Helium-3 disruption in the deep world ocean. Its relation to hydrothermal 3He fluxes and to the terrestrial heat budget

The 3He distribution of the deep ocean was used to estimate the 3He hydrothermal input in the three main ocean basins (Atlantic, India and Pacific). This calculation was done with a simple box model, which allows calculation of the residence time of the main deep reservoirs from natural 14C data. The total 3He flux was found to be in the range of 1-2 atom·cm-2·s-1. This value is consistent with previous estimates, although on the lower side. The 3He fluxes were compared with the convective heat fluxes. The global 3He/heat ratio at the scale of each basin was compared with the 3He/heat ratio measured at individual hydrothermal vents in order to estimate the thermal contribution of the vents to the total convective heat flux from the ocean floor. This contribution was found to be marginal (around 5%) and in agreement with other independent estimates. (author). 83 refs, 7 figs, 8 tabs