The global high-temperature on-axis hydrothermal fluid and element flux to the modern ocean

Seafloor hydrothermal venting is one of the major processes that regulate the composition of the ocean. With a fluid flux orders of magnitudes lower than circulation of mildly-tempered hydrothermal fluids in ridge-flanks, or the riverine runoff, the high temperature fluid flux at oceanic plate boundaries can supply element fluxes that exceed the ones in (c)old lithosphere or river waters. Despite our knowledge on the diversity of hydrothermal vent fluid compositions, estimates of the on-axis fluid and element fluxes were carried out with basalt‑hosted mid‑ocean ridge black-smoker-type fluids imposed to be responsible for the global hydrothermal cooling at ridge axes. In this study, we consider current knowledge on vent fluid diversity and estimate global on-axis element fluxes. Our investigation suggests the global fluid- and corresponding element-fluxes were grossly underestimated, due to ignorance of hydrothermal venting in volcanic arcs and omission of different substrate types associated to oceanic plate boundaries.