Confocal μ-XANES as a tool to analyze Fe oxidation state in heterogeneous samples: the case of melt inclusions in olivine from the Hekla volcano
Here we present a confocal Fe K-edge μ-XANES method (where XANES stands for X-ray absorption near-edge spectroscopy) for the analysis of Fe oxidation state in heterogeneous and one-side-polished samples. The new technique allows for an analysis of small volumes with high spatial 3D resolution of <...
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Göttingen : Copernicus Publications
2024
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ftunivhannover:oai:www.repo.uni-hannover.de:123456789/17282 2024-05-19T07:41:40+00:00 Confocal μ-XANES as a tool to analyze Fe oxidation state in heterogeneous samples: the case of melt inclusions in olivine from the Hekla volcano Botcharnikov, Roman Wilke, Max Garrevoet, Jan Portnyagin, Maxim Klimm, Kevin Buhre, Stephan Krasheninnikov, Stepan Almeev, Renat Moune, Severine Falkenberg, Gerald 2024 https://www.repo.uni-hannover.de/handle/123456789/17282 https://doi.org/10.15488/17154 eng eng Göttingen : Copernicus Publications DOI:https://doi.org/10.5194/ejm-36-195-2024 ESSN:1617-4011 https://www.repo.uni-hannover.de/handle/123456789/17282 https://doi.org/10.15488/17154 CC BY 4.0 Unported https://creativecommons.org/licenses/by/4.0 frei zugänglich European Journal of Mineralogy 36 (2024), Nr. 1 European Journal of Mineralogy Hekla Iceland Glass Iron Magnetite ddc:540 ddc:550 status-type:publishedVersion doc-type:Article doc-type:Text 2024 ftunivhannover https://doi.org/10.15488/1715410.5194/ejm-36-195-2024 2024-05-01T23:49:28Z Here we present a confocal Fe K-edge μ-XANES method (where XANES stands for X-ray absorption near-edge spectroscopy) for the analysis of Fe oxidation state in heterogeneous and one-side-polished samples. The new technique allows for an analysis of small volumes with high spatial 3D resolution of <100 μm3. The probed volume is restricted to that just beneath the surface of the exposed object. This protocol avoids contamination of the signal by the host material and minimizes self-absorption effects. This technique has been tested on a set of experimental glasses with a wide range of Fe3+ / ςFe ratios. The method was applied to the analysis of natural melt inclusions trapped in forsteritic to fayalitic olivine crystals of the Hekla volcano, Iceland. Our measurements reveal changes in Fe3+ / ςFe from 0.17 in basaltic up to 0.45 in dacitic melts, whereas the magnetite-ilmenite equilibrium shows redox conditions with Fe3+ / ςFe ≤0.20 (close to FMQ, fayalite-magnetite-quartz redox equilibrium) along the entire range of Hekla melt compositions. This discrepancy indicates that the oxidized nature of glasses in the melt inclusions could be related to the post-entrapment process of diffusive hydrogen loss from inclusions and associated oxidation of Fe in the melt. The Fe3+ / ςFe ratio in silicic melts is particularly susceptible to this process due to their low FeO content, and it should be critically evaluated before petrological interpretation. Article in Journal/Newspaper Hekla Iceland Institutional Repository of Leibniz Universität Hannover |
institution |
Open Polar |
collection |
Institutional Repository of Leibniz Universität Hannover |
op_collection_id |
ftunivhannover |
language |
English |
topic |
Hekla Iceland Glass Iron Magnetite ddc:540 ddc:550 |
spellingShingle |
Hekla Iceland Glass Iron Magnetite ddc:540 ddc:550 Botcharnikov, Roman Wilke, Max Garrevoet, Jan Portnyagin, Maxim Klimm, Kevin Buhre, Stephan Krasheninnikov, Stepan Almeev, Renat Moune, Severine Falkenberg, Gerald Confocal μ-XANES as a tool to analyze Fe oxidation state in heterogeneous samples: the case of melt inclusions in olivine from the Hekla volcano |
