EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Time-window into the transcrustal plumbing system dynamics of Dominica (Lesser Antilles)

Léa Ostorero1, Georges Boudon1, Hélène Balcone-Boissard2, Daniel J. Morgan3, Thiebaut d'Augustin2, and Clara Solaro1
Léa Ostorero et al.
  • 1Institut de physique du globe de Paris, Université de Paris, CNRS, F-75005 Paris, France (
  • 2ISTeP, Sorbonne Université, CNRS, UMR 7193, 75005, Paris, France
  • 3School of Earth & Environment, University of Leeds, Leeds, LS2 9JT, United Kingdom

A transcrustal mush system has been recognized beneath Dominica (Lesser Antilles) with different magma ponding zones that generated a series of pumiceous eruptions from Morne Trois Pitons–Micotrin volcano. Here, the latest, large, pumiceous eruption (Grand Fond - 24 kyrs cal BP) and four, smaller, Plinian eruptions (18-9 kyrs cal BP) are investigated. Pre-eruptive magma dynamics within the mush are unraveled through orthopyroxene phenocrysts by combining a Crystal System Analysis approach (on unzoned and zoned orthopyroxenes) and timescale estimates derived by intracrystalline Fe-Mg interdiffusion modeling. Two magmatic environments are recognized in the mush and have mixed, more or less vigorously, before the successive eruptions. Few interactions between the two magmas began 15-34 years prior to the small Plinian eruptions, but the sustained mixing occurred in the last 2 years. This contrasts with longer timescales (2-80 years) obtained for the larger eruption of Grand Fond with magmas stored deeper. These magma mixing timescales have significant implications for volcanic risk mitigation, with a growing reactivation signal that could be registered at the surface few years prior to the eruptions.

How to cite: Ostorero, L., Boudon, G., Balcone-Boissard, H., Morgan, D. J., d'Augustin, T., and Solaro, C.: Time-window into the transcrustal plumbing system dynamics of Dominica (Lesser Antilles), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2797,, 2021.


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