Foraminiferal palaeodepth indicators from the lower Palaeogene deposits of the Subsilesian Unit (Polish Outer Carpathians)

The presented research results are an attempt at establishing the relative depth of sediment deposition in the Subsilesian zone of the Carpathian basin. To estimate palaeodepth calcareous and agglutinated foraminifera were investigated, taking into account the preservation conditions, life environment, and bathymetrical preferences of individual species of the calcareous benthic forms. Micropalaeontological analysis were carried out on foraminiferal assemblages from the Palaeocene- Middle Eocene deposits of the Lanckorona-Żegocina Tectonic Zone and the Żywiec Tectonic Window (Subsilesian Unit), which are represented by the Szydłowiec sandstones (Palaeocene part), the Czerwin sandstones, the Gorzeń sandstones, the Radziechowy sandstones, the Lipowa beds as well as shales, that occur above or between these sandstones. The microfauna assemblages indicate that a change in the sedimentation depth of the individual lithosoms is conspicuous in the Early Palaeocene. During the Early Palaeocene the depth was between the CCD and the foraminiferal lysocline (FL); however, during the Late Palaeocene and the Early Eocene a deepening related to the CCD is evident or local shallowing of the CCD. Deposition took place in the lower part of the range between the CCD and FL, achieving the maximum palaeodepth in the latest Palaeocene. The depth changes of the Subsilesian basin zone can be correlated with global trends of the raising level of the World Ocean, and also with a period of increased subsidence of the Carpathian basins.