Hydrothermal Circulation

Hydrothermal circulation is the circulation of hot water through the Earth's crust, most often near a source of heat such as volcanic activity, an intruding magma body, a deeply penetrating fault or an orogenic belt. On the seafloor, cold dense seawater sinks into the basalt of the crust, is heated at depth and rises again, emerging both at the well-known high-temperature vents near mid-ocean ridge crests, including the chimneys called black smokers, and as a much cooler diffuse flow through sediments and buried basalts further away. On land the same convection appears as hot springs, geysers and hydrothermal explosions. Hydrothermal circulation often results in hydrothermal mineral deposits, because the hot fluids dissolve metals and minerals and deposit them elsewhere.