The Dukat gold-silver deposit: structural control of veins

Abstract

Four generations of veins at the Dukat gold-silver deposit are controlled by extensional flower structure, which also controls the entire Balygychan-Sugoi volcanic graben in the rear of the Okhotsk-Chukotka volcanic belt. The Order I faults, controlling the basin, occur some 10–15 km from the mapped Cretaceous volcanic rocks of the basin, which is well expressed on gravity map. The deposit area has numerous ENE-trending Order II faults, forming a parquetry-like structure every 200 to 600 m. Only orebody of Zone I occurs along such faults. The other 120 ore veins and zones fill in the Order III faults of the extensional flower structure. Quartz veins of first generation occur locally. Veins of second, third and fourth generations reveal zoning. Quartz-adularia-chlorite veins of the second generation occur almost exclusively to the southeast of Zone I, whereas quartz-rhodonite veins of third generation are both to the southeast and northwest from Zone I. Quartz-silfide veins of fourth generation are known only to the northwest of Zone I. Previous works showed that veins of third and fourth generations formed after a 20-million-year hiatus after the veins of first and second generations. This time gap corresponds to structural reorganization and unconformity within the volcanic basin that reflects the evolution of the hosting extensional duplex.