Baguamiao superlarge gold deposit in the Qinling orogen:the characteristics of its control by the brittle-ductile shear zone and dynamic mechanism for ore-forming structure

Abstract: The Baguamiao gold deposit is the only superlarge gold deposit in the Qinling orogen. It was once considered to be a sediment? Juan hosted finely disseminated gold Deposit (Carlin type). But the latest study shows that it is characterized by gold? Juan bearing quartz veins with visible and coarse? Juan grained gold. Its spatial location and distribution of the orebodies are controlled In by The Erlihe? Juan Changgou? Juan Baguamiao? The Juan Kongguangou brittle? Juan Ductile shear zone and the rocks in the Deposit show distinct Features of Shear Deformation. During brittle? Juan ductile shearing, NW? Juan trending, rootless, corrugated, bedding? Juan parallel quartz veins were formed. The Au? Juan bearing Quartz Veins, which have an Ar? The Juan the Ar plateau age of 232.58 ± 1.59 Ma and an Ar? Juan Ar Isochron age of 222.14 ± 3.45Ma, are the product of Indosinian to brittle? Juan ductile shearing? Juan dynamic metamorphism and Differentiation. In the Early Yanshanian, the ductile shear zone was uplifted to the shallow level and reworked by brittle deformation, thus enabling the NE-trending Au-bearing quartz veins to be formed under the action of hydrothermal fluids. Such Au? Juan bearing quartz veins are rich ores and contain 1 × 10-6 ~ 4 × 10-6 Au. The strong brittle? Juan Ductile Shear Deformation records that the quartz Dislocation and Differential Stress (△ sigma) had an evolutionary Trend of becoming small from the early to late Phases. The △ σ values ??tended to decrease toward the end for the shearing event and brittle deformation event. Mineralization took place during the metastable stages of tectonic activity in the periods of alternate occurrence of two pulsations of tectonic events. The "stress pump" or "shock pump" formed in the stress periods was the dynamic mechanism for the formation of the Baguamiao superlarge gold deposit.