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The process of super-continent formation and destruction via repeated cycles of creation and destruction of oceanic crust is known as the Wilson Cycle. The oldest large-scale oceanic crust is in the west Pacific and north-west Atlantic — both are about up to 180-200 million years old.
Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types. Plate tectonics is driven by convection cells in the mantle.
A region where this process occurs is known as a subduction zone, and its surface expression is known as an arc-trench complex. The process of subduction has created most of the Earth's continental crust. [1] Rates of subduction are typically measured in centimeters per year, with rates of convergence as high as 11 cm/year. [2]
A process previously proposed to contribute to plate motion and the formation of new oceanic crust at mid-ocean ridges is the "mantle conveyor" due to deep convection (see image). [27] [28] However, some studies have shown that the upper mantle (asthenosphere) is too plastic (flexible) to generate enough friction to pull the tectonic plate along.
The distinction between oceanic crust and continental crust is based on their modes of formation. Oceanic crust is formed at sea-floor spreading centers. Continental crust is formed through arc volcanism and accretion of terranes through plate tectonic processes.
The lower oceanic crust connects the Earth's mantle with the MORB, where around 60% of the total magma production of the Earth happens. The three main processes happening in this region of the oceanic crust are partial melting of the Earth's mantle, melt accumulation at various depths and the chemical modification of this melts during ascent,.
NASA/Goddard Space Flight Center The roughly 60,000-square-mile piece of crust has been hiding below the eastern Mediterranean Sea for about 340 million years (give or take 30 million years).
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 ...