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Despite their appearance, in these instances the fundamental plate-tectonic structure is still an oceanic trench. Some troughs look similar to oceanic trenches but possess other tectonic structures. One example is the Lesser Antilles Trough, which is the forearc basin of the Lesser Antilles subduction zone. [8]
Pull-apart basin caused by offset in a strike-slip or transform fault (example: the Dead Sea area). Oceanic trench: a deep linear depression on the ocean floor. Oceanic trenches are caused by subduction (when one tectonic plate is pushed underneath another) of oceanic crust beneath either the oceanic crust or continental crust.
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.
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.
Mid-ocean ridge – Basaltic underwater mountain system formed by plate tectonic spreading; Mud volcano – Landform created by the eruption of mud or slurries, water and gases; Oceanic trench – Long and narrow depressions of the sea floor; Pull-apart basin – Type of basin in geology
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).
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 ...
A gas main being laid in a trench. A trench is a type of excavation or depression in the ground that is generally deeper than it is wide (as opposed to a swale or a bar ditch), and narrow compared with its length (as opposed to a simple hole or pit). [1] In geology, trenches result from erosion by rivers or by geological movement of tectonic ...