Seamount subduction drives bonanza-grade gold mineralization

Giant gold deposits are invariably related to orogenesis, but the causal link remains enigmatic. Many giant gold (Au) deposits, such as those in the South Tianshan province, exhibit a spatiotemporal relationship with seamount subduction. We report gold contents of mafic rocks of varying metamorphic grades from the accretionary complex using ultra-low-detection-limit analytical methods, where plume-modified samples yield higher gold contents and Au contents decrease during metamorphism. We propose that seamount subduction drives major gold formation following a three-step sequence: (i) a mantle plume pumps gold from the deep mantle into seamounts emplaced in oceanic crust; (ii) subduction of the seamount chain releases and stores gold at the base of the overriding plate; (iii) extensive melt/fluid activity during the magmatic flare-up transports the gold to the shallow crust for mineralization. This model can explain the striking correspondence between the frequency of Au deposits and known subducted seamounts globally over the past 600 million years.