Damage and permeability around faults: Implications for mineralization

Abstract

Mineral deposits are commonly hosted by small-displacement structures around jogs in major faults, but they are rarely hosted by the major fault itself. This relationship may be explained by time-dependent fracturing and healing in and around major faults and associated permeability evolution. A damage mechanics formulation is used here to explore the spatial-temporal evolution of damage in and around a fault following a fault-slip event. We show that regions of increased damage rate correspond to the location of mineral deposits and that these areas correspond to areas of aftershocks predicted by stress-transfer modeling. The fault itself enters a healing regime following the slip event; hence, it is expected to become less permeable than the fracture network outside the fault. Our results support the hypothesis that mineralization occurs in a fracture network associated with aftershocks; this may be due to the higher time-integrated permeability of the fracture network relative to the main fault.