Conodont biostratigraphy of shallow marine Givetian deposits from the Radom-Lublin area, SE Poland

Detailed conodont data were obtained from 66 samples in 9 deep wells representative of three palaeogeographic regions of the Mid Devonian epicontinental basin of southeastern Poland: (1) the elevated part of the East European Platform representing the basin margin, (2) the Lublin Graben with a larger proportion of open marine systems, (3) the Radom Area characterized by more off shore, purely marine deposition and larger subsidence rates in the Radom Area. The 1344 specimens collected were as signed to 8 genera: Icriodus, Polygnathus, Ancyrodella, Belodella, Mehlina, Neopanderodus, Pandorinellina and Skeletognathus, and 38 taxa of species or subspecies rank. The vertical distribution of the conodont as semblages studied in particu ar sections is highly irregular and discontinuous with many barren intervals con rolled by less suitable palaeocological conditions, mostly representing restricted and/or very shallow-water facies. We found only a single index species characteristic of deeper marine facies, as applied in the standard conodont zonation. There -fore the biostratigraphic interpretation also takes into account the total range of all taxa found in particular samples, established after acritical analysis of adequately published total ranges of these taxa. The stratigraphicranges of the following taxa were modified: Icriodus arkonensis arkonensis, I. a. walliserianus, I. eslaensis, I. platyobliquimarginatus, I. subterminus, I. aff. I. subterminus, Polygnathus ansatus, P. latifossatus, P. linguiformis linguiformis, P. timorensis and P. varcus. As a result of the stratigraphic analysis of the conodon't assemblages we distin guished five zones in the Givetian of the studied area, i.e. the rhenanus/varcus, ansatus, hermanni, norrisi (=lower part of Lower falsiovalis Zone) zones, and also two in formal units, the subterminus and insita fau nas. We documented the co-occurrence of I. subterminus and P. latifossatus which supports the earlier supposition of Rogers (1998) that the Lower subterminus Fauna may partly corre pond to the Lower hermanni Zone.