The role of syn-eruptive vesiculation on explosive basaltic activity at Mt. Etna,Italy |
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| Authors: | Margherita Polacci Michael R Burton Alessandro La Spina Filippo Murè Stefano Favretto Franco Zanini |
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| Institution: | 1. Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstraße 41, 80333 Munich, Germany;2. CEA, DES, ISEC, DE2D, Univ Montpellier, Laboratoire de Développement des Matrices de Conditionnement, Marcoule, France;3. Centre for Material Forming, CEMEF, MINES ParisTech, PSL Research University, CNRS UMR 7635, CS 10207, Claude Daunesse, 06904, Sophia Antipolis Cedex, France;1. Facultad de Geología, Minas, Petróleos y Ambiental, Carrera de Ingeniería en Geología, Universidad Central del Ecuador, Casilla 872 A, Quito, Ecuador;2. Departamento de Geología, Universidad de Atacama, Copayapu 485, Copiapó, Chile;3. Departamento de Metalurgia Extractiva, Escuela Politécnica Nacional, Ladrón Guevara E11-253, Quito, Ecuador;1. Dipartimento di Scienze della Terra, Sapienza Università di Roma, P.le Aldo Moro 5, 00185 Rome, Italy;2. Consiglio Nazionale delle Ricerche, Istituto di Geologia Ambientale e Geoingegneria, Sede Secondaria di Roma, c/o Dipartimento di Scienze della Terra, Sapienza Università di Roma, P.le A. Moro 5, Rome, Italy;3. Dipartimento di Scienze, Università degli Studi Roma Tre, L.go San Leonardo Murialdo 1, 00146 Rome, Italy |
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| Abstract: | We investigated the dynamics of explosive activity at Mt. Etna between 31 August and 15 December 2006 by combining vesicle studies in the erupted products with measurements of the gas composition at the active, summit crater. The analysed scoria clasts present large, connected vesicles with complex shapes and smaller, isolated, spherical vesicles, the content of which increases in scoriae from the most explosive events. Gas geochemistry reports CO2/SO2 and SO2/HCl ratios supporting a deep-derived gas phase for fire-fountain activity. By integrating results from scoria vesiculation and gas analysis we find that the highest energy episodes of Mt. Etna activity in 2006 were driven by a previously accumulated CO2-rich gas phase but we highlight the lesser role of syn-eruptive vesicle nucleation driven by water exsolution during ascent. We conclude that syn-eruptive vesiculation is a common process in Etnean magmas that may promote a deeper conduit magma fragmentation and increase ash formation. |
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