The importance of mechanical stratigraphy in the development of faults and joints in sedimentary basins: contribution from experimental models

Abstract

Analogue physical modeling is currently a tool increasingly used to improve the understanding of the formation and development of geological structures. The impulse given to the use of this tool comes mainly (but not exclusively) from the oil industry, where structural analysis is important in determining the geometry of structures that can constitute hydrocarbon traps. In this work, we analyzed the nucleation of faults and joints in a layered sequence composed of materials with different rheological behaviors during an extensional deformation event. Factors like layer width and stratigraphic position were also examined. To simulate a mechanical stratigraphy we used gypsum powder, glass beads and quartz sand. The experiments were monitored by using a PIV (Particle Image Velocimetry) apparatus, which shows the movement of the particles to each
deformation moment. Thus, we observed differences in the nucleation and growth of faults in layers with different rheological behavior. The gypsum powder layers behave in a more competent mode, which allows the generation of a greater number of faults with higher dip angles, when compared to the less competent layers of quartz sand. These experiments could represent an analogue of brittle deformation in carbonate sequences intercalated with clay-rich or siliciclastic strata, where structural traps could play a main role in the migration and/or storage of fluids such as hydrocarbons or even groundwater.