Effect of sulfate on the basaltic liquidus and Sulfur Concentration at Anhydrite Saturation (SCAS) of hydrous basalts – Implications for sulfur cycle in subduction zones

Chowdhury, Proteek; Dasgupta, Rajdeep

doi:10.1016/j.chemgeo.2019.05.020

Cited by 34 publications

(25 citation statements)

References 78 publications

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“…Adding the sulphur from the bubble yields a total S content between 0.3 and 1.6 wt% ( Table 1). Previous experiments have shown that up to 0.5 wt% S can be dissolved in oxidised basaltic melts at 500 MPa 45 . After considering the reduction of the melt due to Fe-migration, we estimate that the actual fO 2 of the MI would be much higher, and consistent with a basaltic melt saturated with sulphate 46 .…”

Section: Does Re-heating Modify the Composition Of A Melt Inclusion?mentioning

confidence: 97%

Melt inclusion vapour bubbles: the hidden reservoir for major and volatile elements

Venugopal

Schiavi

Moune

et al. 2020

Sci Rep

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olivine-hosted melt inclusions (Mis) provide samples of magmatic liquids and their dissolved volatiles from deep within the plumbing system. Inevitable post-entrapment modifications can lead to significant compositional changes in the glass and/or any contained bubbles. Reheating is a common technique to reverse MI crystallisation; however, its effect on volatile contents has been assumed to be minor. We test this assumption using crystallised and glassy basaltic MIs, combined with Raman spectroscopy and 3D imaging, to investigate the changes in fluid and solid phases in the bubbles before and after reheating. Before reheating , the bubble contains CO 2 gas and anhydrite (caSo 4) crystallites. The rapid diffusion of major and volatile elements from the melt during reheating creates new phases within the bubble: So 2 , gypsum, Fe-sulphides. Vapour bubbles hosted in naturally glassy MIs similarly contain a plethora of solid phases (carbonates, sulphates, and sulphides) that account for up to 84% of the total MI sulphur, 80% of CO 2 , and 14% of FeO. In both reheated and naturally glassy MIs, bubbles sequester major and volatile elements that are components of the total magmatic budget and represent a "loss" from the glass. Analyses of the glass alone significantly underestimates the original magma composition and storage parameters.

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Section: Does Re-heating Modify the Composition Of A Melt Inclusion?mentioning

confidence: 97%

Melt inclusion vapour bubbles: the hidden reservoir for major and volatile elements

Venugopal

Schiavi

Moune

et al. 2020

Sci Rep

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“…Alternatively, when the silicate melt is saturated with anhydrite, the chemical potential of CaSO4 in the silicate melt (μ m CaSO4) and anhydrite are equal. The "sulfate content at anhydritesaturation" (S 6+ CAS) is the dissolved S 6+ concentration in the silicate melt in equilibrium with anhydrite (e.g., Baker and Moretti 2011;Chowdhury and Dasgupta 2019;Zajacz and Tsay 2019):…”

Section: Thermodynamic Modellingmentioning

confidence: 99%

“…Similarly, the curve for anhydrite-saturation is defined by Y = μ m CaSO4. Again, although S 6+ CAS is calculated based on Chowdhury and Dasgupta (2019), this is conceptually equivalent to holding μ m CaSO4 equal to a constant chemical potential of pure anhydrite at the relevant conditions. The stable saturation condition (i.e., sulfide melt-or anhydritesaturation) is the one with the lowest w m ST.…”

Section: Silicate Melt + Vapour + (Sulfide Melt And/or Anhydrite)mentioning

confidence: 99%

“…The SS max we have described defines the maximum S content for silicate melts generated by partial mantle melting (i.e., in the presence of sulfide melt + anhydrite ± vapour at a given T). Once either sulfide melt or anhydrite is exhausted, the S content of the partial melt decreases to w m STCAS or w m STCSS, respectively, and then decreases further by dilution when both phases are exhausted (e.g., Chowdhury and Dasgupta, 2019). Chowdhury and Dasgupta (2019) explored the S content of silicate melts generated by mantle melting when the mantle contains either sulfide or anhydrite.…”

