What are Seafloor Massive Sulphide (SMS) deposits?

Seafloor massive sulphides (SMS) are high-grade hydrothermal deposits rich in copper, zinc and lead with a high gold and silver content. Recovered SMS samples generally have significantly higher metal content than those mined onshore around the world.

SMS have been identified worldwide from extensive international research as current ore-forming processes associated with submerged tectonic margins and mid-ocean spreading margins.

Hydrothermal plumes (commonly referred to as “Black Smokers”) occur where metal-rich high-temperature fluids discharge from seafloor vents. Before the fluids enter the ocean, they are commonly between 300^oC and 500^oC and under high pressure. Under these conditions the superheated waters dissolve minerals from the surrounding rocks. As the fluid enters the near-freezing ocean water, the metals in solution precipitate out as sulphide particles and typically build chimneys packed with minerals. Fine particles from the chimney plumes fall to the ocean floor and build up as concentrated metalliferous deposits (SMS).

Over time the hydrothermal plumbing systems close off and migrate to new fracture systems on the seafloor.  The challenge for commercial explorers is to find the cold, inactive SMS deposits on the seafloor. They cannot be traced by following the smoke plumes as happens in active SMS vent fields.

Ancient onshore sulphide ore deposits originally formed on the seafloor occur widely around the world and are termed volcanogenic massive sulphide (VMS) deposits.  SMS deposits are the modern day, currently-forming equivalent to VMS deposits that have been successfully developed into world-class mines onshore.