The Thermodynamic Controls on Sulfide Saturation in Silicate Melts with Application to Ocean Floor Basalts

O’Neill, Hugh St. C.

doi:10.1002/9781119473206.ch10

Cited by 31 publications

(14 citation statements)

References 117 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(b) The partitioning of both C and N into the melt phase during mantle melting is fO 2 dependent, where a smaller fraction of the volatile budget enters the melt at low fO 2 (see Section 2.1). (c) The fO 2 dependence of many gas-melt solubility laws; at low fO 2 , nitrogen outgassing from the melt phase is suppressed (it becomes much more soluble by speciating into the melt as N 3− Libourel et al, 2003), while at high fO 2 sulfur outgassing is enhanced (the sulphide capacity of the melt lowers under more oxidising conditions, e.g., O'Neill, 2021). This creates the stepped trend in surface pressure, with more massive atmospheres formed at higher mantle fO 2 .…”

Section: Volcanic Atmospheres In Thermochemical Equilibriummentioning

confidence: 99%

Growth and Evolution of Secondary Volcanic Atmospheres: I. Identifying the Geological Character of Hot Rocky Planets

et al. 2022

View full text Add to dashboard Cite

Planetary atmospheres can have three different origins: nebular gas accreted from the protoplanetary disk (primordial); early, syn-accretionary gas release from planetesimal accretion or outgassing during the cooling of a magma ocean (primary); or long-term release of volatiles from the planetary interior for example, through volcanism (secondary). The atmospheres of rocky planets may evolve from primordial/primary to secondary as they undergo significant modification by geological and atmospheric processes, altering the atmosphere's mass fraction and chemical composition. Modification processes include hydrodynamic escape, erosion and volatile addition from impacts, and volcanic outgassing of volatiles from the interior (see Table 1 for references). A more extensive list of processes which can modify planetary atmospheres, and associated literature which has investigated these effects, can be found in Table 1.In this paper series, we focus on secondary atmospheres which form as a result of volcanic outgassing. The chemistry of volcanic gases is dependent on the oxygen fugacity (fO 2 ) of the magma (and likewise the mantle from which the magma was formed, e.g., Burgisser et al., 2015;Gaillard et al., 2015;Ortenzi et al., 2020), surface pressure through volatile solubility in magmas (Gaillard & Scaillet, 2014), and the relative abundance of volatile elements (i.e., H, C, O, S and N) within the magma. The secondary atmospheres of volcanically active rocky planets are therefore inextricably linked to their geological state. This is particularly useful when considering

show abstract

Section: Volcanic Atmospheres In Thermochemical Equilibriummentioning

confidence: 99%

Growth and Evolution of Secondary Volcanic Atmospheres: I. Identifying the Geological Character of Hot Rocky Planets

et al. 2022

View full text Add to dashboard Cite

show abstract

“…Differences between the predicted SO 2 gas per unit volume of magma in the chamber and that observed during an eruption may be modified by (a) co-eruptive degassing, (b) epistemic uncertainties in model parameters associated with initial magmatic sulfur content and 𝐴𝐴 𝐴𝐴O 2 , (c) pre-eruptive gas accumulation and loss (e.g., Edmonds et al, 2014;Edmonds & Woods, 2018;Wallace, 2005), (d) sulfur loss due to scrubbing or formation of sulfide globules (e.g., Anderson & Poland, 2016;Hurwitz & Anderson, 2019;Sigmarsson et al, 2013). Furthermore, we note that the solubility of sulfur species are calculated using a sulfide capacity law that is more appropriate for sulfur in reduced melt (O'Neill, 2021;Liggins et al, 2020Liggins et al, , 2021.…”

Section: Limitations Of Our Modelmentioning

confidence: 99%

Contrasting Volcanic Deformation in Arc and Ocean Island Settings Due To Exsolution of Magmatic Water

Yip

Biggs

Edmonds

et al. 2022

Geochem Geophys Geosyst

View full text Add to dashboard Cite

Two of the most widely observed co‐eruptive volcanic phenomena—Ground deformation and volcanic outgassing—Are fundamentally linked via the mechanism of magma degassing and the development of compressibility, which controls how the volume of magma changes in response to a change in pressure. Here we use thermodynamic models—Constrained by petrological data—To reconstruct volatile exsolution and the consequent changes in magma properties. We use the fraction of SO2 exsolved during decompression to predict co‐eruptive SO2 flux and magma compressibility to predict co‐eruptive surface deformation (both normalized by erupted volume). We conduct sensitivity tests using properties of typical basalts to assess how varying magma volatile content, crustal properties, and chamber geometry affect co‐eruptive deformation and degassing. We find that magmatic H2O content has the most impact on both SO2 flux and volume change. Our findings have general implications for typical basaltic systems in arc and ocean island settings. The higher water content of arc magmas makes them more compressible than ocean island magmas and leads to muted or non‐existent deformation being observed during arc eruptions. Our models are consistent with observation: Deformation has been detected during 48% of basaltic eruptions in ocean island settings (16/33) during the satellite era (2005–2020), but only 11% of basaltic eruptions in arc settings (7/61).

