3D deformation in strike-slip systems: Analogue modelling and numerical restoration

Abstract

Regional and local strike-slip systems in Chile are complex and pose interesting questions, such as theinteraction between strike-slip and reverse faults, how they evolve, and the relationship between shortening, rotationand uplift. Within this context, we developed a new analytical method based on analogue and numerical modellingapplied to 3D, pure and transtensional-transpressional strike-slip systems. Analogue modelling results indicate that inrestraining stepovers of strike-slip fault systems, where antiformal pop-up structures are usually formed, pre-existentbasement structures with a high angle to the main strike-slip fault will generate a higher rotation of blocks. However,when these structures are oriented at a high angle with respect to the main stress convergence vector, the rotation willbe less and therefore a higher tendency to uplift will be produced. These results were applied to NW- and SE-strikingbasement faults oblique to N-S mega-thrust faults in central Chile (32º-35ºS), for which we propose a simultaneousdevelopment based on the analogue model results. Moreover, we propose that strike-slip movement occurred on thrustfaults in central Chile. Furthermore, we performed a numerical restoration of an analogue experiment which modeleda pure strike-slip system, and concluded that the restoration is very sensitive to shortening data as well as to rotationaldata. These results are extremely important for future numerical and regional analysis of strike-slip systems.