Author name: Sven Petersen

Seafloor massive sulfides are deposits of metal-bearing minerals that form on and below the seabed as a result of heated seawater interacting with oceanic crust. These occurrences are more variable than previously thought, and this variability is not necessarily reflected in the analogous volcanogenic massive sulfide deposits that are preserved in the ancient rock record. The geological differences affect both the geochemistry and the size of seafloor massive sulfide deposits. Current knowledge of the distribution, tonnage, and grade of seafloor massive sulfides is inadequate to rigorously assess their global resource potential due to the limitations in exploration and assessment technologies and to our current understanding of their 3-D characteristics.

Deep-ocean mineral deposits could make a significant contribution to future raw material supply. Growing metal demand and geopolitics are focussing increasing attention on their resource potential and economic importance. However, accurate assessment of the total amounts of metal and its recoverability are very difficult. Deep-ocean mineral deposits also provide valuable windows through which to study the Earth, including the evolution of seawater and insights into the exchange of heat and chemicals between the crust and the oceans. Exploration for, and potential extraction of, deep-ocean mineral deposits poses many geological, technical, environmental and economic challenges, as well as regulatory and philosophical questions. Great uncertainty exists, and the development and stewardship of these deposits requires an incremental approach, encouraging transparency and scientific and civil societal input to balance the interests of all.