Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
Disseminated pebbles, conglomeratic sandstones and quartzites near the SE margin of České středohoří Mts.
AbstractNumerous blocks of silicified sandstones and quartzites occur near the SE margin of České Středohoří Mts. The blocks are mainly in secondary position on the slopes. The grain-size of these sandstones and quartzites is usually similar to that of sandstones forming the Merboltice Formation which is the youngest unit of the Bohemian Cretaceous Basin. Silicified conglomeratic sandstones occur as blocks near the settlement Lovečkovice. North of the settlement Levín and on the SW slopes of the Dlouhý vrch Hill the conglomeratic sandstones are preserved on some lo-calities in in situ position, overlying the Merboltice Formation. The grain-size and fluvial structures of the conglomeratic sandstones differ from the marine Merboltice sandstones and correspond to fluvial deposits in the České Středohoří Mts. These sediments had been formed in Paleogene fluvial system before the volcanic activity which started in the Upper Eocene. The silicification affected both the Paleogene fluvial deposits and the underlying sandstones of the Merboltice Formation. The silicified layer of variable thickness, locally probably discontinuous, covered a fiat 'prevolcanic' surface. In spite of younger tectonic movements which differentiated the flat relief, most of the quartzite relics keep the elevation of about 500 m a.s.l. Only one occurs at an elevation of 570 m a.s.l..