Accretionary Wedge Numerical Simulation Of Tectonic Deformation

Accretionary wedges also called as first arc, subduction complex, accretionary prism, are formed as the scraped sediments and oceanic crustal fragments are conveyed and pile up in the front of underlying plate in the process of crustal subduction, which are separated by thrust faults. It emerges between the front of subduction crust and obduction crust,and are formed because of the lateral and transverse accretion of continental crust. As the production of crustal subduction, the location of accretionary wedges represent the suture lines between paleoplates. Its tectonic characteristics rely on such structural factors as the angle and speed of subduction crust, the supply speed of sediments and the continuity and discontinuity of subduction processes. Its emplacement state is tightly related with the type of the crust margin and the crustal exhumation. In general, the comprehensive study concerned with the tectonic location ,structural style and the emplacement will greatly help researches on dynamic evolution of crust subduction.Generally speaking, subduction zones also named as Benioff zones have a obliquity approximately near 450. However, based on recent researches, obliquity of Benioff zones changes to some extent along the strike of volcanic island arcs, which occur in a spectrum from 150 to 900. It is discovered that obliquity of Benioff zones is closely related with the speed of the crustal subduction, and there is a inverse ratio between them.Along with the development of computer and finite element method,numerical simulation gradually became a skill broadly used by geologist to quantificationally study the evolution of our earth. Accretionary wedges forming during the process of plates subdution emerge in both the present subduction zones and orogenic belts across our world. In order to study the geometrical style, interior structures and dynamic conditions of accretionary wedges, this article uses finite element method to investigate its dynamic background and dominating effects of subduction zone's obliquity, dynamically simulate its whole tectonic evolution, search for the transmitting modes of materials during its formation and quantificationally reveal the state of stress and strain background during its evolution. In a word, based on structural simulations in these aspects, this article would reveal the forming mechanism and the tectonic evolution of accretionary wedges.