Near-Seafloor Magnetic Exploration of Submarine Hydrothermal Systems in the Kermadec Arc

Friday, 19 December 2014: 8:15 AM
Fabio Caratori Tontini, GNS Science, Lower Hutt, New Zealand, Cornel E J de Ronde, GNS Science-Institute of Geological and Nuclear Sciences Ltd, Lower Hutt, New Zealand, Maurice Tivey, Woods Hole Oceanographic Inst, Woods Hole, MA, United States and James C Kinsey, Woods Hole Oceanographic Institute, Woods Hole, MA, United States
Magnetic data can provide important information about hydrothermal systems because hydrothermal alteration can drastically reduce the magnetization of the host volcanic rocks. Near-seafloor data (≤70 m altitude) are required to map hydrothermal systems in detail; Autonomous Underwater Vehicles (AUVs) are the ideal platform to provide this level of resolution. Here, we show the results of high-resolution magnetic surveys by the ABE and Sentry AUVs for selected submarine volcanoes of the Kermadec arc. 3-D magnetization models derived from the inversion of magnetic data, when combined with high resolution seafloor bathymetry derived from multibeam surveys, provide important constraints on the subseafloor geometry of hydrothermal upflow zones and the structural control on the development of seafloor hydrothermal vent sites as well as being a tool for the discovery of previously unknown hydrothermal sites. Significant differences exist between the magnetic expressions of hydrothermal sites at caldera volcanoes (“donut” pattern) and cones (“Swiss cheese” pattern), respectively. Subseafloor 3-D magnetization models also highlight structural differences between focused and diffuse vent sites.