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Harry Hess proposed the seafloor spreading hypothesis in 1960 (published in 1962 [1]); the term "spreading of the seafloor" was introduced by geophysicist Robert S. Dietz in 1961. [2] According to Hess, seafloor was created at mid-oceanic ridges by the convection of the Earth's mantle, pushing and spreading the older crust away from the ridge. [3]
Spreading rate is the rate at which an ocean basin widens due to seafloor spreading. (The rate at which new oceanic lithosphere is added to each tectonic plate on either side of a mid-ocean ridge is the spreading half-rate and is equal to half of the spreading rate). Spreading rates determine if the ridge is fast, intermediate, or slow.
Correlation of the anomalies to the history of Earth's magnetic field reversals allowed the age of the seafloor to be estimated. [22] This connection was interpreted as the spreading of the seafloor from the ridge crests. [23] [22] Linking spreading centers and transform faults to a common cause helped to develop the concept of plate tectonics ...
A good approximation is that the depth of the seafloor at a location on a spreading mid-ocean ridge is proportional to the square root of the age of the seafloor. [6] The overall shape of ridges results from Pratt isostasy : close to the ridge axis, there is a hot, low-density mantle supporting the oceanic crust.
At a seafloor spreading ridge, plates move away from the ridge, which is a topographic high, and the newly formed crust cools as it moves away, increasing its density and contributing to the motion. At a subduction zone the relatively cold, dense oceanic crust sinks down into the mantle, forming the downward convecting limb of a mantle cell ...
A propagating rift is a seafloor feature associated with spreading centers at mid-ocean ridges and back-arc basins. [1] They are more commonly observed on faster rate spreading centers (50 mm/year or more). [2] These features are formed by the lengthening of one spreading segment at the expense of an offset neighboring spreading segment. [3]
The Wilson cycle theory is based upon the idea of an ongoing cycle of ocean closure, continental collision, and a formation of new ocean on the former suture zone.The Wilson Cycle can be described in six phases of tectonic plate motion: the separation of a continent (continental rift), formation of a young ocean at the seafloor, formation of ocean basins during continental drift, initiation of ...
Blanco fracture zone map Bathymetry map of the North Atlantic Ocean showing the full extent of the Charlie-Gibbs fracture zone (horizontal black lines in the center of the image) Magnetostratigraphy of the East Pacific Rise near the Heirtzler fracture zone showing ages of sea floor spreading in millions of years (Ma) The Romanche fracture zone with red arrows indicating directions of movements ...