Hi-res correlation and dating of Mid-Palaeozoic sedimentary sequences of Peri-Gondwana using integrated biostratigraphy and chemo-physical methods

The basis of the international Czech–Spanish project is a detailed correlation of selected sedimentary successions of the late Silurian and early Devonian in peri-Gondwana (Prague Synform, Spanish Central Pyrenees and Carnic Alps). The correlation is based on application of several methods in the sections: the detailed biostratigraphic framework is supplemented by multiple chemo-physical measurements (i.e., gamma-ray spectrometry and magnetic susceptibility) in order to avoid discrepancies in correlation of the peri-Gondwanan successions. A substantial part of the project is focused on conodont biostratigraphy which is fundamental for time correlation.
The highest precision has been attained in the Lochkovian where numerous cosmopolitan conodont time-marks occur. These are mostly represented by taxa belonging to the genera Ancyrodelloides and Lanea with minor widespread of other relevant taxa as Flajsella, Masaraella, Pedavis and Kimognathus. In three key areas of European peri-Gondwanan sections (Spanish Central Pyrenees; Prague Synform and Carnic Alps) the Icriodus
and Pelekysgnathus record is also remarkable and can help in increasing the detail of correlations. In 2013 the basic correlation of the major Lochkovian conodont time-marks was finished and a draft of a refined biostratigraphical subdivision for the key areas was made. This preliminary subdivision became a basis for correlation with even more distant regions, e.g., Southern Urals and Northeast Asia. The biozonation established for the Pyrenees and Prague Synform has been successfully tested in the Southern Urals (Mavrinskaya & Slavík 2013). According to the plan, the project leaders organized two field campaigns in 2013. First field work in the Prague Synform was focussed on the examination of classical Lower Devonian sections and conodont sampling. The following field campaign in the Pyrenees concentrated on hi-res biostratigraphic correlation between th Czech and Spanish sections. Two Lower Devonian sections (Segre II near Seu d’Urgell and Compte 1 near Baro and Sort) were sampled for magnetic susceptibility, and gamma-ray spetrometric data were obtained. All the samples for MS were already meassured. Evaluation of the results and further fieldwork is planned for 2014.
MAVRINSKAYA T. & SLAVÍK L. (2013): Correlation of Early Devonian (Lochkovian–early Pragian) conodont faunas of the South Urals (Russia). – Bulletin of Geosciences, 88, 2: 283–296.