Abstract 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.

中文翻译：

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富图纳岛东南部（西南太平洋）广泛的火山活动：近海底磁测年和区域后果

摘要 自动水下航行器 (AUV) 和载人潜水器 (DSS) 在西南太平洋法属瓦利斯和富图纳群岛富图纳岛东南部火山活动区收集了近海底测深和磁数据。该地区位于 Lau 盆地和北斐济盆地的边缘，处于太平洋和澳大利亚板块的交汇处，具有强烈的火山和构造活动。潜水器的直接观察表明，海底被最近的熔岩流、火山和被平滑的熔岩流填充的大型活动或非活动火山口所覆盖，并最终成为热液场所。我们通过将 AUV 网格磁数据的贝叶斯反演与专门用于估计岩石磁极性和绝对磁化强度的潜水数据反演相结合来研究火山年代学。我们表明，一些火山早于 780 kyr 前的最后一次（Brunhes-Matuyama）磁极反转，而它们的邻居则表现出正常的极性并且似乎是最近的。这一结果表明，该地区的海底在过去几百万年中经历了持续而稀疏的火山活动。