Global patterns and vigor of ventilated hydrothermal circulation through young seafloor

• Ventilated hydrothermal circulation extracts 8.0 TW from the oceanic lithosphere.
• Heat extraction is greatest in regions with thin, <400 m of sediment cover, 7.8 TW.
• 51% of the oceanic crust presently experiences ventilated hydrothermal circulation.
• Hydrothermal heat extraction accounts for 29% of heat lost through the oceanic crust.
• Hydrothermal related deficits extend to 75 Ma in regions with thin sediment.

Using an updated global heat flow dataset with >14 000 oceanic measurements, we revise the estimated global power deficit due to ventilated hydrothermal circulation. This study differs from previous estimates by taking into account (1) non-Gaussian statistics, (2) an improved seafloor age model, (3) a new plate cooling model calibrated directly to heat flow, and (4) the effect of sediment cover on the heat flow deficit and ventilated cutoff age. We obtain the maximum heat flow deficit (difference between predicted and observed) when the data are separated by seafloor areas with <400 m and ⩾400 m of sediment cover. The estimated power deficit (integrated heat flow deficit with respect to area) for areas of thin (<400 m) sediment cover is 7.8 TW and for areas of thick (⩾400 m) is 0.2 TW. The total power deficit, 8.0 TW with 50% of estimates falling between 5.0 and 10.0 TW, represents a ∼30% reduction in magnitude compared with previous heat flow and fluid flow based estimates. Regions with thick, ⩾400 m, sediment cover experience half the heat flow deficit for one-third of the duration (25 Ma) of regions with thin sediment cover (75 Ma). Based on this study, vigorous fluid exchange between the oceans and seafloor redistributes ∼30% of heat lost through young oceanic crust.

Global heat flow deficit due to ventilated hydrothermal circulation between the ocean and oceanic crust. Heat flow deficit ratio =1−(observed h.f.)/(predicted h.f.)=1−(observed h.f.)/(predicted h.f.).Figure optionsDownload high-quality image (172 K)Download as PowerPoint slide