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Spatio-temporal framework of Mayotte\'s submarine volcanism based on new K-Ar ages.

Mathilde Frey1 , Xavier Quidelleur1, Nathalie Feuillet2, Étienne Médard3, Carole Berthod2, Jean-Christophe Komorowski2, Valentine Puzenat2, Élodie Lebas2, Isabelle Thinon4, Emmanuel Rinnert5, Cécile Cathalot5, Stephan Jorry5, Fabien Paquet5

  • Affiliations: 1Laboratoire Géosciences Paris Saclay, Université Paris Saclay, Orsay, France; 2Institut de Physique du Globe, Université Paris Cité, Paris, France; 3Laboratoire Magmas et Volcans, Université Clermont-Auvergne, Clermont-Ferrand, France; 4Bureau de Recherche Géologiques et Minières, Orléans, France; 5Unité Géosciences Marines, IFREMER, Plouzané, France

  • Presentation type: Poster

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

  • Poster Board Number: 80

  • Programme No: 6.2.16

  • Theme 6 > Session 2

Abstract

In May 2018, a major seismo-volcanic crisis began east of Mayotte (North Mozambique Channel) leading to the eruption of a new submarine volcano, named "Fani Maoré", ~50 km off Mayotte at the eastern end of the submarine Eastern Mayotte Volcanic Chain (EMVC). This chain, oriented N110°E to N130°E, consists of monogenetic pyroclastic cones, lava domes and lava flow fields identified from high-resolution bathymetric data. This chain includes a remarkable horseshoe-shaped morphological structure, 10 km offshore Petite-Terre Island, associated with seismic swarms and liquid CO2 venting. The present study aims at providing a time frame for construction of the submarine edifices of the EMVC, in particular of the Horseshoe volcanic complex. Samples from volcanic cones and lava flows were collected during 9 oceanographic campaigns using dredging and the Victor6000 remotely operated vehicle (ROV). In total, 28 samples, from basanites to phonolites, were dated using the K-Ar method on carefully selected glassy groundmass. Our new ages range from 3.74 ± 0.04 Ma to 3 ± 1 ka. Five ages, all from monogenetic cones, are over one million years, three of them located north of the EMVC along a N40°E alignment. Most of the young ages come from the Horseshoe area, confirming that this volcanic complex was formed recently and may still be active. Together with previously published ages, our new ages suggest regional periods of volcanism and quiescence throughout the Comoros Archipelago, which could be linked to distinct phases of tectonic activity occurring during the last 1 Ma in this key area.