Simulation of mass fluxes and accretion processes in the Torlese accretionary wedge (New Zealand)

• Applicant: Dr. Hagen Deckert
• Subject Area: Palaeontology
• Term: from 2005 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5454938

Accretionary wedges from above subduction zones and are major sites of continental growth. This project will investigate the growth and dynamics of accretionary wedges using distinct-element models (DEM) combined with field data from ancient subduction zones. Current capabilities of DEMs applied to accretionary wedges will be expanded by implementing changing pore fluid pressure and lithification of sediments during progressive accretion into the simulations. Their significance on strength of the subduction décollement, wedge growth and stability, and internal deformation of wedges will be analysed. Furthermore, DEM should ascertain, if the subduction of seamounts might lead to significant tectonic erosion and underplating. An important goal is to restrict the parameter space of the examined processes by comparing results of numerical studies with field observations from accretionary wedges. The Torlesse wedge in New Zealand, one of the largest exposed and best studies subduction-related wedges on Earth, will be used us a case study for simulating the evolution of an accretionary orogen by DEM. Series of models will be performed, in which parameters that influence the wedge stability and geometry will be changed to mimic the evolution of the Torless until it matches with field geologic data. Material flow paths and strain distribution monitored during simulations will be compared to field observations in order to falsify inappropriate scenarios and to find a best-fit model for the accretion history of the Torelesse wedge. The results of DEM will not only lead to new insights into the evolution of accretionary wedges, but also to a new dimension in visualizing the complex dynamics resulting in structural data observed in the field.

• DFG Programme: Research Grants