topic_facet |
Hekla Iceland Glass Iron Magnetite ddc:540 ddc:550 |
description |
Here we present a confocal Fe K-edge μ-XANES method (where XANES stands for X-ray absorption near-edge spectroscopy) for the analysis of Fe oxidation state in heterogeneous and one-side-polished samples. The new technique allows for an analysis of small volumes with high spatial 3D resolution of <100 μm3. The probed volume is restricted to that just beneath the surface of the exposed object. This protocol avoids contamination of the signal by the host material and minimizes self-absorption effects. This technique has been tested on a set of experimental glasses with a wide range of Fe3+ / ςFe ratios. The method was applied to the analysis of natural melt inclusions trapped in forsteritic to fayalitic olivine crystals of the Hekla volcano, Iceland. Our measurements reveal changes in Fe3+ / ςFe from 0.17 in basaltic up to 0.45 in dacitic melts, whereas the magnetite-ilmenite equilibrium shows redox conditions with Fe3+ / ςFe ≤0.20 (close to FMQ, fayalite-magnetite-quartz redox equilibrium) along the entire range of Hekla melt compositions. This discrepancy indicates that the oxidized nature of glasses in the melt inclusions could be related to the post-entrapment process of diffusive hydrogen loss from inclusions and associated oxidation of Fe in the melt. The Fe3+ / ςFe ratio in silicic melts is particularly susceptible to this process due to their low FeO content, and it should be critically evaluated before petrological interpretation. |
format |
Article in Journal/Newspaper |
author |
Botcharnikov, Roman Wilke, Max Garrevoet, Jan Portnyagin, Maxim Klimm, Kevin Buhre, Stephan Krasheninnikov, Stepan Almeev, Renat Moune, Severine Falkenberg, Gerald |
author_facet |
Botcharnikov, Roman Wilke, Max Garrevoet, Jan Portnyagin, Maxim Klimm, Kevin Buhre, Stephan Krasheninnikov, Stepan Almeev, Renat Moune, Severine Falkenberg, Gerald |
author_sort |
Botcharnikov, Roman |
title |
Confocal μ-XANES as a tool to analyze Fe oxidation state in heterogeneous samples: the case of melt inclusions in olivine from the Hekla volcano |
title_short |
Confocal μ-XANES as a tool to analyze Fe oxidation state in heterogeneous samples: the case of melt inclusions in olivine from the Hekla volcano |
title_full |
Confocal μ-XANES as a tool to analyze Fe oxidation state in heterogeneous samples: the case of melt inclusions in olivine from the Hekla volcano |
title_fullStr |
Confocal μ-XANES as a tool to analyze Fe oxidation state in heterogeneous samples: the case of melt inclusions in olivine from the Hekla volcano |
title_full_unstemmed |
Confocal μ-XANES as a tool to analyze Fe oxidation state in heterogeneous samples: the case of melt inclusions in olivine from the Hekla volcano |
title_sort |
confocal μ-xanes as a tool to analyze fe oxidation state in heterogeneous samples: the case of melt inclusions in olivine from the hekla volcano |
publisher |
Göttingen : Copernicus Publications |
publishDate |
2024 |
url |
https://www.repo.uni-hannover.de/handle/123456789/17282 https://doi.org/10.15488/17154 |
genre |
Hekla Iceland |
genre_facet |
Hekla Iceland |
op_source |
European Journal of Mineralogy 36 (2024), Nr. 1 European Journal of Mineralogy |
op_relation |
DOI:https://doi.org/10.5194/ejm-36-195-2024 ESSN:1617-4011 https://www.repo.uni-hannover.de/handle/123456789/17282 https://doi.org/10.15488/17154 |
op_rights |
CC BY 4.0 Unported https://creativecommons.org/licenses/by/4.0 frei zugänglich |
op_doi |
https://doi.org/10.15488/1715410.5194/ejm-36-195-2024 |
_version_ |
1799481273269354496 |