Controls on the iron isotopic composition of global arc magmas

International audience We determined the iron isotope composition of 130 mafic lavas from 15 arcs worldwide with the hypothesis that the results would reflect the relatively high oxidation state of arc magmas. Although this expectation was not realized, this Fe isotope data set reveals important ins...

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Published in:Earth and Planetary Science Letters
Main Authors: Foden, John, Sossi, Paolo A., Nebel, Oliver
Other Authors: Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)
Format: Article in Journal/Newspaper
Language:English
Published: HAL CCSD 2018
Subjects:
Online Access:https://hal-insu.archives-ouvertes.fr/insu-03589345
https://doi.org/10.1016/j.epsl.2018.04.039
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spelling ftinsu:oai:HAL:insu-03589345v1 2023-06-18T03:41:30+02:00 Controls on the iron isotopic composition of global arc magmas Foden, John Sossi, Paolo A. Nebel, Oliver Institut de Physique du Globe de Paris (IPGP) Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS) 2018 https://hal-insu.archives-ouvertes.fr/insu-03589345 https://doi.org/10.1016/j.epsl.2018.04.039 en eng HAL CCSD Elsevier info:eu-repo/semantics/altIdentifier/doi/10.1016/j.epsl.2018.04.039 insu-03589345 https://hal-insu.archives-ouvertes.fr/insu-03589345 BIBCODE: 2018E&PSL.494.190F doi:10.1016/j.epsl.2018.04.039 ISSN: 0012-821X Earth and Planetary Science Letters https://hal-insu.archives-ouvertes.fr/insu-03589345 Earth and Planetary Science Letters, 2018, 494, pp.190-201. ⟨10.1016/j.epsl.2018.04.039⟩ iron isotopes volcanic arcs subduction oxidation thermal parameter [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/article Journal articles 2018 ftinsu https://doi.org/10.1016/j.epsl.2018.04.039 2023-06-05T20:49:51Z International audience We determined the iron isotope composition of 130 mafic lavas from 15 arcs worldwide with the hypothesis that the results would reflect the relatively high oxidation state of arc magmas. Although this expectation was not realized, this Fe isotope data set reveals important insights into the geodynamic controls and style of the melting regimes in the sub-arc mantle. Samples are from oceanic arcs from the circum-Pacific, the Indonesian Sunda-Banda islands, Scotia and the Lesser Antilles as well as from the eastern Pacific Cascades. Their mean δ 57 Fe value is +0.075 ± 0.05‰, significantly lighter than MORB (+0.15 ± 0.03‰). Western Pacific arcs extend to very light δ 57 Fe (Kamchatka = -0.11 ± 0.04‰). This is contrary to expectation, because Fe isotope fractionation factors (Sossi et al., 2016, 2012) and the incompatibility of ferric versus ferrous iron during mantle melting, predict that melts of more oxidized sources will be enriched in heavy Fe isotopes. Subducted oxidation capacity flux may correlate with hydrous fluid release from the slab. If so, a positive correlation between each arc's thermal parameter (ϕ) and δ 57 Fe is predicted. On the contrary, the sampled arcs mostly contribute to a negative array with the ϕ value. High ϕ arcs, largely in the western Pacific, have primary magmas with lower δ 57 Fe values than the low ϕ, eastern Pacific arcs. Arcs with MORB-like Sr-, Nd- and Pb-isotopes, show a large range of δ 57 Fe from heavy MORB-like values (Scotia or the Cascades) to very light values (Kamchatka, Tonga). Although all basalts with light δ 57 Fe values have MORB-like Pb-, Nd- and Sr-isotope ratios some, particularly those from eastern Indonesia, have heavier δ 57 Fe and higher Pb- and Sr- and lower Nd-isotope ratios reflecting sediment contamination of the mantle wedge. Because basalts with MORB-like radiogenic isotopes range all the way from heavy to light δ 57 Fe values this trend is process-, not source composition-driven. Neither the slab-derived influx of fluids with ... Article in Journal/Newspaper Kamchatka Institut national des sciences de l'Univers: HAL-INSU Pacific Sunda ENVELOPE(-6.982,-6.982,62.205,62.205) Tonga ENVELOPE(7.990,7.990,63.065,63.065) Earth and Planetary Science Letters 494 190 201
institution Open Polar
collection Institut national des sciences de l'Univers: HAL-INSU
op_collection_id ftinsu
language English
topic iron isotopes
volcanic arcs
subduction
oxidation
thermal parameter
[SDU]Sciences of the Universe [physics]
spellingShingle iron isotopes
volcanic arcs
subduction
oxidation
thermal parameter
[SDU]Sciences of the Universe [physics]
Foden, John
Sossi, Paolo A.
