Structural Evolution and Deformation Conditions Associated with Gold Mineralisation in the Jinshan Gold Deposit, Jiangnan Orogen

The structural evolution and deformation conditions of ore‐controlling shear zones in the large‐scale Jinshan orogenic gold deposit were studied through structural mapping, petrographic analysis and electron backscatter diffraction (EBSD) observation. Four distinct deformation events are identified, including pre‐mineralisation ductile deformation (D 1 and D 2 ), syn‐mineralisation brittle‒ductile shearing (D 3 ) and post‐mineralisation brittle faulting (D 4 ). Gold‐bearing quartz veins are confined to D 3 ‐stage NE–SW‐trending shear zones characterised by thrust plus sinistral slip movement under NW–SE‐oriented compression. The mineral assemblage includes pyrite, arsenopyrite, chalcopyrite, galena, and native gold associated with quartz‐sericite alteration. The quartz can be divided into two groups: pre‐mineralisation coarse (>100 µm) grains and gold‐related fine (<50 µm) grains. The coarse‐grained quartz displays dominant prism and rhomb slip with intermediate‐ to high‐temperature deformation fabrics (400°C–600°C) and has undergone sub‐grain rotation recrystallisation after its formation. In contrast, the gold‐related quartz distributed along the margins of coarse‐grained quartz displays bulging recrystallisation with dominant basal slip, indicating intermediate‐ to low‐temperature conditions (300°C–400°C). The intermediate‐ to low‐temperature gold mineralisation event overprinted earlier intermediate‐ to high‐temperature fabrics. This study highlights that the reactivation of the pre‐mineralisation shear zones provided fluid pathways for subsequent auriferous fluid flow and gold deposition.