The role of melt composition on aqueous fluid vs. silicate melt partitioning of bromine in magmas

Alessandro Aiuppa, Mimma Emanuela Gennaro, Giada Iacono-Marziano, Anita Cadoux, Antonio Paonita, Etienne Deloule, Emanuela Gennaro, Alessandro Aiuppa, Bruno Scaillet, Tamsin A. Mather, David M. Pyle, Antonio Paonita, Giada Iacono Marziano

Risultato della ricerca: Article

3 Citazioni (Scopus)

Abstract

Volcanogenic halogens, in particular bromine, potentially play an important role in the ozone depletion of the atmosphere. Understanding bromine behaviour in magmas is therefore crucial to properly evaluate the contribution of volcanic eruptions to atmospheric chemistry and their environmental impact. To date, bromine partitioning between silicate melts and the gas phase is very poorly constrained, with the only relevant experimental studies limited to investigation of synthetic melt with silicic compositions. In this study, fluid/melt partitioning experiments were performed using natural silicate glasses with mafic, intermediate and silicic compositions. For each composition, experiments were run with various Br contents in the initial fluid (H2O–NaBr), at T–P conditions representative of shallow magmatic reservoirs in volcanic arc contexts (100–200 MPa, 900–1200 °C). The resulting fluid/melt partition coefficients (DBrf/m) are: 5.0 ± 0.3 at 1200 °C–100 MPa for the basalt, 9.1 ± 0.6 at 1060 °C–200 MPa for the andesite and 20.2 ± 1.2 at 900 °C–200 MPa for the rhyodacite. Our experiments show that DBrf/mincreases with increasing SiO2content of the melt (as for chlorine) and suggest that it is also sensitive to melt temperature (increase of DBrf/mwith decreasing temperature). We develop a simple model to predict the S–Cl–Br degassing behaviour in mafic systems, which accounts for the variability of S–Cl–Br compositions of volcanic gases from Etna and other mafic systems, and shows that coexisting magmatic gas and melt evolve from S-rich to Cl–Br enriched (relative to S) upon increasing degree of degassing. We also report first Br contents for melt inclusions from Etna, Stromboli, Merapi and Santorini eruptions and calculate the mass of bromine available in the magma reservoir prior to the eruptions under consideration. The discrepancy that we highlight between the mass of Br in the co-existing melt and fluid prior to the Merapi 2010 eruption (433 and 73 tons, respectively) and the lack of observed BrO (from space) hints at the need to investigate further Br speciation in ‘ash-rich’ volcanic plumes. Overall, our results suggest that the Br yield into the atmosphere of cold and silicic magmas will be much larger than that from hotter and more mafic magmas.
Lingua originaleEnglish
pagine (da-a)450-463
Numero di pagine14
RivistaDefault journal
Volume498
Stato di pubblicazionePublished - 2018

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cita questo

Aiuppa, A., Gennaro, M. E., Iacono-Marziano, G., Cadoux, A., Paonita, A., Deloule, E., ... Iacono Marziano, G. (2018). The role of melt composition on aqueous fluid vs. silicate melt partitioning of bromine in magmas. Default journal, 498, 450-463.

The role of melt composition on aqueous fluid vs. silicate melt partitioning of bromine in magmas. / Aiuppa, Alessandro; Gennaro, Mimma Emanuela; Iacono-Marziano, Giada; Cadoux, Anita; Paonita, Antonio; Deloule, Etienne; Gennaro, Emanuela; Aiuppa, Alessandro; Scaillet, Bruno; Mather, Tamsin A.; Pyle, David M.; Paonita, Antonio; Iacono Marziano, Giada.

In: Default journal, Vol. 498, 2018, pag. 450-463.

