Lost City (hydrothermal field)

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Lime chimney in Lost City. The exit opening of the hydrothermal spring seems to have been broken off and rebuilt once.

Lost City is the name of an area of ​​hot springs or hydrothermal vents in the Atlantis massif , a submarine mountain range in the central Atlantic .

This massif is part of the Mid-Atlantic Ridge , the volcanically active mountain range that runs through the ocean along its entire length from north to south. Lost City is very different from other hydrothermal areas such as the black smoker chimneys known since the late 1970s . It consists of a field with about 30 chimneys, which consist mainly of calcium carbonate (lime) and are 30 meters to 60 meters high. There are also a number of smaller chimneys. Geologists , chemists and biologists can research the abiotic processes and life forms of a previously unknown ecosystem based on methane and hydrogen as an energy source.

Lost City was discovered in December 2000 on a National Science Foundation expedition. A second expedition, equipped in 2003, used the deep-sea submarine Alvin (DSV-2) to explore the vents. A third expedition by the National Oceanic and Atmospheric Administration (NOAA) followed in 2005 with the Hercules and Argus submarines . Details of the unusual chemistry and biology of the hydrothermal area were published in March 2005.

The chimneys mainly release methane and hydrogen into the surrounding water. These gases come from highly basic fluids , i.e. concentrated solutions that emerge there with a pH value of 9 to 11 and temperatures between 40 ° C and 90 ° C. These fluids are created by the fact that seawater reacts with the rock peridotite in an exothermic process and converts it to serpentine ( serpentinization ), whereby methane (CH 4 ), hydrogen sulphide (H 2 S) and hydrogen gas (H 2 ) can also be generated. This is possible because the peridotite was raised by tectonic processes from the depths close to the sea floor. Further effects are a decrease in the density of the rock and an increase in volume of 20 to 40%, which creates additional cracks in the rock and seawater can penetrate into previously unaffected areas of the peridotite.

Unlike black smokers , these fluids only promote insignificant amounts of carbon dioxide and metals. The temperatures and pH values ​​of the black smoker fluids are also significantly different from those of the Lost City chimneys.

The isotope values ​​of strontium , carbon and oxygen as well as radiocarbon dating prove hydrothermal activity in Lost City for at least 30,000 years, making it at least two orders of magnitude older than the previously known black smokers; other estimates go up to more than 120,000 years. Accordingly, the forms of life in the two types of hydrothermal areas differ enormously. The Lost City chimneys lack the high biomass of microorganisms that are typical of black smokers. However, Lost City is home to a variety of small invertebrates that live mainly on the limestone structures, including snails , clams , polychaete worms , amphipods and ostracods (ostracoda). Inside the chimneys, Methanosarcina-like archaea , which oxidize the methane that are released, live alongside relatives of Firmicutes . Outside the chimneys, other archaea oxidize both methane and sulfur and hydrogen, such as the recently re-described ANME 1, and other bacteria, including Proteobacteria .

Lost City was a location in the IMAX 3D film Aliens of the Deep , directed by James Cameron and Steven Quale .

literature

  • A. Boetius: Lost City Life . In: Science . tape 307 , no. 5714 , 2005, p. 1420-1422 , doi : 10.1126 / science.1109849 , PMID 15746415 .
  • Gretchen L. Früh-Green, Deborah S. Kelley, Stefano M. Bernasconi, Jeffrey A. Karson, Kristin A. Ludwig, David A. Butterfield, Chiara Boschi, Giora Proskurowski: 30,000 Years of Hydrothermal Activity at the Lost City Vent Field . In: Science . tape 301 , no. 5632 , 2003, p. 495-498 , doi : 10.1126 / science.1085582 , PMID 12881565 , JSTOR : 3834682 .
  • Deborah S. Kelley, Jeffrey A. Karson, Gretchen L. Früh-Green, Dana R. Yoerger, Timothy M. Shank, David A. Butterfield, John M. Hayes, Matthew O. Schrenk, Eric J. Olson, Giora Proskurowski, Mike Jakuba, Al Bradley, Ben Larson, Kristin Ludwig, Deborah Glickson, Kate Buckman, Alexander S. Bradley, William J. Brazelton, Kevin Roe, Mitch J. Elend, Adélie Delacour, Stefano M. Bernasconi, Marvin D. Lilley, John A. Baross, Roger E. Summons, Sean P. Sylva: A Serpentinite-Hosted Ecosystem: The Lost City Hydrothermal Field . In: Science . tape 307 , no. 5714 , 2005, p. 1428-1434 , doi : 10.1126 / science.1102556 , PMID 15746419 .
  • Deborah S. Kelley, Gretchen L. Früh-Green, Jeffery A. Karson, Kristin A. Ludwig: The Lost City Hydrothermal Field Revisited . In: Oceanography . tape 20 , no. 4 , 2007, p. 90–99 , doi : 10.5670 / oceanog.2007.09 (free full text).

Web links

Individual evidence

  1. William Martin: Hydrothermal vents and the origin of life. Everything has a beginning, including evolution . In: Biology in Our Time . tape 39 , no. 3 , 2009, p. 166–174 , doi : 10.1002 / biuz.200910391 .
  2. Giora Proskurowski, Marvin D. Lilley, Jeffery S. Seewald, Gretchen L. Früh-Green, Eric J. Olson, John E. Lupton, Sean P. Sylva, Deborah S. Kelley: Abiogenic Hydrocarbon Production at Lost City Hydrothermal Field . In: Science . tape 319 , no. 5863 , 2008, p. 604-607 , doi : 10.1126 / science.1151194 , PMID 18239121 .
  3. ^ Gretchen Früh-Green: The The Lost City 2005 Expedition. National Oceanic and Atmospheric Administration , accessed July 11, 2017 .
  4. ^ University of Washington: The Lost City Hydrothermal Field. Retrieved June 9, 2019 .

Coordinates: 30 ° 7 ′ 0 ″  N , 42 ° 7 ′ 0 ″  W.