Search results
Results from the WOW.Com Content Network
An accretionary wedge or accretionary prism forms from sediments accreted onto the non-subducting tectonic plate at a convergent plate boundary. Most of the material in the accretionary wedge consists of marine sediments scraped off from the downgoing slab of oceanic crust , but in some cases the wedge includes the erosional products of ...
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 accretionary prism or accretionary wedge is formed from sediments that are accreted onto the non-subducting tectonic plate at a convergent plate boundary.Most of the material in the accretionary wedge consists of marine sediments scraped off from the downgoing slab of oceanic crust but in some cases includes the erosional products of volcanic island arcs formed on the overriding plate.
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 outer arc trough.
The first is by frontal accretion, in which sediments are scraped off the downgoing plate and emplaced at the front of the accretionary prism. [2] As the accretionary wedge grows, older sediments further from the trench become increasingly lithified, and faults and other structural features are steepened by rotation towards the trench. [27]
An accretionary wedge forms on the continental crust as deep-sea sediments and oceanic crust are scraped from the oceanic plate. Volcanic arcs form on continental lithosphere as the result of partial melting due to dehydration of the hydrous minerals of the subducting slab. [citation needed]
As a passive margin is pulled into a subduction zone by the attached and negatively buoyant oceanic lithosphere, the sedimentary and volcanic cover is mostly scraped off to form an orogenic wedge. An orogenic wedge is larger than most accretionary wedges due to the volume of material there is to accrete.
The western boundary of this basin was created by the growth and uplift of an accretionary wedge consisting of sedimentary, volcanic and metamorphic rocks scraped off the subducting plate. The uplift of this accretionary wedge acted like a dam to form the western side of a basin in which the Great Valley Sequence was deposited.