Influence of physical and diagenetic processes on fault geomechanics and reactivation

Abstract

Geomechanical and capillary properties of cataclastic and phyllosilicate framework fault rocks are related to physical anddiagenetic processes occurring syn- and post-deformation. Clay content influences mechanical properties both pre- and post diagenesis, although in different ways. Pre-diagenesis, clay-rich sandstones are often weak with lowered friction coefficients and cohesive strengths. Quartz cementation is influenced by temperature and enhanced by the presence of clays up to a certain volume and can strengthen fault rocks considerably. Changes in geomechanical properties of fault rocks resulting from these processes have implications for geomechanical predictive methods that are used to assess fault reactivation risk.