The chemical behaviour of chlorine in silicate melts

Thomas, Richard W.; Wood, Bernard J.

doi:10.1016/j.gca.2020.11.018

Cited by 22 publications

(17 citation statements)

References 63 publications

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“…This concurs with the thermodynamic formulation from Thomas and Wood (2020) for anhydrous basalts, which also shows that Cl solubility in melt should increase with increasing temperature. This effect has been observed previously in experiments on Br partitioning, which show increasing D Br fluid/melt with decreasing temperatures (900-1200 °C (Cadoux et al, 2018).…”

Section: Effect Of Temperaturesupporting

confidence: 89%

“…The influence of melt composition on halogen behaviour is a product of the complexes they form with the cations in the melt. Chlorine dominantly dissolves in the melt by complexation 5 with network modifying alkaline earth metals (Mg, Ca), alkalis (Na, K) and also Al and Fe, whereas it dissolves as an HCl species in aqueous magmatic fluids (Webster 1997;Webster and De Vivo 2002;Thomas and Wood 2020). Conversely, it is thought that F occurs in silicate melts as Si-F, Al-F, Na-F and Ca-F complexes Bell and Simon 2011), while Br forms NaBr complexes at high pressure (>2 GPa) in hydrous felsic melts (Cochain et al 2015;Louvel et al 2020).…”

Section: Introductionmentioning

confidence: 99%

“…These conditions apply to the many active magmatic systems that have low halogen concentrations (Aiuppa et al 2009) and lack a separate brine phase (Baker and Alletti 2012). Recent experimental work by Thomas and Wood (2020) provides new insights into the chemical and thermodynamic basis for chlorine dissolution in silicate melts. The initial Cl dissolution into the melt involves the replacement of O 2by two dissociated Clions:…”

Section: Introductionmentioning

confidence: 99%

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Experimentally derived F, Cl, and Br fluid/melt partitioning of intermediate to silicic melts in shallow magmatic systems

Cassidy¹,

Iveson²,

Humphreys³

et al. 2022

American Mineralogist

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The conditions under which halogens partition in favour of an exsolved fluid relative to the coexisting melt are key for understanding many magmatic processes, including volcanic degassing, evolution of crustal melt bodies, and ore formation. We report new F, Cl and Br fluid/melt partition coefficients for intermediate to silicic melts, for which F and Br data are particularly lacking; and for varying CO 2 -H 2 O contents to assess the effects of changing fluid composition (XH 2 O) on Br fluid/melt partitioning for the first time. The experiments were conducted at pressures 50-120 MPa, temperatures 800-1100°C and volatile compositions (molar XH 2 O = H 2 O/(H 2 O +CO 2 )) of 0.55 to 1, with redox conditions around the Nickel-

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Section: Effect Of Temperaturesupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimentally derived F, Cl, and Br fluid/melt partitioning of intermediate to silicic melts in shallow magmatic systems

Cassidy¹,

Iveson²,

Humphreys³

et al. 2022

American Mineralogist

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“…Previous empirical study on lavas has suggested that Tl degasses as the TlCl species (Churakov et al., 2000), although thermodynamic considerations suggest that reduced Tl 0 gas (Barin et al., 1989) may also be important. Recent study on the relationship between the Cl contents of basalts and their Cl 2 fugacities (Thomas & Wood, 2021) can be used to calculate the ratio of TlCl to Tl 0 during equilibrium degassing. Although we do not know the exact Cl content of the Icelandic basalt used for the experiments, the average Cl content of 64 Icelandic basalts in the GEOROC database is 550 µg/g (1 σ = 190 µg/g).…”

Section: Discussionmentioning

confidence: 99%

“…Although we do not know the exact Cl content of the Icelandic basalt used for the experiments, the average Cl content of 64 Icelandic basalts in the GEOROC database is 550 µg/g (1 σ = 190 µg/g). We used this concentration together with the relationship between Cl content and Cl 2 fugacity from Thomas and Wood (2021) and thermodynamic data on the gas species (Barin et al., 1989) to calculate the ratio of TlCl to Tl 0 at the oxygen fugacities of the experiments. At 1,300°C we obtain values of between 6 (at fO 2 = 10 −13 ) and 180 (at fO 2 = 10 −7 ) for the TlCl:Tl 0 ratio in our experiments.…”

Section: Discussionmentioning

confidence: 99%

Thallium Isotope Fractionation During Magma Degassing: Evidence From Experiments and Kamchatka Arc Lavas

