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The Role of Superheating in Controlling Crystallization Kinetics: Insights from the 2021 Tajogaite Eruption

Barbara Bonechi1, Fabio Arzilli2, Margherita Polacci1, Alessandro Fabbrizio3, Giuseppe La Spina4, Eleni Michailidou5, Jean-Louis Hazemann6, Richard Brooker7, Elisa Biagioli1, Robert Atwood8, Danilo di Genova9, Sumith Abeykoon2, Renat Almeev10, David Neave1, Mike Burton1

  • Affiliations: 1Department of Earth and Environmental Sciences, University of Manchester, Manchester, UK; 2School of Science and Technology, Geology Division, Università di Camerino, Camerino, Italia; 3Dipartimento di Scienze dell'Ambiente e della Terra, Università Milano-Bicocca, Milano, Italia; 4Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, Catania, Italia; 5Institute of Petrology and Structural Geology, Faculty of Science, Charles University, Prague, Czech Republic; 6Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, Grenoble, France; 7School of Earth Sciences, University of Bristol, Bristol, UK; 8Diamond Light Source, Harwell Science and Innovation Campus, Harwell, UK; 9Institute of Science, Technology and Sustainability for Ceramics (ISSMC), National Research Council of Italy (CNR), Italy; 10Institute of Earth System Sciences, Leibniz University of Hannover, Hannover, Germany 

  • Presentation type: Poster

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

  • Poster Board Number: 201

  • Programme No: 1.9.8

  • Theme 1 > Session 9

Abstract

Thermal history of magma strongly affects crystallization behaviour, which, in turn, influences magma rheology and ultimately magma ascent dynamics. This study combines novel 4D (3D space+time) in-situ crystallisation experiments with ex-situ experiments to provide further insights into how different temperature profiles affect nucleation and crystallization kinetics in a tephritic magma composition from the 2021 Tajogaite eruption (La Palma, Spain). Using in-situ synchrotron X-ray microtomography, we directly observed and quantified the dynamic process of crystallization in real-time, capturing unprecedented detail on the interplay between superheating (i.e. temperatures exceeding the liquidus temperature of its most refractory mineral phase) and nucleation. Experiments were conducted under two thermodynamic conditions: (1) in-situ synchrotron X-ray microtomography at 20 MPa without superheating and (2) ex-situ crystallization at 275 MPa after superheating (88 °C above Tliquidus). The timing of clinopyroxene nucleation differed markedly between the two experimental conditions, with nucleation initiating within 20 minutes in the in-situ experiments but delayed by 8 hours in the ex-situ setup. This difference arises from the resorption of pre-existing nuclei during prolonged exposure to superliquidus temperatures (1200 °C) in the ex-situ experiments. The experimental results suggest two alternative crystallization behaviours: (i) without superheating rapid crystallization is promoted due to minimal nucleation delay (in terms of minutes), and (ii) with superheating crystal nucleation is delayed for several hours. These distinct crystallization behaviours critically impact magma rheology, influencing processes like degassing, fragmentation, and eruption dynamics. This study underscores the pivotal role of superheating in crystallization kinetics and its implications for volcanic hazard assessment.