Risultato della ricerca: Article

Aiuppa, A, Gennaro, ME, Iacono-Marziano, G, Cadoux, A, Paonita, A, Deloule, E, Gennaro, E, Aiuppa, A, Scaillet, B, Mather, TA, Pyle, DM, Paonita, A & Iacono Marziano, G 2018, 'The role of melt composition on aqueous fluid vs. silicate melt partitioning of bromine in magmas', Default journal, vol. 498, pagg. 450-463.
Aiuppa, Alessandro ; Gennaro, Mimma Emanuela ; Iacono-Marziano, Giada ; Cadoux, Anita ; Paonita, Antonio ; Deloule, Etienne ; Gennaro, Emanuela ; Aiuppa, Alessandro ; Scaillet, Bruno ; Mather, Tamsin A. ; Pyle, David M. ; Paonita, Antonio ; Iacono Marziano, Giada. / The role of melt composition on aqueous fluid vs. silicate melt partitioning of bromine in magmas. In: Default journal. 2018 ; Vol. 498. pagg. 450-463.
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title = "The role of melt composition on aqueous fluid vs. silicate melt partitioning of bromine in magmas",
abstract = "Volcanogenic halogens, in particular bromine, potentially play an important role in the ozone depletion of the atmosphere. Understanding bromine behaviour in magmas is therefore crucial to properly evaluate the contribution of volcanic eruptions to atmospheric chemistry and their environmental impact. To date, bromine partitioning between silicate melts and the gas phase is very poorly constrained, with the only relevant experimental studies limited to investigation of synthetic melt with silicic compositions. In this study, fluid/melt partitioning experiments were performed using natural silicate glasses with mafic, intermediate and silicic compositions. For each composition, experiments were run with various Br contents in the initial fluid (H2O–NaBr), at T–P conditions representative of shallow magmatic reservoirs in volcanic arc contexts (100–200 MPa, 900–1200 °C). The resulting fluid/melt partition coefficients (DBrf/m) are: 5.0 ± 0.3 at 1200 °C–100 MPa for the basalt, 9.1 ± 0.6 at 1060 °C–200 MPa for the andesite and 20.2 ± 1.2 at 900 °C–200 MPa for the rhyodacite. Our experiments show that DBrf/mincreases with increasing SiO2content of the melt (as for chlorine) and suggest that it is also sensitive to melt temperature (increase of DBrf/mwith decreasing temperature). We develop a simple model to predict the S–Cl–Br degassing behaviour in mafic systems, which accounts for the variability of S–Cl–Br compositions of volcanic gases from Etna and other mafic systems, and shows that coexisting magmatic gas and melt evolve from S-rich to Cl–Br enriched (relative to S) upon increasing degree of degassing. We also report first Br contents for melt inclusions from Etna, Stromboli, Merapi and Santorini eruptions and calculate the mass of bromine available in the magma reservoir prior to the eruptions under consideration. The discrepancy that we highlight between the mass of Br in the co-existing melt and fluid prior to the Merapi 2010 eruption (433 and 73 tons, respectively) and the lack of observed BrO (from space) hints at the need to investigate further Br speciation in ‘ash-rich’ volcanic plumes. Overall, our results suggest that the Br yield into the atmosphere of cold and silicic magmas will be much larger than that from hotter and more mafic magmas.",
author = "Alessandro Aiuppa and Gennaro, {Mimma Emanuela} and Giada Iacono-Marziano and Anita Cadoux and Antonio Paonita and Etienne Deloule and Emanuela Gennaro and Alessandro Aiuppa and Bruno Scaillet and Mather, {Tamsin A.} and Pyle, {David M.} and Antonio Paonita and {Iacono Marziano}, Giada",
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TY - JOUR

T1 - The role of melt composition on aqueous fluid vs. silicate melt partitioning of bromine in magmas

AU - Aiuppa, Alessandro

AU - Gennaro, Mimma Emanuela

AU - Iacono-Marziano, Giada

AU - Cadoux, Anita

AU - Paonita, Antonio

AU - Deloule, Etienne

AU - Gennaro, Emanuela

AU - Aiuppa, Alessandro

AU - Scaillet, Bruno

AU - Mather, Tamsin A.

AU - Pyle, David M.

