Petrology and organic geochemistry of the lower Miocene lacustrine sediments (Most Basin, Eger Graben, Czech Republic)

•Lake level rise affects maceral and geochemical composition.•Linking of the results to the coal-forming peat land environment•Features of lake and delta-mire system

Thirty samples of the lacustrine sediments from three localities of the Most Basin including coal samples were studied by petrological and organic geochemical methods. The consistent results indicate the relatively stable surface development of the sediments in the environment of the Holešice, Lom and Osek Members. Biological material with contribution of microbial activity participated in the storing, which led to the formation of clayey coal. In the results of the chemical composition dominated sesqui-, diand triterpene compounds. Completely different sediments of Libkovice Member contained low proportions of small organic particles dispersed in the sediment. In the extracts of these samples prevailed hopanes, perylene and sulphur after the action of microorganisms. The base of the organic fraction also formed remains of terrestrial plants and liptinite macerals, especially alginite, liptodetrinite and bituminite that are typical for lacustrine sediments.