Structural evolution of the Roudny gold deposit, Bohemian Massif: a combination of paleostress analysis and review of historical documents
Abstract
The Roudny 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we performed a detailed analysis of brittle to brittle-ductile structures on outcrops and of structures described in unpublished historical materials.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 Ratiborske Hory-Stara Vozice 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 Roudny deposit were probably initiated as Riedel R' shears and were later reopened during the extensional phase.