An internally consistent, probabilistic, determination of ridge-axis hydrothermal fluxes from basalt-hosted systems

High-temperature hydrothermal systems at mid-ocean ridges play a critical role in global geochemical cycles. Most of the magmatic heat driving hydrothermal circulation along the global mid-ocean ridge system is released into basalt-hosted systems exemplified by intermediate- to fast-spreading ridges. Constraints on the fluid and chemical fluxes associated with these systems come from the compositions of high-temperature hydrothermal vent fluids and the compositions of altered sheeted dikes. Global data compilations of both of these data types, including 20 mineral components, 10 major fluid species, 13 trace elements and 6 isotope ratios, have been jointly fit using a numerical Bayesian inversion procedure. This new approach provides the first internally consistent estimates of fluid and chemical fluxes, with rigorously quantified uncertainties, for a broad suite of elements. The resulting global fluid flux is 8.0 ± 2.1 × 1012 kg yr− 1, at a water-dike mass ratio of 0.92, sufficient to cool the sheeted dike complex from magmatic to hydrothermal temperatures and remove ~ 50% of the latent heat of crystallization of the plutonic complex. For conservative elements, the fluxes represent inputs into the ocean and should allow more accurate models of the controls on modern and paleo-seawater chemistry to be developed.

► Global compilation of ridge axis altered rock and vent fluid compositions.
► Bayesian inversion to determine hydrothermal fluid and chemical fluxes.
► Water-rock ratio in sheeted dikes of 0.92 ± 0.06.
► Well constrained chemical fluxes into ocean for conservative elements.