Abstrakt
Two shallow boreholes were drilled in 2010 into the Badenian (Langhian) parastratotype at Židlochovice (Carpathian Foredeep, NN5 Zone, Czech Republic). Their profiles (26 m of sediment) were studied comprehensively (sedimentology, palaeontology -calcareous nannoplankton, red algae, palynology, Foraminifera, Bryozoa, Brachiopoda, Ostracoda, Mollusca, Teleostei and Elasmobranchii).
The sedimentary succesion was biostratigraphically correlated with the NN5 Zone (14.9-13.9 Ma), namely with the initial time of the Middle Miocene Climatic Transition. Seven lithofacies representing multiple alternations of mudstone, sandstone and limestone facies were recognised within sedimentary succession.
Fossils generally indicated a normal marine, warm to subtropical environment. The generally shallowing trend from the bottom (epibathyal/ circalittoral) to the top (shallow infralittoral) of the sedimentary succession with repeated palaeobathymetric changes could be recognized in both boreholes.
A mainly subtropical character of terrestrial flora was recorded. Within this framework, either warm wet conditions with seasonal increases, or cooler phases were observed.
The abrupt change from mudstone deposited in a calm palaeoenvironment of the upper bathyal/circalittoral to the variegated deposits of shallow water represents the most significant event correlable with the FO of Orbulina (approximately 14.5-14.6 Ma). The interval below the FO of Orbulina can be characterized by mudstone facies and significantly stable conditions of deposition, high nutrient input and a decrease of oxygen content at the bottom.
Seasonal stratification of the water column is probable. Within this interval, cooling and an increase of seasonality were recorded.
Above the FO of Orbulina, there is evidence of shallowing connected with a higher flow regime and higher sedimentation rate.