Hydrothermal Vent Geochemistry

Hydrothermal circulation occurs when seawater penetrates into the ocean crust, becomes heated, reacts with the crustal rock, and rises to the seafloor. Seafloor hydrothermal systems have a major local impact on the chemistry of the ocean that can be measured in hydrothermal plumes. Some hydrothermal tracers (especially helium) can be mapped thousands of kilometers from their hydrothermal sources, and can be used to understand deep ocean circulation. Because hydrothermal circulation removes some compounds from seawater (e.g. Mg, SO₄) and adds many others (He, Mn, Fe, H₂, CO₂), it is an important process in governing the composition of seawater.