Structural Controls on Mineralization within the Huanggou Gold Deposit in the Southern Mesozoic Xuefengshan Orogen, South China

Abstract

The Mesozoic Xuefengshan Orogen (XFSO) in South China hosts abundant gold ore deposits. The XFSO records a history of polyphase tectonic deformation and the structural controls on gold mineralization are poorly understood. The recently discovered quartz-vein type Huanggou gold deposit in the southern XFSO is characterized by multiple stages of deformation and represents an excellent natural laboratory for deciphering structural controls on gold mineralization in a complex orogenic belt. A systematic structural analysis indicates that the geometry of the Huanggou gold deposit and adjacent areas mainly resulted from four stages of deformation: (1) D1 top-to-the-NW sense of shearing; (2) D2 SE-directed back-folding and back-thrusting; (3) D3 NW–SE upright folding; and (4) D4 NW–SE normal faulting and fracturing. Two sets of quartz veins are exposed in the deposit: (1) SE-dipping Au-bearing quartz veins; and (2) NW-dipping non-mineralized quartz veins. The SE-dipping Au-bearing quartz veins were likely formed by the main deformation phase of the XFSO. During D1 top-to-the-NW simple shearing, these synkinematic Au-bearing quartz veins progressively evolved into sigmoidal shapes and rotated to a preferred SE-dipping orientation. Subsequently, D2 SE-directed back-folding and back-thrusting resulted in the formation of synkinematic NW-dipping non-mineralized quartz veins. D3 upright folding locally steepened the dips of both Au-bearing and non-mineralized quartz veins. Our results may provide new insights into the structural controls of gold mineralization in the XFSO.