Structural evolution of the Roudný gold deposit, Bohemian Massif: a combination of paleostress analysis and review of historical documents

Abstract

The Roudný gold deposit, hosted by a large-scale NNE–SSW trending fault zone (the Blanice Graben), represents a type locality of low-fineness gold (Au–Ag) mineralization in the Bohemian Massif. In order to decipher its structural evolution, we performed a detailed analysis of brittle to brittle–ductile structures on outcrops and of structures described in unpublished historical materials. Three stress phases were distinguished: compressional, strike-slip, and extensional. Most hydrothermal veins originated during the strike-slip and extensional phases. Based on a comparison with the nearby Ratibořske Hory–Stara Vožice deposit, a representative of Ag–Pb–Zn vein type mineralization in the Blanice Graben, we conclude that the structural pattern of both ore deposits/mineralizations (Ag–Pb–Zn and Au–Ag) is compatible with the overall sinistral strike-slip evolution of the Blanice Graben (c. 280–270 Ma). Whereas most of the Ag–Pb–Zn veins represent typical extension veins/fractures, early gold-bearing quartz veins of the Roudný deposit were probably initiated as Riedel R’ shears and were later reopened during the extensional phase.