Widespread volcanism Southeast of Futuna Island (SW Pacific Ocean): Near-seafloor magnetic dating and regional consequences

Florent Szitkar (1) , Jérôme Dyment (2) , Yves Fouquet (3)

1 NGU - Geological Survey of Norway
2 IPGP (UMR_7154) - Institut de Physique du Globe de Paris
3 IFREMER - Institut Français de Recherche pour l'Exploitation de la Mer

Near-seafloor bathymetric and magnetic data have been collected by Autonomous Underwater Vehicle (AUV) and manned submersible (DSS) over a volcanically active area southeast of Futuna Island, French Territory of Wallis-and-Futuna, in the Southwestern Pacific Ocean. Located at the edge of the Lau and North Fiji basins, at the convergence of the Pacific and Australian plates, this area is characterized by intense volcanic and tectonic activity. Direct observation by submersible reveals that the seafloor is covered by recent lava flows, volcanoes and large, active or inactive calderas filled by smooth lava flows and eventually hosting hydrothermal sites. We investigate the volcanic chronology by combining a Bayesian inversion of the AUV-gridded magnetic data with an inversion of the submersible data specifically designed to estimate the rock magnetic polarity and absolute magnetization. We show that some volcanoes predate the last (Brunhes-Matuyama) magnetic polarity reversal 780 kyr ago whereas their neighbors exhibit a normal polarity and appear to be recent. This result suggests that the seafloor in this region has undergone continuous and sparse volcanic activity over the last few million years.

Domaines: Volcanologie; Géophysique [physics.geo-ph]

Florent Szitkar, Jérôme Dyment, Yves Fouquet. Widespread volcanism Southeast of Futuna Island (SW Pacific Ocean): Near-seafloor magnetic dating and regional consequences. Journal of Volcanology and Geothermal Research, In press, ⟨10.1016/j.jvolgeores.2020.107064⟩. ⟨insu-02942530⟩