Explosive volcanism is commonly reconstructed thanks to near-vent deposits, where geological records can provide fundamental insights for evaluating depositional processes, eruptive dynamics and evolution of the volcanic edifice. However, due to the intense volcano-tectonic and sedimentary processes occurring close to the volcano, proximal outcrops are most of the time lacunose and incomplete (Giaccio et al., 2014). In contrast, distal archives can continuously record sedimentation of ash layers, providing useful integrative information for reconstructing history and dynamics of the explosive activity (Albert et al., 2019). In this study, we have stratigraphically and geochemically characterised proximal and distal deposits belonging to the early activity (425-400 ka) of Vico volcano, central Italy. Specifically, we analysed tephra layers hosted in the lacustrine successions of Fucino and Sulmona intermountain basins as well as Rome’s near-coastal aggradational successions, spanning the ca. 430-365 ka interval. A series of chemically-zoned, rhyolitic to trachytic-phonolitic tephra were analysed and, based on stratigraphical, geochemical and geochronological data, were attributed to Vico explosive activity. In addition to the two major eruptive units, known as Vico a and Vico b(Cioni et al., 1987), a series of “minor” events were recognised in distal settings, documenting a much more complex volcanic history and eruptive behaviour (e.g. eruption frequency and intensities, periods of quiescence) than previously thought. Furthermore, new 40Ar/ 39Ar dates based on distal and mid-distal tephra deposits allowed to propose more precise and accurate geochronological constraints for the two main explosive eruptions of Vico (i.e. a and b), dated at 414.5 ± 1.1 ka and 406.6 ± 1.0 ka (2s analytical uncertainty), respectively. Our results highlight how a multidisciplinary approach, which integrates data from distal and near-source sedimentary records, is pivotal to better constrain magnitude, eruptive mechanisms and time history of explosive volcanism. In this perspective, a systematic future application of this approach to other volcanoes is fundamental to improve hazard assessment and risk mitigation.
Early explosive activity at Vico volcano, central Italy: a new perspective from proximal and distal sedimentary archives
Lorenzo Monaco;
2019-01-01
Abstract
Explosive volcanism is commonly reconstructed thanks to near-vent deposits, where geological records can provide fundamental insights for evaluating depositional processes, eruptive dynamics and evolution of the volcanic edifice. However, due to the intense volcano-tectonic and sedimentary processes occurring close to the volcano, proximal outcrops are most of the time lacunose and incomplete (Giaccio et al., 2014). In contrast, distal archives can continuously record sedimentation of ash layers, providing useful integrative information for reconstructing history and dynamics of the explosive activity (Albert et al., 2019). In this study, we have stratigraphically and geochemically characterised proximal and distal deposits belonging to the early activity (425-400 ka) of Vico volcano, central Italy. Specifically, we analysed tephra layers hosted in the lacustrine successions of Fucino and Sulmona intermountain basins as well as Rome’s near-coastal aggradational successions, spanning the ca. 430-365 ka interval. A series of chemically-zoned, rhyolitic to trachytic-phonolitic tephra were analysed and, based on stratigraphical, geochemical and geochronological data, were attributed to Vico explosive activity. In addition to the two major eruptive units, known as Vico a and Vico b(Cioni et al., 1987), a series of “minor” events were recognised in distal settings, documenting a much more complex volcanic history and eruptive behaviour (e.g. eruption frequency and intensities, periods of quiescence) than previously thought. Furthermore, new 40Ar/ 39Ar dates based on distal and mid-distal tephra deposits allowed to propose more precise and accurate geochronological constraints for the two main explosive eruptions of Vico (i.e. a and b), dated at 414.5 ± 1.1 ka and 406.6 ± 1.0 ka (2s analytical uncertainty), respectively. Our results highlight how a multidisciplinary approach, which integrates data from distal and near-source sedimentary records, is pivotal to better constrain magnitude, eruptive mechanisms and time history of explosive volcanism. In this perspective, a systematic future application of this approach to other volcanoes is fundamental to improve hazard assessment and risk mitigation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
