Abstract

Upper Devonian facies sequences were studied in three different structural and paleogeographical settings within the epicontinental marginal basin of southern Poland. Facies and conodont studies show that the Late Devonian transgressive-regressive cycle was punctuated by several short term episodes. This cycle started with a global transgression (most probably in the Lower asymmetricus Zone) which ultimately terminated the development of extensive Middle Devonian coral-stromatoporoid platforms. Localised Frasnian organic buildups were eliminated in the Lower gigas Zone parallel with a global transgression preceded by a rapid regressive pulse in the same zone. The eustatic character of the latter event is not yet clearly evidenced although some published data support such an interpretation. The Frasnian/Famennian boundary (Lower/Middle triangularis Zone) is marked in several sections by a distinct decrease of carbonate content, which is interpreted in terms of a global crisis in carbonate productivity. The re-establishment of “normal” carbonate sedimentation occurred in the Middle crepida Zone simultaneously with the regressive pulse marking the onset of late Famennian regression. The latter event most probably had only a restricted geographical distribution.