Uncovering Seafloor Massive Sulphide Mounds through Integrated Geophysical Mapping and Modelling

The Federal Institute of Geosciences and Natural Resources Germany (BGR) is exploring for polymetallic seafloor massive sulfide (SMS) deposits at the Indian Ridge as part of our license obligations with the International Seabed Authority (ISA). SMS are marine mineral resources in the deep ocean that yield significant amounts of base and precious metals with potential for critical metal supplies. However, the economic viability of these marine mineral deposits critically depends on their abundance, composition and spatial extent, both laterally and vertically.

We apply high-resolution electromagnetic (EM) induction methods alongside three-component electric field measurements for self-potential (SP), induced polarization (IP), and vector magnetic surveys. Data acquisition is performed using deep-towed instruments (GOLDEN EYE EM-profiler, VULCAN and SPOCK SP-systems) and autonomous or remotely operated vehicles (AUV, ROV) at variable altitudes, enabling optimized spatial resolution for both regional and detailed investigations. Integration of complementary geophysical datasets permits refined 3D resistivity and susceptibility modeling, enhancing subsurface imaging of SMS mound geometry and composition. This approach was successfully deployed at a large fossil SMS mound within a newly discovered hydrothermal field. Results demonstrate the critical role of integrated geophysical methods in improving the resolution, reliability, and subsurface characterization of SMS deposits in deep-sea environments.