TY - JOUR
T1 - Dynamic magma mixing revealed by the 2010 Eyjafjallajökull eruption
AU - Sigmarsson, O.
AU - Vlastelic, I.
AU - Andreasen, R.
AU - Bindeman, I.
AU - Devidal, J.-L.
AU - Moune, S.
AU - Keiding, J. K.
AU - Larsen, G.
AU - Höskuldsson, A.
AU - Thordarson, Th.
PY - 2011/7/1
Y1 - 2011/7/1
N2 - Injection of basaltic magmas into silicic crustal holding chambers and
subsequent mixing of the two components is a process that has been
recognised since the late seventies to have resulted 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. From
14 to 19 April the tephra contains three glass types of basaltic,
intermediate, and silicic compositions recording rapid magma mingling
without homogenisation, involving evolved FeTi-basalt and dacite 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, or dynamic magma mixing.
Beginning of May, a new injection of deep-derived basalt was recorded by
deep seismicity, appearance of magnesium-rich olivine phenocrysts
together with high sulphur output and presence of sulphide crystals.
Thus the composition of the basaltic injection became more primitive and
hotter with time prowoking changes in the silicic mixing end-member from
pre-existing melt to the solid carapace of the magma chamber. 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, namely
the dynamic magma mixing. Finally, the rapid compositional changes in
the eruptive products suggest that magma mingling occurs on a timescale
of few hours to days whereas the interval between the first detected
magma injection and eruption was several months.
AB - Injection of basaltic magmas into silicic crustal holding chambers and
subsequent mixing of the two components is a process that has been
recognised since the late seventies to have resulted 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. From
14 to 19 April the tephra contains three glass types of basaltic,
intermediate, and silicic compositions recording rapid magma mingling
without homogenisation, involving evolved FeTi-basalt and dacite 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, or dynamic magma mixing.
Beginning of May, a new injection of deep-derived basalt was recorded by
deep seismicity, appearance of magnesium-rich olivine phenocrysts
together with high sulphur output and presence of sulphide crystals.
Thus the composition of the basaltic injection became more primitive and
hotter with time prowoking changes in the silicic mixing end-member from
pre-existing melt to the solid carapace of the magma chamber. 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, namely
the dynamic magma mixing. Finally, the rapid compositional changes in
the eruptive products suggest that magma mingling occurs on a timescale
of few hours to days whereas the interval between the first detected
magma injection and eruption was several months.
U2 - 10.5194/sed-3-591-2011
DO - 10.5194/sed-3-591-2011
M3 - Journal article
VL - 3
SP - 591
EP - 613
JO - Solid Earth Discussions
JF - Solid Earth Discussions
IS - 2
ER -