Nielsen

Shu

Wood

et al. 2021

Geochem Geophys Geosyst

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Recycling of oceanic crust and sediments into the mantle at subduction zones is one of the most important processes occurring in the solid Earth. It controls the vast majority of mass transfer between the surface and deep Earth including water and other volatiles as well as radiogenic heat-producing elements like K, Th, and U. Thus, crustal recycling is the primary determinant of the viscosity and heat budget of the Earth's mantle. In addition, these recycled crustal reservoirs are thought to give rise to mantle plumes that are expressed at the Earth's surface as ocean island basalts (OIBs) or large igneous provinces (LIPs) (e.g., Hofmann & White, 1982). Much research has focused on understanding the physical and chemical consequences of crustal recycling, both those occurring during subduction itself and those associated with Abstract Thallium (Tl) isotope ratios are an emerging tool that can be used to trace crustal recycling processes in arc lavas and ocean island basalts (OIBs). Thallium is a highly volatile metal that is enriched in volcanic fumaroles, but it is unknown whether degassing of Tl from subaerial lavas has a significant effect on their residual Tl isotope compositions. Here, we present Tl isotope and concentration data from degassing experiments that are best explained by Rayleigh kinetic isotope fractionation during Tl loss. Our data closely follow predicted isotope fractionation models in which TlCl is the primary degassed species and where Tl loss is controlled by diffusion and natural convection, consistent with the slow gas advection velocity utilized during our experiments. We calculate that degassing into air should be associated with a net Tl isotope fractionation factor of α net = 0.99969 for diffusion and natural gas convection (low gas velocities) and α net = 0.99955 for diffusion and forced gas convection (high gas velocities). We also show that lavas from three volcanoes in the Kamchatka arc exhibit Tl isotope and concentration patterns that plot in between the two different gas convection regimes, implying that degassing played an important role in controlling the observed Tl isotope compositions in these three volcanoes. Literature inspection of Tl isotope data for subaerial lavas reveals that the majority of these appear only minorly affected by degassing, although a few samples from both OIBs and arc volcanoes can be identified that likely experienced some Tl degassing.Plain Language Summary Volcanic degassing is an important process for understanding emissions to the atmosphere of greenhouse gasses and toxic metals. Thallium (Tl) is a toxic metal that is highly volatile, which in recent years has been developed as a stable isotope system that can be applied to understand the transfer of material from the Earth surface to the deep mantle via measurements of volcanic lavas. However, degassing of Tl from volcanic lavas could potentially alter the isotope ratio of the residual lava and, thus, render applications of Tl isotopes in lavas difficult to relate to deep Earth material tran...

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Deep sourced magma and ore-metal mobility in the D. João de Castro submarine volcano (Azores): a mineral chemistry and melt inclusion study

Marques

Madureira

Zajacz

et al. 2022

Contrib Mineral Petrol

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The D. João de Castro is a submarine volcano with known hydrothermal activity located in the Terceira ultra-slow spreading rift within the Azores triple junction (ATJ). Several well-known mafic and ultramafic rock-hosted seafloor hydrothermal systems lay along the Mid-Atlantic Ridge, to the north and to the south of the Azores platform, yet little is known about seafloor hydrothermal activity, ore-metal availability, and magmatic-hydrothermal interactions within the ATJ. Here, we investigate multi-phase melt inclusions hosted in early formed phenocrysts (olivine, clinopyroxene and plagioclase), and metallic precipitates found in groundmass vesicles. Combining detailed petrographic observations with geochemical data and thermobarometry calculations, we assess P-T conditions of early formed phenocrysts, melt pathways towards surface, timing of sulfide saturation and composition of immiscible sulfide melts. Results show that D. João de Castro is characterized by a multi-level magmatic system where primary melt segregated from the upper mantle and moved up through the oceanic crust with little residence time. Sulfide saturation with the formation of immiscible magmatic sulfide liquid (Fe-Ni-Cu) occurred early in primitive magmas with clinopyroxene and olivine crystallization and continued during plagioclase crystallization. At shallower levels, the magmatic degassing of volatiles carrying base metals (Cu-Zn-Pb-Co) and Ba have contributed to the element budget of the D. João de Castro hydrothermal system. The study of multi-phase melt inclusions and vesicles at D. João de Castro submarine volcano contributes to the understanding of source to surface magmatic processes at the Terceira Rift and underline the importance of magmatic degassing into seafloor hydrothermal systems.

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The chemical behaviour of chlorine in silicate melts

Cited by 22 publications

References 63 publications

Experimentally derived F, Cl, and Br fluid/melt partitioning of intermediate to silicic melts in shallow magmatic systems

Experimentally derived F, Cl, and Br fluid/melt partitioning of intermediate to silicic melts in shallow magmatic systems

Thallium Isotope Fractionation During Magma Degassing: Evidence From Experiments and Kamchatka Arc Lavas

Deep sourced magma and ore-metal mobility in the D. João de Castro submarine volcano (Azores): a mineral chemistry and melt inclusion study

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