Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/4635
AuthorsFrancalanci, L.* 
Bertagnini, A.* 
Metrich, N.* 
Renzulli, A.* 
Vannucci, R.* 
Landi, P.* 
Del Moro, S.* 
Menna, M.* 
Petrone, C. M.* 
Nardini, I* 
TitleMineralogical, geochemical, and isotopic characteristics of the ejecta from the 5 April 2003 paroxysm at Stromboli, Itlay: Inferences on the Preeruptive Magma Dynamics
Issue Date2008
URIhttp://hdl.handle.net/2122/4635
KeywordsStromboli volcano
Paroxysmal activity
Basaltic pumice
Volatile content
Mineralogy
Geochemistry
Sr isotope
Subject Classification04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology 
04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry 
04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk 
AbstractThe 5 April 2003 explosive eruption at Stromboli emplaced typical basaltic scoria, pumice, and lithic blocks. This paper reports a detailed set of mineralogical, geochemical, and isotopic data on the juvenile ejecta and fresh subvolcanic blocks, including micro-Sr isotope analyses and major and dissolved volatile element contents in olivine-hosted melt inclusions. The juvenile ejecta have compositions similar to those of their analogs from previous paroxysms; the 2003 pumice, however, does not contain stable high-MgO olivine, usually typical of large-scale paroxysms and has lower compatible element contents. Texture, composition, and Sr isotope disequilibrium of crystals in pumice indicate that most of them are inherited from the shallow crystal-rich magma and/or crystal mush. The most primitive magma is recorded as rare melt inclusion in olivine Fo85–86. It has a typical S/Cl (1.1) and a total volatile content of 3.1 wt % from which the total fluid pressure was evaluated ≥240 MPa. Hence, moderate pressure conditions can be envisaged for the mechanism triggering the April 2003 paroxysm. The subvolcanic blocks are shoshonitic basalts with 45–50 vol % of phenocrysts (plagioclase + clinopyroxene + olivine). The late-stage crystallization of the crystal-rich magma lead to the formation of Na-sanidine with plagioclase An60–25 + olivine Fo68–49 + Timagnetite ± apatite ± phlogopite ± ilmenite assemblage. Mineralogy, chemistry, and Sr–Nd isotopic signatures of the subvolcanic blocks indicate they represent the slowly cooled equivalents of batches of crystal-rich basaltic magma stored in the uppermost subvolcanic feeding system. Cooling might be facilitated by short breaks in the summit crater activity.
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