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

Abstract

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 (D₁ and D₂), syn-mineralisation brittle-ductile shearing (D₃) and post-mineralisation brittle faulting (D₄). Gold-bearing quartz veins are confined to D₃-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 <a> and rhomb <a> 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 <a> 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.

Keywords

Jinshan / orogenic gold deposit / quartz dynamic recrystallisation / shear zone / structural controls

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2026 Geological Society of China.