Submarine volcanism: eruption styles, products, and relevance to understanding the host-rock successions to volcanic-hosted massive sulfide deposits

The increasing hydrostatic pressure of the water column with increasing water depth in subaqueous environments limits the ability of superheated volatiles to expand instantaneously against the ambient pressure. Explosive submarine eruptions are only likely in water depths less than 1km, and generally less than 500m, thus refuting models of highly explosive, very deep water calderas popularly proposed as the host volcanic centres for the kuroko volocanic-hosted massive sulfide (VHMS) deposits of Japan. The maximum water depths for submarine explosive eruptions coincide approximately with the minimum pressures and water depths required to prevent boiling of mineralizing hydrothermal fluids in the stockwork before the fluids reach the sea floor. The key elements in evaluating the prospectivity of ancient volcanic successions for VHMS deposits appear to be deep-water sediments and lavas or shallow intrusions in an extensional basin setting. There is little evidence that explosive submarine calderas are essential as host volcanic centers to VHMS deposits. -from Author