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Boron isotope fractionation in magma via crustal carbonate dissolution
Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO(2) fluxes. Here we use boron as a tracer, which substitutes for carbon in l...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Nature Publishing Group
2016
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4973271/ https://www.ncbi.nlm.nih.gov/pubmed/27488228 http://dx.doi.org/10.1038/srep30774 |
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author | Deegan, Frances M. Troll, Valentin R. Whitehouse, Martin J. Jolis, Ester M. Freda, Carmela |
author_facet | Deegan, Frances M. Troll, Valentin R. Whitehouse, Martin J. Jolis, Ester M. Freda, Carmela |
author_sort | Deegan, Frances M. |
collection | PubMed |
description | Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO(2) fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO(2)-dominated vapour phase. The CaO-rich glasses have extremely low δ(11)B values down to −41.5‰, reflecting preferential partitioning of (10)B into the assimilating melt. Loss of (11)B from the reaction site occurs via the CO(2) vapour phase generated during carbonate dissolution, which transports (11)B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ(11)B melt values in arc magmas could flag shallow-level additions to the subduction cycle. |
format | Online Article Text |
id | pubmed-4973271 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2016 |
publisher | Nature Publishing Group |
record_format | MEDLINE/PubMed |
spelling | pubmed-49732712016-08-12 Boron isotope fractionation in magma via crustal carbonate dissolution Deegan, Frances M. Troll, Valentin R. Whitehouse, Martin J. Jolis, Ester M. Freda, Carmela Sci Rep Article Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO(2) fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO(2)-dominated vapour phase. The CaO-rich glasses have extremely low δ(11)B values down to −41.5‰, reflecting preferential partitioning of (10)B into the assimilating melt. Loss of (11)B from the reaction site occurs via the CO(2) vapour phase generated during carbonate dissolution, which transports (11)B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ(11)B melt values in arc magmas could flag shallow-level additions to the subduction cycle. Nature Publishing Group 2016-08-04 /pmc/articles/PMC4973271/ /pubmed/27488228 http://dx.doi.org/10.1038/srep30774 Text en Copyright © 2016, The Author(s) http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
spellingShingle | Article Deegan, Frances M. Troll, Valentin R. Whitehouse, Martin J. Jolis, Ester M. Freda, Carmela Boron isotope fractionation in magma via crustal carbonate dissolution |
title | Boron isotope fractionation in magma via crustal carbonate dissolution |
title_full | Boron isotope fractionation in magma via crustal carbonate dissolution |
title_fullStr | Boron isotope fractionation in magma via crustal carbonate dissolution |
title_full_unstemmed | Boron isotope fractionation in magma via crustal carbonate dissolution |
title_short | Boron isotope fractionation in magma via crustal carbonate dissolution |
title_sort | boron isotope fractionation in magma via crustal carbonate dissolution |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4973271/ https://www.ncbi.nlm.nih.gov/pubmed/27488228 http://dx.doi.org/10.1038/srep30774 |
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