Deep-ocean hydrothermal vent system from the East Pacific Rise

Photo of a deep-ocean hydrothermal vent system from the East Pacific Rise at 9º39’N latitude and 2550 m (8366 ft) depth showing vigorously venting “black smoker” hydrothermal fluids (329 °C, or 624 °F) that are dark gray to black due to rapid precipitation of iron, copper, and zinc sulfide minerals as the hot water mixes with cold bottom waters.  Vent structures, referred to as chimneys, grow upward from the seafloor by precipitation of metal sulfide (dark gray) and calcium sulfate (white) minerals.  Older sulfide deposits in the photo have been oxidized to yellow and orange colors due to reaction with cold (~1.4 °C, or 34.5 °F) oxygenated bottom waters. Photo by Pat Shanks, U.S Geological Survey, from the deep-diving submersible Alvin, in 1991.