Strike-slip kinematics from crustal to outcrop-scale: the impact of material properties on analogue modelling

Abstract. Strike-slip fault zones commonly display complex kinematics and 3D geometries, with high structural variability along strike and with depth. In this regard, analogue modelling techniques are a powerful tool for investigating such complex structural, kinematic, and mechanical deformation processes at various scales. Dynamically scaled experiments allow a direct comparison between models and natural systems. The geometric scaling factor defines the model resolution in terms of model/prototype length equivalence and depends on the mechanical and physical properties of prototype and analogue materials. In this study, systematic strike-slip experiments were performed by using four different model materials to investigate the deformation dynamics at various scales and to highlight the impact of the physical and mechanical properties of the model material on the experiment results. The applied model materials showed a non-linear strain-dependent deformation behaviour while providing different dynamically scaled geometric scaling factors. Digital image correlation (DIC) analyses of the experiments allowed a quantitative comparison of the displacement and strain fields at different stages of the dextral displacement above a single planar basement fault. The analysis of the localisation and development of the faults and fractures in the strike-slip shear zones enabled the comparison of the different structural styles and dynamics observable at various levels of resolution. The increasing resolution enabled by the model materials with higher cohesion allowed a higher detail into the shear zones, with the development of a more complex network of discontinuities, larger shear zone width, and higher vertical relief. Therefore, the application of such a multi-scale approach in dynamically scaled experiments can provide new insights into the investigation of complex deformation processes with analogue modelling techniques.