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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 ...
At the deepest point, the trench is nearly 11,000 m deep (almost 36,000 feet). [38] [3] This is further below sea level than Mount Everest is above sea level, by over 2 kilometers. Volcanic arcs and oceanic trenches partly encircling the Pacific Basin form the so-called Pacific Ring of fire, a zone of frequent earthquakes and volcanic eruptions.
Depth of oceanic trenches seems to be controlled by age of the oceanic lithosphere being subducted. [5] Sediment fill in oceanic trenches varies and generally depends on abundance of sediment input from surrounding areas. An oceanic trench, the Mariana Trench, is the deepest point of the ocean at a depth of approximately 11,000 m (36,089 ft).
An oceanic trench is a type of convergent boundary at which two oceanic lithospheric slabs meet; the older (and therefore denser) of these slabs flexes and subducts beneath the other slab. Oceanic lithosphere moves into trenches at a global rate of about a tenth of a square meter per second.
The Mariana Trench is an oceanic trench located in the western Pacific Ocean, about 200 kilometres (124 mi) east of the Mariana Islands; it is the deepest oceanic trench on Earth. It is crescent-shaped and measures about 2,550 km (1,580 mi) in length and 69 km (43 mi) in width.
On the ocean side of the complex, where the subducting plate first approaches the subduction zone, there is often an outer trench high or outer trench swell. Here the plate shallows slightly before plunging downwards, as a consequence of the rigidity of the plate. [18] The point where the slab begins to plunge downwards is marked by an oceanic ...
As old oceanic crust is "consumed" in the trenches (like Holmes and others, he thought this was done by thickening of the continental lithosphere, not, as later understood, by underthrusting at a larger scale of the oceanic crust itself into the mantle), new magma rises and erupts along the spreading ridges to form new crust.
The mid-ocean ridges of the world are connected and form the Ocean Ridge, a single global mid-oceanic ridge system that is part of every ocean, making it the longest mountain range in the world. The continuous mountain range is 65,000 km (40,400 mi) long (several times longer than the Andes , the longest continental mountain range), and the ...