Nebel, Oliver
Controls on the iron isotopic composition of global arc magmas
topic_facet iron isotopes
volcanic arcs
subduction
oxidation
thermal parameter
[SDU]Sciences of the Universe [physics]
description International audience We determined the iron isotope composition of 130 mafic lavas from 15 arcs worldwide with the hypothesis that the results would reflect the relatively high oxidation state of arc magmas. Although this expectation was not realized, this Fe isotope data set reveals important insights into the geodynamic controls and style of the melting regimes in the sub-arc mantle. Samples are from oceanic arcs from the circum-Pacific, the Indonesian Sunda-Banda islands, Scotia and the Lesser Antilles as well as from the eastern Pacific Cascades. Their mean δ 57 Fe value is +0.075 ± 0.05‰, significantly lighter than MORB (+0.15 ± 0.03‰). Western Pacific arcs extend to very light δ 57 Fe (Kamchatka = -0.11 ± 0.04‰). This is contrary to expectation, because Fe isotope fractionation factors (Sossi et al., 2016, 2012) and the incompatibility of ferric versus ferrous iron during mantle melting, predict that melts of more oxidized sources will be enriched in heavy Fe isotopes. Subducted oxidation capacity flux may correlate with hydrous fluid release from the slab. If so, a positive correlation between each arc's thermal parameter (ϕ) and δ 57 Fe is predicted. On the contrary, the sampled arcs mostly contribute to a negative array with the ϕ value. High ϕ arcs, largely in the western Pacific, have primary magmas with lower δ 57 Fe values than the low ϕ, eastern Pacific arcs. Arcs with MORB-like Sr-, Nd- and Pb-isotopes, show a large range of δ 57 Fe from heavy MORB-like values (Scotia or the Cascades) to very light values (Kamchatka, Tonga). Although all basalts with light δ 57 Fe values have MORB-like Pb-, Nd- and Sr-isotope ratios some, particularly those from eastern Indonesia, have heavier δ 57 Fe and higher Pb- and Sr- and lower Nd-isotope ratios reflecting sediment contamination of the mantle wedge. Because basalts with MORB-like radiogenic isotopes range all the way from heavy to light δ 57 Fe values this trend is process-, not source composition-driven. Neither the slab-derived influx of fluids with ...
author2 Institut de Physique du Globe de Paris (IPGP)
Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)
format Article in Journal/Newspaper
author Foden, John
Sossi, Paolo A.
Nebel, Oliver
author_facet Foden, John
Sossi, Paolo A.
Nebel, Oliver
author_sort Foden, John
title Controls on the iron isotopic composition of global arc magmas
title_short Controls on the iron isotopic composition of global arc magmas
title_full Controls on the iron isotopic composition of global arc magmas
title_fullStr Controls on the iron isotopic composition of global arc magmas
title_full_unstemmed Controls on the iron isotopic composition of global arc magmas
title_sort controls on the iron isotopic composition of global arc magmas
publisher HAL CCSD
publishDate 2018
url https://hal-insu.archives-ouvertes.fr/insu-03589345
https://doi.org/10.1016/j.epsl.2018.04.039
long_lat ENVELOPE(-6.982,-6.982,62.205,62.205)
ENVELOPE(7.990,7.990,63.065,63.065)
geographic Pacific
Sunda
Tonga
geographic_facet Pacific
Sunda
Tonga
genre Kamchatka
genre_facet Kamchatka
op_source ISSN: 0012-821X
Earth and Planetary Science Letters
https://hal-insu.archives-ouvertes.fr/insu-03589345
Earth and Planetary Science Letters, 2018, 494, pp.190-201. ⟨10.1016/j.epsl.2018.04.039⟩
op_relation info:eu-repo/semantics/altIdentifier/doi/10.1016/j.epsl.2018.04.039
insu-03589345
https://hal-insu.archives-ouvertes.fr/insu-03589345
BIBCODE: 2018E&PSL.494.190F
doi:10.1016/j.epsl.2018.04.039
op_doi https://doi.org/10.1016/j.epsl.2018.04.039
container_title Earth and Planetary Science Letters
container_volume 494
container_start_page 190
op_container_end_page 201
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