Early Cretaceous ammonite associations in the Western Carpathians (the Moravian-Silesian area and Western Slovakia)Article PDF
Early Cretaceous ammonite associations in the Western Carpathians (the Moravian-Silesian area and Western Slovakia)
From the geological point of view, the north-eastern part of the Czech Republic and the greater part of the neighbouring Slovakia are built by the Western Carpathian Mountains system. They mainly consist of two basic geological units – i.e. the Outer Western Carpathians and the Central Western Carpathians. The Silesian Unit of the Godula development in the Outer Carpathians, and the Pieniny Klippen Belt together with the Central Carpathians in Slovakia, which is generally spread from the northwest to the southeast, are the most important units in this system, discussed in the first part of the paper submitted. Occurrence of Valanginian to Aptian stratigraphic indexes comprised in ammonite associations in the units described above, are reviewed. On the other hand, the representatives of long living forms of suborders Phylloceratina and Lytoceratina are of minor stratigraphic value. The follow-up discussion is based on information presented in Table, showing only the stratigraphic positions of zonal ammonite indexes, in all three studied units of the Western Carpathians. The findings are parallelized and compared with the current Early Cretaceous ammonite standard zonation of REBOULET et al. (2018). Warm-water Mediterranean ammonite association predominates in all three units studied. Some genera, originated from the Mediterranean bioprovince, extended from west to east across Danish-Polish depression into Boreal zone. The genus Platylenticeras passed from the Boreal zone towards the Silesian Unit for a short time in the early Valanginian; the genera Dichotomites and Neocomites cf. peregrinus passed towards the Central Carpathians in the late Valanginian. In some periods (Barremian and early Aptian), the ammonite association of the Silesian Unit differs somewhat from the association of the Pieniny Klippen Zone and the Central Carpathians, probably due to the palaeogeographic position of the Silesian Unit with a different facial development. The conclusion is focused on palaeogeographic findings which have influenced the composition of ammonite associations in sedimentary areas located southeast-wards from the former North-European platform. The main aim of this paper is to inform about the occurrence of Lower Cretaceous ammonites of current zonal importance in the Mediterranean faunal province of the Western Carpathian units.
Zdeněk Vašíček, Institute of Geonics of the Czech Academy of Sciences, Studentská 1768/9, CZ-708 00, Ostrava-Poruba; email: firstname.lastname@example.org