Most seafloor hydrothermal circulation occurs far from the magmatic influence of mid-ocean
ridges, driving large flows of water, heat and solutes through volcanic rock outcrops on ridge
flanks. Here we create three-dimensional simulations of ridge–flank hydrothermal circulation,
flowing between and through seamounts, to determine what controls hydrogeological
sustainability, flow rate and preferred flow direction in these systems. We find that sustaining
flow between outcrops that penetrate less-permeable sediment depends on a contrast in
transmittance (the product of outcrop permeability and the area of outcrop exposure)
between recharging and discharging sites, with discharge favoured through less-transmissive
outcrops. Many simulations include local discharge through outcrops at the recharge end of
an outcrop-to-outcrop system. Both of these characteristics are observed in the field.
In addition, smaller discharging outcrops sustain higher flow rates than larger outcrops, which
may help to explain how so much lithospheric heat is extracted globally by this process.
Earth and Planetary Sciences Department, University of California Santa Cruz, Santa Cruz, 95064, California, USA
Copyright: DOI: 10.1038/ncomms8567 © 2015 copyright