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| Titel |
Mössbauer Spectroscopy and Electron Microscope Imaging of Samples from the 2010 Flank Eruption at Eyjafjallajökull |
| VerfasserIn |
Haraldur Páll Gunnlaugsson, Kristine Albers Olsen, Sigurdur Steinthorsson, Per Nørnberg |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048767
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| Zusammenfassung |
| The 2010 flank eruption at Eyjafjallajökull (Iceland) preceded the summit eruption that
produced large amounts of fine ash, disturbing air traffic across the N-Atlantic and within
Europe. Two samples were investigated, a tephra sample of relatively fast cooled material,
and a rock sample from the lava flow.
The Mössbauer spectra of the tephra sample shows lines originating from Fe3+ and Fe2+
in glass and Fe2+ in olivine. Details reveal that some small fraction of the Fe2+ assigned to
glass must originate from Fe2+ in pyroxenes. The Fe3+/FeTot ratio of the glass suggests
crystallization close to the magnetite/hematite buffer 2.5 log units above the FMQ
buffer.
Mössbauer spectroscopy of the rock sample is consistent with a high oxidation state as
36% of the area of the Mössbauer spectra are assigned to Fe in titanomaghemite and
hematite. Detailed analysis shows that no additional olivine has formed in the crystallization
process.
Due to the high oxidation state, high amounts of Fe have been incorporated into the
groundmass plagioclase. Analysis of Fe in pyroxenes and plagioclases indicate oxygen
fugacity 3.5-5.5 log units above the FMQ buffer, suggesting that the melt oxidized in the
cooling and crystallization process. Conversely, Fe is much lower in plagioclase phenocrysts,
and FeTi-oxide oxygen geobarometry indicates “normal” (FMQ) oxidation state in the mantle
at depth.
Þór Kristjánsson and Ármann Höskuldsson are acknowledged for providing the
samples. |
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