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Age of oceanic lithosphere; youngest (light colour) is along spreading centers. Seafloor spreading, or seafloor spread, is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.
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]
The second piece of evidence in support of continental drift came during the late 1950s and early 60s from data on the bathymetry of the deep ocean floors and the nature of the oceanic crust such as magnetic properties and, more generally, with the development of marine geology [57] which gave evidence for the association of seafloor spreading ...
The discovery of mid-ocean ridges and the process of seafloor spreading allowed for Wegener's theory to be expanded so that it included the movement of oceanic crust as well as the continents. [49] Plate tectonics was a suitable explanation for seafloor spreading, and the acceptance of plate tectonics by the majority of geologists resulted in a ...
At spreading boundaries where plates move apart, the asthenosphere decompresses and melts to form new oceanic crust. At subduction zones, slabs of oceanic crust sink into the mantle, dehydrate, and release volatiles which lower the melting temperature and give rise to volcanic arcs and back-arc extensions. Several volcanic provinces, however ...
Why this theory is so significant is the interaction between the tectonic plates explains many geological formations. [8] In regards to marine geology, the movement of the plates explains seafloor spreading and mid-ocean ridge systems, subduction zones and trenches, volcanism and hydrothermal vents, and more.
Mid-ocean ridge, also known as Oceanic ridge – Basaltic underwater mountain system formed by plate tectonic spreading; Oceanic trench – Long and narrow depressions of the sea floor; Paleoclimatology – Study of changes in ancient climate; Paleomap – Map of continents and mountain ranges in the past based on plate reconstructions
It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic cumulates. [1] [2] The crust overlies the rigid uppermost layer of the mantle. The crust and the rigid upper mantle layer together constitute oceanic lithosphere. Oceanic crust is primarily ...