Hydrothermal mineralization in rocks of the Soláň Formation in the western part of Chřiby Hills

Hydrothermal mineralization sporadically occurs in the western part of Chřiby Hills in a form of thin carbonate veins and veinlets hosted by sedimentary rocks of the Lukov Member of the Soláň Formation. These veins were found in old quarries and slope debris nearby Koryčany, Cetechovice, and Roštín. The mineral filling of studied veins is formed by calcite or rarely calcite and barite. Based on the investigation of fluid inclusions, hydrothermal calcite crystallized from low-temperature (Th = 70–187 °C) and on average low-salinity (0.2–5.6 wt. % NaCl equiv.) hydrothermal solutions. Hydrothermal veins filling crack systems with the direction NNW–SSE or W–E in quarries Holý kopec near Koryčany and Roštín-Chapel are probably post-tectonic. Their origin can be connected to young tectonic events after the termination of main phase of the Alpine Orogeny. Diagenetic origin cannot be excluded in case of calcite vein which fills a bed joint between layers of conglomerate in old quarry 3.5 km south–southeast from the town Koryčany. The source fluids can be derived from mixing of seawater with diagenetic waters. In case of post-tectonic veins, a contribution of meteoric waters is also possible. In addition, UV-fluorescence microscopy reveals a sporadic presence of inclusion with higher hydrocarbons which exhibits strong blue-white fluorescence. These inclusions document a migration activity of higher hydrocarbons in the northwestern part of the Rača Unit in Chřiby Hills.Hydrothermal mineralization sporadically occurs in the western part of Chřiby Hills in a form of thin carbonate veins and veinlets hosted by sedimentary rocks of the Lukov Member of the Soláň Formation. These veins were found in old quarries and slope debris nearby Koryčany, Cetechovice, and Roštín. The mineral filling of studied veins is formed by calcite or rarely calcite and barite. Based on the investigation of fluid inclusions, hydrothermal calcite crystallized from low-temperature (Th = 70–187 °C) and on average low-salinity (0.2–5.6 wt. % NaCl equiv.) hydrothermal solutions. Hydrothermal veins filling crack systems with the direction NNW–SSE or W–E in quarries Holý kopec near Koryčany and Roštín-Chapel are probably post-tectonic. Their origin can be connected to young tectonic events after the termination of main phase of the Alpine Orogeny. Diagenetic origin cannot be excluded in case of calcite vein which fills a bed joint between layers of conglomerate in old quarry 3.5 km south–southeast from the town Koryčany. The source fluids can be derived from mixing of seawater with diagenetic waters. In case of post-tectonic veins, a contribution of meteoric waters is also possible. In addition, UV-fluorescence microscopy reveals a sporadic presence of inclusion with higher hydrocarbons which exhibits strong blue-white fluorescence. These inclusions document a migration activity of higher hydrocarbons in the northwestern part of the Rača Unit in Chřiby Hills