New Data on Paleontological Characteristics of Middle — Upper Carboniferous Deposits in the Joint Zone of the Pre—uralian Foredeep and West Uralian Folded Zone

Abstract

For the first time, conodonts from the Middle — Upper Carboniferous and Lower Permian deposits were studied in the joint zone of the Pre — Ural’s foredeep and the West Ural megazone. Two sections were studied. The section in the siliceous — carbonate deposits is common in Belsk — Elets tectono — stratigraphic zone (West Ural’s megazone) and the clastic (olistostrome) section located in the southern part of the Karatau sallent (The Pre–Ural’s Foredeep) adjacent with the West Ural’s. Under field research 30 samples were taken in order to identify conodont fauna. Conodonts were found in 16 samples. Studed conodont complexes contain numerous cosmopolitan forms that determine the stratigraphic position of deposits as the Middle Carboniferous in the volume of Tashasty Horizon of the Bashkirian Stage — the Podolian Horizon of the Moscovian Stage. As result, a biostratigraphic sequence in the rank of beds with fauna was outlined: the beds with Declinognathodus marginodosus, Swadelina suberecta, the beds with Idiognathodus postsulcatus, Id. volgensis, the beds with Sw. dissecta and the beds with Id. podolskensis. The presence of the Bashkirian and Moscovian boundary deposits is proposed. The siliceous — carbonate (olistostrome) section contains the Middle, Upper Carboniferous, and Lower Permian olistoliths with conodonts, fusulinids and brachiopods. Conodonts and foraminifers of Early Permian age were identified in the matrix.