The use of synthetic aperture sonar to survey seafloor massive sulfide deposits

Abstract

With the advent of advanced deep sea mining technology, seafloor mining is poised to begin on a global scale. For the success of any mining operation, it is crucial that both the operators and regulatory bodies possess detailed information of the resource and surrounding environment during all stages of the mining process. We propose that synthetic aperture sonar (SAS) is a key emerging technology that can be used by all relevant parties at only a minimal increase in cost. This technology, originally designed for military and offshore oil and gas industry applications, can be readily applied to scientific seafloor mapping. The fine resolution of this technique allows for deposit mapping of active and inactive seafloor massive sulfide deposits. By clearly distinguishing between volcanic and hydrothermal landscapes based on features finer than the resolution of conventional multibeam systems, SAS enables an entirely new level of hydrothermal deposit survey. This technology was employed during a detailed survey of shallow hydrothermal systems on the Arctic Mid-Ocean Ridge system. Here we present preliminary results from a newly discovered venting area adjacent to the Troll Wall field, southern Mohns Ridge. This area has extensive high and low temperature hydrothermal accumulations with variable surface morphology, which appear in SAS imagery to be distinct from adjacent volcanic and tectonic structures. SAS images, when coupled with assays from ROV rock samples, will enable rapid deposit estimation for this novel Arctic hydrothermal mineral resource.