Sections in the western slope of the south urals perspective for the choice of the famennian regional boundary stratotype point

Abstract

The Bol’shaya Barma, Akkyr, Ryauzyak and Kuk-Karauk sections in the western slope of the South Urals are considered to be perspective sections for the identification of Famennian Regional Boundary Stratotype Point (RBSP). In the studied sections the Frasnian-Famennian (F/F) boundary is at the bottom of the Barma Horizon. It is established within a lithologically homogeneous brachiopod coquina by simultaneous emergence of the conodonts Palmatolepis triangularis Sann. and brachiopods Parapugnax markovskii (Yud.). The F/F boundary interval is subdivided into the Upper rhenana, linguiformis, Lower and Middle triangularis zones which are thoroughly characterized by means of conodonts and brachiopods