Section: Mantle Meltingmentioning

confidence: 99%

“…Once either sulfide melt or anhydrite is exhausted, the S content of the partial melt decreases to w m STCAS or w m STCSS, respectively, and then decreases further by dilution when both phases are exhausted (e.g., Chowdhury and Dasgupta, 2019). Chowdhury and Dasgupta (2019) explored the S content of silicate melts generated by mantle melting when the mantle contains either sulfide or anhydrite. They found that the S content of most arc magmas could be generated by mantle melting in the presence of sulfide when S 2is the dominate silicate melt species.…”

Section: Mantle Meltingmentioning

confidence: 99%

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The sulfur solubility minimum and maximum in silicate melt

Hughes¹,

Saper²,

Liggins³

et al. 2021

Preprint

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The behaviour of sulfur in magmas is complex because it dissolves as both sulfide (S2-) and sulfate (S6+) in silicate melt. An interesting aspect in the behaviour of sulfur is the solubility minima (SSmin) and maxima (SSmax) with varying oxygen fugacity (fO2). We use a simple ternary model (silicate–S2–O2) to explore the varying fO2 paths where these phenomena occur. Both SSmin and SSmax occur when S2- and S6+ are present in the silicate melt in similar quantities due to the differing solubility mechanism of these species. At constant T, a minimum in dissolved total S content (wmST) in vapour-saturated silicate melt occurs along paths of increasing fO2 and either constant fS2 or P; for paths on which wmST is held constant with increasing fO2, the SSmin is expressed as a maximum in P. However, the SSmin is not encountered during closed-system depressurisation in the simple system we modelled. The SSmax occurs when the silicate melt is multiply-saturated with vapour, sulfide melt, and anhydrite. The SSmin and SSmax influence processes throughout the magmatic system, such as mantle melting, magma mixing and degassing, and SO2 emissions; and calculations of the pressures of vapour-saturation, fO2, and SO2 emissions using melt inclusions.

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Platinum-group element geochemistry of the shoshonitic igneous suite of Vulcano (Aeolian Arc, Italy): implications for chalcophile element fertility of arc magmas

Costa

Fulignati

Campbell

et al. 2021

Contrib Mineral Petrol

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The intense explosive and effusive volcanic activity of the last 1000 years at La Fossa volcano (Vulcano Island, Italy) 13 was characterized by the eruption of magmas ranging in composition from latites to trachytes and rhyolites, as well as K-14 rich trachytes. Evidence of sin-eruptive mixing among these magmas are frequently observed in the form of magmatic 15 enclaves and bands in lava flows and pyroclastic products. The petrological and volcanological diversity of the erupted 16 materials suggests that complex differentiation processes occurred in the shallow part of the plumbing system. With the 17 aim to reconstruct the magmatic feeding system and to identify the differentiation processes behind such a petrologic 18 complexity, we analyzed lavas and pyroclastic products representative of the recent eruptive sequences at La Fossa and 19 combined the petro-chemical features with thermo-barometric calculations, geochemical modelling and temperature 20 gradient experiments. Thermo-barometric calculations indicate that the K-rich trachytic magma crystallized at lower 21 pressure (16054 MPa) compared to the latitic (30747 MPa) and trachytic (20830 MPa) magmas. Differentiation 22 modelling suggests that both trachytic and rhyolitic compositions can be obtained through differentiation of a common 23 latitic magma, essentially by varying the plagioclase/sanidine ratio. Temperature gradient experiments, performed at the 24 conditions inferred for the shallow plumbing system of La Fossa volcano (150 MPa and 1050-900 °C), indicate different 25 paths of melt differentiation that overall produce an increase of the SiO2/K2O ratio with the increasing H2O in the system 26(from 0 to 4 wt.%). This is consistent with the origin of K-rich trachytes at lower pressure and lower H2O content. In turn, 27 the formation of crystal-poor rhyolites is explained by segregation of the interstitial melt formed in a latitic-trachytic 28 crystal mush, favored by the second boiling of the melt and consequent exsolution of a fluid phase.

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Effect of sulfate on the basaltic liquidus and Sulfur Concentration at Anhydrite Saturation (SCAS) of hydrous basalts – Implications for sulfur cycle in subduction zones

Cited by 34 publications

References 78 publications

Melt inclusion vapour bubbles: the hidden reservoir for major and volatile elements

Melt inclusion vapour bubbles: the hidden reservoir for major and volatile elements

The sulfur solubility minimum and maximum in silicate melt

Platinum-group element geochemistry of the shoshonitic igneous suite of Vulcano (Aeolian Arc, Italy): implications for chalcophile element fertility of arc magmas

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