Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
New geological data on Písečný vrch Hill near Bečov
Abstract
Písečný vrch Hill north of Louny lies near the SE marginal fault of the Eger Graben. It is renowned for the previous (ca. 1920-1990) mining of quartzite. Smaller quartzite bodies are cylindrical, horizontally elongated. Larger bodies are tabular, steeply inclined, sometimes branching in a palm-tree style. They are hosted by a flat-lying, 10 m thick unit of kaolinic sands, probably of Late Eocene age. Results of the new geological and geomagnetic survey, although revealing a minor basaltic dyke swarm in the W part of the hill, did not prove the previously supposed existence of a maar/diatreme structure at this site. This puts any direct relation between the quartzite genesis and volcanic activity into dispute. Instead, the geometries of quartzite bodies are rather compatible with the circulation of warm, silica-laden fluids along faults and joints. The present patchy distribution of quartzite is also a result of later faulting, with a vertical displacement magnitude of up to 30 m.
