Hydrothermal circulation in its most general sense is the circulation of hot water (
Ancient Greek ὕδωρ,
water, and θέρμη,
heat ). Hydrothermal circulation occurs most often in the vicinity of sources of heat within the Earth's
crust. In general, this occurs near
volcanic activity, but can occur in the deep crust related to the intrusion of
granite, or as the result of
orogeny or
metamorphism.