Focused
hydrothermal vents form sulfide chimneys and black smokers where high-temperature
hydrothermal fluids exit the seafloor from a small orifice. These fluids
come almost directly from the high-temperature reaction zone above the
magma reservoir, and mix very little with cooler seawater during their
ascent to the vent. The fluids are between 200 and 400°C
as they exit the seafloor. When they contact the cold seawater, they precipitate
sulfide particles containing Zinc, Copper, Iron, Lead, Cadmium, and Silver.
All these elements are dissolved from the volcanic rock by the highly
corrosive hydrothermal fluids.
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