Frasnian/famennian event in the Holy Cross Mts, Central Poland: Stratigraphic and ecologic aspects

Abstract

Current studies in the Holy Cross Mts, Central Poland did not confirm an idea of the persistence of stromatoporoid-coral build-ups into the Famennian, i.e. distinctly after Frasnian/Famennian reef extinction event. Stepwise termination of the Frasnian-type biotas was joined with successive sea-level fluctuations interfering with local tectonic activity, but diversified and locally abundant coral-dominated coelenterate communities, as well as peculiar reef-related associations (e.g. calcareous microbiota), lasted till the end of Frasnian (gigas Zone). Final turning point was the rapid sedimentation change corresponding to the main Kellwasser Event in the Uppermost gigas Zone. Collapse of carbonate depositional system was recorded directly afterwards by significant sedimentary and biotic crises. Local flourishing of the crinoid, articulate brachiopod and nautiloid associations, as well as blue-green algae biota, on the remaining shoals characterised the earliest Famennian time. More successful colonization by diversified, Famennian-type benthic and pelagic faunas started in the crepida Zone, which reflects progressive habitat recovery within the seriously disturbed shelf ecosystem.