The Devonian/Carboniferous boundary in the Holy Cross Mountains

Five sections from the Kielce Region of the Holy Cross Mountains and one core from a borehole drilled in the nearby western Mesozoic Margin reveal the best recognized beds from the Devonian/Carboniferous boundary interval. In four sections: Ruda Strawczyńska, Bolechowice IG 1, Zaręby IG 2 and Kowala, the Devonian/Carboniferous boundary is located within a continuous series of deep-water carbonates, whereas in the two remaining: Ostrówka Quarry and the Jabłonna IG 1 borehole, the Devonian/Carboniferous boundary interval contains stratigraphic gaps resulting from lack of deposition in submarine conditions. The biostratigraphic position of the analyzed uppermost Devonian and lowermost Carboniferous beds is determined by assemblages of conodonts, microspores and deep-water ostracodes of the Thuringian ecotype. The lithology and biostratigraphic position of particular beds in the Devonian/Carboniferous boundary interval of the Kowala section from the western part of the Holy Cross Mountains resemble those in a succession of equivalent age from the Rhenish Massif. Both areas are characterized by similar lithological horizons and changes of biotic assemblages within the same conodont zones. Strata and fauna from the uppermost Famennian are influenced by the global regressive Hangenberg Event.