Hydrothermal vent
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A hydrothermal vent is a fissure in a planet's surface from which geothermally heated water issues. Hydrothermal vents are commonly found in places that are also volcanically active, where hot magma is relatively near the planet's surface.
Hydrothermal vents are abundant on Earth because it is both geologically active and has large amounts of water on its surface. Common land types include hot springs, fumaroles and geysers. The most famous hydrothermal vent system is probably Yellowstone National Park in the United States.
In 1949 a deep water survey reported anomalously hot brines in the central portions of the Red Sea. Later work in the 1960s confirmed the presence of hot, 60 °C, saline brines and associated metaliferous muds. The hot solutions were emanating from an active subseafloor rift. The highly saline character of the waters were not hospitable to living organisms. The brines and associated muds are currently under investigation as a source of mineable precious and base metals.
Submarine hydrothermal vents (black smokers) were discovered along the East Pacific Rise in 1977. Despite their inaccessible location on ocean floors, many have been thoroughly mapped and explored. Relative to the majority of the deep sea, the areas around hydrothermal vents are biologically productive, often hosting complex communities fueled by the chemicals dissolved in the vent fluids. Chemosynthetic archaea form the base of the food chain, supporting diverse organisms, including giant tube worms, clams, and shrimp.
The water that issues from hydrothermal vents consists mostly of ground water that has percolated down into hot regions from the surface, but it also commonly contains some portion of primordial water that originated deep underground and is only now surfacing for the first time. The proportion varies from location to location. Some of these deep sea black smokers (as in over a mile down) can reach temperatures of over 400 degrees Celsius. Despite the extreme temperature (much higher than the boiling point of water at sea level), the water is still in liquid form due to the immense pressure at that depth.
Hydrothermal vents have been speculated to exist on Mars, and are believed to exist on Jupiter's moon Europa.
References
- Degens, Egon T. (ed.), 1969, Hot Brines and Recent Heavy Metal Deposits in the Red Sea, 600 pp, Springer-Verlag.
- Glyn Ford and Jonathan Simnett, Silver from the Sea, September/October 1982, Volume 33, Number 5, Saudi Aramco World, http://www.saudiaramcoworld.com/issue/198205/silver.from.the.sea.htm Accessed 17 October 2005