Hydrothermal Venting

node · earth · Global - mid-ocean ridges, back-arc basins, submarine volcanic arcs

Seawater percolating into fractured young oceanic crust is heated by underlying magma, leaches metals and sulphides, and returns to the seafloor as hot, chemically reduced fluid. First observed directly at the Galapagos Rift in February 1977. The chemistry matters more than the heat: chemosynthetic bacteria oxidise reduced compounds such as hydrogen sulphide in the vent fluid and turn that energy into biomass, supporting dense animal communities. This was the first known ecosystem on Earth whose base is not photosynthesis. Venting is a process, not a place - it occurs wherever the right geology exists along mid-ocean ridges, back-arc basins and seamounts.