The role of syn-eruptive vesiculation on explosive basaltic activity at Mt. Etna, Italy

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• 作者：Margherita Polacci ; Michael R. Burton ; Aless ; ro La Spina ; Filippo Murè ; Stefano Favretto ; Franco Zanini
• 关键词：Etna ; fire-fountains ; vesicle textures ; volcanic degassing
• 刊名：Journal of Volcanology and Geothermal Research
• 出版年：2009
• 出版时间：20 January 2009
• 年：2009
• 卷：179
• 期：3-4
• 页码：265-269
• 全文大小：770 K

文摘

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.