Macro- and Micro-structural Characteristics of Hupen Shear Zone and its Relationship to Hupen Gold Deposit

Hupen Gold Deposit is an important and unique gold mine located at the Southeast Guizhou. The genesis of it has arisen lots of discussion. Here we carried out field investigation, microstructure study and EBSD analysis and determined characteristics of brittle-ductile shear zone in Hupen gold deposit. In the Hupen shear zone, there are A-type folds, rotated porphyroclast, dense shear quartz veins, mylonite series, and Riedel shear fracture system. The microstructural features in this zone mainly consist of sub solidus plastic deformation and high temperature ductile deformation. These evidences indicate that it is a ductile shear zone type gold deposit, controlled by brittle-ductile shear deformation. Analysis of shear zones indicates that there are least two tectonic activities. The first phase of brittle-ductile dextral shear transtension of smaller tectonic activity in the affected area, only in the local development, mainly in the form of a variety of brittle and ductile deformation Riedel shear fractures (quartz veins) systems. The second phase is brittle dextral shear-shear pressure, tectonic pattern region as a whole, the main features of the formation of brittle shear deformation of a large number of parallel quartz veins cut straight (quartz veins) systems. Quartz C-axis fabrics EBSD analysis can also prove that the mining area has undergone two shear tectonic activity. Early brittle-ductile shear deformation temperature of about 400 500 °, belong to the warm deformation. Late brittle shear deformation temperature of about 250 300 °, belonging to low-temperature deformation.