Search results
Results From The WOW.Com Content Network
Andesite and basaltic andesite are the most abundant volcanic rock in island arc which is indicative of the calc-alkaline magmas. Some Island arcs have distributed volcanic series as can be seen in the Japanese island arc system where the volcanic rocks change from tholeiite—calc-alkaline—alkaline with increasing distance from the trench. [15]
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.
Hotspot volcanoes are considered to have a fundamentally different origin from island arc volcanoes. The latter form over subduction zones, at converging plate boundaries. When one oceanic plate meets another, the denser plate is forced downward into a deep ocean trench.
A back-arc region is the companion region behind the volcanic arc. Many forearcs have an accretionary wedge which may form a topographic ridge known as an outer arc ridge that parallels the volcanic arc. A forearc basin between the accretionary wedge and the volcanic arc can accumulate thick deposits of sediment, sometimes referred to as an ...
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.
The Aleutian Trench, formed by the subduction of the Pacific plate under the North American plate, sits south of the island arc. [2] A forearc basin reaching depths of 7 km occupies the space between the trench and the island arc and leads up to the Aleutian Ridge, the north side of which being the area where the most volcanic activity occurs. [2]
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 ...
Bathymetry of the northeast corner of the Caribbean Plate showing the major faults and plate boundaries; view looking south-west. The main bathymetric features of this area include: the Lesser Antilles volcanic arc; the old inactive volcanic arc of the Greater Antilles (Virgin Islands, Puerto Rico, and Hispaniola); the Muertos Trough; and the Puerto Rico Trench formed at the plate boundary ...