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The life and reactivation of long-dormant PAMS volcanoes: the case of the Late Pleistocene Ciomadul volcano, Romania

Szabolcs Harangi1,2 , Ioan Seghedi3, Barbara Cserép1,2, Krisztina Hajdu1,2, Emese Oeberg-Pánczél1,2, Boglárka M. Kis4, Saskia Erdmann5, Răzvan-Gabriel Popa6, Olivier Bachmann6, Euan J.F. Mutch7, Maurizio Petrelli8, Matthew J. Comeau9, Graham J. Hill10, Réka Lukács2,11

  • Affiliations: 1Department of Petrology and Geochemstry, Eötvös Loránd University, Volcanology Research Group, Budapest, Hungary; 2MTA--HUN-REN CSFK Lendület \"Momentum\" PannonianVolcano Research Group, Institute for Geological and Geochemical Research, HUN-REN Research Centre for Astronomy and Earth Sciences, Budapest, Hungary; 3Institute of Geodynamics "Sabba S. Ştefănescu", Romanian Academy, Bucharest, Romania; 4Department of Geology, Babeș-Bolyai University, Cluj-Napoca, Romania; 5Institut des Sciences de la Terre d'Orléans, Université d'Orléans‐CNRS, Orléans, France; 6Department of Earth Sciences, ETH Zürich, Zürich, Switzerland; 7Earth Observatory of Singapore, Nanyang Technological University, Singapore; 8The Asian School of the Environment, Nanyang Technological University, Singapore; 9Department of Physics and Geology, Petro-Volcanology Research Group, University of Perugia, Italy; 10Department of Geoscience and Engineering, Delft University of Technology, Delft, The Netherlands; 11Institute of Geophysics, Czech Academy of Sciences, Prague, Czech Republic

  • Presentation type: Poster

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

  • Poster Board Number: 53

  • Programme No: 1.7.40

  • Theme 1 > Session 7

Abstract

Long-dormant PAMS volcanoes (those with Potentially Active Magma Storage) are defined as those that last erupted >10 ka but have indications that they are still underlain by a magma reservoir with some melt fractions. Therefore, their future reawakening cannot be excluded. Due to their apparent inactivity, these volcanoes get no or less attention and, as such, pose an underrated potential risk. Ciomadul last erupted 30 ka and represents the youngest volcanism in eastern-central Europe. Zircon geochronology revealed prolonged repose periods, even >100 kyr between eruptive phases, but continuous zircon crystallization over >1 Myr. The eruptive products are rather homogeneous, K-dacite in composition and have an adakitic, wet and oxidized character. Integrated textural and compositional studies of multiple mineral phases suggest the existence of a long-lasting felsic mushy magma reservoir within the upper crust underlain by deeper mafic magma storage. Reactivation of the highly crystalline magma body was mostly due to recharge by Sr--Ba-rich mafic magmas. Rejuvenation occurred rapidly, within weeks to months. The eruptions changed from effusive to explosive with the appearance of strongly hydrous mafic magmas. Results of high-resolution magnetotelluric survey indicate conductive anomalies (<10 ohm-m a value indicative of potenial melt presence) in the subvolcanic crustal level. This is interpreted as a quasi-vertical conduit extending from the near surface to a melt-bearing magma reservoir in the mid-lower crust (depths of 10-25 km), deeper than typically observed for active subduction systems. The presence of magma is also indicated by notable CO2 gas emission with relatively high He-isotope ratio.