What defines a back-arc region?
The backarc is the region landward of the volcanic chain on the other side from the subduction zone.
What is a back-arc spreading center?
: a geological region that forms at a subduction zone when the overriding plate thins and begins to spread out —often used before another noun The hot springs there are not connected at all to the midocean ridge system: they lie on what is called a back-arc spreading center, a geologic feature that occurs not where two …
Why are back arc basins less common today?
The restricted width of back-arc basins is probably because magmatic activity depends on water and induced mantle convection and these are both concentrated near the subduction zone. Spreading rates vary from very slow spreading (Mariana Trough), a few centimeters per year, to very fast (Lau Basin), 15 cm/year.
What is subduction rollback?
Slab rollback refers to the process that involves an older oceanic crust, which is colder and more dense than other slabs, subducting at a steep angle. Slab rollback can pull the upper plate with it, causing an extension in the overlying plate, and possibly resulting in backarc spreading.
What causes back arc spreading?
A back-arc basin is formed by the process of back-arc spreading, which begins when one tectonic plate subducts under (underthrusts) another. Subduction creates a trench between the two plates and melts the mantle in the overlying plate, which causes magma to rise toward the surface.
What is a back-arc volcano?
The back-arc region is the area behind a volcanic arc. In island volcanic arcs it consists of back-arc basins of oceanic crust with abyssal depths, which may be separated by remnant arcs, similar to island arcs.
What causes back-arc spreading?
What is trench rollback?
Trench rollback. This is called trench rollback or hinge retreat (also hinge rollback) and is one explanation for the existence of back-arc basins. Slab rollback occurs during the subduction of two tectonic plates, and results in seaward motion of the trench.
How is a back-arc basin formed?
What causes a subduction zone?
Oceanic crust is denser than continental crust. At a subduction zone, the oceanic crust usually sinks into the mantle beneath lighter continental crust. (Sometimes, oceanic crust may grow so old and that dense that it collapses and spontaneously forms a subduction zone, scientists think.)
What causes a volcanic arc?
Beneath the ocean, massive tectonic plates converge and grind against one another, which drives one below the other. Once in the mantle, they would mix and trigger more melting, and eventually erupt at the surface. …
Where are the back arc basins in the Pacific Ocean?
Back-arc basin. Back-arc basin, submarine basin that forms behind an island arc. Such basins are typically found along the western margin of the Pacific Ocean near the convergence of two tectonic plates. Back-arc basins are sites of significant hydrothermal activity, and the deep-sea vents that occur in these regions often harbour diverse…
Which is the best definition of a back arc?
Definition of back-arc. Weak spots emerge near the edge of the disappearing plate, permitting magma to punch through and form conventional, conical volcanoes that happen to be underwater. These vulnerable areas are known as back-arc basins.
What causes the extension of the back arc basin?
Formation and sedimentation. In some cases, extension is triggered by the entrance of a buoyant feature in the subduction zone, which locally slows down subduction and induce the subducting plate to rotate adjacent to it. This rotation is associated with trench retreat and overriding plate extension.
How old does the back arc basin need to be?
The age need to establish back-arc spreading is oceanic lithosphere that is 55 million years old or older. This includes areas like the western pacific where multiple back-arc spreading centers are located.