| Detailed submarine exploration shows a diversity of hydrothermal sites in terms of geology, minerals, fluids and biology. High0resolution, near0seafloor magnetic surveys have been undertaken on various basalt0hosted or ultramafic0hosted hydrothermal sites using a vector magnetometer mounted on deep0sea submersible Nautile, remotely operated vehicle (ROV) Victor, and autonomous underwater vehicle (AUV) AsterX of Ifremer. These surveys reveal different magnetic signatures, depending the characteristics of the hydrothermal sites. (1) Basalt-hosted sites are characterized by a negative (reduced to the pole) anomaly indicating a reduced magnetization. Two processes are often considered to explain this observation: thermal demagnetization or alteration of the... |
