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Magma dynamics during the 2007 Stromboli eruption (Aeolian Islands. Italy): mineralogical, geochemical and isotopic data
- Publication date
- Publisher
- Elsevier
Abstract
After the 6 month-long effusive event of 2002-2003, a new lava effusion occurred at Stromboli between 27
February and 2 April 2007. Despite the different durations, approximately the same volume of magma was
emitted in both eruptions, in the order of 107
m3
. A paroxysmal eruption occurred at the summit craters in
both the 2002–2003 and 2007 episodes, during which a significant amount of low porphyritic (LP), volatile-
rich magma was erupted. In both cases, the paroxysm did not interrupt the lava emission. Here, we present
compositional data, including texture, mineralogy, chemistry and Sr and Nd isotope ratios of bulk-rock,
groundmass and separated minerals of lavas erupted in 2007, together with chemistry and Sr and Nd isotope
composition of the pumices emitted during the 15 March paroxysm. As a whole, the lavas have the same
texture and chemistry that characterize the highly porphyritic (HP) products usually erupted at Stromboli
during normal Strombolian activity and effusive events. Compared to the previous HP products, the 2007
lavas show minor but systematic mineralogical and isotopic variations which are consistent with a modest
increase of the magma supply rate of the volcano. Compositional variations during the entire duration of the
event are very modest. Glass chemistry changes in lavas erupted in the second half of March can be explained
by theminormixing between the volatile-rich LPmagma rising through the shallowmagmatic systemduring the
15 March paroxysm and the degassed residing HP magma. A first conclusion of this study is that there is no
compositional evidence supporting major changes in the magma dynamics of the volcano accompanying the
effusive activity, as also suggested for the 2002–2003 event. The activity of Stromboli is controlled by a steady
state feeding system in which refilling, mixing, degassing and crystallization at shallow level continuously
operate,withmodest oscillations in themagma supply rate. Switching between normal Strombolian and effusive
activity is related to periods of relatively more vigorous refilling of the shallow system, leading to progressive
pressure increase in the upper conduits associated with only minor compositional variations in the erupted
products