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A schematic cross-section of an island arc from trench to back-arc basin. Below are some of the generalized features present in most island arcs. Fore-arc: This region comprises the trench, the accretionary prism, and the fore-arc basin. A bump from the trench in the oceanward side of the system is present (Barbados in the Lesser Antilles is an ...
A volcanic arc (also known as a magmatic arc [1]: 6.2 ) is a belt of volcanoes formed above a subducting oceanic tectonic plate, [2] with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench , with the arc located further from the subducting plate than the trench.
Volcanic arcs can form as island arc chains or as arcs on continental crust. Three magma series of volcanic rocks are found in association with arcs. The chemically reduced tholeiitic magma series is most characteristic of oceanic volcanic arcs, though this is also found in continental volcanic arcs above rapid subduction (>7 cm/year).
Oceanic-continental convergence and creation of accretionary wedge Stages of accretion through time with accretionary wedge and volcanic island arc. In geology, accretion is a process by which material is added to a tectonic plate at a subduction zone, frequently on the edge of existing continental landmasses.
An example of a volcanic arc having both island and continental arc sections is found behind the Aleutian Trench subduction zone in Alaska. Volcanoes that occur above subduction zones, such as Mount St. Helens, Mount Etna, and Mount Fuji, lie approximately one hundred kilometers from the trench in arcuate chains called volcanic arcs.
The Aleutian island arc formed ~50-55 ma as a result of Kula Plate subduction under the North American Plate before the Pacific plate arrived. [3] There are three stratigraphic units of the Aleutian island arc: volcanic rocks from ~55-33 ma, marine sedimentary rocks from ~23-33 ma, and sedimentary and igneous rocks from ~5 ma-present. [3]
The Tonga–Kermadec Ridge is an oceanic ridge in the south-west Pacific Ocean underlying the Tonga–Kermadec island arc.It is a result of the most linear, fastest converging, and seismically active subduction boundary on Earth, the Kermadec–Tonga subduction zone, and consequently has the highest density of submarine volcanoes.
Oceanic, volcanic island arc; Continental volcanic arc and cordilleran orogen; Adjacent continental masses located along strike (such as Barbados). Material transported into the trench by gravity sliding and debris flow from the forearc ridge (olistostrome) Piggy-back basins, which are small basins located in surface depression on the ...