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The age of oceanic crust is therefore a function of distance from the mid-ocean ridge. [23] The youngest oceanic crust is at the mid-ocean ridges, and it becomes progressively older, cooler and denser as it migrates outwards from the mid-ocean ridges as part of the process called mantle convection. [24]
There are three types of lithospheric plate boundaries: 1.) divergent (where lithosphere and oceanic crust is created at mid-ocean ridges), 2.) convergent (where one lithospheric plate sinks beneath another and returns to the mantle), and 3.) transform (where two lithospheric plates slide past each other).
The mantle within about 200 km (120 mi) above the core–mantle boundary appears to have distinctly different seismic properties than the mantle at slightly shallower depths; this unusual mantle region just above the core is called D″ ("D double-prime"), a nomenclature introduced over 50 years ago by the geophysicist Keith Bullen. [26]
The Pacific Ocean is also an active, shrinking oceanic basin, even though it has both spreading ridge and oceanic trenches. Perhaps the best example of an inactive oceanic basin is the Gulf of Mexico, which formed in Jurassic times and has been doing nothing but collecting sediments since then. [15] The Aleutian Basin is another example of a ...
Marine geophysics is the scientific discipline that employs methods of geophysics to study the world's ocean basins and continental margins, particularly the solid earth beneath the ocean. It shares objectives with marine geology , which uses sedimentological , paleontological , and geochemical methods.
Airy isostasy applied to a real-case basin scenario, where the total load on the mantle is composed by a crustal basement, lower-density sediments and overlying marine water The basis of the model is Pascal's law , and particularly its consequence that, within a fluid in static equilibrium, the hydrostatic pressure is the same on every point at ...
Oceanic crust is formed at an oceanic ridge, while the lithosphere is subducted back into the asthenosphere at trenches. Oceanic trenches are prominent, long, narrow topographic depressions of the ocean floor. They are typically 50 to 100 kilometers (30 to 60 mi) wide and 3 to 4 km (1.9 to 2.5 mi) below the level of the surrounding oceanic ...
Beneath oceanic crust, the LAB ranges anywhere from 50 to 140 km in depth, except close to mid-ocean ridges where the LAB is no deeper than the depth of the new crust being created. [10] Seismic evidence shows that oceanic plates do thicken with age. This suggests that the LAB underneath oceanic lithosphere also deepens with plate age.