Late Quaternary explosive phonolitic volcanism of Petite-Terre (Mayotte, Western Indian Ocean) - BRGM - Bureau de recherches géologiques et minières
Journal Articles Bulletin of Volcanology Year : 2024

Late Quaternary explosive phonolitic volcanism of Petite-Terre (Mayotte, Western Indian Ocean)

Abstract

We studied four Quaternary volcanic phonolitic explosive edifices on Petite-Terre Island (Mayotte, Comoros Archipelago, Western Indian Ocean) to quantify magma fragmentation processes and eruptive dynamics. Petite-Terre explosive volcanism is the westernmost subaerial expression of a 60-km-long volcanic chain, whose eastern tip was the site of the 2018–2020 submarine eruption of the new Fani Maoré volcano. The persistence of deep seismic activity and magmatic degassing along the volcanic chain poses the question of a possible reactivation on land. Through geomorphology, stratigraphy, grain size, and componentry data, we show that Petite-Terre “maars” are actually tuff rings and tuff cones likely formed by several closely spaced eruptions. The eruptive sequences of each edifice are composed of thin (cm–dm), coarse, lithic-poor pumice fallout layers containing abundant ballistic clasts, and fine ash-rich deposits mostly emplaced by dilute pyroclastic density currents (PDCs). Deposits are composed of vesiculated, juvenile fragments (pumice clasts, dense clasts, and obsidian), and non-juvenile clasts (from older mafic scoria cones, coral reef, the volcanic shield of Mayotte, as well as occasional mantle xenoliths). We conclude that phonolitic magma ascended directly and rapidly from depth (around 17 km) and experienced a first, purely magmatic fragmentation, at depth (≈ 1 km in depth). The fragmented pyroclasts then underwent a second shallower hydromagmatic fragmentation when they interacted with water, producing fine ash and building the tuff rings and tuff cones

Domains

Earth Sciences
Embargoed file
Embargoed file
0 5 12
Year Month Jours
Avant la publication
Sunday, March 23, 2025
Embargoed file
Sunday, March 23, 2025
Please log in to request access to the document

Dates and versions

hal-04438898 , version 1 (23-09-2024)

Identifiers

Cite

Tristan Lacombe, Lucia Gurioli, Andrea Di Muro, Etienne Médard, Carole Berthod, et al.. Late Quaternary explosive phonolitic volcanism of Petite-Terre (Mayotte, Western Indian Ocean). Bulletin of Volcanology, 2024, 86 (2), pp.11. ⟨10.1007/s00445-023-01697-2⟩. ⟨hal-04438898⟩
45 View
0 Download

Altmetric

Share

More