Analog modelling of strike-slip fault (lateral) propagation from an elastic to a viscous medium: Insights from trial experiments

A series of analog modeling experiments were carried out to investigate lateral strike-slip fault propagation vs. attenuation across a discrete rheology boundary, and to gain insight on the mechanics governing the generation of associated characteristic structural patterns. Experiments were conceived to simulate the lateral propagation of a strike-slip fault through a Mohr-Coulomb medium (dry quartz sand), from a zone overlying a rigid basement (where the fault is pre-cut) to another one where the sand lies on top of a viscous (Newtonian) silicone layer. Comparison of the obtained results with the natural example of the Gloria Fault - Tore-Madeira intersection (Eurasia-Nubia plate boundary, NE Atlantic) revealed a striking first-order resemblance, allowing speculation about a compliant tectono-magmatic evolution, and stressing the relevance for future enhanced modeling.