Crustal thickening and endogenic oxidation of magmatic sulfur

Tang

Lee

et al. 2020

Sci. Adv.

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Porphyry ore deposits, Earth’s most important resources of copper, molybdenum, and rhenium, are strongly associated with felsic magmas showing signs of high-pressure differentiation and are usually found in places with thickened crust (>45 kilometers). This pattern is well-known, but unexplained, and remains an outstanding problem in our understanding of porphyry ore deposit formation. We approach this problem by investigating the oxidation state of magmatic sulfur, which controls the behavior of ore-forming metals during magma differentiation and magmatic-hydrothermal transition. We use sulfur in apatite to reconstruct the sulfur oxidation state in the Gangdese batholith, southern Tibet. We find that magma sulfate content increased abruptly after India-Eurasia collision. Apatite sulfur content and the calculated magma S6+/ΣS ratio correlate with whole-rock dysprosium/ytterbium ratio, suggesting that residual garnet, favored in thickened crust, exerts a first-order control on sulfur oxidation in magmatic orogens. Our findings link sulfur oxidation to internal petrogenic processes and imply an intrinsic relationship of magma oxidation with synmagmatic crustal thickening.

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Section: Resultsmentioning

confidence: 99%

Crustal thickening and endogenic oxidation of magmatic sulfur

Tang

Lee

et al. 2020

Sci. Adv.

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“…MPa) are likely negligible (Nash et al, 2019), the speciation transition has been shown to shift by ∼1.5 log units of fO 2 between 0.5 and 1.5 GPa (Matjuschkin et al, 2016).…”

Section: Sulfides In Kilauea's Mantle Sourcementioning

confidence: 98%

“…8b-c). g-h) SCSSTot trajectories following a correction for S 6+ using the parameterization of Nash et al (2019;equation 3). As in e), the closed system model shows a sharp increase in S solubility during plagioclase fractionation.…”

Section: δQfm+03mentioning

confidence: 99%

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Chalcophile elements track the fate of sulfur at Kīlauea Volcano, Hawai’i

Wieser

Jenner

Edmonds

et al. 2020

Geochimica et Cosmochimica Acta

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Chalcophile element concentrations in melt inclusions and matrix glasses may be used to investigate low pressure degassing processes, as well as sulfide saturation during crustal fractionation, and mantle melting. Erupted products from Kīlauea Volcano, Hawaii record three stages of sulfide saturation (in the mantle, crust, and within lava lakes), separated by episodes of sulfide resorption (i.e., sulfide undersaturation) during ascent through the thick Hawaiian lithosphere, and during syn-eruptive degassing. The presence of residual sulfides in the mantle source throughout the melting interval accounts for the high S concentrations of Kīlauean primary melts (1387-1600 ppm). Residual sulfides retain chalcophile elements during melting, decoupling the variability of these elements in high MgO melts from that of lithophile elements. Decompression associated with magma ascent through the thick Hawaiian lithosphere drives an increase in the sulfide concentration at sulfide saturation (SCSS 2−), resulting in shallow storage reservoirs (∼1-5 km depth) being supplied with sulfide-undersaturated melts. A drop in temperature, coupled with major element changes during the fractionation of olivine, causes the SCSS 2− to decrease. Combined with an increase in melt S contents during fractionation, this initiates a second stage of sulfide saturation at relatively high MgO contents (∼12 wt%). Syn-eruptive degassing of S drives the resorption of sulfides in contact with the carrier liquid. The covariance structure of Cu, MgO and Ni contents in melt inclusions and matrix glasses indicates that the dissolution of sulfides effectively liberates sulfide-hosted Cu and Ni back into the melt, rather than the vapour phase. The contrasting behaviour of Cu, Ni, Se and S during sulfide resorption indicates that the chalcophile element signature of the Kīlauean plume is largely controlled by silicate melt-vapour partitioning, rather than sulfide-vapour partitioning. The participation of dense sulfide liquids in shallow degassing processes may result from their direct attachment to buoyant vapour bubbles, or olivine crystals which were remobilized prior to eruption. Sulfide resorption obscures the textural and chemical record of sulfide saturation in matrix glasses, but not in melt inclusions, which are isolated from this late-stage release of chalcophile elements. The partitioning of S between the dissolving sulfide, melt and the vapour phase accounts for approximately 20% of the total S release into the atmosphere.

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“…stabilizes Fe 2+ and S 2in the liquid relative to the more oxidized starting materials (ΔFMQ = +0.2 − +0.6) leading to sulfide oversaturation and precipitation of an FeS phase (Fincham & Richardson, 1954;Nash et al, 2019;O'Neill & Mavrogenes, 2002). Three out of 12 unheated Papakolea olivines have one or two visible sulfide blebs in melt inclusions; the natural inclusions had fewer and larger sulfides than most of the experiments, and they do not seem to be associated with the vapor bubble.…”

Section: Textural Description Of Experimental Samplesmentioning

confidence: 99%

Controlled Cooling‐Rate Experiments on Olivine‐Hosted Melt Inclusions: Chemical Diffusion and Quantification of Eruptive Cooling Rates on Hawaii and Mars

Saper

Stolper

2020

Geochem Geophys Geosyst

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Controlled cooling‐rate experiments were conducted on olivine‐hosted melt inclusions to characterize the development of compositional zoning observed in natural inclusions. All of the experimentally cooled inclusions are zoned due to olivine crystallization on the inclusion wall and diffusive exchange between the boundary layer adjacent to the growing olivine and the inclusion centers. Experimentally cooled inclusions are characterized by lower MgO and FeO and higher SiO2, Al2O3, and Na2O (and other incompatible oxides) near the inclusion wall relative to the inclusion center. The compositions at the centers of inclusions are susceptible to modification by diffusion, particularly for small inclusions and those subjected to low cooling rates. Uphill diffusion is evident in every oxide and is recognized by local extrema along a diffusion profile. CaO exhibits the most extreme manifestation of uphill diffusion, and a model attributes the diffusion behavior in CaO to solution nonideality in the boundary layer liquid. MgO profiles from experimentally cooled inclusions were fit with a diffusion model by varying the cooling rate. The cooling rates that resulted in the best fit models were always within a factor of 2 and typically within ±10% of the experimental cooling rates, which ranged from 70 to 50,000 °C/hr. The model was applied to MgO profiles across natural glassy olivine‐hosted melt inclusions from Hawaii and the shergottite Yamato 980459. Cooling rates from zoned melt inclusions in Yamato 980459 range from 85 to 1,047 °C/hr (mean = 383±43 °C/hr, 1σ, n=8) and support the hypothesis that the sample erupted at or near the Martian surface.

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Compositional and temperature effects on sulfur speciation and solubility in silicate melts

Cited by 109 publications

References 38 publications

Crustal thickening and endogenic oxidation of magmatic sulfur

Crustal thickening and endogenic oxidation of magmatic sulfur

Chalcophile elements track the fate of sulfur at Kīlauea Volcano, Hawai’i

Controlled Cooling‐Rate Experiments on Olivine‐Hosted Melt Inclusions: Chemical Diffusion and Quantification of Eruptive Cooling Rates on Hawaii and Mars

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