Constraints on hydrothermal heat flux through the oceanic lithosphere from global heat flow

A significant discrepancy exists between the heat flow measured at the seafloor and the higher values predicted by thermal models of the cooling lithosphere. This discrepancy is generally interpreted as indicating that the upper oceanic crust is cooled significantly by hydrothermal circulation. The magnitude of this heat flow discrepancy is the primary datum used to estimate the volume of hydrothermal flow and the variation in the discrepancy with lithospheric age is the primary constraint on how the hydrothermal flux is divided between near-ridge and off-ridge environments. This study reevaluates the magnitude and age variation of the discrepancy using a global heat flow data set substantially larger than in earlier studies, and the GDH1 (Global Depth and Heat flow) model that better predicts the heat flow, It is estimated that the predicted global oceanic heat flux of 32 × 10¹² W, 34% (11 × 10¹² W) occurs by hydrothermal flow. It is concluded that the age of the crust is the primary control on the fraction of heat transported by hydrothermal flow and that sediment thickness has a lesser effect. -from Authors