On the stratigraphy and tectonics of Zilair synclinorium of the Urals

The purpose of the work was to study the tectonic structure of the Zilair synclinorium of the Western slope of the southern Urals, which is important both from the general scientific point of view and for the needs of oil and gas prospecting of the territory. The main method of research was a detailed study of the stratigraphy of key sites with the search for conodonts in siliceous rocks. We also used data from seismic profiling of the territory. Result of work. The Zilair synclinorium of the southern Urals is an asymmetrically different facies structure; its Western and Eastern wings are composed of deposits belonging to different facies zones – the shelf (neritic) in the West and the continental slope and rise (bathyal) in the East. In the axial zone of the synclinorium, among the Famennian graywacke deposits of the Zilair series, several sites composed of cherts are known. It was believed, that the cherts are of Silurian age and are the klippes of a very large overthrust belonging to the ophiolite association. According to occurences of conodonts, we have established that all these cherts have Devonian, mainly Frasnian age. They are not klippes of an overthrust, but the central parts of the anticlinal folds, complicated by steep thrusts. According to our data, the real overthrust with a great horizontal amplitude is Pokrovsky, where two facial zones come into an abrupt contact without any transition between them.