A currently popular model for the formation of volcanogenic massive sulfide deposits, based largely on isotopic studies and substantiated by water-rock experiments, implies that the ores were formed near the seafloor from hydrothermal solutions of seawater origin. Some of the major questions unanswered from this model have been: (1) the reason for the development of large scale seawater circulation systems through volcanic rocks in particular areas and during specific stages of submarine volcanism (e.g., ore formation after the eruptions of large volumes of volcanic materials), (2) the reason for the association with rapid-subsidence structures, (3) the mechanism for high temperature mineralization on or near the seafloor, and (4) the reason for metal and mineral zonings. Such questions can, however, be answered satisfactorily by a hypothesis that the hydrothermal processes which produced volcanogenic massive sulfide deposits occurred as a result of the creation of submarine calderas.
Geologic and petrochemical data are presented to suggest that the middle Miocene "Hokuroku Basin" in northern Japan, in which the largest concentration of the Kuroko ores occur, was a submarine resurgent caldera, and that the initiation and the termination of the mineralization were controlled, by the subsidence, and then by the resurgency of the caldera. Submarine calderas also appear to have played a major role in the formation of massive sulfide deposits in the other areas, such as the Bathurst district in Canada, the Rosebery-Mt. Lyell district in Tasmania, and in Cyprus.