Discovery of extinct hydrothermal vent sites in the Mohn's Treasure area using near-seafloor magnetics

Extinct sediment-hosted hydrothermal vent fields have been reported to represent more mature and better preserved sulfide deposits than their active analogues, and therefore present higher economic potential, often reaching the size and grade similar to deposits mined onshore (Zierenberg et al., 1998 and references therein). While the presence of sediments play an important role in preserving sulfide deposits from oxidation and weathering, it also complicates their identification. Geophysical remote sensing becomes especially instrumental for locating such fields due to responding to contrasts in the subsurface rather than water-column anomalies, which require a presence of an active plume. In this study, comprehensive data analysis exert two new potential fossil hydrothermal deposits in the vicinity of previously reported Mohn's Treasure deposit discovered by ship-based dredging of sulfide material (Pedersen et al., 2010). We use near-seafloor magnetic data, high-resolution bathymetry, rock samples and ROV imagery analysis to locate, delineate and infer the subsurface structure of the new sulfide deposits: MT-1, MT-2 and MT-3.