show abstract

“…One MI in our suite was found to contain a sulfide globule, and sulfide inclusions were also found in olivine crystals and in the matrix glass, indicating sulfide saturation for at least some and probably most of the melt evolution pathway. The sulfur abundance in the SWIR MIs is not well correlated with their FeO t contents ( r 2 = 0.3) but is comparable (on average within 19 ± 15% or 165 ± 140 ppm) to the predicted sulfur concentrations at sulfide saturation, calculated following O’Neill (2021). Taken together, these observations suggest that the melt S content was at least partially dictated by equilibrium with sulfide liquid.…”

Section: Discussionmentioning

confidence: 67%

“…Unlike CO 2 , the water and sulfur contents of the MIs are uncorrelated with incompatible trace elements (ITE) such as Ce and Dy, respectively ( R 2 = 0.2). Sulfur abundance in MORBs is widely considered to be controlled by equilibrium with sulfide (e.g., Jenner et al., 2010; Mathez, 1976; O’Neill, 2021; Shimizu et al., 2019). One MI in our suite was found to contain a sulfide globule, and sulfide inclusions were also found in olivine crystals and in the matrix glass, indicating sulfide saturation for at least some and probably most of the melt evolution pathway.…”

Section: Discussionmentioning

confidence: 99%

CO₂‐Undersaturated Melt Inclusions From the South West Indian Ridge Record Surprisingly Uniform Redox Conditions

Moussallam,

Georgeais,

Rose‐Koga

et al. 2023

Geochem Geophys Geosyst

View full text Add to dashboard Cite

The behavior of Fe3+ during mantle partial melting strongly influences the oxidation state of the resulting magmas, with implications for the evolution of the atmosphere's oxidation state. Here, we challenge a prevailing view that low‐degree partial melts are more oxidized due to the incompatible behavior of Fe3+. Our study is based on measurements of Fe3+/∑Fe along with major, minor, trace and volatile elements in olivine‐ and plagioclase‐hosted melt inclusions of CO2 undersaturated mantle melts in South West Indian Ridge lava. These inclusions record minimum entrapment pressures equivalent to depths up to 10 km below the seafloor, record magma ascent rates of 0.03–0.19 m/s, and display exceptionally high CO2/Ba, CO2/Rb, and CO2/Nb ratios, indicative of a CO2‐rich mantle source. Accounting for fractional crystallization, we find a uniform melt oxidation state (with an Fe3+/ΣFe at 0.140 ± 0.005 at MgO = 10 wt.%) that displays no systematic variation with major, minor, volatile or trace element contents, thus providing no evidence for a relationship between the degree of partial melting and Fe3+/ΣFe. This can be explained by efficient buffering of Fe3+/∑Fe and fO2 of mid‐ocean ridge basalt melts by their surrounding mantle and/or a decrease in the bulk peridotite‐melt Fe2O3 partition coefficient with increasing partial melting. We conclude that changes in the Earth's upper mantle temperature over geological time need not have affected the oxidation state of volcanic products or of the atmosphere.

show abstract

The Thermodynamic Controls on Sulfide Saturation in Silicate Melts with Application to Ocean Floor Basalts

Cited by 31 publications

References 117 publications

Growth and Evolution of Secondary Volcanic Atmospheres: I. Identifying the Geological Character of Hot Rocky Planets

Growth and Evolution of Secondary Volcanic Atmospheres: I. Identifying the Geological Character of Hot Rocky Planets

Contrasting Volcanic Deformation in Arc and Ocean Island Settings Due To Exsolution of Magmatic Water

CO₂‐Undersaturated Melt Inclusions From the South West Indian Ridge Record Surprisingly Uniform Redox Conditions

Contact Info

Product

Resources

About

The Thermodynamic Controls on Sulfide Saturation in Silicate Melts with Application to Ocean Floor Basalts

Cited by 31 publications

References 117 publications

Growth and Evolution of Secondary Volcanic Atmospheres: I. Identifying the Geological Character of Hot Rocky Planets

Growth and Evolution of Secondary Volcanic Atmospheres: I. Identifying the Geological Character of Hot Rocky Planets

Contrasting Volcanic Deformation in Arc and Ocean Island Settings Due To Exsolution of Magmatic Water

CO2‐Undersaturated Melt Inclusions From the South West Indian Ridge Record Surprisingly Uniform Redox Conditions

Contact Info

Product

Resources

About

CO₂‐Undersaturated Melt Inclusions From the South West Indian Ridge Record Surprisingly Uniform Redox Conditions