EGU22-8927
https://doi.org/10.5194/egusphere-egu22-8927
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Garnet petrochronology reveals the lifetime and dynamics of phonolitic magma chambers at Somma-Vesuvius

Jörn-Frederik Wotzlaw1, Lena Bastian1, Marcel Guillong1, Francesca Forni2, Oscar Laurent1,3, Julia Neukampf1,4, Roberto Sulpizio5, Cyril Chelle-Michou1, and Olivier Bachmann1
Jörn-Frederik Wotzlaw et al.
  • 1ETH Zurich, Institute of Geochemistry and Petrology, Department of Earth Sciences, Zürich, Switzerland (joern.wotzlaw@gmail.com)
  • 2Dipartimento di Scienze della Terra, Università degli Studi di Milano, Milan, Italy
  • 3CNRS, Géosciences Environnement Toulouse, Observatoire Midi-Pyrénées, Toulouse, France
  • 4CNRS, Centre de Recherches Pétrographiques et Géochimiques, Vandœuvre les Nancy, France
  • 5Dipartimento di Scienze della Terra e Geoambientali, University of Bari, Bari, Italy

Vesuvius is one of the most iconic active volcanoes on Earth. Historic and archaeological records document numerous hazardous eruptions with thousands of fatalities. Today, more than one-million people live around Vesuvius and are threatened by future volcanic activity. Petrologic and geochemical studies of eruptive products provide important insights into the evolution of the eruption-feeding magma reservoir prior to eruption. Here we quantify the duration of shallow crustal storage and track the evolution of phonolitic magmas prior to major explosive eruptions of Vesuvius employing in-situ uranium-thorium dating of garnet phenocrysts in tandem with detailed geochemical and textural characterization. Garnet uranium-thorium dates provide evidence for progressively shorter pre-eruption storage times throughout the lifetime of the volcano, decreasing from ~5,000 years for the pre-historic Mercato and Avellino eruptions to approximately 1,000 years for the historic AD 79 Pompeii and AD 472 Pollena eruptions. These decreasing residence times mirror the progressively shorter repose intervals between eruptions implying that distinct phonolite magma batches were present throughout most of the volcano’s evolution thereby controlling the eruption dynamics by preventing the ascent of mafic magmas from longerlived and deeper reservoirs. Frequent lower-energy eruptions during the recent history sample this deeper reservoir and suggest that future Plinian eruptions are unlikely without centuries of volcanic quiescence. Crystal residence times from other volcanoes reveal that discrete long-lived deep-seated reservoirs and transient upper-crustal magma chambers are common features of sub-volcanic plumbing systems.

How to cite: Wotzlaw, J.-F., Bastian, L., Guillong, M., Forni, F., Laurent, O., Neukampf, J., Sulpizio, R., Chelle-Michou, C., and Bachmann, O.: Garnet petrochronology reveals the lifetime and dynamics of phonolitic magma chambers at Somma-Vesuvius, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8927, https://doi.org/10.5194/egusphere-egu22-8927, 2022.