Paleobotanical, palynological, and sedimentological research of the Nýřany Member (Westphal D) in Rakovník area
Abstract
The rich Nýřany flora of the Westphalian D have been found at the locality Za Samotkou near Rakovník. The most common plants are Pecopteris nyranensis and Rhacopteris asplenites. Other plants are rare. Miospores are very common, represented by genera Cyclogranisporites, Cappasporites, Raistrickia, Savitrisporites, Dictyotriletes, Westphalensisporites, Lycospora, Vestispora, Cirratriradites, Triquitrites, Laevigatosporites, Punctatosporites, Speciososporites, Florinites, Wilsonites and Candidispora. Megaspores are rare with genera Calamospora, Bentzisporites, Triangulatisporites and Schopfipollenites. The species Vestispora fenestrata proves the Westphalian D age of the studied strata. Two lithofacies assemblages of the Westphalian D deposits were described on the 350 m long exposure. The basal erosional surface of the Neogene sediments is exposed on the top. Trough-cross-bedded conglomerates to pebbly sandstones are interpreted as the channel fills of the shallow and broad braided channels. Low-angle cross-bedded mid to coarse grained sandstones, fine grained horizontally laminated sandstones and lenses of fosiliferous laminated mudstones to siltstones with solitary thin coal layer are interpreted as the overbank floodplain deposits. Paleoflow direction in the channels was generally to NNE; meanwhile the accretion surfaces within the overbank deposits are inclined to NW and NE.