Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
Records of the terrestrial woody plants and microorganisms in the paleolacustrine deposits of the Žichov-Lužice (České středohoří Mts., NW Bohemia)
AbstractIn the silicified diatomites known as the Žichow opals, resulted from the thermodynamic alteration within the volcanoclastic rocks (the tuffaceous deposits) in the České středohoří Mts., the relicts of the limnic water ecosystem were recognized. It consists of the microalgal components, fungal spores and hyphae, single finds of unicellular microorganisms, fecal pellets and pollen drift of the terrestrial plants. The latter group contained mainly pollen of Platanus and eventually Cercidiphyllum derived from the zonal vegetation. In the nearby area occurred a fern of Polypodium and Ericaceae (the first record at the locality); intrazonal broadleaved trees were recorded rather rarely, represented by Ulmus, Alnus and cf. Betula. The water community prevails in otherwise taxonomically poor assemblage. The algal colonies of Botryococcus braunii Kutz. predominate, terrestrial fungi and probably hyphae of hydrofungi are common, single specimens of algal threads and algal aplano/zygospores occur. In addition to them, large fecal pellets and even the unicellular loricas of protists were recorded. Within the pollen association prevail zonal trees, Platanaceae / Hamamelidaceae. This feature is common with the localities Markvartice (where Platanus neptuni Bůžek, Holý & Kvaček is a common plant), and also with the locality Lochočice-Rovný (both belong to the Ústí Formation sensu Cajz 2000). Till present no palms or Symplocos, the thermophillic plants, and no pinaceous pollen were recorded in the studied opal layer. The locality is famous by its fish fauna and frog finds. The Palaeorutilus rutilus Gaudant (former Leuciscus (Palaeoleuciscus) zichovensis Obrhelová) from the Cyprinidae family and some other fauna are well known. From the plant key microfossils, the Boehlensipollis Krutzsch was identified in Žichov, during the first biostratigraphical research (Konzalová 1981). Němejc (1975) mentioned from the Žichov macroflora Celastraceae, Pterocelastrus, and Kvaček - Walther (2003) Juniperus as the characteristic plants. The microflora and palynomorphs point to the rest of originally rich lake biome, with mutually jointed basal food chain between algae, invertebrates and vertebrates.