Black Smoker Complex In this schematic drawing of the TAG active hydrothermal mound, hydrothermal fluid rises rapidly and exits the mound at the Black Smoker Complex. Cold calcium- and sulfate-rich seawater is entrained into the mound, where it mixes with hydrothermal fluid. The mixing causes anhydrite, pyrite, and chalcopyrite to precipitate inside the mound. This precipitation increases the acidity of the hydrothermal fluid. Zinc and other elements, such as silver, gold, and cadmium, dissolve in this acidic fluid, allowing them to be carried by the white smoker fluid to the edges of the mound at the ?Kremlin? area. Here the cooler temperatures within white smoker chimney walls cause the elements to precipitate. (Illustration by E. Paul Oberlander)
