The Proposal of the Subdivision of the Pridoli Series (silurian) in Jarovian and Radotinian Stages

Přídolí is the fourth series of the Silurian System It represents an interval of faunal changes, which indicate the middle Palaeozoic transformation of marine ecosystem. For long time faunal changes tracing has been limited due to scarcity of widely and/or globally applicable correlation markers. Consequently, the Přídolí Series is the only Series within the International Chronostratigraphic Chart remained undivided formally into stages. The two-fold subdivision of the Series proposed introduces a lower Jarovian Stage and an upper Radotinian Stage. The base of the Jarovian Stage corresponds to the base of the Přídolí in its defined GSSP in the Požáry section (50.0277°N 14.3249°E), Prague Synform, Czech Republic. The Hvížďalka section in the Prague Synform (49.9962625N, 143335619E) is proposed as the GSSP of the proposed Radotinian Stage. Correlation markers applicable for subdivision of the Series were chosen based on data from sections of the type area of the Series in Central Bohemia. The graptolite index Wolynograptus bouceki has been proposed as the primary marker for the base of the Radotinian Stage. The conodont taxon Oulodus elegans detortus enters close to the base of the bouceki graptolite Biozone and is the secondary marker. Both W. bouceki and Oul e. detortus are index taxa in the global graptolite and conodont zonation schemes. The cephalopod Kopaninoceras fluminese, which is abundant in the Přídolí strata across peri-Gondwana, enters approximately at the same level. Benthic faunas complement graptolite-conodont biozonation on the regional scale, bivalves and the brachiopod Dayia bohemica allow for tentative interregional correlation. The appearance and proliferation of scyphocrinid crinoids resulted in origin of a widely distributed time specific biofacies in the upper stage. A shift from slightly negative to slightly positive δ13Ccarb values coincides with the base of the bouceki Biozone in Bohemian sections.