Guyot

from Wikipedia, the free encyclopedia
Historical sonar record of the first guyot discovered by Harry Hess, probably near the Eniwetok Atoll
3-D representation of a guyot

A guyot (also deep sea dome) is a deep sea mountain ( seamount ) with a flattened summit, which (on deep sea gullies) can lie many thousand meters below sea ​​level . There are around 10,000 guyots worldwide.

Origin of the Guyots

Guyots and other seamounts arise at the diverging plate boundaries of the mid-ocean ridges or within an oceanic plate as part of hot-spot volcanism. The movement of the oceanic crust in the course of seafloor spreading the volcanoes lose contact with their Magmenquelle ; the magma production ceases. In contrast to the seamounts, many of the later guyots initially protrude above the sea surface and are therefore subject to the abrasive effects of the surf . As the volcano moves away from the mid-ocean ridge, the cooling ocean floor contracts; the volcano is sinking, while at the same time the erosion caused by the surf flattens the fragile top of the mountain, which consists of volcanic loose material with a basaltic composition, to a plateau. This erosion platform can be several tens of kilometers wide.

Guyots as evidence of plate tectonics

The guyots served as evidence of plate tectonics . In front of deep-sea trenches , where the oceanic crust is submerged under another plate ( subduction ), guyots were found that were slightly tilted, so that it could be shown that the plateau inclined towards the deep-sea channel.

The USS Cape Johnson (AP-172) in San Francisco Bay

The deep sea peaks were discovered in 1941 by Harold Murray in the Gulf of Alaska . They were first described in 1946 by Harry Hammond Hess , an American geologist from Princeton University . He tracked down about 100 of these seamounts in the Pacific when he commanded the USS Cape Johnson (AP-172), a troop carrier, during World War II . With the help of the powerful echo sounder of this type of ship, he created topographical height profiles of the sea floor. He discovered the guyots and correctly suspected that they are submarine volcanoes that have been flattened by erosion . He named it in 1946 after the geographer Arnold Henry Guyot (1807-1884), founder of the geological department at Princeton University. With the help of these and numerous other observations and discoveries in the following years, he formulated the hypothesis of sea ​​floor spreading and published it in 1962 under the title History of Ocean Basins (The formation of the ocean basins). With this he recognized and described the movement of the tectonic plates ( mobilism ).

See also

literature