Earthquake faulting, induced fluid flow, and fault-hosted gold- quartz mineralization

Abstract

Gold-quartz vein systems with textures recording incremental histories of deposition are often hosted in faults and shear zones. Epithermal deposits tend to develop at shallow depths (<1-2 km) in the vicinity of extensional or transtensional fault systems. In contrast, many mesothermal gold-quartz lodes are associated with high-angle reverse or reverse-oblique shear zones of mixed brittle-ductile character, developed under greenschist-facies metamorphic conditions at ~10 km depth. These mesothermal deposits apparently represent the roots of brittle fault zones. Although the mechanisms differ in detail, abrupt fluctuations in fluid pressure induced by earthquake faulting seem likely to play a key role effecting mineral precipitation in both of these depositional environments, which bracket the continental seismogenic regime. -from Author