Hydrothermal Vent

Hydrothermal Vent, spring of hot water on the deep ocean floor. In 1965, such springs were proposed to exist as part of the developing theory of plate tectonics. Since then more than 80 such vents have been found in the Pacific Ocean (most recently in 2002) at sites of rapid seafloor spreading, emitting sulphur-rich water at temperatures that can reach 350° C (660° F). A few vents have also been found in the Atlantic Ocean at sites of slower spreading; the water from these vents tends to be cooler but still rich in sulphur.

In both oceans, the vents form when cold seawater sinks deep into cracks in the ocean floor until warmed by rock heated by magma (igneous rock). The water then expands and rises, leaching minerals from surrounding rocks until it reaches an opening or vent on the cold ocean floor. Pouring out of the vent, it precipitates its load of dissolved sulphide compounds. In this way, thick deposits of minerals rich in copper, iron, manganese, and zinc form. Strange forms of marine life have also been found nearby.