Seamounts in the subduction factory

Abstract

The "Subduction Factory" is a metaphor for the geochemical processing of subducted oceanic crust and sediment into components that are either incorporated into the volcanic arc or recycled into Earth's mantle. Seamounts may be a significant source of material to the Subduction Factory, in particular, by providing trace elements such as K, Ba, La, Ce, U, Th, Pb, Rb, and Cs. Seamount subduction might also play a role in the global distribution of chemical mantle heterogeneities. Neither one of these effects of seamount subduction is well understood. The Izu-Bonin-Marianas (IBM) volcanic arc is a region where the potential impact of seamount subduction may be explored most effectively. There, sections of the IBM arc and many of the incoming seamounts display unusually high 206Pb/204Pb ratios, which offer a particularly promising geochemical tracer that may help quantify seamount input into the Subduction Factory. Although this process remains to be explored in a quantitative manner, it is apparent that the demise of seamounts in subduction zones offers an exciting research target with important consequences for globally relevant geochemical processes.