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| Titel |
Remobilization of silicic intrusion by mafic magmas during the 2010 Eyjafjallajökull eruption |
| VerfasserIn |
O. Sigmarsson, I. Vlastelic, R. Andreasen, I. Bindeman, J.-L. Devidal, S. Moune, J. K. Keiding, G. Larsen, A. Höskuldsson, Th. Thordarson  |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 2, no. 2 ; Nr. 2, no. 2 (2011-12-02), S.271-281 |
| Datensatznummer |
250000599
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| Publikation (Nr.) |
 copernicus.org/se-2-271-2011.pdf |
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| Zusammenfassung |
| Injection of basaltic magmas into silicic crustal holding chambers and
subsequent magma mingling or mixing is a process that has been recognised
since the late seventies as resulting in explosive eruptions. Detailed
reconstruction and assessment of the mixing process caused by such intrusion
is now possible because of the exceptional time-sequence sample suite
available from the tephra fallout of the 2010 summit eruption at
Eyjafjallajökull volcano in South Iceland. Fallout from 14 to 19 April
contains three glass types of basaltic, intermediate, and silicic
compositions recording rapid magma mingling without homogenisation,
involving evolved FeTi-basalt and silicic melt with composition identical to
that produced by the 1821–1823 AD Eyjafjallajökull summit eruption. The
time-dependent change in the magma composition suggests a binary mixing
process with changing end-member compositions and proportions. Beginning of
May, a new injection of primitive basalt was recorded by deep seismicity,
appearance of Mg-rich olivine phenocrysts together with high sulphur dioxide
output and presence of sulphide crystals. Thus, the composition of the
basaltic injection became more magnesian and hotter with time provoking
changes in the silicic mixing end-member from pre-existing melt to the solid
carapace of the magma chamber. Finally, decreasing proportions of the mafic
end-member with time in the erupted mixed-magma demonstrate that injections
of Mg-rich basalt was the motor of the 2010 Eyjafjallajökull explosive
eruption, and that its decreasing inflow terminated the eruption.
Significant quantity of silicic magma is thus still present in the interior
of the volcano. Our results show that detailed sampling during the entire
eruption was essential for deciphering the complex magmatic processes at
play, i.e. the dynamics of the magma mingling and mixing. Finally, the rapid
compositional changes in the eruptive products suggest that magma mingling
occurs on a timescale of a few hours to days whereas the interval between the
first detected magma injection and eruption was several months. |
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