Sokolov site description
The Sokolov lignite mining area is located in the North-West of the Bohemia province, west of the town of Karlovy Vary, close to the German border. The area is largely affected by mining activities: open casts and dump sites (Fig. 1).
The Sokolov basin is part or the Eger rift that was strongly rifted into numerous horsts and grabens (Rojík et al, 1998) and gave rise to several brown coal deposits in Czech Republic, Germany and Poland.
The Sokolov basin, dating from the Oligocene to Miocene epochs, extends over 8 to 9 km in width and 36 km long with a total area of about 200 km2. The basin comprises 60 % volcanic ejecta resulting from faults and volcanic cones and 40 % sediments. It is bordered by a complex SW – NE faulting system and is cut by NW – SE faults. The basin is limited to the North by the Lipniza faulting system. Hydrothermal fluids have been circulating along the faults where silicification and sulphur are found, and exposure of the latter can result in Acid Mine Drainage.
Lignite is found only in the western part of the basin and comprises three coal seams. The Josef coal seam represents the lower one, just over the basement rocks. It is very rich in sulphur (up to 5%) and arsenic (60 – 70 ppm). The seam Anežka is of more recent genesis than the Josef seam and is developed only in the western part of the basin. The Josef and Anežka seams have been exploited in particular in the Medard open pit. The Antonin seam is currently exploited in the Jiří open pit, and contains up to 8 % sulphur, together with arsenic. Thick (130 – 200 m) overburden is represented by the clays of the Cypris Formation (Burdigalian), dominantly kaolinite at base, passing to illite and montmorillonite (smectite) to the top. The Cypris Formation is capped by limestone.Thick (130 – 200 m) overburden is represented by the clays of the Cypris Formation (Burdigalian), dominantly kaolinite at base, passing to illite and montmorillonite (smectite) to the top. The Cypris Formation is capped by limestone (Rojík et al., 2003, 2004).
Satellite view of the Sokolov mining area and its location in the Czech Republic