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Multiple mush generations provide insight into the longevity of open conduit basaltic volcanoes

Beatrice Schiavon1, Chiara Maria Petrone^2^, Francesca Forni3, Alessio Pontesilli4, Haiyang Hu5, Piergiorgio Scarlato4, Daniele Andronico6, Elisabetta Del Bello4, Manuela Nazzari4, Silvio Mollo1,4

  • Affiliations:  1 Department of Earth Sciences, Sapienza - University of Rome, P. le Aldo Moro 5, 00185 Roma, Italy; 2 Natural History Museum, Volcano Petrology Group, Cromwell Road, SW7 5BD London, UK; 3 Department of Earth Sciences "Ardito Desio", University of Milan, via Mangiagalli 34, 20133 Milan, Italy; 4 Istituto Nazionale di Geofisica e Vulcanologia - Sezione Roma 1, Via di Vigna Murata 605, 00143 Roma, Italy; 5 Imperial College, Exhibition Road, South Kensington, SW7 2AZ London, UK; 6 Istituto Nazionale di Geofisica e Vulcanologia - Osservatorio Etneo, Piazza Roma 2, 95123 Catania, Italy 

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 201

  • Programme No: 3.2.24

  • Theme 3 > Session 2

Abstract

Investigating the dynamics and timescales of magmatic processes in open-conduit basaltic volcanoes is crucial for improving our understanding of explosive eruptions and better assessing volcanic hazards. Among these processes, the role of mush disaggregation and remobilisation within the plumbing system remains rather underexplored. This study examines the longevity and dynamics of the mush system beneath Stromboli volcano (Aeolian Islands, Southern Italy), whose persistent activity results from variable degrees of interaction between different magmatic components. The complex zoning patterns of plagioclase phenocrysts from 2003-2021 eruptions have been interrogated by combining in-situ Sr isotope compositions, thermometric modelling, and Mg diffusion chronometry. Our findings shed new light on the physicochemical changes within the plumbing system, the timescales of crystal residence in the shallow reservoir, and the timing of magma recharge events. The response of plagioclase to magma-mush dynamics is rapid during violent explosions but more sluggish during normal activity. Sr isotope heterogeneities in plagioclase reveal that multiple mush generations at Stromboli have been active over millennia, with remobilisation events and crystal recycling driven by mafic magma recharges from depth. This is further supported by a complementary in-situ investigation of clinopyroxene phenocryst cores. A previously unseen, prehistoric, highly radiogenic mush has been actively remobilised in recent years, pointing out that older components of open-conduit basaltic systems may persist longer than previously hypothesised.