Gakkel back
The Gakkel Ridge (also Mittelarktischer back , Hackel back or Nansen back ) is about 1800 km long mid oceanic ridge in the Arctic Ocean .
location
The Gakkel Ridge is a northern continuation of the North Atlantic Ridge in the Arctic Ocean between Greenland and Siberia .
There the submarine sill runs roughly parallel to the Lomonossow Ridge and divides the Eurasian Basin into a northern half, the Amundsen Basin (also known as the Pole Deep Sea Plain or Eurasian Basin ), and a southern half, the Nansen Basin (also known as the Barents Deep Sea Plain or Fram Basin ). Its central rift valley runs roughly along a line from the estuary delta of the Lena in the east to the Greenland north-east ring in the west.
The deep-sea basins surrounding the Gakkel ridge have a sea depth of approx. 4000 m, of which the ridge rises to a maximum of approx. 1000 m below sea level. The rift valley in the middle of the ridge is approx. 20 to 40 km wide and a maximum of approx. 5500 m deep.
History, exploration and geology
The Gakkel Ridge is the slowest spreading mid-ocean ridge in the world . It was named in 1966 after the Soviet oceanographer Jakow Jakowlewitsch Gakkel .
Until 1999, when scientists discovered volcanoes along the ridge from a nuclear submarine , the Gakkel Ridge was believed not to be volcanic. In 2001, several groups of scientists who traveled with the research icebreakers Polarstern and Healy explored the Gakkel ridge and took soil samples. The discovery of hydrothermal activities that made it necessary to review the current model concepts for the formation of the seabed was particularly surprising .
In 2007, an expedition discovered signs of explosive volcanism in the Arctic Ocean with a specially developed camera in 4,000 meters water depth on the Gakkel Ridge: extensive layers of ash on the sea floor, which indicate a gigantic volcanic eruption.
In the Arctic Ocean, at 85 ° N 85 ° E, a violent volcanic explosion occurred almost unnoticed in 1999 - but here under a layer of water four kilometers thick. Previously, the researchers assumed that explosive volcanism in water depths of more than three kilometers cannot occur because of the high ambient pressure. The Gakkel Ridge opens so slowly, at six to fourteen millimeters per year, that common theories considered volcanism to be unlikely, until a series of 300 strong earthquakes over eight months signaled a volcanic eruption in 1999.
See also
literature
- Jörn Thiede et al .: POLARSTERN ARKTIS XVII / 2. Cruise Report: AMORE 2001 (Arctic Mid-Ocean Ridge Expedition) , Polar and Marine Research Reports 421, 2002, hdl : 10013 / epic.10426.d001 .
- Jörn Hatzky: Analysis of bathymetry and acoustic backscattering of various fan sonar and sediment echo sounder systems for the characterization and classification of the seabed on the Gakkel Ridge, Arctic Ocean (PDF; 45 MB). Dissertation, University of Bremen, 2008.
- Martin Jakobsson et al .: An improved bathymetric portrayal of the Arctic Ocean: Implications for ocean modeling and geological, geophysical and oceanographic analyzes . In: Geophysical Research Letters . Volume 35, L07602, 2008, 5 pages, doi : 10.1029 / 2008GL033520 .
- Martin Jakobsson et al .: The International Bathymetric Chart of the Arctic Ocean . In: Geophysical Research Letters . Volume 39, L12609, 2012, 6 pages, doi : 10.1029 / 2012GL052219 .
- Valery Mitko: Arctic Mid-Ocean Ridge . In: Mark Nuttall (Ed.): Encyclopedia of the Arctic . tape 1 . Routledge, New York and London 2003, ISBN 1-57958-436-5 , pp. 131 f . ( limited preview in Google Book search).
Web links
- C. Riedel: The 1999 earthquake swarm on Gakkel Ridge , Tough cone, Projects (English)
- Labeled map of the Arctic Ocean , the Gakkel Ridge is called Arctic Mid-Ocean Ridge
- J. Snow: Glowing elemental forces under the ice , Max Planck Society, Geoforschung, July 8, 2003
- H.-W. Schencke et al .: AMORE - Arctic Mid Ocean Ridge Expedition to Gakkel Ridge , Alfred Wegener Institute for Polar and Marine Research (English)