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In situ XANES study of the influence of varying temperature and oxygen fugacity on iron oxidation state and coordination in a phonolitic melt
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In: Contributions to Mineralogy and Petrology (2022)
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Abstract:
Iron oxidation state and environment in magmas afect their phase diagram and their properties, including viscosity and density, which determine magma mobility and eruptive potential. In turn, magma composition, pressure, temperature and oxygen fugacity afect iron oxidation state and coordination, potentially leading to complex feedbacks associated with magma ascent, degassing and eruption. While equilibrium experiments and models have led to a deep understanding of the role of iron in melts, our knowledge of the efects of disequilibrium processes on iron oxidation state and its structural role in lavas and magmas remains limited. Accordingly, we performed a series of dynamic disequilibrium experiments on a natural melt composition (a phonolite lava from Erebus volcano, Antarctica) at atmospheric pressure, in which oxygen fugacity and temperature were controlled and varied. During the experiments, we continuously measured iron oxidation and coordination using Fe K-edge dispersive X-ray Absorption Spectroscopy (XAS). We found that iron oxidation state changes in the phonolite melt are reversible and well reproduced by existing models. Changes in iron oxidation state are driven by joint difusion of alkali cations and oxygen anions at magmatic temperatures (~1000 °C for Erebus phonolite). However, redox difusion timescales are too slow for any signifcant oxygen exchange with the atmosphere at the lava/air interface or via air entrainment. Turning to iron coordination, while Fe2+ and Fe3+ are present mostly in an average fve-fold coordination, complex coordination variations decoupled from redox changes were detected. The data suggest transitions between Fe3+ in four-fold and six-fold coordination prior to reduction or as a consequence of oxidation. This questions the possible implication of Fe coordination changes in triggering crystallisation of magnetite nanolites upon magma ascent, and, through such crystallisation events, in promoting magma explosivity. ; CLL acknowledges support received from the Australian Research Council Laureate Fellowship (FL130100066) of Hugh St. C. O’Neill as well as from the Chaire d’Excellence of the University of Paris during data processing and manuscript preparation. CO acknowledges support from the Natural Environment Research Council (Grant NE/N009312/1).
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Keyword:
Coordination; Iron; Magmas; Oxidation state; Volcano; XANES spectroscopy
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URL: https://doi.org/10.1007/s00410-020-01701-4
https://openresearch-repository.anu.edu.au/bitstream/1885/259047/3/01_Le%2bLosq_In_situ_XANES_study_of_the_2020.pdf.jpg
http://hdl.handle.net/1885/259047
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| 2 |
On the Limits of Across-the-Board Movement: Distributed Extraction Coordinations
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In: Philosophies; Volume 7; Issue 1; Pages: 10 (2022)
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| 3 |
English adjectives of very similar meaning used in combination: an exploratory, corpus-aided study
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In: Lexis: Journal in English Lexicology, Vol 19 (2022) (2022)
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| 4 |
Surgical Video Summarization: Multifarious Uses, Summarization Process and Ad-Hoc Coordination
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In: ISSN: 2573-0142 ; EISSN: 2573-0142 ; Proceedings of the ACM on Human-Computer Interaction ; CHI '21: CHI Conference on Human Factors in Computing Systems ; https://hal.archives-ouvertes.fr/hal-03160860 ; Proceedings of the ACM on Human-Computer Interaction , Association for Computing Machinery (ACM), 2021, 4 (4), ⟨10.1145/3449214⟩ (2021)
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| 5 |
Similar but different: investigating temporal constructions in sign language
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In: ISSN: 2397-1835 ; EISSN: 2397-1835 ; Glossa: a journal of general linguistics (2021-.) ; https://hal.archives-ouvertes.fr/hal-03509783 ; Glossa: a journal of general linguistics (2021-.), Open Library of Humanities, 2021, 6 (1), ⟨10.5334/gjgl.999⟩ (2021)
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| 6 |
Entre phraséologie et conditionnement contextuel : le cas des constructions pseudo-coordonnées en russe et en grec moderne
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In: ISSN: 0756-7138 ; EISSN: 2804-7397 ; Lexique ; https://halshs.archives-ouvertes.fr/halshs-03519049 ; Lexique, UMR 8163 « Savoirs, Textes, Langage » Université de Lille, 2021, pp.191-209 (2021)
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| 8 |
The grammar of engagement I: framework and initialexemplification
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In: Language and Cognition (2021)
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| 9 |
Koordinierungsstelle "Sprachliche Bildung und Mehrsprachigkeit" (KoMBi). Abschlussbericht zur Förderperiode 3, Förderkennzeichen 01JM1301
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In: Hamburg : Universität 2021, 45 S. (2021)
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| 10 |
When verbs come (and) clash together: the diachrony of multiverb constructions in Juǀ'hoan and ǃXun ...
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| 11 |
When verbs come (and) clash together: the diachrony of multiverb constructions in Juǀ'hoan and ǃXun ...
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| 12 |
Coordination without grammar-internal feature resolution ...
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| 13 |
Word order in French: the role of animacy
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In: Glossa: a journal of general linguistics; Vol 6, No 1 (2021); 55 ; 2397-1835 (2021)
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| 14 |
Koordinierungsstelle "Sprachliche Bildung und Mehrsprachigkeit" (KoMBi). Abschlussbericht zur Förderperiode 3, Förderkennzeichen 01JM1301 ...
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| 15 |
СРАВНИТЕЛЬНЫЙ АНАЛИЗ СЛОВОСОЧЕТАНИЙ В ДАГЕСТАНСКИХ ЯЗЫКАХ ... : COMPARATIVE ANALYSIS OF WORDS IN DAGESTAN LANGUAGES ...
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| 16 |
The prosody of coordinative suffixal alternate forms in German ...
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| 17 |
The prosody of utterances containing the German gender asterisk ...
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| 18 |
The Analysis of the Spatial Production Mechanism and the Coupling Coordination Degree of the Danwei Compound Based on the Spatial Ternary Dialectics
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In: Processes; Volume 9; Issue 12; Pages: 2281 (2021)
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| 19 |
Quantitative Comparison between Traditional and Intensive Face-to-Face Education through an Organizational Model
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In: Education Sciences; Volume 11; Issue 12; Pages: 820 (2021)
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| 20 |
Similar but different: investigating temporal constructions in sign language
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In: Glossa: a journal of general linguistics; Vol 6, No 1 (2021); 2 ; 2397-1835 (2021)
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