Numerical simulation of cool hydrothermal processes in the upper volcanic crust beneath a marine sediment pond: North Pond, North Atlantic Ocean

Low temperature hydrothermal systems hosted in the volcanic oceanic crust are responsible for ~20% of Earth's global heat loss. Marine sediment ponds comprise an important type-setting on young ridge flanks where hydrothermal circulation advectively extracts lithospheric heat, but the nature of coupled fluid-heat transport in these settings remains poorly understood. Here we present coupled (fluid-heat) numerical simulations of ocean crustal hydrogeology in and below North Pond, a sediment pond on ~8 Ma seafloor of the North Atlantic Ocean. Two- and three-dimensional simulations show that advective transport beneath North Pond is complex and time-varying, with multiple spatial and temporal scales, consistent with seafloor and borehole observations. A unidirectional, single-pass flow system is neither favored nor needed to match the spatial distribution of seafloor heat flux through North Pond sediments. When the permeability of the crustal aquifer is relatively high (10-10 to 10-9 m2), simulations can replicate much of the observed variability and suppression of seafloor heat flux, and can explain basement overpressures and transient perturbations in pressure and temperature in the upper volcanic crust. Simulation results can also help explain heterogeneity in pore fluid chemistry and microbiology in the crust. Although driven by the same physical processes, the dynamics of hydrothermal circulation below North Pond are different from those seen on "discharge-dominated" ridge flanks, where the permeability and exposed area of isolated basement outcrops control the extent of regional heat extraction.

Methods
These data are input files for the numerical simulation code Finite Element Heat and Mass Transfer Code (FEHM; https://fehm.lanl.gov/). This dataset complements the publication titled "Numerical Simulation of Cool Hydrothermal Processes in the Upper Volcanic Crust Beneath a Marine Sediment Pond: North Pond, North Atlantic Ocean" published in the Journal of Geophysical Research: Solid Earth. The data here are model input files for the numerical code Finite Element Heat and Mass Transfer Code (FEHM) for the simulation of coupled fluxes of fluid and heat beneath the sedimented pond, North Pond in the North Atlantic Ocean. These files represent the characteristic simulation of permeability for each of the resulting aquifer thicknesses simulated 100, 300, 600, and 1000m.