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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).
The fluids released at mud volcanoes and cold seeps are rich in methane and hydrogen sulfide, providing chemical energy for chemotrophic microorganisms that form the base of a unique trench biome. Cold seep communities have been identified in the inner trench slopes of the western Pacific (especially Japan [ 39 ] ), South America, Barbados, the ...
The topographic expression of the accretionary wedge forms a lip, which may dam basins of accumulated materials that, otherwise, would be transported into the trench from the overriding plate. Accretionary wedges are the home of mélange, intensely deformed packages of rocks that lack coherent internal layering and coherent internal order. [3]
There is a high supply of sediment from turbidity currents, slumps, and creeps into the eastern portion of the Aleutian trench. The sediments accumulated here were originally part of the Alaskan Abyssal Plain. The maximum depth of the trench is 2 km, and the deposition at the maximum depth has been 10 times faster than the abyssal plain.
Volcanic arcs typically parallel an oceanic trench, with the arc located further from the subducting plate than the trench. The oceanic plate is saturated with water, mostly in the form of hydrous minerals such as micas, amphiboles, and serpentines. As the oceanic plate is subducted, it is subjected to increasing pressure and temperature with ...
A bump from the trench in the oceanward side of the system is present (Barbados in the Lesser Antilles is an example). The fore-arc basin forms between the fore-arc ridge and the island arc; it is a region of undisturbed flat-bedded sedimentation.
The forearc is the region between the trench and the volcanic arc. A forearc is a region in a subduction zone between an oceanic trench and the associated volcanic arc . Forearc regions are present along convergent margins and eponymously form 'in front of' the volcanic arcs that are characteristic of convergent plate margins.
The backward motion of the subduction zone relative to the motion of the plate which is being subducted is called trench rollback (also known as hinge rollback or hinge retreat). As the subduction zone and its associated trench pull backward, the overriding plate is stretched, thinning the crust and forming a back-arc basin.