LOCHKOVIAN DEPOSITS OF THE WESTERN SLOPE OF THE SOUTH URALS, THEIR DIVISION AND GLOBAL CORRELATION BASED ON CONODONTS
Relevance of the research. Today, the development of a standard conodont scale for the Lochkovian and Pragian stages of the Lower Devonian is among the global priorities. In accordance with this, the study of regularity of conodonts distribution in Lower Devonian deposits is actively carried out in various regions of the world. The aim of the study is to identify regularity of conodonts distribution in the Lochkovian deposits of the western slope of the South Urals to create a regional conodont zonation. Methods. The Lochkovian stage in the carbonate sections of the western slope of the South Urals has a two-membered division corresponding to Siyak and Sherlubay Horizons. A field paleontological investigation of the sections with the Siyak and Sherlubay deposits was carried out on the base of conodont fauna. Mindigulovo section on the Belaya River was selected as a complete one for the biozonal subdivision. The samples were taken with an interval of 15-20 cm. The weight of the samples was 1-2 kg. Under laboratory conditions, limestones were disintegrated in 5-8 % solution of formic acid. The insoluble residue was viewed under a binocular microscope in order to identify conodonts. The selected conodont fauna was analyzed. Results. Numerous conodonts were found in the Sherlubay Horizon in the Mindigulovo section. They are represented by cosmopolitan species that allowed the creation of a regional biozonal conodont scale for the western slope of the South Urals. Seven conodont zones were identified: L. omoalpha, A. transitans, L. eleanorae, A. trigonicus, A. kutscheri, Mas. pandora beta, Ped. gilberti. The developed conodont scale is equivalent to other scales of the peri-Gondwana regions, making it appropriate for direct global correlation. The data obtained in the research allow us to accept the point of view on three-term division of the Lochkovian stage. According to this, the Sherlubay Horizon is equal to «Middle» and «Uppersubstages» of Lochkovian.