Work

Timing of volcano-tectonic events in the East Mayotte Volcanic Chain (Comoros Archipelago) since 3.5 Ma

Year: 2026

Type: article

Abstract: Active submarine volcanism poses significant hazards (explosions, landslides, tsunamis, lava flows) but remains poorly documented because sampling and dating of young lava flows are still challenging. We present a unique dataset of ages obtained using the K-Ar method on carefully selected groundmass from fifteen submarine lava samples collected offshore Mayotte (northern Mozambique Channel) where a massive eruption occurred between 2018 and 2020, with the emission of 6.5 km 3 of magma. The Fani Maoré volcano erupted at the tip of a 50-km-long volcanic chain (EMVC) composed of several monogenetic pyroclastic cones, lava domes and lava flow fields. Our ages range from 3.74 ± 0.04 Ma to 29 ± 3 ka and are all but one from Quaternary volcanic products younger than 1.5 Ma. Their temporal distribution indicates an older volcanic activity around 3.7 Ma and since 1.5 Ma, and eruptions occurring in eight main volcanic episodes separated by ~0.2–0.4 Myr. Some of these episodes are coeval with other volcanic events in the Comoros Archipelago. The most recent episode is marked by the birth of the Fani Maoré volcano. We interpret those episodes as the result of rifting with diking events driven by regional tectonic along NE-SW and NW-SE-trending ridges. Emplacement of volcanic material from the EMVC may originate from a translithospheric fault system and could have started with the formation of a large caldera collapse that occurred prior to 1.5 Ma. This study, combining precise sampling and groundmass K-Ar dating, offers a new perspective for understanding the evolution of recent submarine volcanic fields and the resulting risk assessments.

Source: Marine Geology

DOI: 10.1016/j.margeo.2026.107898