AU - Paonita, Antonio

AU - Iacono Marziano, Giada

PY - 2018

Y1 - 2018

N2 - Volcanogenic halogens, in particular bromine, potentially play an important role in the ozone depletion of the atmosphere. Understanding bromine behaviour in magmas is therefore crucial to properly evaluate the contribution of volcanic eruptions to atmospheric chemistry and their environmental impact. To date, bromine partitioning between silicate melts and the gas phase is very poorly constrained, with the only relevant experimental studies limited to investigation of synthetic melt with silicic compositions. In this study, fluid/melt partitioning experiments were performed using natural silicate glasses with mafic, intermediate and silicic compositions. For each composition, experiments were run with various Br contents in the initial fluid (H2O–NaBr), at T–P conditions representative of shallow magmatic reservoirs in volcanic arc contexts (100–200 MPa, 900–1200 °C). The resulting fluid/melt partition coefficients (DBrf/m) are: 5.0 ± 0.3 at 1200 °C–100 MPa for the basalt, 9.1 ± 0.6 at 1060 °C–200 MPa for the andesite and 20.2 ± 1.2 at 900 °C–200 MPa for the rhyodacite. Our experiments show that DBrf/mincreases with increasing SiO2content of the melt (as for chlorine) and suggest that it is also sensitive to melt temperature (increase of DBrf/mwith decreasing temperature). We develop a simple model to predict the S–Cl–Br degassing behaviour in mafic systems, which accounts for the variability of S–Cl–Br compositions of volcanic gases from Etna and other mafic systems, and shows that coexisting magmatic gas and melt evolve from S-rich to Cl–Br enriched (relative to S) upon increasing degree of degassing. We also report first Br contents for melt inclusions from Etna, Stromboli, Merapi and Santorini eruptions and calculate the mass of bromine available in the magma reservoir prior to the eruptions under consideration. The discrepancy that we highlight between the mass of Br in the co-existing melt and fluid prior to the Merapi 2010 eruption (433 and 73 tons, respectively) and the lack of observed BrO (from space) hints at the need to investigate further Br speciation in ‘ash-rich’ volcanic plumes. Overall, our results suggest that the Br yield into the atmosphere of cold and silicic magmas will be much larger than that from hotter and more mafic magmas.

AB - Volcanogenic halogens, in particular bromine, potentially play an important role in the ozone depletion of the atmosphere. Understanding bromine behaviour in magmas is therefore crucial to properly evaluate the contribution of volcanic eruptions to atmospheric chemistry and their environmental impact. To date, bromine partitioning between silicate melts and the gas phase is very poorly constrained, with the only relevant experimental studies limited to investigation of synthetic melt with silicic compositions. In this study, fluid/melt partitioning experiments were performed using natural silicate glasses with mafic, intermediate and silicic compositions. For each composition, experiments were run with various Br contents in the initial fluid (H2O–NaBr), at T–P conditions representative of shallow magmatic reservoirs in volcanic arc contexts (100–200 MPa, 900–1200 °C). The resulting fluid/melt partition coefficients (DBrf/m) are: 5.0 ± 0.3 at 1200 °C–100 MPa for the basalt, 9.1 ± 0.6 at 1060 °C–200 MPa for the andesite and 20.2 ± 1.2 at 900 °C–200 MPa for the rhyodacite. Our experiments show that DBrf/mincreases with increasing SiO2content of the melt (as for chlorine) and suggest that it is also sensitive to melt temperature (increase of DBrf/mwith decreasing temperature). We develop a simple model to predict the S–Cl–Br degassing behaviour in mafic systems, which accounts for the variability of S–Cl–Br compositions of volcanic gases from Etna and other mafic systems, and shows that coexisting magmatic gas and melt evolve from S-rich to Cl–Br enriched (relative to S) upon increasing degree of degassing. We also report first Br contents for melt inclusions from Etna, Stromboli, Merapi and Santorini eruptions and calculate the mass of bromine available in the magma reservoir prior to the eruptions under consideration. The discrepancy that we highlight between the mass of Br in the co-existing melt and fluid prior to the Merapi 2010 eruption (433 and 73 tons, respectively) and the lack of observed BrO (from space) hints at the need to investigate further Br speciation in ‘ash-rich’ volcanic plumes. Overall, our results suggest that the Br yield into the atmosphere of cold and silicic magmas will be much larger than that from hotter and more mafic magmas.

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UR - http://www.sciencedirect.com/science/journal/0012821X/321-322

M3 - Article

VL - 498

SP - 450

EP - 463

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