The Požáry section in the Prague Synform – a possible candidate auxiliary section for the basal Emsian GSSP redefinition

Abstract

The global correlation of the basal Emsian boundary is the most problematic issue within the Devonian System and still remains among the most problematic issues in the global Palaeozoic stratigraphy. The Požár 3 section in the Prague Synform, Czech Republic presented herein has many similarities with the published proposal for candidate section for the prospective basal GSSP redefinition – the Mramorka section, from the same area. It has strikingly similar lithology with the typical varied development of the Praha Formation which contains the Bohemian Graptolite Event (BGE), i.e. a prominent lithological marker in the NW part of the Prague Synform. The data from complex multiproxy studies including biostratigraphy, sedimentology, gamma-ray spectrometry, magnetic susceptibility, multi-element geochemistry (INAA, EDXRF), and stable isotopes (δ¹⁸O, δ¹³C) were integrated. These mostly show the same trends as in the Mramorka section and can also be interpreted accordingly. The gracilis Event, an alternative marker approximating the traditional boundary between the Pragian and Emsian stages has been confirmed in the Požár 3 section. The conodont index Latericriodus bilatericrescens gracilis Bultynck, 1985 enters, however, higher than in the Mramorka section, but still below the BGE. This confirms the Mramorka section as the best candidate for the basal Emsian GSSP relocation, whereas the Požár 3 section presented here has a great potential to be prospectively selected as Standard Auxiliary Boundary Stratotype (SABS).